evaluation of parameters infuencing · pdf filea-values and influencing factors for mbrs....

UNIVERSITY OF HAWAI'I LIBRARY

EVALUATION OF PARAMETERS INFUENCING OXYGEN TRANSFER EFFICIENCY IN A MEMBRANE BIOREACTOR

A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HA WAI'I IN PARTIAL FULFILLMENT OF THE

REQUIREMENTS FOR THE DEGREE OF.

MASTER OF SCIENCE

IN

CIVIL & ENVIRONMENTAL ENGINEERING

DECEMBER 2006

By JingHu

Thesis Committee:

Roger W. Babcock, Chairperson Albert S. Kim

Chittaranjan Ray

We certify that we have read this thesis and that, in our opinion, it is satisfactory in scope

and quality as a thesis for the degree of Masters of Science in Civil & Environmental

Engineering.

THESIS COMMIITEE

ii

ABSTRACT

Design of fine-bubble aeration systems for membrane bioreactors (MBRs) is

challenging due to high mixed liquor suspended solids (MLSS) concentrations that cause

changes in alpha value, which is the ratio of mass transfer rate under process conditions

to that under clean water conditions.

This study describes the results of pilot-scale fine-pore aeration testing to determine

a-values and influencing factors for MBRs. Clean water and process water aeration tests

were performed at the Honouliuli WWTP during the period of December 2005 and

October 2006. Three different 9-inch diameter fine-pore diffusers were tested.

Comprehensive analyses of the sludge properties were conducted.

Through this study, correlations were found to exist between a-value and oxygen

uptake rate (OUR), particle size distribution (PSD), MLSS and viscosity of activated

sludge, thereby providing better understanding and design guidance for MBR aeration

systems.

iii

TABLE OF CONTENTS

ABSTRACT .................................................................................................................... iii

LIST OF TABLES .......................................................................................................... vi

LIST OF FIGURES ...................................................................................................... viii

LIST OF ABBREVIATIONS & SYMBOLS .................................................................. x

CHAPTER I: INTRODUCTION .................................................................................... I

1.1. Background ......................................................................................................... 1

1.2. Characteristics of Activated Sludge in MBRs .................................................... 3

CHAPTER 2: LITERA TORE REVIEW ......................................................................... 6

2.1. Methods for OTE/OTR measurement ................................................................. 6

2.2. Correlation ofOTE or a-value with Influencing Factors in Aeration ................. 9

CHAPTER 3: SCOPE AND OBJECTIVES OF WORK .............................................. 17

CHAPTER 4: FUNDAMENTALS OF OXYGEN TRANSFER TESTS ..................... 18

4.1. Fundamentals of the non-steady state method .................................................. 18

4.2. Fundamentals of the off-gas method ................................................................. 21

4.2.1. Theory of analysis ..................................................................................... 21

4.2.2. Correction to standard conditions ............................................................ 24

CHAPTER 5: MATERIALS AND METHODS ........................................................... 25

5.1. Pilot aeration column ........................................................................................ 25

5.2. Diffusers ............................................................................................................ 25

5.3. Apparatus .......................................................................................................... 25

5.4. MBR pilot description ....................................................................................... 27

5.5. Methods ............................................................................................................. 30

iv

5.6. Chemicals .......................................................................................................... 33

CHAPTER 6: DISCRIPTION OF FIELD STUDIES .................................................... 35

6.1. Clean water aeration column testing ................................................................. 35

6.2. Process water aeration column testing .............................................................. 37

CHAPTER 7: RESULTS AND DISCUSSION ............................................................. 42

7.1. Clean water aeration test ................................................................................... 42

7.2. Process water aeration test ................................................................................ 43

7.2.1. Evaluation of Diffuser Type on a-value .................................................... 43

7.2.2. Evaluation of Air Flow on a-value ............................................................ 44

7.2.3. Evaluation of MLSS and ML VSS concentration on a-value ..................... 45

7.2.4. Evaluation of Viscosity on a-value ............................................................ 48

7.2.5. Evaluation of OUR on a-value .................................................................. 50

7.2.6. Evaluation ofPSD on a-value ................................................................... 53

7.2.7. Evaluation ofSMP, EPS, TDS and SCOD on a-value .............................. 56

7.2.8. Evaluation ofMLSS. MLVSS, Viscosity, OUR and PSD on OTE ............. 58

CHAPTER 8: CONCLUSIONS, LIMITATIONS AND RECOMMENDATIONS .... 60

8.1. Conclusions from the study ............................................................................... 60

8.2. Limitations of the study .................................................................................... 61

8.3. Recommendations for future research .............................................................. 62

APPENDIX I: RAW DATA TABLES .......................................................................... 63

APPENDIX II: DATA SUMMARIES .......................................................................... 74

APPENDIX III: PHOTOGRAPHS ................................................................................ 90

REFERENCES ............................................................................................................... 96

v

LIST OF TABLES

T~le P~e

I. Comparisons of the Methods for OTE Measurement ...................................... 7

2. Factors Affecting Oxygen Transfer in Aeration Systems .............................. 10

3. Review of the Effect ofMLSS on Oxygen Transfer for MBRs .................... 13

4. Enviroquip 5MBR Pilot System Summary .................................................... 27

5. Chemicals Used in the Experiments .............................................................. 34

6. Comparison of a-value of 3 Diffusers ............................................................ 43

7. Clean Water Test (I) Raw Data ..................................................................... 63

8. In Situ OUR Test (1) Raw Data ..................................................................... 66


10. In Situ OUR Test (3) Raw Data .................................................................... 68

II. In Situ OUR Test (4) Raw Data ..................................................................... 69


13. In Situ OUR Test (6) Raw Data .................................................................... 71



16. Clean Water Test Results Summary ............................................................. 74

17. Off-gas Analysis (1) Data Summary ............................................................. 75




vi





25. Sludge Properties at Various MLSS Concentrations .................................... 89

vii

LIST OF FIGURES

Figure ~

1. Effect of SCOD Values on OTEzo ..................................................................... 10

2. Alpha-value as a function ofML VSS .............................................................. 11

3. Alpha-MLSS relationships for fine-bubble systems ........................................ 14

4. Specific oxygen transfer efficiency as a function ofMLSS ............................ IS

5. Alpha-Viscosity relationships for fine-bubble systems ................................... 16

6. Schematic of the Analyzer Structure ................................................................ 26

7. Anatomy of the Membrane Cartridge .............................................................. 28

8. Cutaway Illustration of Membrane Unit .......................................................... 28

9. Process Flow Diagram of the Enviroquip MBR .............................................. 29

10. Aeration Column Setup for Clean Water Testing ............................................ 36

11. Aeration Column Setup for Process Water Testing ......................................... 38

12. Average mass transfer coefficient for three fine pore diffusers ....................... 42

13. Average SOTE for three fine pore diffusers .................................................... 43

14. Alpha-value of the membrane diffuser at varied AFR ..................................... 45

15. Alpha-value of the ceramic diffuser at varied AFR ......................................... 44

16. Comparison of the a-value under different process conditions via MLSS ........................................................................... 46

17. Comparison of the a-value under different process conditions via MLVSS ........................................................................ 46

18. Correlation ofMLSS and a-value .................................................................... 47

19. Correlation of ML VSS and a-value ................................................................. 48

20. Correlation ofMLSS and viscosity .................................................................. 48

viii

21. Comparison of the a-value under different dit· .. .ty 49 process con IOns Via VlSCOSI ...................................................................... .

22. Correlation of viscosity and a-value ................................................................ 49

23. Correlation of OUR and MLSS ....................................................................... 50

24. Comparison of the a-value under different process conditions via OUR .............................................................. 51

25. Correlation of OUR and a-value ...................................................................... 51

26. Particle size distributions at various MLSS conc .............................................. 53

27. Correlation of particle size and MLSS ............................................................. 54

28. Comparison of the a-value under different process conditions via particle size ................................................... 55

29. Correlation of particle size and a-value ........................................................... 55

30. Relationship between SCOD and MLSS ......................................................... 56

31. Relationship between TDS and MLSS ............................................................ 57

32. Relationship between total SMP and MLSS .................................................... 57

33. Relationship between total EPS and MLSS ..................................................... 57

34. Correlation ofMLSS or MLVSS and VOTE ................................................... 58

35. Correlation of viscosity and VOTE ................................................................. 58

36. Correlation of OUR and VOTE ....................................................................... 59

37. Correlation of particle size and VOTE ............................................................. 59

ix

LIST OF ABBREVIATIONS & SYMBOLS

The following abbreviations and symbols are used in this paper:

ABS Acrylonitrile-Butadiene-Styrene

AECOR Aemtion Engineering Resources Corp.

AFR Air flow mte

ASCE American Society of Civil Engineers

ASP Activated sludge process

BOD Biological oxygen demand, mgIL

CASP Conventional activated sludge process

CST Capillary suction time

CER Cation exchange resin

DO Dissolved oxygen, mgIL

EMBR External membrane bioreactor

EPDM Ethylene Propylene Diene Monomer

EPS Extracellular polymeric substances, mgIL

HOPE High density polyethylene

HRT Hydmulic retention time, hr

MBR Membrane bioreactor

MCRT Mean cell residence time, hr

MOD Million gallons per day

MLSS Mixed liquor suspended solids, mgIL

"

MLVSS

OTE

OTR

OUR

PSD

PTFE

SCFM

SCOD

SMP

5MBR

SOTE

TDS

TSS

VOTE

VSS

a

C

Co

C' w

Mixed liquor volatile suspended solids, mgIL

Oxygen transfer efficiency in percent

Oxygen transfer rate, mg/L

Oxygen uptake rate, mg I L . hr

Particle size distribution

Polytetrafluoroethylene

Standard cubic foot per minute

Soluble chemical oxygen demand, mgIL

Soluble microbial products, mgIL

Submerged membrane bioreactor

Standard oxygen transfer efficiency in percent

Total dissolved solids, mg/L

Total suspended solids, mg/L

Volumetric oxygen transfer efficiency in percent

Volatile suspended solids, mg/L

Diffuser specific area, m 2 •

DO concentration, mg/L

DO concentration at time zero, mg/L

Equilibrium DO concentration at tested conditions, mg/L

Equilibrium DO concentration at 20'C, 1 atm and zero salinity. mg/L

Equilibrium DO concentration at the test temperature T, 1 atm and zero salinity. mg/L

xi

C· ST

D

MRog/i

ND

t

T

P,

v

Vo

Wo.

Tabular value of DO saturation concentration at 20°C, I atm and 100% relative humidity, mg/L

Tabular value of DO saturation concentration at the test temperature T, 1 atm and 100% relative humidity, mg/L

Particle diameter, J.Ull

Mass rate ofinerts, kg/s

Volumetric mass transfer coefficient, S-I

Volumetric mass transfer coefficient at 20·C, S-I

Molecular weights of oxygen

Molecular weights of inerts

Mole ratio of oxygen to inerts in the inlet stream

Mole ratio of oxygen to inerts in the off-gas stream

Total diffuser number

Time, s

Temperature, ·C

Barometric pressure during the test, psi

Standard atmospheric pressure 14.7 psi at 100% relative humidity

Total volumetric gas flow rates of inlet gas, m3 /s

Total volumetric gas flow rates of outlet gas, m3 /s

Liquid volume of water in the test tank, m3

Gas hold-up volume, m3

Mass flow of oxygen in air stream, kg/ s

Mole fractions of oxygen in the inlet gas

xii

Yco,(R)

z

a

aSOTE

TJr,40

p

T

n

Mole fractions of oxygen in the exit gas

Mole fractions of CO2 in the reference gas(R)

Mole fractions of CO2 in the off-gas (og)

Mole fractions of water vapor in the reference gas (R)

Mole fractions of water vapor in the off-gas (og)

Diffuser submergence, m

The ratio of the value of KLa measured in process water to the KLa measured in clean water

Oxygen transfer efficiency corrected for all process conditions such as DO, salinity, temperature and barometric pressure, except for a factor

Correction factor for salinity

Shear strain rate imposed on the sample, S-I

Shear stress, mPa

Yield stress, mPa

Absolute viscosity, mPa· s or cP

Absolute viscosity at a shear rate of 40 S·I, mPa· s

Empirical temperature correction factor

Absolute viscosity, mPa· s or cP

Density of oxygen at temperature and pressure of gas flow, kg/ m3

Temperature correction factor

Barometric pressure correction factor

xiii

1.1 Background

CHAPTERl INTRODUCTION

Statewide in Hawaii, approximately 16% (23 MOD) of municipal wastewater is

currently recycled. With the potential for compact, decentralized water reclamation

installations combined with very high quality permeate water, membrane bioreactors

(MBRs) promise to be an effective method for enhancing water recycling if they can be

shown to be reliable and cost effective (Babcock et al., 2003).

MBR systems can sustain higher biomass concentrations by replacing the secondary

clarifier with membrane filtration and allowing smaller aeration basins to be used. In an

MBR, the membranes create a physical barrier of solids and therefore the process is not

subject to gravity settling solids limitations. However, they are limited instead by fluid

dynamics of high solids mixed liquor, and by the effect of high solids on oxygen transfer.

Oxygen transfer is a major factor influencing the efficient and economic operation of

all aerobic bioprocesses, including MBRs. The overall volumetric mass transfer

coefficient, K La, is a parameter to characterize the rate of oxygen transfer in aeration

processes; where K L represents the mass transfer coefficient based on the liquid film

resistance and a, the interfacial area.

The value of alpha (11) is another parameter commonly used to describe the oxygen

transfer in biological aerated systems, which is the ratio of mass transfer rate under

process conditions (mixed liquor) to that under clean water conditions. This correction

factor quantifies the influence of mixed-liquor constituents on aeration capacity. It is an

important operating and design variable for aeration systems in activated sludge process

(ASP).

MBR systems utilize aeration in two forms. First, they utilize coarse-bubble (cross

flow) aeration for membrane scour to control permeability and fouling. Second, they use

fine-pore aeration for mass transfer of oxygen to meet biological requirements as well as

for mixing in the aeration tank. According to the report prepared for the Water

Environment Research Foundation (WERF, 2004), energy costs associated with aeration

in submerged MBR (SMBR) systems represent more than 90 percent of the total energy

cost. Therefore, potential oxygen limitations appear to be a serious cost issue for 5MBR

systems, and acquiring accurate oxygen transfer information on these systems is of great

necessity. Substantial savings in overall energy costs of WWTPs with MBRs can be

realized by using this information to improve the energy efficiency of the aeration

system. In addition, if designers understand the oxygen transfer in mixed liquor of an

aeration tank and factors that affect it, they can provide more optimized designs to treat

the wastewater to the required effluent quality.

The aeration, the oxygen transfer and the biomass characteristics interrelate with and

impact on each other. When studying aeration operations in MBRs, we need to consider

both the effects of biomass characteristics on aeration efficiency, represented by the

oxygen transfer parameters (Le., KLa and a-value), and the effects of aeration (intensity

and type of diffusers) on biomass characteristics (Germain and Stephenson, 2005).

Fine-pore aeration system design requires the determination of an appropriate a

value. However, this design in MBRs is challenging at high MLSS due to changes in a

values. Currently there is a lack of good data on a-values at the high MLSS found in

2

MBRs. If the wrong value of alpha is used, the aeration system can be either over

designed or under-designed. Previous studies have obtained correlations of a-values at

high solids with MLSS and with viscosity. However, the existing data have considerable

variability in the solids range of interest in current MBR designs (Babcock, 2006).

This context highlights the need for further research on accurate detennination of

oxygen transfer efficiencies and a-values in MBR process, as well as exploration of

relationships between a-values and more parameters describing mixed liquor properties

besides MLSS and viscosity. Better correlations may be obtained with these parameters.

1.2 Characteristics of Activated Sludge in MBRs

Activated sludge is a complex and variable heterogeneous suspension containing both

feed water components and metabolites produced during the biological reactions as well

as the biomass itself (Chang et al., 2002). It is a mixture of particles, microorganisms,

colloids, organic polymers and cations, which all have different shapes, sizes and

densities.

MBRs and conventional activated sludge process (CASP) have many similarities,

particularly in tenns of microbial metabolism and kinetics. However, substituting

membrane separation for gravity sedimentation allows much higher MLSS

concentrations (8,000 to 20,000 mgIL) in MBRs with resulting high metabolic rates.

Mainly due to the high MLSS, the sludge characteristic differs from conventional

activated sludge.

The activated sludge suspension is a non-Newtonian liquid with pseudoplastic

properties (Dick and Ewing, 1967). For Newtonian fluids, shear stress is proportional to

shear rate, with the proportionality constant being the viscosity, while the viscosity of

3

non-Newtonian fluids changes as the shear rate is varied. A pseudoplastic liquid is a non

Newtonian fluid whose viscosity decreases as the applied shear rate increases. This type

of behavior is also called shear-thinning.

High biomass concentrations give rise to non-Newtonian behavior with high apparent

viscosities. This can largely be attributed to the fact that cross-linked filamentous

organisms and flocs are present in the sludge. These high apparent viscosities affect the

energy required for pumping and oxygen supply of the microorganisms. They may

impede oxygen transfer and the degree of mixing by influencing bubble coalescence

(Germain and Stephenson, 2005; WERF, 2004).

High biomass also forms a high production of soluble microbial products (SMP) and

extracellular polymeric substances (EPS) in the bioreactor, which are both important

components in describing biomass kinetics. EPS are a complex mixture of proteins,

carbohydrates, acid polysaccharides, DNA, lipids, and humic substances that surround

cells and form the matrix of microbial flocs and films (Liao et al., 2004). They are an

essential part of activated sludge. The importance of EPS in controlling membrane

fouling has been studied extensively while there is little information on the role of EPS in

affecting oxygen transfer. SMP are the pool of organic compounds that are released into

solution from substrate metabolism (usually with biomass growth) and biomass decay

(Barker and Stuckey, 1999). Like EPS, SMP are primarily composed of proteins, humic

compounds and polysaccharides. In order to be able to reach the active sites of the

bacterial cell membrane, the oxygen contained in the air bubbles needs to penetrate the

liquid film surrounding the floes (SMP) and then diffuse through the floc matrix (EPS)

4

(Gennain and Stephenson, 2005). Therefore both compounds are likely to affect the

oxygen transfer.

Particle size is another parameter characterizing the biomass. Compared to

conventional activated sludge, the average diameter of a particle in a MBR is

considerably smaller, because bacteria are not selected for their ability to aggregate to

large, settleable floes. Moreover, the high shear forces introduced, particularly by

pumping during cross-flow filtration, can break up floes. In conventional activated

sludge, floes may reach several 100 J.lm in size (Wisniewski et aI., 1999). Hydrodynamic

stress in MBRs reduces floc size to approximately 30--60 J.lm in immersed systems

(Zhang et aI., 1997; Song et aI. 2003) and 3.5 J.lm in sidestream MBRs (Cicek et aI.,

1999).

Oxygen uptake rate (OUR) is a measure of the rate of oxygen utilization of

microorganisms in a body of liquid. It is a good indicator of metabolic activity of the

biological system and has been traditionally used in aerobic processes to estimate on-line

the biomass activity (Oca et aI., 2004). In MBRs, higher MLSS concentrations and

accordingly higher possible sludge age affects the bacterial numbers and the composition

of the microbial community, and thus changes OUR (Drews et aI., 2005; Li et aI. 2006).

OUR is a potential oxygen transfer parameter and could be used to control the aeration

rate or the sludge recycling rate in wastewater treatment.

Other biomass characteristics in MBRs may also have an impact on oxygen transfer

and accordingly a-values, such as the soluble COD fraction (SCOD) and the total

dissolved salt content (TDS). It's necessary to comprehensively investigate the influences

of these parameters on the diffusion of oxygen in MBR process.

5

CHAPTER 2 LITERATURE REVIEW

2.1 Methods/or OTE or OTR measurement

A variety of techniques exist for estimating oxygen transfer efficiency (OTE) or

oxygen transfer rate (OTR) of an aeration system, which can be generally divided into

four categories (Stenstrom, 1997; Stenstrom, 2005):

• Adsorption or re-aeration method

It adopts the same procedures as in clean water testing and converts the results to

field rates with conversion factors. This method determines KLa and the

equilibrium dissolved oxygen concentration C: for process water by first

removing DO from then re-oxygenating the water to near the saturation level.

• In-situ oxygen uptake rate (OUR) method

It's process water testing using methods to account for the biological consumption

of oxygen during the transfer test. It determines KLa for a mixed aeration tank

under process conditions by measuring the in-situ OUR under steady-state

conditions. The in-situ OUR is measured by monitoring the DO concentration

after stopping aeration.

• Material balance methods

They attempt to determine difference in inputs and outputs of oxygen consuming

material.

• Off-gas method

This method estimates the oxygen transfer capability by a gas phase mass balance

over the aerated volume. It requires the capture of a representative sample of the

6

gas, which exits the aeration basin surface, and analysis of this gas for its

composition.

The advantages and disadvantages of the above four methods presented in literature

studies (Capela et ai., 2004; Cornel P. et aI., 2003; and Krause S. et aI., 2003) are

summarized in Table 1.

Table 1. Comparisons of the Methods for OTE Measurement

Method Advantage Main Drawback

It is very difficult to accurately estimate the a-factor. Constant process conditions should be

Adsorption - maintained during the test duration. A minimum, incremental DO cone. of 2 mgIL should occur for implementing this method. It is difficult to accurately estimate oxygen consumption rate, especially in oxygen limiting conditions occurring in overloaded

OUR It's simple to perfonn. treatment plants. It requires that the aeration and mixing functions be dissociated to maintain the mixed liquor in suspension when aeration is stopped. It requires long-tenn knowledge of process operating conditions such as sludge wasting

Material rate. Balance - It's susceptible to error from sludge settling

in the aeration basin or stripping of volatile oxygen consuming compounds.

It is perfonned at real in-process It requires an accurate measurement of the conditions without requiring airflow rate and an estimate of the DO process modification or chemical saturation cone. in process water. addition to complete the test.

Off-gas The DO concentration or OUR does not interfere with the test procedure. It offers the advantage of differentiation in location and time.

7

Adopting the improved off-gas technique - mole fraction approach, the mass

transfer efficiency can be determined without measuring flow rates of gas entering and

exiting the fluid. This improvement overcomes the main drawback of traditional off-gas

method. By knowing the molar percents of the reacting or changing gas constituents

(oxygen, carbon dioxide, and water vapor), OTE can be calculated based on the gas phase

mass balance. In the meanwhile, there is no need to estimate the DO saturation

concentration in process water. Only equilibrium DO concentrations in clean water at

20°C and test temperature( C:20 and C:T ) need to be determined. Conclusively, the off

gas method is preferable to the other three methods for determining OTE in mixed liquor,

since it can be applied on a continuous mode at any particular location in the aeration

tank and under a wide range of process conditions.

Capela et aI. (2004) systematically compared the four measurement techniques under

process conditions in conventional WWTPs: the off-gas, hydrogen peroxide (HzOz), re

aeration, and in situ OUR methods. The HzOz method is based on the same principle as

the re-aeration method. It determines OTE by monitoring the DO concentration over the

time after adding HzOz. With the comparisons of pilot-scale and full-scale results of

oxygen-transfer coefficients obtained by different methods, the off-gas technique was

recommended for the analysis of diffused systems when applicable.

Krause et aI. (2003) conducted a comparison of the adsorption method with the off

gas method in full scale MBRs. Nevertheless with both methods comparable OTRs were

obtained, the varying results achieved by application of off-gas analysis revealed the big

advantage ofthls method, being able to record exactly the time-variation of the OTR. It's

8

also pointed out that the off-gas method only can be applied at DO concentration below

50% of the saturation concentration and at low air flow rates.

Currently off-gas method is widely accepted and has been the preferred method for

measuring OTE in operating aeration basins, because of its combination of reliability and

convenience. (Groves et al. 1992; lranpour et aI., 2000; Jranpour et aI., 2002; Mueller et

aI., 2000; and Stenstrom, 1989). The modern off-gas test was developed by Redmon et aI.

(1983) in conjunction with the U.S. EPA-sponsored ASCE Oxygen Transfer Standard

Committee. The technique measures actual OTE at process conditions assuming that inert

gases (nitrogen, argon) are conserved and can be used as a tracer. The fundamentals of

this method are described in detail in Chapter 4.

Brochrup (1983) and Babcock et aI. (1999) evaluated the precision and accuracy of

off-gas analysis. Brochrup estimated a coefficient of variation of 6% or less. Babcock et

aI. estimated an error of less than 10% for fine pore aeration systems and pointed out

these errors can be easily avoided by diligent maintenance of test equipment and by

maintaining good quality control practices. Therefore, if conducted carefully, with

maintained equipment, off -gas testing is a very accurate method for determining OTE

under process conditions.

2.2 Co"elation of OTE or a-value with Influencing Factors in Aeration

Due to complex mechanisms underlying oxygen transfer in aeration systems, OTE

and a-value could be affected by three groups of factors including equipment factors,

operation factors and wastewater conditions as listed in Table 2. The information was

obtained from U.s. EPA (1989) EPA/ASCE Design Manual on Fine Pore Aeration.

9

Table 2. Factors Affecting Oxygen Transfer in Aeration Systems

Equipment Factors Diffuser type Diffuser density Diffuser submergence Diffuser layout Diffuser age Flow regime Basin geometry

Operation Factors Solids retention time/nitrification Food to microorganisms ratio Airflow rate per diffuser Mixed liquor DO Diffuser fouling

Wastewater Conditions Wastewater characteristics Mixed liquor temperature

Some correlations linking oxygen transfer and aerobic biological system

characteristics are found in CASP in the literature, depending on the parameters

considered.

Mueller et aI. (2000) found that solution-phase COD (SCOD) concentration is a

principal factor influencing OTE and alpha for the plug-flow systems. In this study, OTE

was measured with the membrane diffusers utilizing the off-gas technique. The difference

in a-values was correlated with the impact of SCOD on the individual station OTE2o

values (tank weighted avemge process OTE at zero DO and 20°C) as shown in Fig. 1. An

increase in SCOD leads to a decrease in OTE2o.

30 ,--------------------------------------------,

o

'" W I-o 10

OTE,. = -0.405 SCOD + 5 1.1

a L-~ __ ~ __ ~ __ ~ __ ~ __ ~ __ ~ __ ~ __ ~~ __ ~ __ -"

a 20 40 60 80 100 120

seOD (mgll)

Fig. 1. Effect ofSCOD Values on OTE2o

10

Stenstrom (1989) observed a good correlation between ML VSS concentration and a-

value in the full-scale study of 6 conventional WWTPs. Process oxygen transfer rates

were determined using off-gas analysis and different fine pore diffusers were evaluated.

A trend for a-value to increase with ML VSS at the aeration basin inlet is shown in Fig. 2

while the correlating equation wasn't given.

o~,-----------------------------------,

.. .., 1.5 0.20

:I .~

l: 15

0.15

0 :z:= • II 10 .... 0.10 .. 0 0 oD If: ..

D 0.0$ CI~ .....

0.00 400 SOD 800 1000 1200

MLVSS (mgIL)

Fig. 2. Alpha-value as a function ofMLVSS concentration

Rosso et a1. (2005) summarized 15 years ofOTE measurements of fine-pore diffusers

using the off-gas technique. The dataset was based on 30 nationwide conventional

activated sludge plants treating municipal wastewater with mean cell retention time

(MCRT) ranging from 1.6 to 36 days. The normalized airflow rates QN and MCRT were

correlated with a and aSOTE as follows:

aSOTE = 5.717 ·logX - 6.815

a = 0.172 ·logX -0.131

II

where:

MCRT 'X,=--

QN

Q _ AFR

N-a·ND ·z

AFR = air flow rate, m3 Is

a = diffuser specific area, m2

N D = total diffuser number

Z = diffuser submergence, m

In MBR process, biomass and membranes interact in a number of ways and mass

transfer interactions are different, making it difficult to extrapolate phenomena and

correlations known from CASP. However, the affecting factors mentioned above can still

be taken into account when research is carried out to explore the correlations between

oxygen transfer and potential influencing parameters in MBRs.

Recently some investigations have been performed to identify the effect of MLSS

concentration on oxygen transfer rates, particularly on a-values in MBRs (Cornel et a1.,

2003; GOnder and Krauth, 1999; GOnder, 2001; Krampe and Krauth, 2003; Muller et a1.,

1995; and Wagner et a1., 2002). As reviewed in Table 3, different magnitudes of a-values

at high MLSS were reported in the literature.

These studies observed an exponential relationship between a-value and MLSS

concentration. The results are summarized in Fig. 3. Despite the differences between the

systems and the sludge type, high solids concentrations affected the oxygen transfer in

the same way. Muller et a1. (1995), found a-values of 0.98, 0.5, 0.3, and 0.2 for MLSS

concentrations of3, 16,26 and 39 g.L·' respectively, but didn't correlate a to MLSS. An

exponential equation representing the impact of the solids concentrations on the a-value

was calculated from this data.

12

Table 3. Review of the Effect of MLSS Concentration on Oxygen Transfer for MBR Systems

Reactor Config. Membrane MLSS Aeration OTE Determination Measured Ana[yzed Sludge Reference and Scale Modu[es Range (gIL) System(s) Method a-value Properties

Ranl!e EMBRa UFandMF 3-39 A diffused air Not specified 0.98-0.2 MLSS& Muller et aI., (pilot scale) system Particle size [995

5MBR6 Plate, Hollow (pilot scale) fiber 8-25 Fine-bubb[e. Not specified 0.5-0.15 MLSS GOnder and

Coarse-bubble. Krauth, 1999 EMBR Tubu[ar Surface (pilot sca[e)

Single-tank 5MBR (full scale). Not specified 7-17 Fine-bubb[e Clean water (adsorption). 0.7-0.4 MLSS& Wagner et aI .• Dual-tank 5MBR mixed liquor (adsorption) Viscosity 2002 (full scale)

Single-tank 5MBR (full scale). Not specified 7-17 Fine-bubble Clean water (adsorption), 0.7-0.4 MLSS. Cornel et aI., Dual-tank 5MBR mixed liquor (off-gas. Viscosity, 2003 (full scale) adsorption) Air f10wrate &

Surfactant conc.

Pilot scale. Several activated Not specified 8-28 Fine-bubble, Clean water (adsorption). 0.5-0.1 MLSS, ML VSS, Krampe and sludge types lajector mixed liquor (adsorption) Viscosity. EPS. Krauth, 2003

CST". Polymer contents &

Surface tension

a EMBR = external MBR b 5MBR = submerged MBR • CST = capillary suction time

13

1.0 ~--------------------,

Gl = e,o.017l ·MISS (Gunder, 2001) 0.8+-~~~

Gl = e,O.0446 ·MLSS (Muller et al,1995) ., ::J Oi 0.6

(Wagner et aI, 2002; Cornel et ai, 2003) a = e,O.046 ·MLSS %

.<:

~0.4 Gl = e ,0.082 . MLSS

.lGunder an~ Krauth,I9921n _ ~~~:::::~~~~~] a = e,O.08788 ·MLSS

0.2

(Krampe and Krauth,2003) 0.0 +---~-~~c.:...:.~-----~::":"~~--~------l

o 5 10 15 20

MLSS concentration (gil)

25 30

Fig. 3. Alpha-MLSS concentration relationships for fine-bubble systems in MBRs

All of the evidence exists that MBRs, which operate at high MLSS concentrations,

have suppressed a-values, and that a-value is inversely proportional to MLSS. However,

the decrease rate of a with MLSS varies among studies.

Wagner et aI. (2002) and Cornel et aI. (2003) determined a-values for the fine-bubble

aeration systems in full-scale municipal MBRs. They indicate that a-value decreases

from 0.6 to 0.4 in the MLSS concentration range of 10 to 20 gIL. Daily a-value variations

in the range of ± 0.1 were detected, which were attributed to varying surfactant loading.

Additionally, the coarse bubble "cross-flow" aeration system was found indicating no

dependence of a-value and MLSS.

Cornel et aI. (2003) also obtained the relationship between MLSS and specific

oxygen transfer efficiency. Fig. 4 shows the specific oxygen transfer efficiency as a

function of MLSS, which means the oxygen transfer efficiency per unit depth of aeration

tank.

14

10

co 6 ui b o 4 !5 Q) Co en 2

------------ ----------------------~

TJ = 9.00-S.63x 10-4 MLSS+2.56xI0-s MLSS2

O+---,----,--~---,----r_--._--~--_r--~

o 2000 4000 6000 8000 10000 12000 14000 16000 18000

MLSS (mg/L)

Fig. 4. Specific oxygen transfer efficiency as a function of MLSS

Furthennore, some researchers evaluated the effect of mixed-liquor viscosity on ex-

value. GUnder (2001) and Krampe and Krauth (2003) formulated equations linking the a-

value to the viscosity at a shear rate of 40 S·1 in activated sludge with high MLSS

concentrations (Fig. 5). An increase in viscosity has been shown to have a negative

influence on the oxygen transfer. The same trend was also observed by Wagner et aI.

(2002) while the correlating equation wasn't given.

In these studies, a-value was correlated better with viscosity than with MLSS

concentration, which suggests that the effect of MLSS on a might be better explained in

terms of the influence of MLSS on viscosity. Explanations concerning this phenomenon

have been given in the literature (WERF, 2004). High viscosity may lower a by

increasing the rate of bubble coalescence, and thus reducing the interfacial area of oxygen

transfer. Additionally, the ability of bubbles to induce turbulence and mixing decreases

with viscosity.

15

1.2 -- - ------------------

1.0

~ 0.8

a = I1r.40 ·0456 (Krampe and Krauth, 2003)

:./ --- ------

~ IV 0.6 .£: Q.

;( 0.4 a= I1r.40 -OAS (Gunder, 2001)

I 0.2 ---- ---j 0.0

0 20 40 60 80 100 120

ll,40 [mPa . sl

Fig. 5. Alpha-Viscosity relationships for fine-bubble systems

So far some limited work has been done to observe the impact of other biomass

properties besides MLSS and viscosity on aeration efficiency in MBR process. Krampe

and Krause (2003) analyzed the sludge in regard to MLSS, viscosity, polymer contents,

EPS components and capillary suction time (CSn. However, only the solid contents and

the viscosity were found to be possible parameters to describe the relations. In this study,

all sludge types were gradually diluted in order to get a series of solids contents. This is

very different than growing or accumulating sludge in the aeration tank and obtaining the

desired solids contents in sequence gradually. The dilution method wouldn't be expected

to accurately capture sludge characteristics under different growth conditions.

In conclusion, although several practical experiences and data are available for MBR

aeration processes, no systematic and comprehensive investigation has been conducted so

far on other sludge properties such as OUR, PSD, TOS, SCOD, SMP and EPS in addition

to MLSS and viscosity. The influence of other sludge properties on oxygen transfer still

remains unclear. Therefore additional or further studies are needed to determine how

other variables affect the a-MLSS concentration relationship in MBRs.

16

CHAPTER 3 SCOPE AND OBJECTIVES OF WORK

The pilot-scale aeration study was conducted under existing operating conditions at

Honouliuli WWTP located at Ewa beach, Honolulu, Hawaii, where an investigation of

parallel pilot MBR systems is underway. A 20 ft tall pilot column had been constructed

for aeration testing and was filled with clean or process water. Clean water tests were

performed with 3 different 9-inch diameter fine-pore diffusers, ceramic, membrane, and

high density polyethylene (HDPE) types, to determine standard oxygen transfer

efficiency (SOTE) under specific airflow rates. This was followed by off-gas testing with

process water at varied MLSS concentrations (5, 7.5, 10, 12.5, IS, 17.5, and 20 gIL) to

determine OTE. The process water consisted of mixed liquor from a MBR pilot. An off-

gas analyzer was constructed to measure OTE under steady-state conditions. In addition,

the comprehensive analyses of the activated sludge were carried out to investigate the

relationship between the sludge properties and a-value.

The main goal of the study was to determine a-value and provide better

understanding for more efficient fine-bubble aeration system design of full-scale MBRs.

The specific objectives included:

1. To acquire good data on OTE and a-values at the high MLSS concentrations in a

MBRsystem.

2. To systematically examine the effects of aeration intensity, diffuser type, and

various sludge characteristics, such as TSS, VSS, viscosity, SMP, EPS, PDS,

OUR, SCOD and TDS, on oxygen transfer; identify potential factors affecting

OTE and a-value.

3. To obtain better correlations of these identified factors with a-value in MBRs.

17

CHAPTER 4 FUNDAMENTALS OF OXYGEN TRANSFER TESTS

4.1 Fundamentals of the non-steady state method

Interfacial oxygen transfer involves transport from the bulk gas phase to the interface,

and then from the interface into the liquid. For sparingly soluble gases, such as oxygen,

mass transfer on the gas side of the interface is much quicker; therefore, transfer on the

liquid side is expected to control oxygen transfer at the interface. Then oxygen transfer

can be described by the following two-resistance mass transfer model, which is most

commonly used to predict oxygen transfer in water (Aeration A Wastewater Treatment

Process, 1988; ASeE, 2000):

(4.1)

where:

e = DO concentration, mg I L

e: = DO saturation concentration, mg I L

KLa = apparent volumetric mass transfer coefficient, S-I

t = time, s

The method for determining KLa and e: in clean water is the unsteady adsorption

method, which involves first removing dissolved oxygen (DO) from the water volume by

the addition of a chemical reductant (normally sodium sulfite) and then re-oxygenating

the water to near the saturation level using the specific aeration device. The KLa and e: values are estimated by regression analysis of the measured DO data using the integrated

form of Equation (4.1), which is shown in Equation (4.2):

(4.2)

18

where:

Co = DO concentration at time zero, mg I L

The values of KLa and C: are dependent on water temperature and the barometric

pressure (under process conditions) and they are adjusted to standard conditions. The

standard oxygen transfer efficiency (SOTE) is obtained as follows:

(4.3)

where:

C:ao = equilibrium DO concentration at 20 °C, I atm and zero salinity, mg/L

KLaao = apparent volumetric mass transfer coefficient at 20 °C, 5-1

V = liquid volume of water in the test tan k, m3

W 02 = mass flow of oxygen in air stream, kg I s

The equilibrium DO concentration C:ao and apparent volumetric mass transfer

coefficient KLa aO are calculated as follows:

where:

• • ( I ) C"ao = CooT to

K a - K a·e(20-T) L 20 - L

(4.4)

(4.5)

C:T = equilibrium DO concentration at temperature T,I atm and zero salinity, mg/L

KL a = apparent volumetric mass transfer coefficient at the test temperature, S-1

t = temperature correction factor

o = barometric pressure correction factor

e = empirical temperature correction factor

19

T = temperature, °C

The pressure correction factor n accounts for the effect of non-standard barometric

pressures. It is calculated as follows for basins less than 6.1 m (20 ft) deep:

where:

n = Ph P,

Pb = barometric pressure during the test, psi

(4.6)

P, = standard atmosphere pressure 14.7 psi at I 00% relative humidity

The influence of temperature on the oxygen transfer coefficient and oxygen saturation

value can be expressed in terms of the factors e and 1", defined by:

e(T -20) = KL aT

K La 20

(4.7)

(4.8)

The influence of temperature on the various oxygen saturation concentrations will be

similar. Therefore, 1" can be calculated based on published DO surface saturation values:

where:

C' ST

(4.9)

= tabular value of DO saturation conc. at 20°C, I atm and 100% relative humidity, mg/L

= tabular value of DO saturation conc. at the test temperature, 1 atm and 100% relative humidity, mg/L

Values of e reported in the literature have ranged from 1.008 to 1.047 and are

influenced by geometry, turbulence level, and type of aeration device. The clean water

20

test standard recommends that the value of e be taken to1.024 unless experimental data

for the particular aeration system indicate conclusively that the value is significantly

different from 1.024 (Aeration A Wastewater Treatment Process, 1988).

4.2 Fundamentals of the off-gas method

4.2.1 Theory of analysis

The off-gas method is based on a gas-phase mass balance, which measures the change

in oxygen content of the air entering and exiting an aeration tank. By comparing the

composition of the off-gas to that of the gas entering an aeration tank, it is possible to

calculate the oxygen transfer occurring within the tank. If the flow rates of gas entering

an exiting the fluid are known, then the following mass balance can be made (Stenstrom

1997; Stenstrom 2005):

(4.10)

where:

p = density of oxygen at temperature and pressure of gas flow, kg! m 3

q;,qo = total volumetric gas flow rates of inlet and outlet gasses, m3 !s

YR, YOg = mole fractions (equivalent to volumetric fractions) of oxygen in

the inlet and exit gasses

KLa = volumetric oxygen transfer coefficient, 5-1

C: = equilibrium DO concentration in the test liquid at the given conditions, mgIL

C = oxygen concentration, mgIL

v = liquid volume, m3

21

Vo = gas hold-up volume, m3

At steady state the equation reduces to:

(4.11)

Since it is often difficult to measure the entering gas flow rate to an aeration system, a

procedure which does not rely on gas flow rates is needed. If one assumes that the inert

portions of the entering gas stream do not change, a mole fraction approach can be

developed which does not require gas flow rate. This assumption means that the

nitrogen, argon, and inert trace gases do not change as they pass through the aeration

system. The new technique (Redmon et aI., 1983) relies upon this assumption to

calculate oxygen transfer efficiency (aTE). It must be further assumed that the transfer at

the fluid surface and the atmosphere is negligible when compared to the transfer caused

by the aeration system, and that steady state conditions exist during the test. Both

assumptions are very good for the wastewater treatment systems.

aTE expressed as a fraction, can be derived as follows:

where:

OTE = mass O2 in - mass O2 out mass O2 in

MRo/i -MRog/i

MRo/i (4.12)

= mass rate of inerts, which is constant (by assumption) in both the inlet and off-gas streams, kg I s

= molecular weights of oxygen and inerts, respectively

22

MRo1;, MRogii = mole ratio of oxygen to inerts in the inlet and off-gas streams

The mole ratio of oxygen to inerts is calculated by subtracting the mole fractions of

oxygen, carbon dioxide and water vapor, as follows:

(4.13)

Yog MRog/i = -;-1---;Y-;-o-g~-Y;-;C-O-2--'(::"og-)--~Y'--W-(O-g-) (4.14)

where:

= mole fractions of C02 in the reference gas(R), or

off-gas (og)

YW(R) , YW(og) = mole fractions of water vapor in the reference gas (R)

and off-gas (og)

The value of YR is the mole ratio of oxygen in air, and can be calculated by

subtracting the humidity from the known (handbook) mole fraction of oxygen in dry air

as follows:

YR = 0.2095(J.-YW(R» (4.15)

To use Equations (4.12) through (4.15) to calculate OTE, it is necessary to measure

water vapor, CO2 , and O2 partial pressure in the inlet air and in the off-gas (six

measurements). The water and CO2 vapor pressures can be reduced to zero by drying

and adsorption, which can reduce the number of measurements to two (only YR , YOg need

to be determined). Using this more convenient method, the value of YR should be exactly

20.95% and equation (4.13) and (4.14) reduce to:

Y MRo,; =--R-=0.2650

l-YR

23

(4.16)

Vag MRagli = I-V

og

4.2.2 Correction to standard conditions

(4.17)

If the mixed-liquor dissolved oxygen, temperature and IDS are measured at the same

time OTE is measured, and if the equilibrium DO concentration (C:) is known, it is

possible to calculate aSOTE. The correction is made in the same way as clean water data

are corrected to standard conditions, as follows:

(4.18)

where:

DO = operating DO concentration, mg/L

~ = correction factor for salinity

If the standard oxygen transfer efficiency (SOTE) of the aeration systems is known

from clean water tests, the a-value can be calculated as follows:

aSOTE a

SOTE

24

(4.19)

CHAPTERS MATERIALS AND METHODS

5.1 Pilot Aeration Column

A pilot column (30-inch diameter, 20 ft tall) has been constructed and used for

aeration testing. Column leveling and leakage tests were conducted before the experiment

started. Rubber hoses and silicone were used to eliminate the leaks at the bottom.

5.2 Diffusers

Three different fme-pore diffusers - membrane, ceramic and HDPE disc were tested

throughout the course of the experiment.

The membrane and ceramic disc diffusers are both manufactured by Aeration

Engineering Resources Corporation (AERCOR). The membrane diffuser kit consists of

three pieces: one glass filled reinforced polypropylene membrane support plate; one glass

filled reinforced polypropylene rise ring and one 9" diameter EPDM (Ethylene Propylene

Diene Monomer) disc membrane. The orifice diameter of the membrane is WI. The

ceramic disc diffuser is 9.187" diameterxO.75" thick. The orifice diameter is also \4".

Discs are provided with a simple adapter gasket to fit existing ceramic holders.

The 250mm (9.8425") diameter fine bubble disc diffuser is provided by Lakeside

Equipment Corporation.

5.3 Apparatus

The YSI Model 52 Dissolved Oxygen Meters and 5739 Field Probes were adopted for

DO concentration and water temperature measurement. Two craftsman air compressors

25

(Shp, 20 gal, single cylinder/oil-free) supplied compressed air to the diffuser. Two

rotameters for gas flow measurement were connected to the compressors.

For performance of the off-gas method, an off-gas analyzer has been constructed to

measure OTE under steady-state conditions. As shown in Fig. 6, the off-gas instrument

includes a fuel cell gaseous oxygen analyzer (Teledyne Model 320P) and a carbon

dioxide and water vapor sorption column (SP Refillable Indicating Moisture Trap). The

oxygen mole fraction is measured with Model 320P, which provides a signal proportional

to mole fraction, and can be calibrated directly at the pressure of the inlet air.

I t I Outlet

Oxygen Analyzer

{(

0 D Inlet P A

Stripper Column Manometer Amp Meter

Fig. 6. Schematic of the Off-gas Analyzer Structure

The stripper column was installed and operated in the vertical mode. It's filled with

the adsorbent - drierite (Anhydrous CaS04 Hammond) as well as the mixture of glass

beads & granular NaOH. As the gas flows through the absorber column, moisture is

adsorbed with drierite and C02 is absorbed with sodium hydroxide. Drierite changes

dramatically from bright blue to pink as the gas stream approaches 40% relative

humidity.

26

In addition, a differential pressure manometer, Extech Model 407910, was employed

to indicate gas pressure. Model 320P is provided with an external output of 0-100 m V

DC. A Fluke Model 87 True RMS Digital Multimeter was used as an external recorder to

supplement the detector cell's integral meter. After removal of moisture and C02 from

the sample stream, the 02 partial pressure results in a DC current output from the fuel

cell.

5.4 MBR pilot description

The activated sludge used in the second-phase testing came from an existing pilot-

scale 5MBR system treating raw domestic wastewater at the Honouliuli WWTP, which is

supplied by Enviroquip Inc., USA. The main equipment specifications for this unit are

summarized in Table 4.

Table 4. Enviroquip 5MBR Pilot System Snmmary

Membrane Module Type Flat-Plate Membrane Location Aeration Basin (Cartridge)

Membrane Type Microfiltration Membrane Arrangement Vertical

Membrane Material Chlorinated Effective Filtration Area 630 ft" Polyethylene

Support Material ABS Flow Rate 2.5 gal/d

Cartridge Dimensions 19"X39"xO.25" Design Flux 14.7GFD

Cartridge Membrane 8.6 ft" TMP 0.1 - 4 psi Surface Area Cartridge Dry Weight 106 oz. Air Use 3.0 CFMlIOO ft'

Mean Pore Diameter 0.4 11m Operating Mode Continuous air scour and Permeation relax

Acceptable PH Range 1 - 10 Recommended SoC -40°C Temperature Range

27

An Enviroquip membrane cartridge,

as shown in Fig. 7, is constructed by

ultrasonicall y welding sheets of polymer

to the back and front of a support panel.

Between the panel and the membranes,

a porous spacer material serves to

di stribute filtered water into a series of

grooves that lead to a nozzle on top of

the cartridge. Membrane cartridges are

housed in membrane unit.

Anatomy of the Membrane Cartridge

Nozzle

Membrane P1'Inei

Spacer

Microstructure

Mixed Liquor Flow

Permeate

Fig. 7. Anatomy or lhe Membrane Cartridge

Each membrane unit is comprised of a lower diffuser case and an upper membrane

cassette. In the MBR, several submerged membrane units are connected via common

permeate, air supply and flushing lines as shown in Fig. 8.

Fig. 8. Cutaway Illustration of Membrane Unit

28

The Enviroquip MBR treatment system operated at the Honouliuli WWTP consists of

a penneate pump, a membrane tank, a blower, mixed liquor re-circulation equipment,

anoxic and aerobic tanks as shown in Fig. 9. The anoxic zone is un-aerated, and is

equipped with surface mixers where the DO concentration is maintained below 0.5 mgIL

and the majority of denitrification occurs.

Fig. 9 illustrates the process flow diagram of the MBR pilot in nonnal operation

mode. The influent wastewater is pumped to the headworks where it passes through a 3-

mm traveling band screen. The screen is employed for pre-treatment to protect the

membranes from abrasive and stringy waste components (hair in particular). The

wastewater then flows through the anoxic tank for biological nitrogen removal.

Raw Wastewater

Fine Screen Blower

______ v_

Mixer

o 0

o 0

o 0

Mixed Li uor Recirculation

Suction Pump

oO~ o 0 0cJ-0~.lI CO 00

i

Permeate

Anoxic Zone MBR Re-circulation Pump

Fig. 9. Process Flow Diagram of the Enviroquip MBR

Then the wastewater goes to the membrane bioreactor where the membrane modules

are submerged in the activated sludge compartment. Air is introduced into the system to

scour the membranes, drive the biological treatment, and uniformly distribute suspended

29

solids throughout the aeration tank. Mixed liquor was pumped from the bottom of the

MBR and re-circulated to the anoxic zone. A slight vacuum is applied through a permeate

pump downstream of the membranes to allow for the solid-liquid separation process to

occur.

During the second-phase experiment of this study, in order to achieve the desired

solids concentrations in sequence, the activated sludge was completely retained in the

MBR without being discharged or recirculated.

5.5 Methods

The sludge in the membrane tank was characterized by measuring TSS, VSS,

viscosity, SMP, EPS, PDS, OUR, SCOD and IDS. Analysis of TSS, VSS, IDS and

OUR for the mixed liquor samples was conducted using the procedures described in

Standard methods (APHA, 1992). Soluble COD was determined on samples filtered

through a 0.45 J.11l1 filter.

Measurement of OUR

In this study, OUR was measured in situ using the BOD bottle technique. From the

slope of the DO reduction vs. time the OUR can be calculated using following equation:

where:

OUR = 8C 8t

8C = change in DO concentration, mgIL

8t = timeframe of measurement, h

The specific procedures of OUR measurement are described in Chapter 6.

30

Measurement ofViscositv

The viscosity of mixed liquor samples was determined with the Brookfield DV

II+Pro programmable Viscometer which measures fluid viscosity at given shear rates.

The principal of operation of the DV -JI+Pro is to drive a spindle (which is immersed in

the test fluid) through a calibrated spring. The viscous drag of the fluid against the

spindle is measured by the spring deflection. Spring deflection is measured with a rotary

transducer.

As the rheological behavior of the activated sludge mixed liquor correlates to that of a

non-Newtonian, shear thinning liquid, the Herschel-Bulkley model is suggested for the

analysis of viscometer data (Krampe and Krauth, 2003). However, due to the

unreasonable values obtained by this approach, the viscometer data were analyzed by the

Bingham plastic fluid model instead which gave the more realistic results:

11=11. +1]'1

where:

II = shear stress, mPa

II. = yield stress, mPa

1 = shear strain rate imposed on the sample, S-I

1] = viscosity, mPa·s

The viscosity of mixed liquor samples was measured under the selected viscometer

speed of 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 RPM. The corresponding shear rates

were 12.23,24.46,36.69,48.92,61.15,73.38,85.61,97.84, 110.07 and 122.30 S·I. Then

the measured viscosity data were analyzed using the Bingham model.

31

Measurement of SMP and EPS content

EPS is most commonly measured by analyzing the supernatant of a centrifuged

sludge that has been treated with one or more of the following techniques: heat,

sonication, EDT A or formaldehyde, cation exchange resin (CER), sodium hydroxide. The

most widely used extraction method is by CER treatment that removes bridging divalent

cations (Ca2+, Mg2~ from the sludge matrix and releases the EPS into solution. This

method provides a high yield of extracted EPS without denaturing protein

macromolecules by heating, and it minimizes cell lyses (Frolund et al., 1996).

In this study, EPS was extracted from microbial floc using the CER method. A mixed

liquor (ML) sample was immediately cooled to 4°C to minimize microbial activity. The

exchange resin (70 g of CERlg VSS) was added to a SO-mL sample and mixed at 600

rpm using a single blade paddle for 2 h at 4°C. The mixture (8 mL) was centrifuged for

IS min at 12,000 g to remove MLSS. Supernatant carbohydrate and protein were

measured colorimetrically.

At the same time, 8 mL of untreated ML was centrifuged for 15 min at 12,000 g, and

the protein and carbohydrate concentrations were determined on the supernatant to

represent the soluble fraction (SMP).

The centrifuged supernatant of the untreated ML sample represented the SMP

concentration and the centrifuged supernatant of the sample after CER addition

represented the sum of SMP and EPS concentrations. The difference between these

measurements was the EPS concentrations.

EPS concentrations were determined as the sum of carbohydrates and proteins

because they are the dominant components typically found in EPS (Frolund et al., 1996;

32

Lee et aI., 2003). Carbohydrates were detennined by the phenol-sulphuric acid method of

Dubois et aI. (1956). Glucose was used for standard and samples were analyzed at the

wavelength of 490 nm. To determine protein concentrations, the Folin method proposed

by Lowry et aI. (1951), modified by Frolund et aI. (1996) was applied. Bovine serum

albumin (BSA) was used as a standard.

Measurement ofPSD

Particle size distribution of the mixed liquor samples was analyzed with the Lasentec

M 1 00 Particle System Characterization Monitor. The instrument utilizes a technique

called focused-beam reflectance measurement (FBRM) to measure the size distributions

of sludge particles that flow by the probe window. Specifically, it uses a laser diode

source and measures the light scattered off individual particles suspended in a liquid.

FBRM is a real-time, in-process measure of particle count and dimension by chord

length distribution. The chord length distribution is a function of the shape and dimension

of the particles and particle structures as they exist in the process. The Lasentec MIOO

provides a continuous, high-speed count of particle population by dimension, making it

possible to track the rate and degree of change of solids composition in activated sludge

on the basis of both particle count and particle dimension. The particles ranging from 0.8

to 1000 IlII1 in diameter are measured.

5.6 Chemicals

During this study, many chemicals were used for the deoxygenation of clean water in

the field testing and for the analytical analysis of sludge properties in the lab. The name

or molecular formula and function of each chemical are presented in Table 5.

33

Table 5. Chemicals Used in the Experiments

Name

NazS03

CoCh.6HzO

Phenol

Sulfuric acid

Glucose

Folin-phenol

NazC03

CuSO •. 5HzO

NaK Tartrate

NaOH

Bovine serum albumin (BSA)

Granular NaOH

Orierite

Fnnction

Deoxygenation

Catalyst of the deoxygenation reaction

Carbohydrate measurement

Carbohydrate measurement

Carbohydrate standard

Protein measurement

Protein measurement

Protein measurement

Protein measurement

Protein measurement

Protein standard

Adsorbent of COz

Adsorbent of moisture

SCOD measurement

MBR Membrane cleaning

34

CHAPTER 6 DESCRIPTION OF FIELD STUDIES

Two types of column test were performed at the Honouliuli WWTP. Clean water tests

were conducted using tap water obtained from a fresh water supply at the WWTP. Hoses

were used to transport the water to the column. Tests were also performed using process

water. The column was located near the existing pilot MBR units.

6.1 Clean water aeration column testing

Clean water testing began on Dec. 14th, 2005 and ended on Jan. 30th, 2006. A total of

18 tests were conducted with fresh tap water. Clean water process efficiency was

measured for several flow rates with each diffuser following the ASCE (2000) standard

procedures. Airflow rates per diffuser were those typical values suggested by

manufacturers. Because of the small scale of the test column, as compared to a full-scale

aeration tank, only two probes were used. Clean water tests have been conducted with

each diffuser in triplicate at multiple specific airflow rates.

The ASCE 2-91 protocol specifies a non-linear regression technique (DOPAR) to

solve for KLa and C:. What we need to do is to enter DO and time data, get the values of

KLa, andC:, and calculate SOTE using equation (4.3).

The experimental setup is schematically represented in Fig. 10. A fine-pore diffuser

was installed at the bottom of the column. In this test, 3 types of different air diffusers

were included. The column was fitted with 2 DO probes mounted upside down. One was

placed at the 1/3 depth of the column water, and the other at the 2/3 depth of the column

water. The water depth over the diffuser (submergence) was 15 feet. It's important to

3S

place the sensor facing upward so that air bubbles do not cause DO readings to fluctuate

during the tests.

-- - ----~----

00 Sensors

DO Meters

Compressor Test Column

Fig. 10. Aeration Column Setup for Clean Water Testing

The following experimental procedures were carried out:

- Fill the column with tap water.

- Place the diffuser in the column. Take the dimension of water depth and submergence.

- Calibrate each DO meter.

Place sensors in a beaker of tap water. Adjust DO meters to ensure each meter reads

same DO concentration. Record and label actual position of each sensor. Then take

initial DO reading.

- Prepare deoxygenation chemicals.

10-15 mg/L of Na2S03 is required for per 1.0 mg/L DO. A solution of cobalt

catalyst is needed to achieve a soluble cobalt concentration of 0.50 mg/L in the test

water. Completely dissolve each amount in hot water outside the column prior to its

addition.

- Remove 02 from the water by adding deoxygenation chemicals.

36

Pour cobalt chloride into column first. The cobalt catalyst was added once for each

run. For unifonn distribution, the cobalt solution was dispersed throughout the tank by

operating the aeration system for 30 minutes upon each addition. Then gradually add

sufficient sulfite solution to depress the DO level below 0.10 mgIL at all points in the

test water. A pump was used to distribute sulfite solution unifonnly into the column.

- Re-aerate the water using the air diffuser and take the DO readings.

Tum on and set the compressors at the desired airflow rate. Record DO

concentrations from the two DO meters every 10 seconds until 98% DO saturation is

reached.

Repeat above procedures for each type of diffuser with varied airflow rates in triplicate.

6.2 Process water aeration column testing

In the second phase of the research, OTE was measured utilizing the off-gas

technique at different MLSS concentrations. Over 250 tests were completed during the 3-

month investigation period. Since the tests were perfonned in a pilot column and the

entire off-gas flow can be captured, no flow weight averaging is required in this case.

Fig. 11 shows the column set up for process water testing. For perfonnance of the off

gas method a supplementary gas analyzer and an off-gas collection system were required.

The sealed wooden cover on the top was used to obtain representative off-gas samples of

the column. Off-gas is a quantity of gas being released from the surface of the aerated

mixed liquor. This gas was collected from the Teflon PTFE pipe in the center of the

cover that ultimately necked down for the stripper column connection. By the hose

connection the off-gas and the ambient air reached the gas analyzer, where the oxygen

partial pressure (equivalent to mole fraction) had to be measured. The C02 and water

37

vapor in reference air and off-gas was removed from the gas by a stripper column prior to

analysis as described previously.

Cover

Overflow .---~==----i~H-... ·.- .... :!V! ••••

PilotMBR

o o 0

o o o

Test Column

Air

Off gas

DO Meter

Valves i-L __ -.J Gas Analyzer

Fig. 11. Aeration Column Setup for Process Water Testing

A lower DO sensor was put in the column to measure the operating DO concentration

and water temperature. The mixed liquor from the MBR unit was continuously pumped

into the bottom of the column. Overflow from the column was returned to the MBR. The

airflow through the diffuser was adjusted to the desired value after the liquid level

stabilizes. The column was allowed to come to steady state. The DO and off-gas were

analyzed throughout the course of the experiment.

The process water tests were performed at varied MLSS concentration. A MLSS

concentration of5, 7.5,10,12.5, IS, 17.5 to 20 gIL in the MBR was targeted; however,

the actual readings fluctuated between 3 and 18 gIL. The sludge had been accumulated in

38

the MBR without being discharged or recycles and was transported into the aeration

column for testing.

At each MLSS concentration, the following experimental steps were realized:

I. Take the in-situ OUR measurement of the mixed liquor.

OUR was determined immediately after activated sludge samples were collected

from the Enviroquip MBR as follows.

Calibrate the DO probe and set up the magnetic stirring bar equipment.

Collect sludge sample from the aeration tank. Pour the sample into a 500-rnL

sample bottle. Increase DO cone. of sample by shaking it vigorously for

approximately 30 seconds in the partially filled bottle.

Fill the BOD bottle completely to the top. Immediately insert the DO probe,

making sure that the probe tightly seals the sludge from the atmosphere. Activate

probe stirring mechanism and magnetic stirrer.

- After the meter reading has stabilized, record the initial DO and temperature

reading. Record levels at time intervals of 10 seconds. Record data over a 15-

minute period or until the DO is less than 1.0 mgIL. Record the final temperature.

2. Perform off-gas testing for the mixed liquor in the column with 3 types of diffusers.

Pump the mixed liquor from the aeration tank to the column. Put the calibrated DO

probe and the diffuser (connected to the compressors) into the column. Then cover the

column with the hood. Make sure the hood is sealed well.

We planed to test each diffuser over the same range of airflow rates applied to the

clean water testing. However, due to higher pressure drop in the process water, the

airflow rate of3 SCFM couldn't be achieved.

39

For each diffuser under a specific air flow rate:

- Take the partial oxygen fraction of reference gas (air) and off-gas.

Connect the gas hose to the off-gas analyzer. The gas sample passed through the

stripper column and then flew over the oxygen cell using the accessory flow-through

adapter. A radial connector was used as the inlet considering the high gas flow rates.

Record the ampere reading in IlA on the Model 87 Digital Multimeter until the Ch

partial pressure stabilized. To diminish the effect of the variability in the off-gas

oxygen concentration readings, a reference gas followed by an off-gas reading were

taken for each condition 3-5 times. Oxygen cell calibration was conducted prior to each

test at various times. Control the reference gas flow to maintain the same pressure

reading (recorded by the monometer) as under the off-gas flow.

- Measure operating DO concentration and temperature of the mixed-liquor in the

column under each condition. A YSI Model 52 DO probe was used for mixed liquor

DO and temperature measurements.

According to the acquired off-gas analysis data, MRo/i and MRog/i , the mole ratio of

oxygen to inerts in the inlet and off-gas streams were calculated using Equation (4.16),

(4.17) respectively. Then the oxygen transfer rate at process conditions, OTE, was

obtained through Equation (4.12). The salinity correction factor p was determined based

on conductivity of the mixed liquor samples because accurate conductivity can be easily

measured from a field measurement. In addition, since the standardized C:20 and SOTE

were already known from the clean water tests, andC:T (the equilibrium DO

concentration at test temperature, 1 atm and zero salinity) can be deduced from C :20

40

using Equation (4.4) and (4.9), the values of aSOTE and corresponding a under each

condition were obtained with equation (4.18) and (4.19) respectively. The data of the off

gas testing was summarized in Appendix II.

In addition to the OUR measurements and oxygen transfer tests in the field, we

conducted the comprehensive analyses of the activated sludge in the lab, in order to

observe the changes of the a-value in dependence on the sludge properties. During the

variation of the MLSS concentration, besides those known parameters such as MLSS,

MLVSS and viscosity, many other parameters were measured including SMP, EPS, PSD,

TDS, and SCOD.

41

CHAPTER 7 RESULTS AND DISCUSSION

7.1 Clean Water Aeration Test

Clean water aeration test results summary in Table 16 (Appendix II) presents all of

the data collected in clean water testing. The table shows the standard oxygen transfer

efficiency SOTE, the mass transfer coefficient KLazo and the equilibrium DO

concentration C:20 for the three diffusers. Each diffuser was tested over a range of two or

three flow rates suggested by the manufacturers.

Fig. 12 gives the average overall KLazo for the three different diffusers. Fig. 13 shows

the average values of SOTE determined. These data generally compare well with vendor

literature and were used to determine the alpha factor in the following off-gas testing of

mixed liquor.

30 -+- Membrane Dlffuer __ Ceramic Diffuser

25 -+- HOPE Diffuser

c E 20 ~ ~

0

~ 15

flO 5

0 0.5 1 1~ 2 ~5 3 3.5

Air Flow Rate (SCFM)

Fig. 12. Average mass transfer coefficient for three fine pore diffusers

42

5 __ Membrane Diffuser

i~ _.- .. __ .

----~-. -

__ Ceramic Diffuser

......... HOPE Diffuser I-

~ /. .. \ ... -- --------

1.5 f--- ..

1 o 0.5 1 1.5 2 2.5 3 3.5


Fig. 13. Average SOTE per foot of submergence for three fine pore diffusers

7.2 Process Water Aeration Test

Summaries for off-gas analysis (I) to (8) in Appendix II show all of the data collected

in off gas testing. including the calculated OTEs and a-values for the various process

conditions. The properties of mixed liquor of varied concentrations are presented in Table

2S (Appendix 11).

7.2.1. Evaluation of Diffuser Type on a-value

Table 6. Comparison of a-value of 3 Diffusers

MLSS AFR' a a AFR a a AFR a a (mg/L) (SCFM) (Memb.) (Cera.) (SCFM) (Memb.) (Cera.) (SCFM) (Cer .. ) (HDPE)

3082 I 0.32 0.04 2 0.58 0.40 1.5 0.16 0.27

3867 I 0.53 0.17 2 0.36 0.27 1.5 0.16 0.19

5436 I 0.22 0.09 2 0.21 0.21 1.5 0.12 0.16

8367 I 0.19 0.13 2 0.29 0.27 1.5 0.13 0.18

10533 I 0.17 0.09 2 0.17 0.14 1.5 0.08 0.11

11967 I 0.16 0.09 2 0.14 0.12 1.5 0.07 0.10

14760 I 0.14 0.06 2 0.11 0.09 1.5 0.05 0.08

17667 I 0.12 0.05 2 0.09 0.08 1.5 0.05 0.05

• AFR - all" flow rate.

43

The a-values of the 3 different fine-pore diffusers are compared in Table 6. We can

see that diffuser type has an effect on oxygen transfer. Under the same airflow at a certain

MLSS concentration, a-value changed with different diffusers.

7.2.2. Evaluation of Air Flow on a-value

The influence of air flow on a-value with the membrane and ceramic diffuser is

depicted in Fig. 14 and 15. We were unable to see the influence of AFR variation on a-

value of the HDPE diffuser because the AFR of 3 SCFM couldn't be achieved in the

process water testing. For the same reason, the dependence of a-value on AFR variation

from 2 to 3 SCFM wasn't observed for the membrane diffuser either.

0.6 .-------------:------,

0.55 ---=---0.5 -

0.45 +--

gj 0.4+--iii > 0.35 d! ii 0.3

« 0.25

__ MLSS = 3082 mg/l

---MLSS = 3867 mg/l __ MLSS " 5436 mg/l

--*'" MLSS = 8367 mg/l --lIf- MLSS = 10533 mg/l ___ MLSS = 11967 mg/l

0.2

0.15

0.1

--+- MLSS " 14760 mg/l i - MLSS " 17667 mg/l

0.05 +---.--------r---.------1 0.5 1 1.5 2 2.5


Fig. 14. Alpha-value of the membrane diffuser at varied AFR

Fig. 14 shows that with the membrane diffuser at the MLSS concentration of 3867,

5436, 10533, 11967, 14760 and 17667 mgIL, a-value decreased or remained the same

when the air flow rate increased from 1 to 2 SCFM. The exceptions occurred at the

MLSS concentration of 3082 and 8367 mgIL where a increased with airflow.

44

0.45

0.4

0.35 +----------I'-----------j

CD 0.3 +-------+-----j ::J

1 0.25 •

{ 02

« 0.15 t------;;=::;~~~~--1 0.1

0.05

O+---r---.---r------j 0.5 1 1.5 2 2.5


__ MLSS = 3082 mgll ___ MLSS " 3867 mgll

--.- MLSS " 6436 mgll

--*"" MLSS " 8367 mgll --lI!- MLSS " 10533 mgll --+- MLSS " 11967 mgll -+- MLSS " 14760 mgll - MLSS = 17667 mgll

Fig. 15. Alpha-value of the ceramic diffuser at varied AFR

Fig. 15 shows that with the ceramic diffuser, a-value declined or remained the same

as the air flow changed from I to 1.5 SCFM, and then increased as the air flow rose to 2

SCFM at the MLSS concentration of3867, 8367,10533,11967,14760 and 17667 mgIL.

The exceptions occurred at the MLSS concentration of 3082 and 5436 mgIL where a-

value continuously rose with air flow. The optimum air flow rate for the ceramic diffuser

was 2 SCFM.

The discrepancies observed in the effect of air flow on a-value with both of the

diffusers at the MLSS concentration of 3082 mgIL could be explained by the different

sludge behavior at low MLSS concentrations, whereas the ones occurred under other

process conditions might be caused by experiment errors.

7.2.3. Evaluation of MLSS and ML VSS concentration on a-value

Fig. 16 and 17 summarizes the average a-values in dependence of MLSS or ML VSS

concentration over the study.

45

0.6 IJ

0.5

_. )I(

0.2 - -.. 0.1

o 2500

IJ

-- ------ --

x

r ! .. )I( ..

5000

---- -[J- ---- --

x

. -----~-

--

• • .. ~ IJ X .. ..

7500 10000 12500

MLSS (mglL)

• Membrane 1 SCFM

IJ Membrane 2 SCFM

.. Ceramic 1.5 SCFM

x Ceramic 2 SCFM

)I( HOPE 1.5 SCFM

- -- --- - --- ---- - -- -- ! I I I

- ------------- --- ------ -- -i

~ • ~

--5!

--

.. • 15000 17500 20000

Fig. 16. Comparison of the a-value under different process conditions via MLSS

0.6

0.5

0.4 gj

~ i! 0.3 Q.

« 0.2

0.1

o

~---- --- ---

o 2000

IJ

IJ

• -----)I( X

• )I( .. .. )I( ..

4000

- ------- ------ -- - --

• Membrane 1 SCFM

IJ Membrane 2 SCFM

.. Ceramic 1.5 SCFM

x Ceramic 2 SCFM

)I( HOPE 1.5 SCFM

IJ X

--_._- -r • ~ .. x • )I( X IJ • -.. .. lI! ~ .. • 6000 8000 10000 12000 14000 16000

MLVSS (mglL)

Fig. 17. Comparison of the a-value under different process conditions via ML VSS

The results of each diffuser under various AFR show the same tendencies as expected

that a-values declined with MLSS or ML VSS concentration, which confirm the

46

conclusions drawn in the literature (Chapter 2). No appreciable correlation between a-

value and MLSS or ML VSS was found with the ceramic diffuser under 1 SCFM of air

flowmte.

Due to the low DO concentmtion maintained in the test column and the low re-

circulation of mixed liquor realized between the column and the MBR during the process

water testing, lower a-values were obtained in this study in comparison with the values

reported in the literature.

As shown in Fig. 18 and 19, the correlation between MLSS or MLVSS concentmtion

and a-value under each process condition is expressed by an exponential equation. The

regression coefficients (R2) of the correlating curves in both figures are 0.94 (Membrane

I SCFM), 0.87 (Membrane 2 SCFM), 0.93 (Cemmic I.S SCFM), 0.89 (Cemmic 2

SCFM) and 0.93 (HOPE 1.5 SCFM), respectively.

0.50,-------

0.45 +-------------------1 --Membrane 1 SCFM ........ Membrane 2 SCFM

- .. - ... ceramI<: 1.5 SCFM .... a =O.3366e-6E-05.MLSS

0.40 +---,,"" o:---r--------------I a =O.5868e ... oool

•MLSS ----·ceraml<: 2SCFM

0.35 +-------j'--"-~------,1~---------I

!!l 0.30

1 0.25 .t::

~ 020

0.15

0.10

0.05

-'- -.

..... '. '.

-'-'-'HDPE 1.5SCFM __ _ ____ . '--===-:c--==' '. .... a = 0.4592e ...... " "LIS

~.~-;-;-;:-

". a = O.325Se ... ·OOOI •MLSS '" '" ---" ... , ........... -..... ", ------ ~;:~~~~~~~~=== ------~.~---- .. -.. -:::..~~.:~~~ -:~~=~--~- -~ .... ~~.~ .......

a = O.2162e'O£,,,,MLSS .-.. - .. - .. - .. _ .. ~~:_ '---'-' ----. ---,-"=--=-- .. :::.--' -"".:;.;:....-0.00 +---,---~--~--~-~~---,----,----,------j

2000 4000 6000 8000 10000 12000 14000 16000 16000 20000

MLSS (rTlJIL)

Fig. 18. Correlation of MLSS and a-value

47

0.50 ------------ -------------'. a = 0.61 S1 e-O001"· MLVSS --N'embrane1 SCFM

0.45 +-~.c:... .. " .. :-... ----/+----------------l ........ N'embrane2SCFM

0.40 +----.. ...: ... ~-d--------------_1 -··-··Ceramlcl.5SCFM " ······t.. a =0.4792e;ooo, . .,LVSS ----. Ceramic 2 SCFM

,:: >--- '-;;j ,':-"-j :: :---:'--'-::-:~:~--::-~:~Z~:'~"7~-'-

0.15 -'/'-."_"_"_"_"_"_"_ -.-._._._._._._ '----1. 0.10 +--_____ '_" '-'-'-'- /I '--. -"-.. -.-.-a =0.223ge ... ·...,'·MLVSS - •• - •• - •• - •• - •• - •• _ •• _ •• _.

0.05

0.00 +----~--~-----r"---~---~---,.---__I 2000 4000 6000 8000 10000 12000 14000 16000

ML VSS (mgJL)

Fig. 19. Correlation ofMLVSS and a-value

7.2.4. Evaluation of ViscosiJy on a-value

Fig. 20 distinctly shows that viscosity of activated sludge is linearly dependent on

MLSS concentration. An increase in solids content leads to a higher viscosity of sludge.

14

12

'El: 10 S ::L 8 ~ <II

6 3 <II :> 4

2

0 2000

-------- --_.- --------,

p - 0.0008 MLSS-1.9481 2

4000 6000 6000 10000 12000 14000 16000 18000 20000

M.SS (mgIL)

Fig. 20. Correlation of MLSS and viscosity

48

As shown in Fig. 21, as viscosity increased, a-values decreased accordingly under

different process conditions over the study. In Fig. 22, a-value is correlated well with

viscosity for each process condition in tenns of a power law equation.

0.6

0.5

., 0.4

'" "iii

0 • tlembrane 1 SCFM

o tlembrane 2 SCFM

.. Ceramic 1.5 SCFM

x Ceramic 2 SCFM 0 )I( HOPE 1.5 SCFM

• =;t 0.3 ii

0 - ~ -- - ----------- _._----_. ---

x x

:1(1 t

&)1( • • <C

0.2

0.1 .. x 0 • .. x ~4- -- -1- • . .

51 I .. .. .. • I o o 2 4 6 8 10 12 14

Viscosity (cp)

Fig. 21. Comparison of the a-value under different process conditions via viscosity

0.45 --r===========~~ --Wembrane1 SCFM ......... Wembrane 2 SCFM

a = 0.4399.11-<>625 0.40 +----'r----"'-=-"'/~=--------___1

·······Ceramlc 1.5 SCFM 0.35 +----:..: .. -..;--cr---------------1 _____ Ceramlc2SCFM

t ----:\""":·.···t· ."::-_---"a'-=_0'-'.5J4:..:.9-"7jJ!::. .. _·_ .... _______ -L...::-...::.-::..: . .::.-.:...'HD~P=E.:1.5~SC~F~M~J-j

1 :: ,::~ _~-':::L: _a ~!_2~-o37M :.:: ~___ ,-.::.:~.t:~ .. ,-.~.~ ~~~~~~~:~. _ .. ~:~.:.:.::.~.~.~~~~.~ ......... :.: .... ':~'c~_-I . I"~ "'''1,;.'''- -.--.-.-.-._._ --- - --

a = 0.30 16jJ-<> 5849 ,\' ._ ........... - ... _ •• _ •• _ ... :~' - ~ --'-.-. -~-.-. -.-. 0.05 m \ ... _- .. - •• - •• _ •••••

a = 0.2077 p-o.S404 0.00 +---~-----.=:........;:..=.:.:...:...!.=-r----~--~---~----I

o 2 4 6 8

Viscosity ~ (cp) 10

Fig. 22. Correlation of viscosity and a-value

49

12 14

The regression coefficients (R2) of the correlating functions in Fig. 22 are 0.92

(Membrane 1 SCFM), 0.83 (Membrane 2 SCFM), 0.92 (Ceramic 1.5 SCFM), 0.86

(Ceramic 2 SCFM) and 0.85 (HDPE 1.5 SCFM), respectively. No dependence of a-value

on viscosity was observed with the ceramic diffuser under 1 SCFM of AFR.

The solids concentration in a MBR system can be adjusted around a targeted value

through controlling the amount of sludge wasted. The low viscosity of mixed liquor can

be kept by maintaining the low solids concentration in the system, leading to a better

oxygen transfer.

7.2.5. Evaluation of OUR on a-value

M.-~~~~~~~~~~~~~~~~~~~~~,

50

~ 45 .c ~40 .§. 35

0::30 :::l 0 25

--~--~

•

.--~ ____ OUK=()'J~41 MLSS°.s08

• R2 = 0.91

2O~-

15+-~~~~~~~~~~~-'~~~r---~.-----~

2500 5000 7500 10000 12500 15000 17500 20000

MLSS (mgIL)

Fig. 23. Correlation of OUR and MLSS

Fig. 23 shows that the parameter of OUR of activated sludge is a function of MLSS

concentration. An increase in wastewater strength leads to an increase in micro-organism

metabolic activity and higher OUR. As shown in Fig. 24, decreasing a-values were

observed at increasing OUR over the study except for the ceramic diffuser under I SCFM

of air flow rate.

50

0.6 a • IIfoembrane 1 SCFM

0.5 a IIfoembrane 2 SCFM

• Ceramic 1.5 SCFM

x Ceramic 2 SCFM a )I( HOPE 1.5 SCFM

-- . • a -

)I( X x

0.4 !!! ~ Jl! 0.3 c.

0.2 It ----_._-l{ t---

• • )I( • ~ •• x • )I( • x t--- --- --- ------- ----)(1-•

«

0.1

• • o

15 20 25 30 35 40 45 50 55

OUR (mg/L.hr)

Fig. 24. Comparison of the a-value under different process conditions via OUR

0.60

a = 56.344 OUR -1.'415

0.50

0.40

,

, ............ / a = 107.87 OUR-I 716

.. :::I iil ~ 0.30

.<: c. ;;:

0.20

0.10

0.00 15 20 25 30 35 40

OUR (rrg/L.h)

Fig. 25. Correlation of OUR and a-value

--Membrane 1 SCFM i,

........ Membrane 2 SCFM

-"·"·Ceramlc 1.SSCFM ~ - - - -. Ceramic 2 SCFM

-·-·_·HDPE 1.5SCFM

45 50 55

In Fig. 25, good correlations are observed between a-value and OUR for each process

condition. The regression coefficients (R2) of the correlating curves are 0.88 (Membrane

51

I SCFM). 0.91 (Membrane 2 SCFM). 0.90 (Ceramic 1.5 SCFM). 0.92 (Ceramic 2

SCFM) and 0.83 (HDPE I.S SCFM). respectively.

The observed relationship between a-value and OUR can be interpreted by the effect

ofMLSS concentration on oxygen transfer. In Fig. 23. the OUR is shown to increase with

MLSS because bacterial activity is highly related to the substrate concentration. As

discussed previously. a lower a-value is obtained at a higher MLSS concentration due to

the higher viscosity of the activated sludge. Thus a-value displays a correlation with

OUR.

The treatment efficiency of the ASP depends heavily on the metabolic activity of the

viable microorganisms in the mixed liquor. However. present control practices in the

treatment plants still depend mainly on a determination of MLSS or ML VSS. Because of

their inability to express the dynamic behavior of the active biomass in the mixed liquor.

routine monitoring methods (such as MLSS and ML VSS) should be supplemented by

additional rapid biochemical tests (Liu. 1983).

OUR can be measured directly in real time and is a meaningful indicator of the viable

organism concentration. From the relationship of it to process performance (a-value)

obtained in this study. OUR is suggested to be used as an on-line control parameter of

treatment processes where tests having a much more rapid response time and indicative

of reaction rates are essential.

It must be pointed out that the sludge samples for OUR measurement in this study

were collected from the MBR aeration tank. not from the test column. The suggestion of

measuring the OUR of the mixed liquor in the test column under various process

conditions could be made to explore the more dynamic correlation between a and OUR.

52

7.1.6. Evaluation of PSD on ex-value

PSD data had been analyzed for the sludge samples of varied concentrations in the

study. Particle size was investigated in the range of 0.8-1000 JI.m. As shown in Fig. 26,

wider PSD dimensions were observed at higher MLSS concentrations, and median

particle sizes generally decreased as MLSS increased.

1400

1200

'"' ()

1000 c:

'" :0 0"

'" ~ u. 800 ~ Q) .0 E :0 600 z Q)

13 t 400 '" !l.

200

0

1 10 100

Particle Diameter (pm)

--- MLSS = 3082 mg/L

-a- MLSS = 3867 mg/L

-+- MLSS = 5436 mg/L

--><- MLSS = 8367 mg/L

--lI!- MLSS = 10533 mg/L

--MLSS = 11967 mg/L

MLSS = 14760 mg/L

- MLSS = 17667 mg/L

1000

Fig. 26. Particle size distributions at various MLSS concentrations

As previously described in Chapter 5, the activated sludge was completely retained in

the MBR without being wasted or recirculated during the study, to achieve the desired

solids contents. Consequently, the longer the sludge retention time (SRT) and

accordingly the higher solids concentration, the broader the size range of the biomass

particles.

53

Median particle sizes at MLSS of3082, 3867, 5436, 8367, 10533, 11967, 14760 and

17667 mgIL were 55.0,55.7,37.7,33.5,33.3,33.9,29.4 and 29.1 !JlIl, respectively. The

correlation between median particle size and MLSS concentration is depicted in Fig. 27.

60

Cii 55

1 50 'SE 45 Je"::4Q

~ 35 30

-- ----

• '\

" 1--

--

D -1169.4 MLSs-O.3831 R2 - 0.89

~ -

• ----• ....... • 25

2500 5000 7500 10000 12500 15000 17500 20000

MLSS (rTWLl

Fig. 27. Correlation of median particle size and MLSS

Small particles in the activated sludge could either come from the influent or from the

cellular debris generated by cell decay and break-up. In the Enviroquip MBR pilot, the

membrane pores (nominal 0.4 !JlIl in diameter) are small enough to retain significant

amounts of colloidal material that most colloids remain in the mixed liquor. Due to the

complete sludge retention during the study, more non-aggregate small particles could be

retained in the reactor at prolonged SRTs and higher MLSS concentrations. This is a

possible explanation for the phenomenon observed in the study that increased solids

content leads to an increase in fine population of biomass.

The relationships between a-value and median particle size under different process

conditions over the study are summarized in Fig. 28. Decreasing a-values were observed

at increasing median particle size, except for the ceramic diffuser under I SCFM of air

flow rate. In Fig. 29, a-value and median particle size are correlated for each process

condition. The regression coefficients (R2) of the correlating functions are 0.84

54

Membrane I SCFM), 0.78 (Membrane 2 SCFM), 0.85 (Ceramic I.S SCFM), 0.74

(Ceramic 2 SCFM) and 0.79 (HDPE 1.5 SCFM), respectively.

0.6 c • Membrane 1 SCFM

0.5 c Membrane 2 SCFM • • Ceramic 1.5 SCFM

x Ceramic 2 SCFM 0.4

~ x HOPE 1.5 SCFM c

~ 0.3 t • -[]

--- --------x xx

« 0.2 --- L--~ ----_._--_.

.! • x

0.1 • ~ ~ • 51 - -

•• .. 0

25 30 35 40 45 50 65 60

Median Particle DIameter (101m)

Fig. 28. Comparison of the a-value under different process conditions via particle size

0.5

0.5

0.4

0.4

§ 0.3

;.,~ 0.3 .r: ~ 02

02

0.1

0.1

0.0

--- ----- ---_._. ----------- -- ----

Membmne 1 SCFM a = 0.000 W, + 0.OOO8D + 0.16f!9

.•...••• Membmne 2 SCFM ..

a = -0.OOO2D' + 0.030 W -0.6077 .. ' -"-"'Ceramlc 1.5SCFM

.. ' -p

~ ..... <--- -- - - - - Ceramic 2 SCFM .' ,.' ... -- ... • ~ ---m~"_ ~ I

.. n. - ---- _-~c.-.-··~- --. _ _ -------........ -:., ,.' ..... I

a =-O.0004D' _+0.0452D ....,.._-: ....... _ .. ___ . . _ _ _ ._ .• - .. -' -0.8697 "-.... -' ...... "-"-"7

~' ..... ..- .......... -~~ .... ~ .. _.,- I

,,'~.~. ...,.- a = -o.ooow' + 0.0242D - 0.4525 ~.,,~ .' .......... ,.. . ' -.-

~ .... -._._._ ........

" .-.-..... -..... -~~ ,'" r-- ." -' ,. ....... a =-O.OOO4D' +0.036D-0.6856

25 30 35 40 45 50 55 eo Median Particle Diameter (~m)

Fig. 29. Correlation of particle size and a-value

55

The influence of MLSS concentration on oxygen transfer can account for the

observed relationship between a-value and particle size. Since increased solids content

results in an increase in fine biomass population and median particle diameter decreases

with solids concentration, a-value displays a correlation with particle size.

7.2.7. Evaluation of SMP, EPS, SeOD and TDS on a-value

The contents of seOD, IDS, total SMP and total EPS in mixed liquor were also

evaluated. Each of these parameters is plotted against MLSS concentration. As shown in

Fig. 30, 31 and 32, the data points are highly scattered and no appreciable trend is

observed of seOD, TDS or total SMP with MLSS. And accordingly no dependence of a-

value on these parameters was discovered over the study.

In Fig. 33, a trend is observed that the total EPS content increased and then decreased

with solids content. At the MLSS concentration of 8367 mg/L, the minimum value of

total EPS was obtained. This interesting phenomenon might be interpreted by the

biological activity of the microorganisms in the sludge.

00,-------------------------------------------, !

50

~ E 40 f-----~

c • • 030 -!;l

---------.--------- ~--~ •

20 - • ----- • 10~--~--~--~----~--~--~--~--~----~__,

o 2000 4000 0000 0000 10000 12000 14000 16000 16000 20000

MLSS concentration (mg/L)

Fig. 30. Relationship between SCOD and MLSS

S6

1050

1000

950

~ 900 --

g 850 rJl g 800

750

700

650 0

30

25

~ e20 ~

a. 15 ::;; rJl

~ 10 f"

5

0 0

350

-

100

50

• . --

• •

• ••

--~-~-. --- • • 2000 4000 6000 6000 10000 12000 14000 16000 16000 20000

MLSS concentration (mgIL)

Fig. 31. Relationship between IDS and MLSS

• •

~~~~~----.. • •

.-~~--~ • • ---

2000 4000 6000 6000 10000 12000 14000 16000 16000 20000


Fig. 32. Relationship between total SMP and MLSS

• -

-

• • ..

• • • -

020004000 6000 6000 100001200014000160001600020000


Fig. 33. Relationship between total EPS and MLSS concentration

57

7.2.8. Evaluation ojMLSS, MLVSS, Viscosity, OUR and PSD on OTE

The effect of sludge properties on OTE was only observed for the membrane diffuser

with 1 SCFM of air flow rate. Under other process conditions, no clear trend was

obtained.

In the following graphs. volumetric OTE (VOTE) is plotted versus and correlated to

MLSS. MLVSS. viscosity. OUR and particle size. separately.

0.10 ,.-----------------------------,

0.09

'" 0.08 f------=-.""=~c_-----------__;;_:;o_;_;_____,-----___1 E VOTE = 3.5955 MLS~·4m • R2 = 0.98 ~ 0.07

I!! 0.06

o ~~~~::::~~==:====_---> 0.05 r---VOTE =4.2264 MLVSS-0 4802

• R2 = 0.98 0.04 ... a·

0.03 '---~--~--~-~--~--~-~--~-----'

2000 4000 6000 8000 10000 12000 14000 16000 18000 20000

MLSS or MLVSS concentration (mgIL)

Fig. 34. Correlation ofMLSS. MLVSS and VOTE

Fig. 34 shows that VOTE decreased as MLSS (or MLVSS) increased. Good

correlations were observed between VOTE and MLSS (or ML VSS) concentration.

0.10

0.09

iW)' 0.08

~0.Q7 I':! 0.06

~ 0.05

0.04

• . ---. _ .. _. - . --------------,

..... _-- -----------

VOTE = 0.1014 ,u-OJ289.R 2 = 0.95 - -- -----------j

• 0.03 '--~-~-~~-~-~--~-~-~~-~-~----'

o 2 4 6 8

Vlscoslly ~ (cp)

10

Fig. 35. Correlation of viscosity and VOTE

58

12 14

In Fig. 35, it is shown that VOTE decreased as mixed liquor viscosity increasing,

which is expressed by a power function.

0.10 ,---,---

0.09

C") 0.08

~ 0.07

I!! 0.06 o > 0.05

0.04 ---------+

• ---~ 0.03 +---~--~--~--~---~--~--~--__I

15 20 25 30 35 40 45 50 55

OUR (mgll.h)

Fig. 36. Correlation of OUR and VOTE

Fig. 36 shows that decreasing VOTE was observed at increasing OUR. A power law

function is formulated to correlate VOTE and OUR.

0.10

0.09

M' 0.08 +-----~ 0.07

I!! 0.06 -o > 0.05

0.04 +---

• yOT~ = 0.0015 D'D334 ... R2 = 0.84

• •

0.03 +---~---,---~--~~--~--~--_____4 25 30 35 40 45 50 55 50

MedIan Particle Diameter (pm)

Fig. 37. Correlation of particle size and VOTE

In Fig. 37, increasing VOTE was observed at increasing particle diameter. The

relationship is also expressed by a power law function.

S9

CHAPTER 8 CONCLUSIONS, LIMITATIONS AND RECOMMENDATIONS

8.1 Conclusious from the study

Within the scope of the presented investigations, the 4-month pilot-scale aemtion tests

were performed in an aemtion column. The research was successful in meeting its

objective of exploring the dependence of a-value and oxygen tmnsfer efficiency on

possible factors in MBR systems, including diffuser type, air flow mte and sludge

properties. Several new parameters such as IDS, SCOD, OUR, PSD, SMP and EPS

content of sludge have been tried to correlate with a-value and OTE. Off-gas technique

was utilized for OTE measurements in the wastewater. From the completed experiments,

the following conclusions can be drawn:

(1) Supplied air flow rate influences a-value.

(2) Diffuser type is another factor affecting a-value.

(3) Among the tested properties of activated sludge, the possible parameters identified to

correlate a-value or oxygen tmnsfer efficiency are MLSS or ML VSS concentmtion,

viscosity, OUR and median particle size.

(4) No dependence of a-value on total SMP, SCOD or IDS was observed over the study.

(5) An interesting trend was observed that the total EPS content increased and then

decreased with solids content. At the MLSS concentration of 8367 mgIL, the

minimum value of total EPS was obtained.

(6) The a-values observed in this investigation are lower than those reported in the

litemture.

60

8.2 Limitations of the study

The limitations of the study are summarized as follows:

(I) Low DO concentration was maintained in the test column during the process water

testing.

DO concentration in the column is the most important parameter in converting OTE

to aSOTE and thus is critical in the successful operation of a-value measurement.

Low DO concentration provided by the low air flow of each diffuser in this study

couldn't maintain proper process conditions in the test column. This caused the

biological conditions in the column to be different than in the MBR aeration tank.

And Iowa-values were obtained accordingly. The inaccuracy oftest results increased

with MLSS concentration.

(2) Low mixed liquor re-circulation rate was realized between the column and the MBR.

The low mixed liquor re-circulation was caused by the imperfection in the re

circulation system design. This limitation also contributed to low DO in the column.

(3) Old membranes were used in the MBR pilot.

The membranes immersed in the aeration tank of Enviroquip system have been used

over 3 years. And the system was used as a sludge thickener for a period of time

before this study. Although the membranes were physically and chemically cleaned

(using hypo chloride acid), the irreversible fouling could have existed and influenced

the solids build up and sludge properties in the aeration tank.

Although this study has the limitations listed above, it still provides a possible starting

point and insights for similar work.

61

8.3 Recommendations/or future research

Based on the limitations in this study, the following modifications of the experiment

system are recommended to improve the accuracy ofOTE or a-value measurement:

(1) Simulate the actuaI operation in the aeration tank as more as possible.

This can be accomplished through the both improvements:

i. Control the DO level in the test column.

The number of diffusers employed at a time in the test column and the air flow per

diffuser must be in a range that provides adequate DO concentration for

maintaining proper process conditions as well as providing accurate test results.

And it should be noted that if the air flow rate is too high, high a-values may result

from column tests operating at excessive DO concentration.

ii. Increase the re-circulation rate and shorten the HRT of mixed liquor in the column.

To achieve this purpose, a big feeding hose and a powerful re-circulation pump may

need to be used in the experiment.

(2) Employ new membranes in the MBR units during the research to avoid the adverse

effect of membrane fouling on the activated sludge.

It's also recommended to employ different types of MBR units in the study to

compare the results between the activated sludge of the different systems and investigate

if there is dependence of a-value or OTE on activated sludge type.

62

Testing Date: 12121105 Local Temp: 79 of

Time Time DOl D02

(sec) (min) (mgIL) (mgIL)

o 10

20

30

40

SO 60

70

80

90

100

110

120

130

140

ISO 160

170

180

190

200

0.00

0.17

033

0.50

0.67

0.83

1.00

1.17

133

1.50

1.67

1.83

2.00

2.17

233

2.50

2.67

2.83

3.00

3.17

333

0.05 0.09

O.OS 0.08

0.Q7 0.70

0.19 1.47

0.09 135

0.05 1.01

0.03 0.90

033 0.91

0.60 0.64

127 0.51

1.42 0.53

1.47 0.56

1.13 0.64

1.01 0.73

\38 139

2.26 1.56

1.49 1.43

2.05 1.48

225 1.84

2.05 2.12

2.56 1.98

APPENDIX I: RAW DATA TABLETS

TABLE 7. Clean Water Test (1) Raw Data

Diffuser Type: Membrane Disc Local Barometric Pressure: 29.84 in Hg

TIme Time DOl D02

(sec) (miD) (mgIL) (mgIL)

210

220

230

240

250

260

270

280

290

300

310

320

330

340

3SO 360

370

380

390

400

410

3.50 2.63 2.05

3.67 2.65 3.48

3.83 2.91 3.19

4.00 2.44 3.08

4.17 2.43 2.94

433 2.51 3.13

4.50 2.61 3.50

4.67 2.74 3.52

4.83 2.86 3.77

5.00 3.03 331

5.17 3.09 320

533 3.19 320

5.50 328 3.29

5.67 3.40 3.41

5.83 3.48 3.77

6.00 3.61 3.93

6.17 3.74 3.77

633 3.75 4.13

6.50 3.79 4.56

6.67 3.91 4.74

6.83 4.02 4.89

63

Air Flow: I SCFM Water Temp: 25.0 DC

Time Time DOl D02

(see) (mID) (mgIL) (mgIL)

420

430

440

450

460

470

480

490

500

510

520

530

540

550

560

570

580

590

600

610

620

7.00 4.10 4.75

7.17 4.16 4.59

7.33 4.37 4.44

7.50 4.73 430

7.67 4.57 434

7.83 4.57 437

8.00 4.74 4.75

8.17 4.89 5.44

833 4.94 5.44

8.50 5.17 5.53

8.67 530 5.08

8.83 5.55 4.99

9.OQ 530 4.92

9.17 5.17 4.89

933 5.29 5.00

9.50 528 5.06

9.67 5.83 5.18

9.83 5.87 526

10.00 5.55 525

10.17 5.59 524

1033 5.73 527

TIme

(sec)

630

640

650

660

670

680

690

700

710

720

730

740

750

760

770

780

790

800

810

820

830

TIme DOl D02

(miD) (mgIL) (mgIL)

10.50 5.79 5.33

10.67 5.65 539

10.83 5.60 5.68

11.00 5.90 5.99

11.17 5.78 5.89

1133 5.84 5.71

11.50 5.90 6.08

11.67 5.86 5.84

11.83 5.84 5.77

12.00 5.% 6.01

12.17 6.13 6.07

12.33 6.10 6.10

12.50 6.12 5.95

12.67 6.14 6.\6

12.83 6.19 6.45

\3.00 6.40 621

\3.17 638 6.18

1333 6.67 620

\3.50 6.44 624

13.67 6.41 628

13.83 6.46 6.54

TIme TIme DOl DOl

(sec) (min) (mg/L) (mg/L)

840 14.00 6.47 6.43

850 14.17 6.48 6.38

860 14.33 6.54 6.45

870 14.50 6.56 6.40

880 14.67 6.58 6.42

890 14.83 6.63 6.83

900 15.00 6.81 6.94

910 15.17 7.04 6.97

920 15.33 7.02 7.04

930 15.50 6.88 6.91

940 15.67 6.85 6.78

9SO 15.83 6.87 6.95

960 16.00 6.89 7.07

970 16.17 6.94 7.15

980 16.33 7.04 7.07

990 16.SO 7.04 7.06

1000 16.67 6.97 7.07

1010 16.83 7.09 7.22

1020 17.00 7.08 7.11

1030 17.17 721 7.10

1050 17.SO 7.40 7.06

1060 17.67 729 724

1070 17.83 727 7.36

1080 18.00 7.32 7.64

1090 18.17 7.31 8.30

1100 18.33 727 8.43

TABLE 7. (Continued) Clean Water Test (1) Raw Data

TIme TIme DOl DOl


1110 18.50 7.35 827

1120 18.67 7.42 7.63

1130 18.83 7.35 7.60

1140 19.00 7.48 7.89

1150 19.17 7.53 7.77

1160 19.33 7.59 7.56

1170 19.50 7.57 7.46

1180 19.67 7.61 7.37

1190 19.83 7.74 7.36

1200 20.00 7.67 7.52

1210 20.17 7.66 7.62

1220 20.33 7.74 7.66

1230 2O.SO 7.75 7.66

1240 20.67 7.78 7.59

1250 20.83 7.79 7.51

1260 21.00 7.78 7.46

1270 21.17 7.81 7.54

1280 21.33 7.85 7.59

1290 21.SO 7.83 7.62

1300 21.67 7.82 7.71

1310 21.83 7.78 7.72

1320 2200 7.82 8.12

1330 2217 7.83 7.92

1340 2233 7.80 7.88

1350 2250 7.81 7.81

1360 2267 7.88 7.81

TIme TIme DOl DOl


1370 22.83 7.91 7.73

1380 23.00 7.87 7.96

1390 23.17 7.93 7.90

1400 23.33 7.96 8.01

1410 23.50 7.92 8.02

1420 23.67 7.98 8.62

1430 23.83 8.03 8.05

1440 24.00 7.99 7.97

1450 24.17 7.97 8.11

1460 24.33 8.00 7.93

1470 24.50 8.02 7.96

1480 24.67 8.04 7.94

1490 24.83 8.00 7.97

1500 25.00 8.01 7.95

1510 25.17 8.05 7.85

1520 25.33 8.06 7.96

1530 25.SO 8.03 7.96

1540 25.67 8.07 8.00

15SO 25.83 8.16 7.97

1560 26.00 821 8.05

1570 26.17 8.22 8.02

1580 26.33 8.17 8.19

1590 26.50 829 8.31

1600 26.67 8.38 827

1610 26.83 8.44 8.08

1620 27.00 8.40 823

64

TIme TIme DOl DOl

(se<) (min) (mg/L) (mg/L)

1630 27.17 8.39

1640 27.33 8.38

1650 27.50 8.43

1660 27.67 8.43

1670 27.83 8.35

1680 28.00 8.32

1690 28.17 8.41

1700 28.33 8.42

1710 28.50 8.40

1720 28.67 8.44

1730 28.83 8.43

1740 29.00 8.43

1750 29.17 8.42

1760 29.33 8.52

1770 29.SO 8.57

1780 29.67 8.51

1790 29.83 8.49

1800 30.00 8.56

1810 30.17 8.53

1820 30.33 8.46

1830 30.SO 8.51

1840 30.67 8.52

1850 30.83 8.51

1860 31.00 8.55

1870 31.17 8.57

1880 31.33 8.58

8.15

8.01

8.13

8.12

824

8.43

8.31

821

8.22

8.38

827

8.32

8.38

8.36

8.46

8.68

8.55

8.44

8.47

8.41

828

829

8.30

8.32

8.31

8.45

TIme

(se<)

1890

1900

1910

1920

1930

1940

1950

1960

1970

1980

1990

2000

2010

2020

2030

2040

2OSO

2060

2070

2080

2090

2100

2110

2120

2130

2140

TIme DOl D02

(min) (mg/L) (mg/L)

31.50 8.62 8.49

31.67 8.69 8.62

31.83 8.61 8.73

32.00 8.67 8.72

32.17 8.72 8.75

32.33 8.69 8.63

32.SO 8.55 8.52

32.67 8.64 8.35

32.83 8.68 8.47

33.00 8.70 8.51

33.17 8.66 8.63

33.33 8.63 8.62

33.50 8.65 8.63

33.67 8.78 8.47

33.83 8.78 8.49

34.00 8.86 8.55

34.17 8.82 8.55

34.33 8.71 8.58

34.50 8.79 8.61

34.67 8.80 8.67

34.83 8.69 8.64

35.00 8.66 8.46

35.17 8.69 8.64

35.33 8.78 8.87

35.50 8.76 8.83

35.67 8.69 8.64

Table 7. (Continued) Clean Water Test 1 Raw Data

TIme TIme DOl DOl Time Time DOl DOl

(sec) (miD) (mgIL) (mgIL) (sec) (miD) (mgIL) (mgIL)

2150 35.83 8.73 8.61 2380 39.67 8.99 8.85

2160 36.00 8.74 8.59 2390 39.83 8.92 8.76

2170 36.17 8.74 8.51 2400 40.00 8.96 8.73

2180 36.33 8.80 8.53 2410 40.17 8.96 8.79

2190 36.50 8.80 8.55

2200 36.67 8.80 8.57

2210 36.83 8.77 8.71

2220 37.00 8.81 8.73

2230 37.17 8.80 8.68

2240 37.33 8.77 8.71

2250 37.50 8.78 8.58

2260 37.67 8.87 8.60

2270 37.83 8.89 8.77

2280 38.00 8.87 8.68

2290 38.17 8.86 8.62

2300 38.33 8.89 8.66

2310 38.50 8.90 8.68

2320 38.67 8.87 8.78

2330 38.83 8.88 8.64

2340 39.00 8.90 8.64

2350 39.17 8.91 8.72

2360 39.33 8.94 8.27

2370 39.50 9.02 8.80

6S

Table 8. In Sitn OUR Test (1) Raw Data

Testing Date: 5126/06 MLSS = 3082 mgIL Initial T ..... = 28.7 °C Final T ..... = 322°C

TIme TIme DO TIme TIme DO TIme TIme DO TIme TIme DO

(see) (miD) (mg/L) (see) (miD) (mg/L) (sec) (miD) (mg/L) (see) (mID) (mg/L)

0 0.00 824 230 3.83 5.65 460 7.67 4.43 690 11.50 321

10 0.17 7.33 240 4.00 5.60 470 7.83 4.37 700 11.67 3.16

20 0.33 7.11 250 4.17 5.55 480 8.00 4.32 710 11.83 3.10

30 0.50 6.96 260 4.33 5.50 490 8.17 428 720 12.00 3.05

40 0.67 6.83 270 4.50 5.43 500 8.33 422 730 12.17 3.00

50 0.83 6.73 280 4.67 5.39 510 8.50 4.17 740 12.33 2.95

60 1.00 6.65 290 4.83 5.34 520 8.67 4.11 750 12.50 2.89

70 1.17 6.56 300 5.00 529 530 8.83 4.06 760 12.67 2.84

80 1.33 6.50 310 5.17 523 540 9.00 4.01 770 12.83 2.79

90 1.50 6.43 320 5.33 5.18 550 9.17 3.95 780 13.00 2.74

100 1.67 639 330 5.50 5.13 560 933 3.89 790 13.17 2.69

110 1.83 634 J40 5.67 5.06 570 9.50 3.84 800 13.33 2.64

120 2.00 627 350 5.83 5.01 580 9.67 3.80 810 13.50 2.58

130 2.17 622 360 6.00 4.96 590 9.83 3.74 820 13.67 2.53

140 2.33 6.15 370 6.17 4.91 600 10.00 3.68 830 13.83 2.48

150 2.50 6.07 380 633 4.85 610 10.17 3.63 840 14.00 2.43

160 2.67 6.04 390 6.50 4.80 620 10.33 3.58 850 14.17 238

170 2.83 5.99 400 6.67 4.75 630 10.50 3.53 860 14.33 233

180 3.00 5.93 410 6.83 4.69 640 10.67 3.47 870 14.50 228

190 3.17 5.87 420 7.00 4.64 650 10.83 3.41 880 14.67 222

200 333 5.82 430 7.17 4.59 660 11.00 3.37 890 14.83 2.17

210 3.50 5.71 440 7.33 4.53 670 11.17 3.32 900 15.00 2.12

220 3.67 5.72 450 7.50 4.48 680 11.33 326

66

Table 9. In Situ OUR Test (2) Raw Data

Testing Date: 6/9/06 MLSS = 3867 mgIL Initial T....., = 24.5 °C Final T....., = 24.4 °C

Time TIme DO TIme TIme DO TIme TIme DO TIme Time DO

(sec) (miD) (mgIL) (-) (miD) (mgIL) (-) (miD) (mgIL) (-) (mIo) (mgIL)

0 0.00 8.12 230 3.83 5.99 46() 7.67 4.36 690 ILSO 2.83

10 0.17 7.88 240 4.00 5.92 470 7.83 429 700 11.67 2.76

20 0.33 7.77 250 4.17 5.85 480 8.00 422 710 11.83 2.68

30 0.50 7.65 260 4.33 5.77 490 8.17 4.15 720 12.00 2.61

40 0.67 7.54 270 4.50 5.70 500 8.33 4.11 730 1217 2.55

50 0.83 7.46 280 4.67 5.63 510 8.50 4.04 740 1233 2.48

60 1.00 7.37 290 4.83 5.56 520 8.67 3.95 750 1250 2.42

70 1.17 727 300 5.00 5.49 530 8.83 3.88 760 1267 2.35

80 1.33 7.18 310 5.17 5.42 S40 9.00 3.81 770 12.83 229

90 1.50 7.07 320 5.33 5.35 550 9.17 3.74 780 13.00 222

100 1.67 6.98 330 5.50 527 560 9.33 3.67 790 13.17 2.16

110 1.83 6.90 340 5.67 520 570 9.50 3.61 800 13.33 2.09

120 2.00 6.82 350 5.83 5.13 580 9.67 3.56 810 13.50 2.03

130 2.17 6.75 360 6.00 5.06 590 9.83 3.50 820 13.67 1.97

140 2.33 6.66 370 6.17 4.99 600 10.00 3.44 830 13.83 1.90

150 2.50 6.58 380 6.33 4.91 610 10.17 3.36 840 14.00 1.84

160 2.67 6.51 390 6.50 4.84 620 10.33 327 850 14.17 1.77

170 2.83 6.43 400 6.67 4.77 630 10.50 322 860 14.33 1.71

180 3.00 6.36 410 6.83 4.70 640 10.67 3.16 870 14.50 1.65

190 3.17 628 420 7.00 4.63 650 10.83 3.10 880 14.67 1.59

200 3.33 621 430 7.17 4.56 660 11.00 3.03 890 14.83 1.52

210 3.50 6.14 440 7.33 4.49 670 11.17 2.% 900 15.00 1.46

220 3.67 6.06 450 7.50 4.42 680 11.33 2.89

67


Testing Date: 6130/06 MLSS = 5436 mgIL Initial T-., = 29.4·C Final T.-= 29.6·C

TIme TIme DO TIme TIme DO TIme TIme DO

(sec) (miD) (mgIL) (see) (miD) (mglLl (sec) (miD) (mgIL)

0 0.00 6.84 230 3.83 4.51 460 7.67 2.72

10 0.17 6.61 240 4.00 4.42 470 7.83 2.64

20 033 6.48 250 4.17 434 480 8.00 2.57

30 0.50 6.35 260 4.33 427 490 8.17 2.50

40 0.67 622 270 4.50 4.19 500 8.33 2.41

50 0.83 6.09 280 4.67 4.11 510 8.50 234

60 1.00 5.98 290 4.83 4.03 520 8.67 227

70 1.17 5.87 300 5.00 3.95 530 8.83 2.19

80 1.33 5.75 310 5.17 3.87 S40 9.00 2.12

90 1.50 5.67 320 533 3.79 550 9.17 2.04

100 1.67 5.58 330 5.50 3.72 560 9.33 1.%

110 1.83 5.49 340 5.67 3.63 570 9.50 1.89

120 2.00 5.41 350 5.83 3.56 580 9.67 1.81

130 2.17 529 360 6.00 3.48 590 9.83 1.74

140 2.33 523 370 6.17 3.41 600 10.00 1.66

150 2.50 5.15 380 6.33 332 610 10.17 1.58

160 2.67 5.07 390 6.50 325 620 10.33 1.51

170 2.83 4.99 400 6.67 3.18 630 10.50 1.44

180 3.00 4.91 410 6.83 3.10 640 10.67 1.36

190 3.17 4.83 420 7.00 3.03 650 10.83 129

200 333 4.74 430 7.17 2.95 660 11.00 121

210 3.50 4.66 440 733 2.88 670 11.I7 1.14

220 3.67 4.58 450 7.50 2.79 680 11.33 1.06

68


Testing Date: 7t1.8/06 MLSS = 8367 mgIL Initial T""" = 29.8 ·C Final T""" = 29.9 ·C

TIme TIme DO TIme TIme DO TIme TIme DO

(sec' (miD' (mgIL) (see) (min, (mgIL, (sec' (min' (mgIL)

0 0.00 6.89 230 3.83 4.75 460 7.67 2.84

10 0.17 6.69 240 4.00 4.67 470 7.83 2.75

20 0.33 6.55 250 4.17 4.59 480 8.00 2.67

30 0.50 6.43 260 4.33 4.52 490 8.17 2.59

40 0.67 6.33 270 4.50 4.43 500 8.33 2.51

50 0.83 625 2SO 4.67 4.35 510 8.50 2.43

60 1.00 6.15 290 4.83 428 520 8.67 2.35

70 1.17 6.04 300 5.00 420 530 8.83 227

80 1.33 5.96 310 5.17 4.04 540 9.00 2.19

90 1.50 5.87 320 5.33 3.96 550 9.17 2.11

100 1.67 5.79 330 5.50 3.87 560 9.33 2.03

110 1.83 5.70 340 5.67 3.80 570 9.50 1.95

120 2.00 5.63 350 5.83 3.72 5SO 9.67 1.86

130 2.17 5.S4 360 6.00 3.64 590 9.83 1.78

140 2.33 5.46 370 6.17 3.56 600 10.00 1.70

ISO 2.50 5.38 3SO 6.33 3.48 610 10.17 1.61

160 2.67 5.31 390 6.50 3.40 620 10.33 1.54

170 2.S3 523 400 6.67 3.32 630 10.50 1.46

ISO 3.00 5.15 410 6.S3 324 640 10.67 1.37

190 3.17 5.07 420 7.00 3.16 650 10.83 129

200 3.33 4.99 430 7.17 3.0S 660 11.00 121

210 3.50 4.91 440 7.33 3.00 670 11.17 1.13

220 3.67 4.83 450 7.50 2.92 680 11.33 1.05

69


Testing Date: 8110/06 MLSS = 10533 mgIL Initial T ..... = 29.4 °C FinaIT ..... =29.l oC

Time TIme 00 Time Time 00 Time Time DO

(-) (miD) (mgIL) (sec) (miD) (mgIL) (sec) (miD) (mgIL)

0 0.00 6.36 230 3.83 3.94 460 7.67 1.48

10 0.17 6.26 240 4.00 3.83 470 7.83 1.37

20 0.33 6.15 250 4.17 3.73 480 8.00 1.27

30 0.s0 6.05 260 4.33 3.61 490 8.17 1.16

40 0.67 5.94 270 4.50 3.51 500 8.33 1.06

50 0.83 5.84 280 4.67 3.40

60 1.00 5.73 290 4.83 3.30

70 1.17 5.63 300 5.00 3.19

80 1.33 5.52 310 5.17 3.08

90 LSO 5.41 320 5.33 2.98

100 1.67 5.31 330 5.s0 2.87

110 1.83 5.20 340 5.67 2.76

120 2.00 5.10 350 5.83 2.66

130 2.17 5.00 360 6.00 2.s5 140 2.33 4.89 370 6.17 2.44

150 2.50 4.78 380 6.33 2.33

160 2.67 4.68 390 6.s0 2.23

170 2.83 4.58 400 6.67 2.12

180 3.00 4.46 410 6.83 2.01

190 3.17 4.36 420 7.00 1.90

200 3.33 4.26 430 7.17 1.79

210 3.50 4.15 440 7.33 1.69

220 3.67 4.04 450 7.50 1.58

70


Testing Date: 8/17/06 MLSS = 11967 mgIL Initial T __ = 32.9 °C Final T ..... = 30.9 °C

Time Time DO TIme Time DO

(sec) (miD) (mg/L) (see) (miD) (mg/L)

0 0.00 6.13 230 3.S3 3.44

10 0.17 6.0S 240 4.00 3.30

20 0.33 6.02 250 4.17 3.16

30 0.50 5.97 260 4.33 3.02

40 0.67 5.S7 270 4.50 2.88

50 0.83 5.7S 280 4.67 2.74

60 1.00 5.67 290 4.S3 2.60

70 1.17 5.56 300 5.00 2.46

80 1.33 5.44 310 5.17 2.32

90 1.50 5.31 320 5.33 2.IS

100 1.67 5.1S 330 5.50 2.04

liO 1.83 5.06 340 5.67 1.90

120 2.00 4.93 350 5.S3 1.75

130 2.17 4.S1 360 6.00 1.62

140 2.33 4.67 370 6.17 1.47

ISO 2.50 4.54 380 6.33 1.33

160 2.67 4.39 390 6.50 1.19

170 2.83 427 400 6.67 1.05

ISO 3.00 4.12

190 3.17 3.9S

200 3.33 3.S5

210 3.50 3.71

220 3.67 3.57

71


Testing Date: 8131106 MLSS = 14760 mgIL Initial T .... (test 7.1) =32.2 °C Final T __ (test 7.1) = 30.S °C Initial T ..... (test 7.2) = 33.S °C Fina\T __ (test7.2)= 32.loC

Test7.! Time Time DO Time Time DO Test 7·2 Time TIme DO Time Time DO

(sec) (min) (mgIL) (sec) (min) (mgIL) (sec) (min) (mgIL) (see) (min) (mgIL)

0 0.00 526 150 2.50 3.45 0 0.00 526 150 2.50 3.45

10 0.17 5.18 160 2.67 327 10 0.17 5.18 160 2.67 327

20 033 5.10 110 2.83 3.11 20 033 5.10 110 2.83 3.11

30 0.50 4.98 180 3.00 2.95 30 0.50 4.98 180 3.00 2.95

40 0.61 4.88 190 3.17 2.19 40 0.61 4.88 190 3.11 2.19

50 0.83 4.14 200 333 2.62 50 0.83 4.74 200 333 2.62

60 1.00 4.66 210 3.50 2.44 60 1.00 4.66 210 3.50 2.44

70 1.11 4.55 220 3.67 221 70 1.11 4.55 220 3.61 227

80 133 4.44 230 3.83 2.11 80 133 4.44 230 3.83 2.11

90 1.50 432 240 4.00 1.95 90 1.50 432 240 4.00 1.95

100 1.67 420 250 4.17 1.19 100 1.61 420 250 4.17 1.19

110 1.83 4.06 260 433 1.63 110 1.83 4.06 260 433 1.63

120 2.00 3.92 210 4.50 1.46 120 2.00 3.92 210 4.50 1.46

130 2.11 3.16 280 4.61 130 130 2.11 3.16 280 4.61 1.30

140 233 3.62 290 4.83 1.13 140 233 3.62 290 4.83 1.13

Note: The OUR of activated sludge at this MLSS concentration was tested twice in·situ. The reported value in this study is an average.

72


Testing Date: 9f14f06 MLSS = 17667 mgfL Initial T __ = 32.8 °C Final T __ = 30.4 °C

TIme TIme DO Time Time DO

(sec) (min) (mg/L) (sec) (min) (mg/L)

0 0.00 5.69 230 3.83 2.80

10 0.17 5.55 240 4.00 2.66

20 0.33 5.41 250 4.17 2.54

30 0.50 5.30 260 4.33 2.41

40 0.67 5.20 270 4.50 2.28

50 0.83 5.09 280 4.67 2.15

60 1.00 4.% 290 4.83 2.02

70 1.17 4.84 300 5.00 1.88

80 1.33 4.70 310 5.17 1.75

90 1.50 4.56 320 5.33 1.63

100 1.67 4.45 330 S.50 1.50

110 1.83 4.32 340 5.67 1.36

120 200 4.20 350 5.83 1.23

130 2.17 4.07 360 6.00 1.11

140 2.33 3.95

ISO 2.50 3.83

160 2.67 3.70

170 2.83 3.57

180 3.00 3.45

190 3-17 3.32

200 3.33 3.18

210 3.50 3.06

220 3.67 2.93

73

APPENDIX n: DATA SUMMARIES

TABLE 16. Clean Water Aeration Column Test ResuIfli Snmmary

Clean Water Test ResuItJ -- I No. I Dimlser Air Oowratc I Local T""", WaterT""", KLa" 1 I Kt.8" 2 I C.,. 1 C." 2 SOTE 1 SOTE2

AECOR

AECOR

1 "2 T 4

5

SCFM degF in Hg degj IIhr IIhr mg/L mg/L % % (Probe 1) - (probe 2) (probe 1 (probe 2) (pJOIiC 1) -~

1 79 29.84 25.0 5.043 5.090 10.003 9.835 23.876 1 73 29.92 24.6 5.490 5.860 10.016 10.603 26.025 , 2 76 29.77 25.0 14.387 13.235 10.269 10.991 34.962 ' 2 71 29.80 24.1 IS.991. ~504 9.Sll 10.381 35.993 3 29.91 24.2 40.774

29.84 24.4 42.961 Ceramic 1 I 69 I 29.91 23.5 72.445 Ceramic ----I 69 - --- 29.91 25.6 12.180 11.253 11.188 11.278 64.496 60.070

I ~ Ceramic 1 76 29.90 25.8 8.614 7.893 10.924 10.417 44.540 38.916 I .n Ceramic 1 74 29.91 25.6 7.349 7.173 9.668 10.406 33.628 38.332

Ceramic 1.5 71 29.94 24.5 23.449 20.833 10.324 10.908 76.389 71.707 I " Ceramic 1.5 71 29.94 25.1 18.956 17.357 10.269 10.703 61.423 58.621 I 13 Ceramic 2 74 29.96 24.2 18.230 16.893 10.137 10.853 43.733 43.390 I 14 Ceramic 2 74 29.96 24.4 18.m 15.392 8.540 10.934 37.947 39.829

15 HOPE 1.5 77 29.92 25.6 15.172 16 HOPE 1.5 74 29.91 24.6 17 HDPE 3 72 29.Tl 24.0 I ~".I.I~ ~~"'J I IV • .., ...... I .WIN'" JO~J .11 • .-, I

I III' unDI:' '::t "'0 29.77 24~J..... ....... ..., n" I ...... " .. I Oft 1ft.<'" ", .... ..JIj - I

I Clean Water 1 _ Difflrser Q .. Avg. C'." I Avg. Kca" I Avg. SOTE Avg.SOTE

(SCFM) (mgIL) (11hr) (%) per II of

1.11~ 1 5.370 1 25.752 ± 1.717 ~ I IU..... . 14.780 35.868 _~J.9.1

12 i2 27.148 43.906 I 2.927 Ceramic I 10.556 10.499 52.886 3.526 I I I I I Ceramic 1.5 10.551 20.419 67.035 4.469 I I I I I Ceramic 2 10.116 17.423 41.225 2.748 HOPE 1.5 10.536 14.738 47.954 3.197 HOPE 3 10.419 25.404 41.747 2.783

Note: Probe I is the upper DO probe in the aeration column and probe 2 is the lower one. The di1fuser submergence is 15 Il

74

Testing Date: May 26, 2006 Air Temp ("F): 92 Barom Pres (in Hg): 29.99

DiflUser Airflow Test Rate No. (SCFM)

1 Memb. 1

2 Memb. 1

3 Memb. 1

4 Memb. 2

5 Memb. 2

6 Memb. 2

7 Memb. 2

8 Ceramic 1

9 Ceramic I

10 Ceramic 1

11 Ceramic 1.5

12 Ceramic 1.5

13 Ceramic 1.5

14 Ceramic 2

15 Ceramic 2

16 Ceramic 2

17 HOPE 1.5

18 HOPE 1.5

19 HOPE 1.5

20 HOPE 1.5

Water 00 Temp. (mgIL) ("C)

30.0 1.11

30.1 636

30.1 3.76

30.0 5.06

29.9 7.04

28.4 5.84

TABLE 17. Off-gas Analysis (1) Data Summary

MLSS = 3082 mgIL Theta = 1.024

Ref-gas Off-gas M Ampere Ampere Fra<lion

(pA) (pA) Off-gas

557 527 0.1982

563 528 0.1%5

565 528 0.1958

567 539 0.1992

564 542 0.2013

557 533 0.2005

545 524 0.2014

525 516 0.2059

513 508 0.2075

51\ 508 0.2083

491 472 0.2014

490 471 0.2014

489 471 0.2018

480 466 0.2034

477 469 0.2060

478 470 0.2060

534 518 0.2032

538 516 0.2009

538 518 0.2017

539 517 02009

75

YR =0.2095 MR oIi = 0.2650

MRatio C.T Off-gas (mgIL)

0.2472

0.2445 8.40

0.2434

0.2487

0.2521 8.53

0.2S07

0.2522

0.2593

0.2618 8.75

0.2631

0.2522

0.2522 8.76

0.2528

0.2553

0.2594 8.41

0.2594

0.2551

0.2515 8.99

0.2527

0.2515

C." (mgIL)

10.11

10.29

10.56

10.55

10.12

10.54

aTE OTE aSOTE SaTE Alpha (%) a>g. avg. avg. avg.

("10) ("10) (%)

6.72

7.74 7.53 8.34 25.75 032

8.14

6.17

4.88 532 20.66 35.87 0.58

539

4.83

2.16

123 \38 2.34 52.89 0.04

0.74

4.85

4.86 4.77 10.99 67.04 0.16

4.61

3.66

2.11 2.63 16.36 4123 0.40

2.11

3.76

5.12 4.66 13.15 47.95 0.27

4.66

5.11

Testing Date: June 9, 2006 Air Temp ("F): 95 Barom Pres (in Hg): 30.01

Test Diffuser Airflow No. Rate

(SCFM)

1 Memb. 1

2 Memb. 1

3 Memb. 1

4 Memb. 1

5 Memb. 2

6 Memb. 2

7 Memb. 2

8 Memb. 2

9 Memb. 2

10 Commie 1

11 Commie 1

12 Commie 1

13 Commie 1

14 Ceramic 1.5

15 Commie 1.5

16 Commie 1.5

17 Cemmic 1.5

Water 00

~~. (mg/L)

30.3 4.43

30.5 6.45

31.0 4.56

31.1 5.14

- ..


MLSS = 3867 mg/L Theta = 1.024

Ref_ 00_

~;;e ~e 634 600

634 603

638 604

639 604

603 588

596 578

579 567

576 562

570 557

524 510

530 51!

531 511

531 510

520 501

522 502

521 503

522 503

M Fraction 00_ 0.1983

0.1993

0.1983

0.1980

02043

02032

02052

02044

02047

02039

02020

02016

02012

02018

02015

02023

02019

76

VR =02095 MR"" =02650

MRalio C'T 00_ (mg/L)

02473

02488 8.36

0.2474

02469

02567

025SO

02581 8.47

02569

02574

02561

02531 8.61

02525

02519

02529

02523 8.60

02535

02529

C.,. (mg/L)

10.11

10.29

10.56

10.55

OTE Avg. oSOTE SOTE Alpha ("10) OTE ("10) (%)

('Vol

6.69

6.11 6.57 13.53 25.75 0.53

6.65

6.83

3.13

3.79

2.61 3.09 12.81 35.87 0.36

3.06

2.87

3.36

4.49 4.38 8.99 52.89 0.17

4.72

4.95

4.58

4.80 4.57 10.98 67.04 0.16

4.33

4.56

TABLE 18. (Continued) Off-gas Analysis (2) Data Summary

Test Airflow Water 00 Ref-gas Off-gas M MRatio C'T C." OTE Avg. aSOTE SOTE No. Diffuser Rate ~e~r (1llfIL) Ampere Ampere Fradion Off-gas (1llfIL) (mg/L) ("/0) OTE ("/0) ("/0)

Alpha (SCFM) (..A) (~A) Off-gas (%)

18 Ceramic 2 513 501 0.2046 0.2572 2.94

19 Ceramic 2 514 501 0.2042 O~ 3.18 31.3 6.07 8.22 10.12 3.00 11.23 41.23 0.27

20 Ceramic 2 513 501 0.2046 0.2572 2.94

21 Ceramic 2 513 501 0.2046 0.2572 2.94

22 HOPE 1.5 495 478 0.2023 0.2536 4.31

2J HOPE 1.5 495 478 0.2023 0.2536 4.31 31.5 4.90 8.53 10.54 4.12 9.32 47.95 0.19

24 HOPE 1.5 493 478 0.2031 0.2549 3.82

25 HOPE 1.5 494 478 02027 0.2543 4.06

77

Testing Date: June 30, 2006 Air Temp ("F): 98 Barom Pres (in Hg): 29.97

Test D_ Airtlow No. Rate

(SCFM)

I Memb. I

2 Memb. I

3 Memb. 1

4 Memb. 1

5 Memb. 1

6 Memb. 2

7 Memb. 2

8 Memb. 2

9 Memb. 2

10 Memb. 2

11 Memb. 2

12 Memb. 2

13 Ceramic 1

14 Ceramic 1

15 Ceramic 1

16 Ceramic 1

17 Ceramic I

18 Ceramic 1.5

19 Ceramic 1.5

20 Ceramic 1.5

21 Ceramic 1.5

W_ OO Temp. rci

(mtVL)

29.3 0.10

29.5 420

29.7 0.65

29.8 2.08



Ref-gas Off-gas

~:;. ~= 578 551

569 542

570 542

573 545

581 557

576 555

576 557

575 557

578 558

577 560

581 564

581 563

589 571

589 568

591 567

590 566

590 56S

589 559

589 559

588 557

587 556

M Fraction Off ..... 0.1997

0.1996

0.1992

0.1993

02008

02019

02026

02029

02023

02033

02034

02030

02031

02020

02010

02010

02006

0.1988

0.1988

0.1985

0.1984

78

Ya =0.2095 MR .. =0.2650

M Ratio C _r Off-gas (mtVL)

02496

02493

02488 8.50

02488

02513

02529

02541

02546

02535 8.62

02552

02553

02547

02549

02532

02516 8.81

02515

02510

02482

02482 8.79

02476

02476

C ,'" (mgIL)

10.114

10288

10.556

10.551

OTE Avg. oSOTE SOTE Alpha ("10) OTE ("10) ("10)

(%1

5.84

5.93

6.13 5.83 5.69 25.75 022

6.10

5.17

4.57

4.14

3.93

4.34 4.03 7.64 35.87 021

3.70

3.67

3.89

3.83

4.47

5.08 4.76 4.95 52.89 0.09

5.09

5.30

6.36

6.36 6.47 8.17 67.04 0.12

6.58

6.59

TABLE 19 (Continued). otT-gas Analysis (3) Data Summary

Test Airflow w_ oo Rcf-gas OO-gas M

M Ratio CoT C.", OTE

Avg. oSOTE SOTE Ditfuser Rate Temp. ~ ;:re Fraction (mgIL) (mgIL) OTE Alpha

No. (SCFM) ('ci (mgIL) 00_ OO-gas ('10) ('10) (%) (%)

22 Ceramic 2 569 551 02029 02545 3.97

23 Ceramic 2 573 554 02026 02S40 4.16

24 Ceramic 2 30.0 4.60 575 556 02026 02540 8.40 10.116 4.14 3.99 8.57 4123 021

2S Ceramic 2 573 556 02033 02552 3.72

26 Ceramic 2 574 556 02029 0.2546 3.93

27 HOPE 1.5 535 514 02013 02520 4.91

28 HOPE 1.5 535 512 02005 0.2508 5.38

29 HOPE 1.5 302 3.00 534 512 02009 02514 8.72 10.536 5.16 528 7.75 47.95 0.16

30 HOPE 1.5 536 512 02001 02502 5.60

31 HOPE 1.5 535 512 02005 02S08 5.38

79

Testing Date: July 28, 2006 AirTemp("F): 99 Barom Pres (in Hg): 30.00

Test DiflUser Airflow No. ~ I Memb. I

2 Memb. I

3 Memb. I

4 Memb. I

5 Memb. I

6 Memb. I

7 Memb. I

8 Memb. 2

9 Memb. 2

10 Memb. 2

11 Memb. 2

12 Memb. 2

13 Ceramic I

14 Ceramic I

15 Ceramic I

16 Ceramic I

17 Ceramic I

w_ 00g/L) Temp. I"ci

29.9 0.18

30.0 420

30.2 1.80



Ref-gas OIT-gas

~;'ie "(:je S63 541

567 543

567 545

S68 547

578 554

575 556

575 551

592 566

593 S66

596 569

597 572

59S 570

570 549

570 545

570 543

571 S44

570 543

M Fraction OIT-gas

020)3

02006

02014

02018

02008

02026

02008

02003

02000

02000

02007

02007

02018

02003

0.1996

0.1996

0.1996

80

VR =0.2095 MR oIi = 0.2650

MRatio C .T OIT-gas (mgIL)

02521

02510

02521

02527 8.41

02513

02540

02512

02S05

02499

02500 8.54

02511

02511

02528

0250S

02493 8.73

02494

02493

C"" (mgIL)

10.114

10.288

10.556

OTE Avg. aSOTE SOTE Alpha COA,) OTE COA,) COA,)

(%)

4.89

5.30

4.86

4.63 4.89 4.80 25.752 0.19

520

4.14

522

5.49

5.69

5.66 5.47 1M3 35.868 029

524

526

4.62

5.48

5.92 5.57 6.75 52.886 0.13

5.91

5.92


Test Airflow Water Rol_ Off_ M MRatio C _y C-.,. Avg. oSOTE SOTE

Diffuser RlIk ~~r COWL) ;;:ee ;;:ee FlBdion (mg/L) (mg/L) OTE OTE Alpha No. (SCFM) Off_ Off_ ("16) (%)

(%) (%)

18 Ceramic 1.5 570 547 02010 02516 5.05

19 Ceramic 1.5 574 550 02007 0.2512 5.23

20 Ceramic 1.5 577 554 02011 02518 4.99

21 Ceramic 1.5 582 556 02001 02502 5.59 30.3 3.30 8.72 10.551 5.51 8.54 67.035 0.13

22 Ceramic 1.5 582 556 02001 02502 5.59

23 Ceramic 1.5 579 552 0.1997 02496 5.83

24 Ceramic 1.5 581 553 0.1994 02491 6.02

25 Ceramic 1.5 582 555 0.1998 02497 5.80

26 Ceramic 2 570 552 02029 02S45 3.96

27 Ceramic 2 570 551 02025 02539 4.18

28 Ceramic 2 568 554 02043 02568 3.10

29 Ceramic 2 30.4 5.82 571 555 02036 02557 8.34 10.116 3.52 3.38 10.97 41225 027

30 Ceramic 2 577 564 02048 02575 2.83

31 Ceramic 2 581 567 02045 02570 3.03

32 Ceramic 2 583 569 02045 02570 3.02

33 HOPE 1.5 564 541 02010 02515 5.10

34 HOPE 1.5 563 539 02006 02509 5.33

35 HOPE 1.5 562 539 02009 02514 5.12

36 HOPE 1.5 562 S40 02013 02520 4.90 30.5 3.68 8.67 10.536 5.01 8.39 47.954 0.18

37 HDPE 1.5 566 S44 02014 02521 4.87

38 HOPE 1.5 573 550 02011 02517 5.02

39 HOPE 1.5 576 555 02019 02529 4.57

40 HOPE 1.5 583 559 02009 02514 5.15

81

Testing Date: August 10,2006 Air Temp ("F): 99 Barom Pres (in Hg): 30.00

Test Diffuser Airflow No.

~ I Memb. I

2 Memb. I

3 Mcmb. I

4 Memb. I

5 Memb. I

6 Memb. 2

7 Memb. 2

8 Mcmb. 2

9 Memb. 2

10 Mcmb. 2

II Mcmb. 2

12 Cenunic I

13 Cenunic I

14 Cenunic I

IS Ceramic I

16 Cenunic I

17 Cenunic I

18 Cenunic I

Water 00 Temp. (mg/L) ("q

29.8 0.07

30 l.05

30.2 0.10

.--



Ref-gas Off-gas

~: ~: 582 559

580 560

582 561

582 561

582 561

600 573

604 576

60S 577

60S 578

60S 578

60S 578

626 603

631 608

639 613

640 613

643 618

650 620

646 615

M Fraction Off ....

02012

02023

02019

02019

02019

02001

0.1998

0.1998

02002

02002

02002

02018

02019

02010

02007

02014

0.1998

0.1994

82

Va =0.2095 MR ali = 0.2650

MRatio C .T Off-gas (mg/L)

02519

02536

02530 8.43

02530

02530

02501

0.2497

0.2497 8.54

02502

02502

0.2502

0.2528

02529

02515

02510 8.73

0.2521

02497

0.2491

C.'" (mg/L)

10.114

10.288

10.556

--

OTE Avv,. aSOTE SOTE Alpha ("k) OTE ("16) (%)

("16)

4.95

4.32

4.52 4.57 4.43 25.752 0.17

4.52

4.52

5.63

5.79

5.78 5.66 6.20 35.868 0.17

5.58

5.58

5.58

4.60

4.57

5.09

5.28 5.17 5.02 52.886 0.09

4.87

5.77

5.99 -

TABLE 21 (Continued). otT-gas Analysis (5) Data Summary

Test Airflow Water 00 Ref-gas Off-gBS M MRatio ~} c.,.

OTE Avg.

aSOTE SOTE No. Diffuser (~ T~. (mgIL)

Ampere ~

Fnu:tioo Off-gas (mgIL) (,A» ~Z (,A» ('A» Alpha

("C (Ju\) Off-gas

19 Ceramic I.S 600 S74 0.2004 0.2S07 S.42

20 Ceramic I.S 600 S73 0.2001 0.2S01 S.63 30.3 0.20 8.72 10.SSI S.63 S52 67.03S 0.08

21 Cemmic 15 600 S72 0.1997 0.2496 S.83

22 Ceramic 15 S98 S71 0.2000 0.2S01 S.64

23 Ceramic 2 S90 S68 0.2017 0.2S26 4.67

24 O:nmtic 2 S91 S69 0.2017 0.2S27 4.66

2S Ceramic 2 30.4 1.93 S92 S70 0.2017 0.2S27 8.34 10.116 4.66 4.61 5.76 41.22S 0.14

26 Ceramic 2 S93 S71 0.2017 0.2S27 4.6S

27 Ceramic 2 594 S73 0.2021 0.2S33 4.43

28 HOPE 15 S80 5S6 0.2008 0.2S13 S.l8

29 HOPE I.S S78 SS3 0.2004 0.2S07 S.41

30 HOPE I.S 30.S 0.24 S77 SSI 0.2001 0.2S01 8.67 10.S36 S.63 S.47 5.38 47.954 0.11

31 HOPE I.S S7S S49 0.2000 O.2Soo S.6S

32 HOPE 15 573 S48 0.2004 0.2S06 S.46

83

Testing Date: August 17, 2006 Air Temp ("F): 99 Barom Pres (in Hg): 30.00

Test Dif!iJser Airflow No. Rate

(SCFMl

I Mo:mb. I

2 Mcomb. I

3 Mcomb. I

4 Mcomb. I

5 Mcomb. I

6 Memb. I

6 Mo:mb. 2

7 Mo:mb. 2

8 Mcomb. 2

9 Mcomb. 2

10 Mcomb. 2

II Memb. 2

12 Mcomb. 2

13 Cemmic I

14 Cemmic I

IS Cemmic I

16 Cemmic I

17 Cemmic I

18 Cemmic I

19 Ceramic I

20 Cemmic I

w_ oo

~6' (mgIL)

30.3 026

30.5 0.45

30.7 0.42



Ref-gas Oft'-gas

~ ~::;. 610 590

609 590

610 589

609 589

610 589

610 589

610 586

610 586

610 586

609 585

608 584

608 583

607 583

595 574

594 573

595 572

594 571

593 568

591 566

588 565

586 563

M Fraetion Off .....

02026

02030

02023

02026

02023

02023

02013

02013

02013

02012

02012

02009

02012

02021

02021

02014

02014

02007

02006

02013

02013

84

VR =0.2095 MR ali = 0.2650

MRalio Cor Oft'-gas (mgIL)

02541

02546

02536 8.36

02541

02536

02536

02520

02520

02520

02519 8.47

02519

02514

02519

02533

02533

02522

02522 8.66

02510

02510

02520

02520

C." (mgIL)

10.114

10288

10.556

OTE Avg. oSOTE SOTE Alpha ("/0) OTE (%) ("/0)

{"!ol

4.11

3.91

4.32 4.18 4.13 25.752 0.16

4.12

4.32

4.32

4.93

4.93

4.93

4.93 4.% 5.01 35.868 0.14

4.94

5.15

4.95

4.42

4.43

4.84

4.85 4.87 4.89 52886 0.09

527

529

4.90

4.91


Test Airflow Water 00 Ref_ 00_ M M Ratio C .T :;,,~) OTE Ayg. .sOTE SOTE No. Diftilser Rate T~. (mgIL) ~ =- Fraction 00_ (mgIL)

("/0) OTE (";.,) ("/0) Alpha (SCFM) 00_ {"/oj

21 Ceramic 1.5 579 558 02019 02530 4.54

22 Caamic 1.5 580 556 02008 02513 5.18 30.9 0.40 8.63 10.551 4.92 4.92 67.035 0.07

23 Ceramic 1.5 578 555 0.2012 02518 4.98

24 Ceramic 1.5 577 554 02011 02518 4.99

2S Ceramic 2 570 547 02010 02516 5.05

26 Ceramic 2 S69 S46 02010 02516 5.06 31.0 0.38 826 10.116 5.12 5.12 41225 0.12

27 Ceramic 2 568 545 02010 02516 5.07

28 Ceramic 2 567 543 02006 02510 5.30

29 IIDPE 1.5 529 511 02024 02537 427

30 IIDPE 1.5 528 509 I

02020 02531 4.51 I

31 IIDPE 1.5 31.2 0.32 527 507 02015 02524 8.57 10.536 4.75 4.66 4.61 47.954 0.10

32 IIDPE 1.5 526 506 02015 02524 4.76

33 IIDPE 1.5 S2S 504 02011 02518 5.01

85

Testing Date: August 31, 2006 Air Temp ("F): 99 Barom Pres (in Hg): 30.00

Test Diffuser Airtlow No. Rate

(SCFM)

1 Memb. 1

2 Memb. 1

3 Memb. 1

6 Memb. 2

7 Memb. 2

8 Memb. 2

13 Ceramic I

14 Ceramic I

15 Ceramic 1

21 Ceramic 1.5

22 Ceramic 1.5

23 Ceramic 1.5

2S Ceramic 2

26 Ceramic 2

27 Ceramic 2

29 HOPE 1.5

30 HOPE 1.5

31 HOPE I.S "---

Water 00

~~r (mg/L)

31.4 022

31.6 0.72

31.7 0.30

31.6 0.38

31.6 0.63

31.3 028

-- - L.



Ref-gas Off-gas

~: '7::e

495 480

495 480

495 480

490 476

491 476

491 476

444 432

444 432

444 432

441 428

441 428

441 428

436 423

436 423

436 423

431 418

431 419

432 419

M Fraction Off ......

02032

02032

02032

02035

02031

02031

02038

02038

02038

02033

02033

02033

02033

02033

02033

02032

02037

02032

86

VR =02095 MR oil = 02650

MRatio C.T Off-gas (mgIL)

02S49

02549 820

02S49

02555

02S49 8.31

02549

02560

02S60 8.52

02560

02552

02S52 8.S3

02552

025S1

02551 8.18

02SS1

02550

025SS 8.56

02550

C.,. (mg/L)

10.114

10.288

10.556

10.551

10.116

10.536

OTE A.g. aSOTE SOTE Alpha (%) OTE (%) (%)

("10)

3.80

3.80 3.80 3.71 25.752 0.14

3.80

3.59

3.83 3.75 3.90 35.868 0.11

3.83

3.39

3.39 3.39 3.33 52.886 0.06

3.39

3.70

3.70 3.70 3.68 67.035 0.05

3.70

3.74

3.74 3.74 3.85 41225 0.09

3.74

3.79

3.50 3.69 3.63 47.954 0.08

3.78 - '----- --

Testing Date: September 14, 2006 Air Temp ("F): 99 Barom Pres (in Hg): 30.00

Test DiIliJser AiJIlow Water No.

~ Temp. ("ci

I Memb. I

2 Memb. I

3 Memb. I 30.0

4 Memb. I

5 Memb. I

6 Memb. 2

7 Memb. 2

8 Memb. 2 30.2

9 Memb. 2

10 Memb. 2

13 Ceramic 1

14 Ceramic 1

15 Ceramic 1 30.2

16 Ceramic 1

17 Ceramic 1

18 Ceramic 1

21 Ceramic 1.5

22 Ceramic 1.5 30.2

23 Ceramic 1.5

24 Ceramic 1.5 -

00 (mg/L)

0.19

0.22

0.28

029

TABLE 24. otT-gas Analysis (8) Data Summary

MLSS = 17667 mWL Theta = 1.024

Ref-gas Q1I.glIS

'(:ie ~:;e 581 566

585 571

590 575

594 579

597 582

613 601

613 599

613 597

612 595

608 591

556 S44

554 543

5SJ 542

5S2 S40

552 539

551 538

S44 531

545 531

545 532

S46 532

M Fm:tion Off-gas

0.2041

0.2045

0.2042

0.2042

0.2042

0.2054

0.2047

0.2040

0.2037

0.2036

0.2050

0.2053

0.2053

0.2049

0.2046

0.2046

02045

02041

02045

0.2041

87

YR =0.2095 MR ali = 02650

MRalio C .T

Off-gas (mgIL)

0.2564

0.2570

0.2566 8.40

0.2566

0.2567

0.2585

0.2574

0.2563 8S1

0.2558

0.2557

0.2578

0.2584

0.2584 8.73

0.2578

0.2572

0.2572

0.2571

0.2S6S 8.73

0.2571

0.2S6S

C • ., (mgIL)

10.114

10.288

10.556

10.551

OTE Avg. aSOTE SOTE Alpha (%) ~: (%) ("10)

3.24

3.01

3.19 3.16 3.10 25.752 0.12

3.17

3.16

2.46

2.87

3.2S 3.12 3.07 35.868 0.09

3.49

3S1

2.71

2.50

2.50 2.73 2.71 52.886 0.05

2.73

2.96

2.97

3.00

3.23 3.11 3.08 67.035 0.05

3.00

3.22


Test Airflow Water 00 Ref_ Off_ M M Ratio c"oT c·..,lIl OTE Avg. aSOTE SOTE DiIJilser ~ ~d· ::;ae =- Fraction OTE Alpha

No. (mg/L) Off ..... Off_ (mg/L) (mg/L) (%) ("/0)

("/0) ("/0)

25 Ceramic 2 543 528 02037 02558 3.47

26 Ceramic 2 541 527 02041 02564 325 30.3 0.30 8.36 10.116 3.31 3.29 41225 0.08

27 Ceramic 2 S40 526 02041 02564 326

28 Ceramic 2 539 52S 02041 02564 326

29 HOPE 1.5 541 532 02060 02595 2.10

30 HOPE 1.5 542 532 02056 02589 232 0.05 30.3 029 8.7 10.536 2.32 2.30 47.954

31 HOPE 1.5 542 532 02056 02589 2.32

32 HOPE 1.5 542 531 02052 02583 2.55

88

TABLE 25. Sludge Properties at Varied MLSS Concentrations

SampUIIg TSS vss VIscosity Carbobydrate ProteiD SMP EPS TOS SCOD OUR MediaD Date (mg/L) (mg/L) «p) (mg/L) (mg/L) (mg/L) (mg/L) (mglL.b) ParDd.

SMP EPS SMP EPS Slzo

(mg/L) (mg/L) (mg/L) (mg/L) (Jim)

05126106 3082 2661 1.57 11.43 196.27 2.82 53.63 14.25 249.90 740 25.4 19.86 54.97

06109106 3867 3290 1.63 4.12 16.42 2.02 17.34 6.14 33.76 738 22.2 25.37 55.70

06/30106 5436 4521 2.02 19.87 14.40 4.44 100.40 24.31 114.80 1005 50.4 28.84 37.65

07128106 8367 6700 3.98 4.70 24.29 3.63 81.05 8.33 105.34 670 34.8 29.83 33.52

08110106 10533 8233 6.09 4.97 34.63 2.82 100.40 7.79 135.03 973 33.4 38.27 33.31

08117106 11967 9633 8.37 7.25 37.59 4.44 131.86 11.69 169.45 691 29.5 47.65 33.91

08131106 14760 11491 10.7 5.25 32.55 4.44 263.31 9.69 295.86 789 17.5 51.05 29.39

09114106 17667 13900 13.1 5.80 69.24 4.84 184.67 10.64 253.92 879 30.3 45.85 29.06

89

APPENDIX III: PHOTOGRAPHS

Picture 1. Column set-up

90

Picture 2. Clean water testing

91

Sealed cover

Picture 3. Process water testing

92

Picture 4. Diffuser in the test column

Picture 5. Aeration in the test column

93

Picture 6. Membrane disc diffuser

Picture 7. Ceramic disc diffuser

94

Picture 8. HOPE disc diffuser

Picture 9. OfT-gas analyzer being used in testing

95

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99

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