AquaSBR. Sequencing Batch Reactor Process

Transcription

1 AquaSBR Sequencing Batch Reactor Process

2 Presentation Outline What is the AquaSBR? Five Phases of the AquaSBR Cycle Structure Applications Summary

3 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

4 Flow Through Activated Sludge System Aeration and Mixing Biological Processes Filtration Membranes Controls

5 AquaSBR System

6 AquaSBR System RAS

7 Time Based vs. Multi-Stage Systems Time Equalization Aeration Denitrification Sludge Wasting Anoxic Mix Clarification

8 Five Phases of the AquaSBR Mixed Fill React Fill React Settle Decant/Sludge Waste/ Idle Animate

9 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

10 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

11 AquaExcel - Characterize Waste Variations in Flow

12 Cycle Structure Animate

13 Mixed Fill Anoxic / Anaerobic Mixing Denitrification Phosphorus Release Filament Control Six Phases of AquaSBR

14 React Fill Mixing and Aeration Nitrification BOD/COD Removal Phosphorus Uptake Denitrification

15 React Mixing and Aeration True Batch Reaction Nitrification BOD/COD Removal Effluent Polishing Metal Salt Addition (as required)

16 Settle Quiescent Environment No Entrance / Exit Flow Adjustable

17 Decant/Sludge Waste/Idle Supernatant Removal Continued Settling Subsurface Withdrawal Follows Liquid Level Sludge Removal Maintains Constant Cycle Duration SBR Total

18 Biological Nutrient Removal BNR

19 Nitrogen

20 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

21 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)

22 Nitrogen Removal Biological Treatment Processes (oxidation by living organisms): Assimilation Nitrification Denitrification

23 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)

24 Nitrification Ammonia Nitrogen O2 Nitrite (NO2-N) O2 Nitrate (NO3-N)

25 Characteristics Nitrification Optimum ph Consume 4.6 lbs O2/lbs NH3-N converted D.O. > 2.0 Consume 7.14 mg/l alkalinity

26 Denitrification Nitrate (NO3-N) Organic Carbon Absence of O2 Nitrogen Gas (N2)

27 Characteristics Denitrification Optimum ph 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

28 Nitrogen Removal Physical/Chemical Processes (Not Necessary in Activated Sludge Processes): Breakpoint Chlorination Selective Ion Exchange Air Stripping

29 Phosphorus

30 Sources of Phosphorus Fecal and Waste Materials Carriage Water Industrial and Commercial Uses Synthetic Detergents and Cleaning Products Typical Range 4-8 mg/l

31 Why Remove Phosphorus? Contribute to massive aquatic plant growth Contribute to Eutrophication

32 Division of the Influent P Into Constituent Fractions TOTAL INFLUENT P ORTHOPHOSPHATE Reactive P (PO 4-3) Predominant ORGANIC PHOSPHATES POLY PHOSPHATES (Condensed Phosphates)

33 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.

34 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.

35 Biological Solids are Typically 3-5% Phosphorus (No Chemical Involved) Effluent TSS P in Effluent TSS

36 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

37 Biological Phosphorus Removal (BPR) Incorporate P into Sludge Reduce Metal Salt Costs Reduce Polymer Costs Reduce Alkalinity Costs Denitrification Side Benefit

38 Aqua-Aerobic Systems, Inc. Biological Phosphorus Removal

39 BPR: Basic Features Bacteria Storage Capacity Anaerobic: Removal of Fermentation Substrates (VFA) Re-aeration: Store Phosphorus

40 BPR: Reactor Conditions Dissolved Oxygen =< 0.5 mg/l Nitrates < 8-12 mg/l Substrate Availability Soluble Organics Volatile Fatty Acids (VFA)

41 BPR: Design Considerations Provision for Chemicals in Aeration Basin and Digester Sludge Supernatant Introduction of Nitrates Alkalinity Depletion

42 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 )

43 Common Chemicals Used Alum Al 2 (SO 4 ) 3-18H 2 O Ferric Chloride FeCl 3 Poly Aluminum Chloride

44 Aqua-Aerobic Systems, Inc. Aluminum Dosage as a Function of Ortho-phosphate Removal % P Reduction Mg Al per mg P

45 Chemical Coagulation Aluminum Coagulation (Alum) Al (3+) + PO 4 (3-) AlPO 4 Iron Coagulation (Ferric) Fe (3+) + PO 4 (3-) FePO 4

46 Aqua-Aerobic Systems, Inc. Effect of ph on Equilibrium Ortho-PO 4

47 Chemical Dosage Points Primary Treatment: 1-3 mg/l After Secondary Treatment: 1-3 mg/l Combined Introduction: mg/l Tertiary Treatment: <0.5 mg/l

48 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)

49 Aqua-Aerobic Systems, Inc. Effluent Total-P < 2.0 mg/l Bio-P Removal

50 Aqua-Aerobic Systems, Inc. Effluent Total-P < 1.0 mg/l Bio-P Removal Single-Point Metal Salt Addition Tertiary Filtration

51 Aqua-Aerobic Systems, Inc. Effluent Total Phosphorus < 0.5 mg/l Bio-P Removal Single Point Metal Salt Addition Organic Polymer Addition Tertiary Filtration

52 Aqua-Aerobic Systems, Inc. Effluent Total Phosphorus < 0.2 mg/l Bio-P Removal Multiple-Point Metal Salt Addition Organic Polymer Addition Tertiary Filtration

53 Reporting Phosphorus As P: 1.0 mg/l P = mg/l PO 4 As PO 4 : 1.0 mg/l PO 4 = mg/l P Note: Although the Total phosphorus can be reported as PO 4, all species still may be present.

54 AquaSBR How to Control BNR in the AquaSBR

55 D. O. Control

56 AquaSBR - Oxygen

57 AquaSBR - BOD5

58 AquaSBR - NH3-N

59 AquaSBR - NO3-N

60 AquaSBR - Total P

61 AquaSBR - O.U.R

62 Process Control Recommendations

63 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)

64 Process Recommendations Target consistent ph ( ) 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

65 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)

66 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

67 Process Control and Troubleshooting

68 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.

69 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

70 Plant Operation Current Organic Loading vs. Design F/M DO Profile Settling Test Sludge Age SVI OUR and SOUR Microorganisms Effluent Values

71 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.

72 Food To Mass Ratio F/M = Qavg x BOD. (MLSSLWL x LWLVol x No. Basins) Target for typical domestic, depending on the % of design loading. Sludge wasting time Calculate with MLSS at LWL

73 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

74 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

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

76 Slow Settling Filamentous bacteria High MLSS concentrations (> 6000 mg/l) Low sludge age Lack of nutrients (N or P) Low ph

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

78 Rapid Settling Long sludge age Toxic shock to biomass Low MLSS

79 Poor Settling (Settled quickly, leaving solids behind)

80 Rising Sludge Denitrification Incorporate anoxic time to promote denitrification Basin vs. Settlometer

81 Poor Settling due to denite or filaments

82 Sludge Volume Index (SVI) SVI = Interface Height 30 min (ml/l) x 1,000 (mg/g) MLSS (mg/l) Target with a reasonable settling speed.

83 Sludge Age Ts = Total Lbs. TSS. (Lbs. TSS Effluent/day) + (Lbs. waste sludge/day) Target days, depending on % of design loading Sludge Wasting time

84 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

85 Microorganism Identification Function of sludge age Young = lower life forms Old = higher life forms Balance is the key

86 Microorganism Identification

87 Microorganism Identification

88 Microorganism Vs. Sludge Quality

89 Amoeba (Sign of a young sludge)

90 Amoeba

91 Flagellate

92 Crawling Ciliates

93 Free Swimming Ciliates

94 Stalk Ciliates

95 Multiheaded Stalk Ciliates

96 Rotifer (Sign of a longer sludge age)

97 Rotifer (Note forked tail)

98 Nematode (Indicating a long sludge age)

99 Amoeba, Green Flagellate, Rotifer and Stalk Ciliate

100 Filaments (overabundance leads to poor settling)

101 Mix Fill React Activated Sludge System React Settling Problems

102 Most Common Causes for Settling Problem - High MLSS concentration React - Young Sludge (No Floc Forming) - Filamentous Bulking - Poor Floc Formation - Toxicity - Polysaccharide Bulking

103 Filamentous Bulking - Over 25 Different Types Mix Fill React React - Usually Three or More Types Present - Quantify Under Microscope - Visually Inspect Basin for Foam

104 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

105 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

106 Polysaccharide Overproduction (Slime Bulking) - DO deficiency Mix Fill - High F/M ratio - Nutrient Deficiency React React

107 Filament Control - May Occur at any time Mix Fill React React - Need to control Immediately - Provide Long Term Control - Remove Causative Agent

108 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

109 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)

110 Mix Fill AquaSBR React React Troubleshooting Examples

111 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?

112 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?

113 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?

114 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?

115 Questions