aquasbr sequencing batch reactor - stuarthumphries.com · sbr plc controls max/min d.o....

1

Superior Wastewater Treatment Utilizing SBR Technology

GRWA SBR Training

November 6, 2008

Stuart Humphries, Crocker & Associates, Inc.770-855-8090, [email protected]

www.crocker-associates.com, www.stuarthumphries.com

AQUA-AEROBIC

SYSTEMS, INC.

Crocker & Associates, Inc.

Presentation Topics

• SBR Introduction

• Nutrient Removal – Nitrogen

• AquaSBR® Operating Cycles & Phases

• AquaSBR® System Components

• AquaSBR® Process Control

• AquaSBR® Biological Process Control Example

• Nutrient Removal – Phosphorus

• Enhanced Biological Phosphorus Removal (EBPR)

• AquaSBR® EBPR Example

• Chemical Phosphorus Removal

• AquaSBR® Chemical Phosphorus Removal Example

• Wrap Up

Your Wastewater Specialists

AquaSBR®

Sequencing Batch Reactor

Aqua-Aerobic Systems, Inc.

2

Main

AquaSBR - Activated Sludge


AquaSBR - Activated Sludge Types


AquaSBR® - Activated SludgeAquaSBR vs. Flow-Through Activated Sludge

• Equalization

• Anaerobic Mix

• Staged Aeration

• Oxidation

• Nitrification

• Anoxic Mix

• Denitrification

• Clarification

• Sludge Wasting


3

Typical Flow Through System Layout:


SBR Comparison to Flow Through:SBR: Reduced Space Requirements


AquaSBR


4

AquaSBR


AquaSBR


AquaSBR


5

AquaSBR - Process Capabilities

Tolerates Hydraulic Fluctuations

Tolerates Organic Fluctuations

Excellent Solids-Retention Capabilities

Process Flexibility


AquaSBR - Applications

Organic Reduction

Total Nitrogen Reduction

Phosphorous Reduction

Municipal


Why Remove Nutrients in

Wastewater?

• Ammonia is toxic to aquatic organisms

• Ammonia exerts oxygen demand on receiving waters

• Nitrates pose health hazard if consumed by infants

• P and N contribute to Eutrophication

• High NO2- (i.e., partial denitrification) interferes

with Cl- disinfection (Nitrite Lock)

Aqua-Aerobic Systems, Inc.Crocker & Associates, Inc.

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• Contributes to eutrophication, which leads to deterioration of water quality in lakes

• Eutrophication is a condition in an aquatic ecosystem where high nutrient concentrations stimulate blooms of algae (e.g., phytoplankton).

• Creates conditions that interfere with the recreational use of lakes and estuaries, and the health and diversity of indigenous fish, plant, and animal populations.

Why Remove Nutrients in

Wastewater?


Algal blooms hurt the ecosystem in two ways:

1. Cloud the water and block sunlight, causing underwater grasses to die.

- Because these grasses provide food and shelter for aquatic creatures, spawning and nursery habitat is destroyed and waterfowl have less to eat when grasses die off.

2. When algae die and decompose, oxygen is consumed

- Dissolved oxygen in the water is essential to most organisms living in the water

- For coastal waters such as the Gulf of Mexico, hypoxia is especially severe due to the shallow waters of the coastal shelf and differences in water salinity.


• Nitrogen and phosphorus loading concerns on receiving waters

• Both point source and non-point sources are a concern

• Trend is towards lower discharge levels due to TMDLsand Waste Load Allocation

• Nutrient removal can play a role in reuse applications

Nutrient Removal Trends


7

• GA 0.5 NH3-N, 1.5 Org N (discussed), 0.13 Total P “Metro Atlanta Limits”

• FL 3.0 Total N, 1.0 Total P

• Chesapeake Initiative: State specific, 4.0-8.0 Total N, 0.3-2.0 Total P

• Michigan 5 TIN (NH3 + NO2- + NO3

-), 1 TP

NOTE: EPA-Region 4 is encouraging GAEPD to develop nutrient standards for all waters. Currently, GAEPD is requiring 1.0 mg/L TP for

new and expanding facilities >1.0 MGD (or 8.34 lbs/day for <1.0 MGD);

and for existing facilities renewing their permit, monitor TP only. This is being done because of nutrient criteria coming soon.

Regional Target Levels


Nitrogen



Nitrogen Basics

• Domestic wastewater contains Organic (40%),

Ammonium (60%), and Nitrates (<1%)

• Ammonium + Organic N = TKN

8


Nitrogen Basics

• From protein metabolism in human body

• 16 grams/cap/day

• 21 to 42 mg/L TKN typical

• Watch out for WWTP recycle streams

– Digester Supernatant

– Belt Press Filtrate

O2

O2

Nitrate (NO3-N)

Nitrite (NO2-N)

Ammonia Nitrogen

Nitrification


Carbon

Carbon



Nitrification

2NH4HCO3 + 3O2 Nitrosomonas 2HNO2 + 4 H2O + CO2

2HNO2 + O2 + 2 HCO3 Nitrobacter 2NO3 + 2H2O + 2CO2

Lose alkalinity


9

Organic

CompoundsNH3

NO2-NO3

-

N2O

N2

Nitrification

Denitrification

NO

Fixation

Nitr

ate

Assim

ilatio

n

Ammonification by Microorganisms

Ammonia Assimilation

Nitr

ific

atio

n

Assim

ilative

Nitr

ate

R

ed

uctio

n (

Ind

ustr

ial)

Nitrogen Cycle



Generally, SRT > 5 days for stable nitrification

– Nitrifiers work very slowly

– Cannot control very well (either fully nitrifying or NO nitrification)

– Best at SRT = 12-15 days


Best to be here!


Characteristics

– Optimum pH 7.0 - 8.0, stops below 6.0

– Maximum temp 40oC

– Consumes 4.6 lbs O2/lbs NH3-N converted

– D.O. > 1.0, preferably 2.0 mg/L, distributed throughout basin (If Low D.O., must have higher SRT)

– Consumes 7.2 Gm alkalinity (ability of the water to neutralize acid) /Gm ammonia oxidized

– 0.15 Gm new cells Formed/Gm ammonia oxidized

Nitrification


10

pH Control/Alkalinity Addition

3.6NO3-N denitrified

0.9Na2CO3 (Sodium Carbonate)

1.2NaOH (Sodium Hydroxide)

1.4Mg(OH)2

(Magnesium Hydroxide)

1.8CaO (Calcium Oxide)

Mg Alkalinity as CaCO3 per mg of Source Mat’l

Source Material



Organic Carbon Absence of O2

Nitrogen Gas (N2)

Nitrate (NO3-N)

Denitrification

Absence of O2Carbon

Note: Must Nitrify first to be able to Denitrify!



Denitrification

NO3- + (5/6)CH3OH (5/6)CO2 + ½ N2 + (7/6)H2O + OH-

Methanol

(or other

carbon source) Increase alkalinity


11


Characteristics

– Optimum pH 7.0 - 8.5

– Produces 2.86 lbs O2/lb NO3-N converted (“Denitrification O2 Credit”)

– D.O. < 0.5 mg/l

– Recovers 3.6 Gm alkalinity /Gm NO3-N denitrified

– 0.45 Gm new cells formed

– Consumes 1.9 Gm Methanol/Gm NO3-N reduced

Denitrification



Benefits prior to clarification

– Returns 63% of nitrification O2

– Returns 50% of nitrification alkalinity

– Eliminates discharge of algal nutrient

– Eliminates discharge of toxic NO2-

– Eliminates drinking water issues

– Controls nitrite chlorine demand

Denitrification



Typical Nitrification WWTP Processes Include:

Activated Sludge

• Conventional

• Pure Oxygen

• Contact Stabilization

• Extended Aeration

• Oxidation Ditch

• Sequencing Batch Reactor

Trickling Filters

Rotating Biological Contactors

In my opinion, most

flexible and easily enables denitrification

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AquaSBR®

Operating Phases



AquaSBR - Operating Phases


13

Time Based Operation

Increased Operator Control

Mix Fill React Fill React Settle

React Settle Decant Mix Fill React Fill

SBR 1

SBR 2

Decant

SBR 1 SBR 2

AquaSBR - Operating Phases



AquaSBR - Operating PhasesProposed Peurifoy WPCP Phase Structure

AquaSBR - Mixed Fill


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Mixer: AquaDDM


AquaSBR - Mixed Fill

Mixed Fill

Anaerobic/Anoxic

Environment

OrganicLoading

CompletelyMixed

ConditionsBiomass

Alkalinity recovery through denitrification can occur


AquaSBR - React Fill


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AquaSBR - React Fill

React Fill

Aerobic/Anoxic

Environment

OrganicLoading

CompletelyMixed

Aerobic/Anoxic Metabolism

Nitrification consumes alkalinity



AquaSBR - React


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AquaSBR - React

React

Aerobic/Anoxic

Environment

Termination of Organic Loading

CompletelyMixed

Polishing ofEffluent

Nitrification and metal salt addition consumes alkalinity


AquaSBR - Settle


AquaSBR - Decant/Waste Sludge


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AquaSBR - Decant/Waste Sludge


AquaSBR - Decant

Maintains Design MLSS

1-1.5% Concentration (Fluidized)

Subsurface Withdrawal

Follows Liquid Level

Absolute Seal

AquaSBR – Sludge Waste


AquaSBR®

System Components• Aeration System• Mixer • Decanter • Controls


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Aeration

•Retrievable/fixed fine-bubble diffusers•Retrievable/fixed coarse-bubble diffusers

•Mechanical surface aerators


SURFACE AERATOR: Aqua-Jet®


RETRIEVABLE

COURSE-BUBBLE


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RETRIEVABLE

FINE-BUBBLE


0

1

2

3

4

5

6

7

8

9

10

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

Air Flow - SCFM/Diffuser

SAE - lb. O2/Hr/HP

MixAir® - Aeration ComparisonSAE – lbs. O2 delivered/hour/bHP

Fine Bubble Diffused Air

5-7 lbs. O2/bhp-hr

Surface Low-Speed: 2.0-4.0 lbs. O2/bhp-hr


0

1

2

3

4

5

6

7

8

9

10

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

Air Flow - SCFM/Diffuser

SAE - lb. O2/Hr/HP

MixAir® - Aeration ComparisonSAE – lbs. O2 delivered/hour/bHP

Fine Bubble Diffused Air

5-7 lbs. O2/bhp-hr

Savings of 2 lbs. O2/hp-hour = saves $15,000 annually per 1.0 MGD treated


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Mixing

Direct drive Mixer-blender


AquaDDMProven Mixing Efficiency

The AquaDDM establishes

a powerful downflow

mixing pattern that

transports surface liquid downward and increases

mass transfer. Flow

entrainment and regenerative flow create

high reactor turnover rates

for efficient mixing.


AquaMixAir®

Independent Mixing — Improved aeration efficiency

The MixAir System utilizes

fine/coarse-bubble diffusers or

floating aerators along with

the AquaDDM mixer. The MixAir System provides full

range aeration control without

compromising mixing, by enabling the operator to

operate the aeration system

only when oxygen is required.

Click to animate


21

Decanting

Floating Decanter


DECANTER: AquaDecanter®


DECANTER


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SLUDGE PUMP


Controls



CONTROL SYSTEM

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AAS SCADA: Plant Overview


AAS SCADA: SBR Overview


AAS SCADA: Equipment Detail


24

SBR Biological Process Control


What Can You Change with an AquaSBR?

• Number of Basins online

• Number of Cycles

– e.g., 4/day/basin, 5/day/basin

• Phase length times within Cycle

– Mix Fill, React Fill, React, Settle, Decant

• Aeration cycling and duration (D.O. control)

• Sludge Waste duration

• Chemical Feed set points

Process Control


Dissolved Oxygen (D.O.) Control

SBR PLC controls max/min D.O. concentration using probe signals during aeration “on” time


0.0

1.0

2.0

3.0

4.0

5.0

0 50 100 150 200 250 300 350

Time (min)

D.O

. SBR #1

SBR #2

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What can be done to stay on top of

process conditions?

• Keep good eye on control parameters– Flow

– MLSS

– Settleability

– Microscope observation

– D.O.

– SRT

• Trend it! Make a Chart—


Which is easier to evaluate?

MLSS

8/1/2005 2502

8/3/2005 2490

8/5/2005 2530

8/7/2005 2480

8/9/2005 2470

8/11/2005 2450

8/13/2005 2455

8/15/2005 2420

8/17/2005 2425

8/19/2005 2410

8/21/2005 2440

8/23/2005 2390

8/25/2005 2410

8/27/2005 2380

8/29/2005 2400

8/31/2005 2360

MLSS

2250

2300

2350

2400

2450

2500

2550

8/1/2

005

8/3/2

005

8/5/2

005

8/7/

2005

8/9/

2005

8/11/

2005

8/13/

2005

8/15

/200

5

8/17

/2005

8/19/

2005

8/21/

2005

8/23/

2005

8/25/2

005

8/27

/200

5

8/29

/200

5

8/31/

2005

MLSS

(A)

(B)-OR-


How to make changes

• Slowly—No more than 10% per data

collection point period unless “emergency”

• Consider what might happen in reaction to

your changes—Good AND Bad

• Don’t be scared! You’re the professional—You know the plant better than anyone


26

SBR Biological Process Control

Example


Two SBRs

Two ABFs

Stephen D. Peurifoy WPCP, Stockbridge GA

Control Room

Post-EQ


Changes in Conditions at Peurifoy WPCPAugust 2005

• Increased flow: 0.6 MGD to 0.8 MGD

• Loading still about 250 mg/L BOD5

• Max D.O. during React Fill & React from

0.6 mg/L to 0.8 mg/L

• Settling not quite as good but still OK

• What do you do?


Process Control Example

27

Summary of Control Changes at

Peurifoy WPCPJuly Aug

MF 100 80

RF 80 100

R 75 80

S 60 60

D 45 40

MLSS 2400 2600

Blowers

Cycle 1 45/30 50/30

Cycle 2 45/25 50/30

Cycle 3 30/15 30/15

Cycle 4 20/20 20/10

Cycle 5 15/15 30/30


Phosphorus



What is Phosphorus?

• Essential part of the nutrient cycle in nature,

along with others such as sodium, potassium,

calcium, iron, copper, etc.

• Atomic Number = 15

• Word derives from Greek phosphoros: light

bearing; ancient name for the planet Venus

when appearing before sunrise)

• Brand discovered phosphorus in 1669 by

preparing it from urine.

28

Sources of Phosphorus

• Fecal and waste materials

• Paint strippers, soft drinks, toothpaste, and baking powder

• Industrial and commercial uses

• Synthetic detergents and cleaning products



Phosphorus Limits in GA Lakes:

Lake Lanier

36,900 pounds / year

West Point Lake (from Chattahoochee River)

1,400,000 pounds / year

Lake Allatoona

16,200 pounds / year to each of:

Bartow County

Cobb County

City of Canton

Cherokee Co. WSA

Lake Jackson

Discharge specific basis

Division of the Influent P Into Constituent

Fractions

TOTAL INFLUENT P

ORTHOPHOSPHATEReactive P

PO4-3 Predominant

ORGANICALLY-BOUNDPHOSPHATES

POLY-PHOSPHATES(Hydrolyzable)


29

Poly-Phosphates:

• Poly-phosphates include molecules with two or more

phosphorus atoms, oxygen atoms, and hydrogen atoms,

combined in a complex molecule

• Not removable by metal salt addition

• Reduced over time through hydrolysis to orthophosphate

• De-polymerized in anaerobic step of biological

phosphorus removal


Orthophosphates:

• Available for biological metabolism without further

breakdown

• This is the reactive form of phosphorus

It is the ONLY form of phosphorus whose removal

can be enhanced by metal salt addition.


• Goal: Incorporate Phosphorus into TSS

• Conventional: 1-2% P in WAS(typical 10-30% removal using secondary

treatment)

• Augmented: 3-6% P in Waste Sludge

– Biological

– Chemical

Available Phosphorus Removal Options


30

Biological Solids are Typically

3 - 5% Phosphorus(No Chemical Involved)

Effluent TSS P in Effluent TSS

2

5

10

15

0.06 - 0.10

0.15 - 0.25

0.3 - 0.5

0.45 - 0.75


• Should NOT be thought of as cure-all for

phosphorus removal

• Membranes are just a type of filter

(A relatively expensive one, too)

• Should phosphorus be in soluble form,

membranes will not take it out

• Other options available

Membranes


Enhanced Biological Phosphorus Removal


31

• Incorporate P into sludge

Earliest research performed by Levine and Shapiro in 1965

• Reduce metal salt costs

• Reduce polymer costs

• Reduce alkalinity adjustment costs

• Denitrification benefit

Enhanced Biological Phosphorus Removal

(EBPR)


Schematic of EBPR


EBPR: Basic Features

• Anaerobic Conditions: Release Phosphorus

• Aerobic Conditions: Store Phosphorus

• Selects microorganisms that accumulate

higher levels of intracellular phosphorus than

other microorganisms

– Phosphorus accumulating organisms (PAOs)

exhibit “luxury uptake”


32

EBPR Issues

• Low BOD/TP ratios result in BPR failure because PHA storage becomes too

low to produce the reducing equivalents for ATP production in the aerobic stage

• Excessive BOD/TP ratios have been found to act as an inhibitor to PAOs

• Appropriate BOD/TP ratios ~ 20-30:1 (Peurifoy WPCP~31:1)

• Only readily biodegradable COD can be converted to VFAs, which are taken up

by PAOs in anaerobic stage

• Phosphorus release in anaerobic conditions is faster in higher concentration

sludge than lower

• If TKN/COD ratio > 0.14, insufficient denitrification occurs— Complete

denitrification occurs at < 0.08

• Recycles must be accounted for (P and N)

• Too long of an anaerobic contact time allows phosphorus release to occur

without the uptake of VFAs. When this occurs, there is not enough energy to

force the full uptake of the released phosphorus in the aerobic contact period


EBPR Systems

• BardenPho (Phoredox)

• Oxidation Ditch

4Q

Q

Q


SBR EBPR Example


33

• 4 cycles/day/Basin– MF = 100 min.

– RF = 80 min.

– R = 75 min.

– S = 60 min.

– D = 45 min.

360 min. Total

• MLSS = 2,400 mg/l

• Aeration Timers:

Total/On

– 45/30

– 45/25

– 30/15

– 20/20

– 15/15

Stephen D. Peurifoy WPCP Operation:

July, 2005


0.0

1.0

2.0

3.0

4.0

5.0

0 50 100 150 200 250 300 350

Time (min)

D.O

. SBR #1

SBR #2

Aeration

–45/30

–45/25

–30/15

–20/20

–15/15

Mix Fill React Fill React Settle Decant

Stephen D. Peurifoy WPCP

Anerobic, Aerobic, and Anoxic Periods within SBR Cycle

05/13/05, 05/18/05


AquaSBR® - Total Phosphorus (typical)


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Design Data

Peurifoy AquaSBR®

Influent Effluent

ADF (MGD) 1.5 - -

MDF (MGD) 1.9 - -

BOD5 (mg/L) 250 6.0

TSS 250 20

TKN 40 - -

NH3-N - - 1.3

Total P 5.0 0.3

0.15 mg/L Total P without chemical addition


Actual (June 2008)Influent Effluent

ADF (MGD) 0.534 0.461

MDF (MGD) - - - -

BOD5 (mg/L) 245 2.0

TSS 305 1.4

TKN - - - -

NH3-N 22.3 0.09

Total P 7.9 0.15

Total Phosphorus in EffluentJan – Dec 2004

Stephen D. Peurifoy WPCP

0

0.2

0.4

0.6

0.8

1

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

TP

(m

g/L

)

Note: Sampling indicates TP ~0.2 mg/L prior to filters

– Phosphorus being removed overwhelmingly through EBPR –


Chemical Phosphorus Removal


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• Goal: Create insoluble forms of P

• Basic Elements to Precipitate P

– Ferrous Iron — Fe(II)

– Ferric Iron — Fe(III)

– Aluminum

– Lime — Ca(OH)2

Chemical Phosphorus Removal


• Alum (Aluminum Sulfate) — Al2(SO4)3.14H2O

Al+3 + HnPO4n-3 AlPO4 + nH+

• Ferric Chloride — FeCl3

Fe+3 + HnPO4n-3 FePO4 + nH+

• Poly Aluminum Chloride (PAC)

Common Chemicals Used


• Ideal pH for AlPO4(s) is 6.3

• Ideal pH for FePO4(s) is 5.3

Metal Salt Addition Considerations


36

• Ideal pH for AlPO4(s) is 6.3

• Ideal pH for FePO4(s) is 5.3

• Actual Requirements > Stoichiometry

– Typically 1-3 metal ions per one Phosphorus ion

• Proper location(s) for chemical addition

– Headworks, Mixed Liquor, Secondary Effluent, Digester

• Chemical Cost

• Dry or liquid

Metal Salt Addition Considerations


• Storage Issues

• Increased removals increase sludge production

• Sludge handling issues

• Disposal issues

• Corrosion and Staining

• Alkalinity supplementation

– In low alkalinity waters, addition of base may be

needed to keep pH in appropriate range

Metal Salt Addition Considerations (cont.)


% P Reduction Mg Al per mg P

75

85

95

1.2 – 1.5

1.6 – 1.9

2.1 – 2.6

Typical Aluminum Dosage as a Function of

Ortho-Phosphate Removal


37

AquaSBR®: Chemical Feed

Metal Salt Addition, Alkalinity Addition

Alkalinity Addition


SBR Chemical Phosphorus Removal

Example


AquaSBR


38

• 5.33 cycles/day/Basin– MF = 50 min.

– RF = 85 min.

– R = 50 min.

– S = 55 min.

– D = 30 min.

270 min. Total

• MLSS = 3,210 mg/L

• MLVSS = 2,735 mg/L

• DO Control Program

Blower Always ON

Set 3.5-4 mg/L

• pH Control Program

Setpoint – 6.58

Gain – 5 (0-10)

• Alum Addition Program

Dosage - 105 mg/L

Dick Creek WRF Operation:

Crocker & Associates, Inc.Aqua-Aerobic Systems, Inc.

pH Control System

• pH meter/controller for each SBR

• Caustic Feed pump skids with motorized valves

• Caustic added to SBRs during React-Fill and React cycles

• Flow rate of caustic is in response to SBR tank pH in

comparison to setpoint input through SBR control panel

interface

• Flow rate is adjusted according to a proportional-integral loop

• Caustic pump will shut off when the process variable reaches

an adjustable threshold of the desired setpoint

• Gain input value determines output reaction – high gain,

quicker response


Alum (or Polymer) Feed System

• Alum feed pump skid with motorized valves

• Volume of each batch calculated by pressure transducer level

indication at the end of React-Fill

• Quantity of alum fed is directly proportional to batch volume

• Alum dosage (mg/L) is input by Operator through SBR

control panel interface

• Calculated gallons of alum are paced into SBR through the

length of the React cycle minus an “end” Offset Time

• This Offset Time allows for React cycle mixing without alum

feed to ensure sufficient alum dispersion and phosphorus

precipitation prior to Settle phase


39

Dick Creek WRF – Sampling Data

Dick Creek WRF Direct Discharge Effluent Permit (Nov-Apr, 83.0 MG total):5 mg/L BOD, 5 mg/L TSS, 3 NTU, 1 mg/L NH3-N, 0.13 mg/L Total P


Influent

Pump

Station Screening AquaSBR®

PAC

Filtration

BOD5 < 4 mg/LNH3-N < 0.5 mg/LTotal P < 0.13 mg/L

High-Level SBR Treatment Process Flow


Grit Removal

Mag Meter

PAC

Inline Mixer Post-EQMag Meter Flow Control

Valve

UV

Effluent

Questions?


40

Superior Wastewater Treatment Utilizing SBR Technology

GRWA SBR Training

November 6, 2008

Stuart Humphries, Crocker & Associates, Inc.770-855-8090, [email protected]

www.crocker-associates.com, www.stuarthumphries.com

AQUA-AEROBIC

SYSTEMS, INC.

aquasbr sequencing batch reactor - stuarthumphries.com · sbr plc controls max/min d.o....

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