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TRANSCRIPT
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