AquaSBR®

Sequencing Batch Reactor

Process

• What is the AquaSBR®?

• Five Phases of the AquaSBR®

• Cycle Structure

• Applications

• Summary

Presentation Outline

What is AquaSBR®?

• Sequencing Batch Reactor (SBR)

• Activated Sludge System

• True Batch Process

• Aqua MixAir® System – Independently

Controllable Aeration and Mixing

• Decanter – Floating, Subsurface Withdrawal

• Controls – Time Based with Level Overrides

Flow Through Activated Sludge System

Aeration and Mixing Biological Processes Filtration Membranes Controls

AquaSBR® System

AquaSBR® System

RAS

Time Based vs. Multi-Stage Systems

• Equalization

• Aeration

• Denitrification

• Sludge Wasting

• Anoxic Mix

• ClarificationTime

Animate

Five Phases of the AquaSBR®

• Mixed Fill • React Fill • React • Settle • Decant/Sludge Waste/ Idle

Time Based Operation

Increased Operator Control

Mix Fill React Fill React Settle

React Settle Decant Mix Fill React Fill

SBR 1

SBR 2

Decant

ONE (1) TREATMENT CYCLE

React

Mix Fill React

AquaSBR® - OperationCycle Structure Example

Aeration Timers Example

3-Basin Mode

R

MF

R

S

RF

S

D

R

D

MF

S

MF

RF

D

RF

R

1

2

3

Ba

sin

#

Phases

AquaExcel® - Characterize Waste

Variations in Flow

Animate

Cycle Structure

Mixed Fill

Six Phases of AquaSBR®

• Anoxic / Anaerobic Mixing • Denitrification • Phosphorus Release

• Filament Control

React Fill

• Mixing and Aeration • Nitrification • BOD/COD Removal

• Phosphorus Uptake • Denitrification

React

• Mixing and Aeration • True Batch Reaction • Nitrification

• BOD/COD Removal • Effluent Polishing

Metal Salt Addition (as required)

Settle

• Quiescent Environment • No Entrance / Exit Flow • Adjustable

Decant/Sludge Waste/Idle

SBR Total

• Supernatant Removal • Continued Settling • Subsurface Withdrawal

• Follows Liquid Level • Sludge Removal • Maintains Constant Cycle Duration

Biological Nutrient Removal

BNR

Nitrogen

Source of Nitrogen

• Prevalent in wastewater: Organic,

Nitrates and Ammonium

• Domestic wastewater contains

Ammonium and Organic (TKN)

• From protein metabolism in human

body.

• Typically 20 to 85 mg/l

• Ammonia toxic to aquatic organisms

• Nitrates Health Hazard if consume by

infants

• In all forms contribute to Eutrophication

• High NO2- interferes with Cl- disinfection

(Nitrite Log)

Why Remove Nitrogen?

• Biological Treatment Processes (oxidation

by living organisms):

– Assimilation

– Nitrification

– Denitrification

Nitrogen Removal

Bacterial Decomposition

and Hydrolisis

Assimilation

AssimilationAutooxidation

and Lysis

Refractory1 - 2 mg/l as N

Organic Nitrogen(Proteins; Urea)

Organic Nitrogen(Net Growth)

Organic Nitrogen(Bacterial Cell)

Ammonia Nitrogen

Assimilation

O2

O2

Nitrate (NO3-N)

Nitrite (NO2-N)

Ammonia Nitrogen

Nitrification

Nitrification

– Optimum pH 7.0 - 8.0

– Consume 4.6 lbs O2/lbs NH3-N

converted

– D.O. > 2.0

– Consume 7.14 mg/l alkalinity

Characteristics

Organic Carbon Absence of O2

Nitrogen Gas (N2)

Nitrate (NO3-N)

Denitrification

Denitrification

– Optimum pH 7.0 - 8.0

– Recovers 2.86 lbs O2/lb NO3-N

converted

– D.O. < 0.5 mg/l

– Recovers 0.5 mg/l alkalinity per mg/l of

NO3-N denitrified

Characteristics

• Physical/Chemical Processes

(Not Necessary in Activated Sludge Processes):

– Breakpoint Chlorination

– Selective Ion Exchange

– Air Stripping

Nitrogen Removal

Phosphorus

• Fecal and Waste Materials

• Carriage Water

• Industrial and Commercial Uses

• Synthetic Detergents and Cleaning

Products

• Typical Range 4-8 mg/l

Sources of Phosphorus

• Contribute to massive aquatic plant growth

• Contribute to Eutrophication

Why Remove Phosphorus?

Division of the Influent P

Into Constituent Fractions

TOTAL INFLUENT P

ORTHOPHOSPHATEReactive P (PO 4 -3)

PredominantORGANIC PHOSPHATES

POLY PHOSPHATES(Condensed Phosphates)

1. Organic / Hydrolyzable

Phosphates:

These are organically bound and poly-

phosphates. These forms of phosphorus

are not removable by either ferric chloride

or alum addition. The only current means

of reduction of this fraction is through

optimization of the biological treatment

process.

2. Orthophosphates:

This is the reactive form of phosphorus.

It is the ONLY form of phosphorus whose

removal can be enhanced by either ferric

chloride or alum addition.

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

• Goal: Incorporate Phosphate into TSS

• Conventional: 1-2% P in W.A.S.

• Augmented: 3-6% P in W.A.S.

– Chemical

– Biological

Available Removal Options

• Incorporate P into Sludge

• Reduce Metal Salt Costs

• Reduce Polymer Costs

• Reduce Alkalinity Costs

• Denitrification Side Benefit

Biological Phosphorus Removal (BPR)

Aqua-Aerobic Systems, Inc.

Biological Phosphorus Removal

• Bacteria Storage Capacity

• Anaerobic: Removal of Fermentation

Substrates (VFA)

• Re-aeration: Store Phosphorus

BPR: Basic Features

• Dissolved Oxygen =< 0.5 mg/l

• Nitrates < 8-12 mg/l

• Substrate Availability

– Soluble Organics

– Volatile Fatty Acids (VFA)

BPR: Reactor Conditions

• Provision for Chemicals in Aeration Basin

and Digester

• Sludge Supernatant

• Introduction of Nitrates

• Alkalinity Depletion

BPR: Design Considerations

Aqua-Aerobic Systems, Inc.

• Goal: Create insoluble forms of P

• Basic Elements to Precipitate P

– Ferrous Iron (FeII)

– Ferric Iron (FeIII)

– Aluminum (AlII)

Chemical Phosphorus Removal

• Alum Al2(SO4)3-18H2O

• Ferric Chloride FeCl3• Poly Aluminum Chloride

Common Chemicals Used

Aqua-Aerobic Systems, Inc.

% P Reduction Mg Al per mg P

75

85

95

1.2

1.5

2.0

Aluminum Dosage as a Function of Ortho-phosphate Removal

Aluminum Coagulation (Alum)

Al(3+) + PO4(3-) AlPO4

Iron Coagulation (Ferric)

Fe(3+) + PO4(3-) FePO4

Chemical Coagulation

Aqua-Aerobic Systems, Inc.

Effect of pH on Equilibrium Ortho-PO4

• Primary Treatment: 1-3 mg/l

• After Secondary Treatment: 1-3 mg/l

• Combined Introduction: 0.5-1.0 mg/l

• Tertiary Treatment: <0.5 mg/l

Chemical Dosage Points

< 2.0 mg/l

< 1.0 mg/l

< 0.5 mg/l

< 0.2 mg/l

< 0.13 mg/l (GA)

Typical Effluent Total Phosphorus Levels

Aqua-Aerobic Systems, Inc.

Effluent Total-P < 2.0 mg/l

Bio-P Removal

Aqua-Aerobic Systems, Inc.

Bio-P Removal

Single-Point Metal Salt Addition

Tertiary Filtration

Effluent Total-P < 1.0 mg/l

Aqua-Aerobic Systems, Inc.

Bio-P Removal

Single Point Metal Salt Addition

Organic Polymer Addition

Tertiary Filtration

Effluent Total Phosphorus < 0.5 mg/l

Aqua-Aerobic Systems, Inc.

Bio-P Removal

Multiple-Point Metal Salt Addition

Organic Polymer Addition

Tertiary Filtration

Effluent Total Phosphorus < 0.2 mg/l

As P: 1.0 mg/l P = 3.066 mg/l PO4

As PO4: 1.0 mg/l PO4 = 0.326 mg/l P

Note: Although the Total phosphorus can be

reported as PO4, all species still may be present.

Reporting Phosphorus

AquaSBR®

How to Control BNR in the AquaSBR®

D. O. Control

AquaSBR® - Oxygen

AquaSBR® - BOD5

AquaSBR® - NH3-N

AquaSBR® - NO3-N

AquaSBR® - Total P

AquaSBR® - O.U.R

Process Control Process Control

RecommendationsRecommendations

Process Recommendations

• Influent and effluent samples in middle of channel or basin (To avoid interference)

• Measure MLSS at LWL or convert to LWL equivalent

• Target to maintain consistent MLSS with consideration for temperature variation. (Sludge wasting time)

• Set aeration timers based on % of design load, while leaving slight excess air to handle variations in load

• Target D.O. no higher than 4 mg/l during aerated phases (DO Profile)

• Target consistent pH (6.5-7.5) and avoid drastic changes in pH through the SBR

• Recommend sludge judge in SBR during Settle as way to check supernate depth

• If Settling poorly, lengthen Settle and consider increased wasting if MLSS is unnecessarily high

• If effluent BOD is high, consider more MLSS or more aeration time

Process Recommendations

• Rule of thumb, plants can run all tanks at >15% of design load

• Food addition may be required at high hydraulic loading and low organic loading

• Check for possible toxic compounds in the influent wastewater

• Nutrient addition in a rate of 100:5:1 (BOD:N:P)

Process Recommendations

Aqua-Aerobic Systems, Inc.

Sampling

- Visual Inspection

- Take MLSS sample (Preferably at the

beginning of MF)

- Settle-o-meter (Preferably at end of R)

- Microscopic Evaluation

Process Control Process Control

and and

TroubleshootingTroubleshooting

Process Considerations

� We cannot control the influent parameters

� We can control the environment to favor good microbiology.

� The “paper” design is usually based on a future flow.

� Consider the actual influent load (% of design loading)

� The target MLSS, sludge wasting and aeration should be adjusted proportionally based on the actual load.

� Treatment Cycles / Day:

� Hydraulic decision

� Hydraulic underloading allows for reducing cycles while hydraulic overload leads to more cycles

� Fill phase times must be equal to non-fill phase times for dual basin systems

� Aeration time <= 1/2 cycle time for shared blower systems

� Aeration counter changes are separate from cycle changes

Process Considerations

Plant Operation

� Current Organic Loading vs. Design

� F/M

� DO Profile

� Settling Test

� Sludge Age

� SVI

� OUR and SOUR

� Microorganisms

� Effluent Values

• % Design = Current Qavg x Current BOD5

Design Qavg x Design BOD5

• Control and operation of the aeration system and the reactor’s biomass will depend on the percent loading of the system

• Calculate target MLSS concentration based on % of design loading. Adjust wasting as required.

Organic Loading

• F/M = Qavg x BOD .

(MLSSLWL x LWLVol x No. Basins)

• Target 0.04 - 0.09 for typical domestic, depending on the % of design loading.

• Sludge wasting time

• Calculate with MLSS at LWL

Food To Mass Ratio

Dissolved Oxygen Control

� Calculate Influent Loadings

� Program Aeration counters as function of design organic loading

� DO Profiles should be performed weekly

� Inline D.O. Control would automatically react to changes load

� Nitrification DO>= 2mg/l

� Denitrification DO<= 0.5 mg/l

Settleability

� Run settleometer test near end of React phase just before Settle, test 3x/week

� Important to visually estimate settleability in basin as well

� Sludge judge or sludge interface detector

Good Settling (Clean with rate of 400 ml after 30 min)

Slow Settling

� Filamentous bacteria

� High MLSS concentrations (> 6000 mg/l)

� Low sludge age

� Lack of nutrients (N or P)

� Low pH

Slow Settling (Clean but with rate of 650 ml after 60 min)

Rapid Settling

� Long sludge age

� Toxic shock to biomass

� Low MLSS

Poor Settling (Settled quickly, leaving solids

behind)

Rising Sludge

� Denitrification

� Incorporate anoxic time to promote denitrification

� Basin vs. Settlometer

Poor Settling due to denite or filaments

• SVI = Interface Height 30 min (ml/l) x 1,000 (mg/g)

MLSS (mg/l)

• Target 75 – 150 with a reasonable settling speed.

Sludge Volume Index (SVI)

• Ts = Total Lbs. TSS .

(Lbs. TSS Effluent/day) + (Lbs. waste sludge/day)

• Target 15 – 30 days, depending on % of design loading

• Sludge Wasting time

Sludge Age

• OUR = (DOi – DOf) mg/l x 60 min/hr(Tf – Ti) min

• Expressed in mg/l/hr

• Can be done in 10 to 15 minutes. For DOi and DOf do not take into account the first and last readings after blower is off.

• Convert to SOUR by multiplying by 1000 mg/g and dividing by the MLVSS (mg/l) at the time taken.

• Normal SOUR range = 6 – 12 mg/hr/g

Oxygen Uptake Rate (OUR)

Microorganism Identification

� Function of sludge age

� Young = lower life forms

� Old = higher life forms

� Balance is the key

Microorganism Identification

Microorganism Identification

Microorganism Vs. Sludge Quality

Amoeba (Sign of a young sludge)

Amoeba

Flagellate

Crawling Ciliates

Free Swimming Ciliates

Stalk Ciliates

Multiheaded Stalk Ciliates

Rotifer (Sign of a longer sludge age)

Rotifer (Note forked tail)

Nematode (Indicating a long sludge age)

Amoeba, Green Flagellate, Rotifer and Stalk Ciliate

Filaments (overabundance leads to

poor settling)

React

Mix Fill React

Activated Sludge System

Settling Problems

React

Most Common Causes for

Settling Problem

- High MLSS concentration

- Young Sludge (No Floc Forming)

- Filamentous Bulking

- Poor Floc Formation

- Toxicity

- Polysaccharide Bulking

React

Mix Fill React

Filamentous Bulking

- Over 25 Different Types

- Usually Three or More Types Present

- Quantify Under Microscope

- Visually Inspect Basin for Foam

React

Mix Fill React

Filamentous Bulking

- Old Sludge (Nocardia – Common)

- Low F/M ratio

- Low DO (S. Natans and Type 1701 – Common)

- Low pH (Fungi)

- Lack of Nutrient

- Dissolved Oxygen

- Septicity

- Oil and Grease

- Filaments in Digester Re-circulated

React

Mix Fill React

Poor Floc Formation

- High F/M Ratio (Fast Growth ratio)

- Very Low F/M ratio (Starvation – Pin Floc)

- High Sludge Age

Toxicity

- Sulfide Toxicity (Septicity)

- Direct Toxic Discharge to Plant

React

Mix Fill React

Polysaccharide Overproduction

(Slime Bulking)

- DO deficiency

- High F/M ratio

- Nutrient Deficiency

React

Mix Fill React

Filament Control

- May Occur at any time

- Need to control Immediately

- Provide Long Term Control

- Remove Causative Agent

React

Mix Fill React

Filament Control Methods

- Short Term Control

- Coagulants

- Flocculants

- Chlorination

Reactor: 3 – 5 lbs Cl2 per 1000 lb MLSS

Digester: 7 – 10 lbs Cl2 per 1000 lb MLSS

React

Mix Fill React

Filament Control Methods

- Long Term Control

- Change Environment

- Cycle Structure

- Sludge wasting

- D.O.

- F/M

- pH, etc.

- Nutrient Addition (If Required)

React

Mix Fill React AquaSBR®

Troubleshooting

Examples

� Plant operates through the summer at F/M of 0.1, and MLSS of 2,000. The plant has an effluent ammonia target of 1.0 mg/l. As temperature cools, effluent NH3 values increase. D.O. profiles show D.O. peaking at 1 mg/l during React Phase.

� What should the operator do?

Nitrification

� A plant has an effluent Total Nitrogen target of 5.0 mg/l. The system is achieving an effluent Total N of 12 mg/l with an effluent ammonia of < 1.0 mg/l. D.O. profiles show D.O. varying between 2.0 and 5.0 mg/l React Fill and React Phase.

� What should the operator do?

Denitrification

Example

� Plant designed for 0.3 MGD Avg. Flow with influent 300/300 BOD/TSS

� Design F/M of 0.06 with MLSS of 4500 and two basins operating 5 cycle/day/basin

� Actual Influent 15,000 gpd with influent of 300/300 BOD/TSS

� How would you operate the plant?

� Example:

� Settleometer shows rate of 950 ml/l after 30 minutes.

� Basin has brown foam 6-12 inches thick

� D.O. 3-4 mg/l during React phase.

� What steps does the operator need to take?

Slow Settling

Questions