AquaSBR Sequencing Batch Reactor Process
Presentation Outline What is the AquaSBR? Five Phases of the AquaSBR Cycle Structure Applications Summary
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 Time Equalization Aeration Denitrification Sludge Wasting Anoxic Mix Clarification
Five Phases of the AquaSBR Mixed Fill React Fill React Settle Decant/Sludge Waste/ Idle Animate
Time Based Operation Increased Operator Control SBR 1 Mix Fill React Fill React Settle Decant React Settle Decant Mix Fill React Fill SBR 2 ONE (1) TREATMENT CYCLE
AquaSBR - Operation Cycle Structure Example Mix Fill 3-Basin Mode Phase s React 1 MF RF R S D Basin # 2 R 3React S R D MF S RF D MF R RF Aeration Timers Example
AquaExcel - Characterize Waste Variations in Flow
Cycle Structure Animate
Mixed Fill Anoxic / Anaerobic Mixing Denitrification Phosphorus Release Filament Control Six Phases of AquaSBR
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 Supernatant Removal Continued Settling Subsurface Withdrawal Follows Liquid Level Sludge Removal Maintains Constant Cycle Duration SBR Total
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
Why Remove Nitrogen? 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)
Nitrogen Removal Biological Treatment Processes (oxidation by living organisms): Assimilation Nitrification Denitrification
Assimilation Bacterial Decomposition and Hydrolisis Organic Nitrogen (Proteins; Urea) Refractory 1-2 mg/l as N Ammonia Nitrogen Assimilation Assimilation Organic Nitrogen (Bacterial Cell) Autooxidation and Lysis Organic Nitrogen (Net Growth)
Nitrification Ammonia Nitrogen O2 Nitrite (NO2-N) O2 Nitrate (NO3-N)
Characteristics 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
Denitrification Nitrate (NO3-N) Organic Carbon Absence of O2 Nitrogen Gas (N2)
Characteristics 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
Nitrogen Removal Physical/Chemical Processes (Not Necessary in Activated Sludge Processes): Breakpoint Chlorination Selective Ion Exchange Air Stripping
Phosphorus
Sources of Phosphorus Fecal and Waste Materials Carriage Water Industrial and Commercial Uses Synthetic Detergents and Cleaning Products Typical Range 4-8 mg/l
Why Remove Phosphorus? Contribute to massive aquatic plant growth Contribute to Eutrophication
Division of the Influent P Into Constituent Fractions TOTAL INFLUENT P ORTHOPHOSPHATE Reactive P (PO 4-3) Predominant ORGANIC PHOSPHATES POLY PHOSPHATES (Condensed Phosphates)
1. Organic / Hydrolyzable Phosphates: These are organically bound and polyphosphates. 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 2 5 10 15 P in Effluent TSS 0.06-0.10 0.15-0.25 0.3-0.5 0.45-0.75
Available Removal Options Goal: Incorporate Phosphate into TSS Conventional: 1-2% P in W.A.S. Augmented: 3-6% P in W.A.S. Chemical Biological
Biological Phosphorus Removal (BPR) Incorporate P into Sludge Reduce Metal Salt Costs Reduce Polymer Costs Reduce Alkalinity Costs Denitrification Side Benefit
Aqua-Aerobic Systems, Inc. Biological Phosphorus Removal
BPR: Basic Features Bacteria Storage Capacity Anaerobic: Removal of Fermentation Substrates (VFA) Re-aeration: Store Phosphorus
BPR: Reactor Conditions Dissolved Oxygen =< 0.5 mg/l Nitrates < 8-12 mg/l Substrate Availability Soluble Organics Volatile Fatty Acids (VFA)
BPR: Design Considerations Provision for Chemicals in Aeration Basin and Digester Sludge Supernatant Introduction of Nitrates Alkalinity Depletion
Aqua-Aerobic Systems, Inc. Chemical Phosphorus Removal Goal: Create insoluble forms of P Basic Elements to Precipitate P Ferrous Iron (Fe II ) Ferric Iron (Fe III ) Aluminum (Al II )
Common Chemicals Used Alum Al 2 (SO 4 ) 3-18H 2 O Ferric Chloride FeCl 3 Poly Aluminum Chloride
Aqua-Aerobic Systems, Inc. Aluminum Dosage as a Function of Ortho-phosphate Removal % P Reduction Mg Al per mg P 75 85 95 1.2 1.5 2.0
Chemical Coagulation Aluminum Coagulation (Alum) Al (3+) + PO 4 (3-) AlPO 4 Iron Coagulation (Ferric) Fe (3+) + PO 4 (3-) FePO 4
Aqua-Aerobic Systems, Inc. Effect of ph on Equilibrium Ortho-PO 4
Chemical Dosage Points 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
Typical Effluent Total Phosphorus Levels < 2.0 mg/l < 1.0 mg/l < 0.5 mg/l < 0.2 mg/l < 0.13 mg/l (GA)
Aqua-Aerobic Systems, Inc. Effluent Total-P < 2.0 mg/l Bio-P Removal
Aqua-Aerobic Systems, Inc. Effluent Total-P < 1.0 mg/l Bio-P Removal Single-Point Metal Salt Addition Tertiary Filtration
Aqua-Aerobic Systems, Inc. Effluent Total Phosphorus < 0.5 mg/l Bio-P Removal Single Point Metal Salt Addition Organic Polymer Addition Tertiary Filtration
Aqua-Aerobic Systems, Inc. Effluent Total Phosphorus < 0.2 mg/l Bio-P Removal Multiple-Point Metal Salt Addition Organic Polymer Addition Tertiary Filtration
Reporting Phosphorus As P: 1.0 mg/l P = 3.066 mg/l PO 4 As PO 4 : 1.0 mg/l PO 4 = 0.326 mg/l P Note: Although the Total phosphorus can be reported as PO 4, all species still may be present.
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 Recommendations
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)
Process Recommendations 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)
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 and Troubleshooting
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.
Process Considerations 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
Plant Operation Current Organic Loading vs. Design F/M DO Profile Settling Test Sludge Age SVI OUR and SOUR Microorganisms Effluent Values
Organic Loading % Design = Current Q avg x Current BOD 5 Design Q avg x Design BOD 5 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.
Food To Mass Ratio 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
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
Sludge Volume Index (SVI) SVI = Interface Height 30 min (ml/l) x 1,000 (mg/g) MLSS (mg/l) Target 75 150 with a reasonable settling speed.
Sludge Age Ts = Total Lbs. TSS. (Lbs. TSS Effluent/day) + (Lbs. waste sludge/day) Target 15 30 days, depending on % of design loading Sludge Wasting time
Oxygen Uptake Rate (OUR) 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
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)
Mix Fill React Activated Sludge System React Settling Problems
Most Common Causes for Settling Problem - High MLSS concentration React - Young Sludge (No Floc Forming) - Filamentous Bulking - Poor Floc Formation - Toxicity - Polysaccharide Bulking
Filamentous Bulking - Over 25 Different Types Mix Fill React React - Usually Three or More Types Present - Quantify Under Microscope - Visually Inspect Basin for Foam
Filamentous Bulking - Old Sludge (Nocardia Common) Mix Fill - Low F/M ratio - React Low ph (Fungi) React - Low DO (S. Natans and Type 1701 Common) - Lack of Nutrient - Dissolved Oxygen - Septicity - Oil and Grease - Filaments in Digester Re-circulated
Poor Floc Formation - High F/M Ratio (Fast Growth ratio) - Very Low F/M ratio (Starvation Pin Floc) Mix Fill - High Sludge Age React React Toxicity - Sulfide Toxicity (Septicity) - Direct Toxic Discharge to Plant
Polysaccharide Overproduction (Slime Bulking) - DO deficiency Mix Fill - High F/M ratio - Nutrient Deficiency React React
Filament Control - May Occur at any time Mix Fill React React - Need to control Immediately - Provide Long Term Control - Remove Causative Agent
Filament Control Methods - Short Term Control Mix Fill React - Coagulants - Flocculants - Chlorination React Reactor: 3 5 lbs Cl 2 per 1000 lb MLSS Digester: 7 10 lbs Cl 2 per 1000 lb MLSS
Filament Control Methods - Long Term Control Mix Fill React - Change Environment - Cycle Structure - Sludge wasting - D.O. - F/M - ph, etc. React - Nutrient Addition (If Required)
Mix Fill AquaSBR React React Troubleshooting Examples
Nitrification 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?
Denitrification 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?
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?
Slow Settling 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?
Questions