Wastewater Design & Best Practices

Transcription

1 Wastewater Design & Best Practices American Meat Institute Conference on Worker Safety, Human Resources and the Environment Kansas City, Missouri Brian Mulinix, P.E. Brian Bakke, P.E. HDR Engineering, Inc. March 20, 2013

2 Overview Wastewater what are we treating Preliminary Treatment Anaerobic Treatment Aerobic Treatment Nitrogen Removal Phosphorus Removal Tertiary Treatment

3 What Are We Treating? BOD 5 TSS FOG TKN Phosphorus OR OR Proteins Fats Carbohydrates Partially-Digested Feed Manure Urine

4 What are We Treating? Slaughterhouse Proteins (blood, meat, etc.) Fat Partially digested feed from stomachs and intestines Manure from pens Urine from pens, kidneys, bladders, etc. Processing Proteins Fat Carbohydrates Animal Feeding Operations Manure Urine Some uneaten feed (protein, carbs, fat/oil)

5 What Type of Food is Being Treated? Example Protein Fat Carbohydrates Slaughterhouse Processing Hams Some Some (from the pickle liquor) Bacon Little (from the pickle liquor) Cooked Sausage Little Chicken-Fried Steaks (from the breading) Rendering Ready-to-Eat Foods Some Some (noodles, sauces, seasonings, etc )

6 Pretreatment Can Shift Type of Food DAF reduces fat and some protein Ferric pretreatment greatly reduces both fat and protein Many carbohydrates Go into true solution Unaffected by physical or chemical pretreatment

7 Determine Waste Loads from Food Protein BOD 5 = TKN x 6.25 x 0.8 Fat BOD 5 = FOG x ( 1.7± ) Carbohydrate BOD 5 = Total BOD 5 Protein BOD 5 Fat BOD 5

8 Why is Type of Food Important? Anaerobic Sludge Production ph Buffering Proteins make their own alkalinity Fats and carbs require alkalinity for buffering Nutrient Requirements Proteins are a complete food source Fats and carbs are deficient in nutrients and micronutrients Different Physical Characteristics Fats may coat media, float Fat Protein Carbs

9 Swine Farms are Slightly Different Swine farm waste is similar to human waste without the dilution water Virtually everything has been through digestive or urinary tract Pigs have utilized much of readily-digestible food (energy), leaving less easily-digestible to treat

10 What is Your Discharge Requirement? Municipality Limits specific to system Surcharges Land Application Agronomic rates Direct Discharge Effluent guidelines Nutrient limits

11 PRETREATMENT

12 Screening Remove solid materials, prevent avoidable BOD and TSS Types: Static Screens Vibrating Screens Rotary Screens Channel Screens

13 Gravity Clarifiers Removal BOD 20-30% TSS 30-40% TKN 10-20% FOG 50-60%

14 Dissolved Air Flotation Removal Without Chemicals With Chemicals BOD 30-40% 60-80% TSS 50-60% 70-80% TKN 20-30% 40-60% FOG 50-70% 70-90%

15 ANAEROBICTREATMENT

16 Anaerobic Treatment A Marvelous Tool Reduce CBOD 5 by 85-90% Reduce TSS by 70-80% Biogas produced containing 74±% Accept/treat shock organic loads Serves as equalization Accomplishes with minimal energy required and minimal sludge production

17 Anaerobic Degradation of Organic Materials Complex Organics Acid-Forming Bacteria Organic Acids Methane-Forming Bacteria Methane + CO2+ small amt. Cell Mass Waste Conversion (minimal energy lost, minimal BOD reduction) Waste Stabilization (waste energy converted to methane energy, big BOD reduction)

18 Anaerobic Treatment Technologies Low Rate Anaerobic lagoon Medium Rate Anaerobic contact system Anaerobic SBR High Rate Upflow Anaerobic Sludge Bed (UASB) Anaerobic filters; upflow, downflow, expanded bed Hybrids

19 Anaerobic Treatment Comparison Process/Reactor Low Rate Medium Rate High Rate Lagoon Contact process ASBR UASB Filters Loading, lbs BOD5/1000 ft 3 /day > HRT,days SRT, days unknown, but long >20 >30 > In summary, anaerobic lagoon is lightly loaded with a long detention time and sludge age and all the more robust for it

20 Covered Anaerobic Lagoon Synthetic or Natural Cover Storm Water Collection Peripheral Biogas Collection

21 Design Considerations / Common Operating Problems Solids Accumulation FOG at lagoon < 350 mg/l Prevent sand, mud, grit, paunch manure, pen waste, truck bedding, etcl keep out of lagoon Measure/plot grease cover and settled sludge thickness Spring, Summer and Fall Remove sludge every Fall to maximize active volume < 15% of WAS digests in lagoon, serves more for thickening; remove WAS sent 1-2X/year

22 Design Considerations / Common Operating Problems (cont.) Anaerobic Temperatures Ideally 95 F Can go as low F, or lower for shorter periods Chemicals Chlorides: sudden swings of > 1,200 mg/l may disrupt anaerobic treatment Processing plants with brine chills, pickle liquors Beef plants with brine hide curing

23 Design Considerations / Common Operating Problems (cont.) Chemicals (cont.) Sulfates/Sulfides Sulfates typically from water supply Ferric sulfate in pretreatment Processing mucosa Tannery wastewater Sulfates in anaerobic influent reduced to hydrogen sulfide Reduces methane generation At high concentrations can be toxic to methanogens» Rule of thumb COD:S < 4:1 Most in effluent, but released in biogas (depending on ph and temperature) For every 26 mg/l H 2 S in the liquid, 1% in gas phase (35⁰C) For each 1 mg/l sulfide in effluent, requires 2 mg/l of dissolved oxygen to oxide back to sulfate Can use ferric/ferrous to tie up sulfide

24 Design Considerations / Common Operating Problems (cont.) Chemicals (cont.) Quaternary Ammonium Compounds (Quat) Inhibitory levels at 5-15 mg/l active ingred. Macronutrients: nitrogen, phosphorus, potassium Micronutrients Cobalt, copper, manganese, molybdenum, nickel (0.1 mg/l deficient) Iron (1.0 mg/l deficient)

25 Meat Processing Plant Anaerobic Lagoon Effluent CBOD mg/l Volatile Acids TEMP (ºF) Micronutrient Addition /4/07 4/15/07 5/27/07 7/8/07 8/19/07 9/30/07 11/11/07 12/23/07 2/3/08 3/16/08 4/27/08 6/8/08 7/20/08 8/31/08 10/12/08 11/23/08 1/4/09 2/15/09 3/29/09 5/10/09 6/21/09 8/2/09 9/13/09 10/25/09 12/6/09 1/17/10 2/28/10 4/11/10 5/23/10 CBOD (mg/l) Temperature ( F)

26 Anaerobic Lagoon Operating Problems Reactions to upsets, not causes: Drop in biogas production Low ph Increase in ORP High volatile acids Increased acid:alkalinity ratio If performing poorly, check: New plant operations, like processing mucosa Temperature Quats Sudden chloride swings Nutrients and micronutrients

27 AEROBICLAGOONTREATMENT

28 Aerated Lagoons/Basins Hydraulic and Sludge detention time 1-5 days Detention time, not oxygen transfer rate dictates size As CBOD 5 drops, TSS climbs due to microorganism growth

29 Aerated Lagoons/Basins Advantages Simple to operate No sludge to handle BOD reduction 50% in winter 75% in summer Convert anaerobic effluent to aerobic Nitrify NH 3 under certain conditions Disadvantages Electrical energy req d TSS increase Nitrification requires Longer detention time Temperatures > 50 F Small influent flows require vertical-wall tanks

30 ACTIVATEDSLUDGE NITROGENREMOVAL

31 Activated Sludge Process Influent Continuous or semi-continuous CBOD oxidation Nitrification Represents most wide-spread Aeration used in meat and poultry industries Conversion into settleable solids Develop ideal biomass Balance of floc and filamentforming organisms Clarification Biomass Recycle Biomass Waste Effluent Activated Sludge is like a loop with no beginning and no end

32 BOD Only Activated Sludge Design Parameters to consider Dissolved oxygen supply Maintain 2.0 mg/l DO Alkalinity Maintain ph Detention/contact time 4 to 8 hours Mixed Liquor Concentration 2,000 to 3,000 mg/l Oxygen Uptake Rate 40 to 50 mg/l/hour Sludge age 1 to 3 days Temperature range 10 to 30 deg. C. Consumes: 1.1 g O 2 / g BOD

33 Typical Meat Industry Activated Sludge Anaerobic Influent Anaerobic Effluent Pork/Beef Poultry Meat Proc. Pork/Beef Poultry Meat Proc. CBOD 5 (mg/l) TKN (mg/l) Nitrate/Nitrite(mg/L) Phosphorus (mg/l) BOD:N:P 100:10: :10: :10: :60:10 100:50:10 100:40:14 Anaerobic Lagoon Aeration Basin Final Clarification RAS WAS

34 Ammonia Nitrification 2-step conversion Ammonia to Nitrite - Nitrosomonas Nitrite to Nitrate - Nitrobacter Design Parameters to consider Consumes: 4.57 g O 2 / g NH 4 -N 7.14 g AlkCaCO 3 / g NH 4 -N Dissolved oxygen supply Maintain 2.0 mg/l DO Alkalinity Maintain ph Detention/contact time 4 to 24 hours Mixed Liquor Concentration 3,000 to 5,000 mg/l Oxygen Uptake Rate 40 to 50 mg/l/hour Sludge age 8 to 15 days depending on temperature Temperature range 10 to 30 deg. C.

35 Traditional Nitrification/Denitrification Autotrophs Nitrification-Aerobic 25% O 2 1 mol Nitrate (NO 3 -) 40% Carbon (BOD) Heterotrophs Denitrification-Anoxic 1 mol Nitrite (NO 2 -) 1 mol Nitrite (NO 2 -) 60% Carbon (BOD) 75% O 2 1 mol Ammonia (NH3/ NH4 +) ½ mol Nitrogen Gas (N 2 ) 4.57 g O 2 /g NH 4 -N oxidized g COD/g NO 3 -N reduced 7.14 g CaCO 3 /g NH 4 -N oxidized recover 3.57 g CaCO 3 /g NO 3 -N reduced

36 Nitrogen Removal Processes Single Stage Nitrification-Denitrification Simultaneous/Combined Nitrification Denitrification Sequential BOD-Nitrification-Denitrification Biological Options Suspended Growth Fixed Biofilm

37 Nitrogen Removal Processes - Classic Zoned Wuhrman Effluent: NH 4 -N < 1 mg/l TN < 10 mg/l Ludzack-Ettinger Modified Ludzack Etinger (MLE Process) Bardenpho (4 stage Phoredox) Step Feed Tilmann WRP, Los Angeles

38 Nitrif/Denitrif: +70% TN Removal Modified Ludzack-Ettinger(MLE) system From Anaerobic Lagoon Carbon Alkalinity Anoxic Basin Aeration Basin Final Clarifiers Mixed Liquor Return (4Q) (nitrate source) RAS (1Q) TN 200 mg/l WAS TN 40mg/L

39 Denitrification vs Recycle 100% 80% 60% 40% 20% 0% Recycle Ratio (RAS + MLSS)

40 Nitrif/Denitrif: 6-8 mg/l Effluent TN 4-Stage Bardenphosystem Carbon Carbon, Alkalinity From Anaerobic Lagoon Anoxic Basin Aeration Basin Post-Anoxic Basin Reaeration Basin Final Clarifiers Mixed Liquor Return (4Q) (nitrate source) TN 200 mg/l RAS (1Q) TN 40 mg/l WAS TN 7 mg/l

41 Pork Plant Effluent Nitrogen Influent TKN averaged 199 mg/l Effluent TN Total Nitrogen, mg/l Probably lost nitrification Switched from Final Clarifier to UF Membranes 0 1-Nov-08 3-Jan-09 7-Mar-09 9-May Jul Sep Nov Jan-10

42 Simultaneous Nitrification/Denitrification Biological process occurring concurrently in same reactor Relies on dynamic balance of DO/BOD/NH 3 Utilizes control of aeration by DO or ammonia concentration Reduces oxygen requirements and recovers alkalinity Total nitrogen removal

43 Simultaneous Nit/Denit Autotrophs Nitrification-Aerobic 25% O 2 1 mol Nitrate (NO 3 -) 40% Carbon Heterotrophs Denitrification-Anoxic 1 mol Nitrite (NO 2 -) 1 mol Nitrite (NO 2 -) 60% Carbon 75% O 2 1 mol Ammonia (NH 3 / NH 4 + ) ½ mol Nitrogen Gas (N 2 ) 3.43 g O 2 /g NH 4 -N oxidized g COD/g NO 3 -N reduced 5.7 g CaCO 3 /g NH 4 -N oxidized recover 2.38 g CaCO 3 /g NO 2 -N reduced

44 Nitrogen Removal Simultaneous SBR Effluent: NH 4 -N < 4 mg/l TN < 6 mg/l Oxidation Ditch Biodenitro Cyclic Aeration Two Zone Activated Sludge with DO Control

45 Simultaneous Nit/Denit Target effluent NH 3 in first stage Target DO in first stage mg/l Denitrification dependent on DO control and BOD availability From Anaerobic Lagoon Carbon Alkalinity SND Basin NH3 / DO Control Post Aeration Final Clarifiers RAS (1Q) WAS

46 Simultaneous Nit/Denit Potential Advantages Elimination of separate tanks, internal recycle Simpler process design Reduction of carbon, oxygen, energy, and alkalinity consumption Potential Disadvantages Limited controlled aspects of the process Flocsizes Internal COD storage DO profile within floc Slower Growth Rates Larger Tank Sizes Sludge bulking, filamentous bacteria growth Complex instrumentation

47 Autotrophs Nitrification-Aerobic 25% O 2 Anammox 1 mol Nitrate (NO 3 -) 40% Carbon Heterotrophs Denitrification-Anoxic 1 mol Nitrite (NO 2 -) 1 mol Nitrite (NO 2 -) 60% Carbon 40-50% O 2 75% O 2 1 mol Ammonia (NH 3 / NH 4 + ) 1.83 g O 2 /g NH 3 -N oxidized 0 g COD/g NO 2 -N reduced 3.1 g CaCO 3 /g NH 3 -N oxidized ½ mol Nitrogen Gas (N 2 )

48 Definition Developed in Europe Bacteria Autrophic Use CO 2 as Carbon Growth Conditions Anaerobic/Anoxic Temperature C Very slow growers Long sludge age > 30 days NH 4 + : NO 2 - ratio 1 : 1.32 ph (neutral range) Nitrite (maintain at <40 mg/l) Free Ammonia (maintain at <10 mg/l) Once Grown Very Stable - Can be stored for months with no food.

49 Anammox Providers Paques BV Upflow gravity separation Anita Mox TM by Veolia Water Technologies Plastic biofilm carriers Similar to MBBR DEMON by World Water Works WAS cyclone separation SBR reactor

50 Anammox (DEMON ) Operational Philosophy 1 process cycle of the DEMON involves 4 timecontrolled phases: Aeration phase Fill / React phase Settling phase Discharge phase Standard Effluent 90% removal NH 4 -N 10% production NO 3 -N 80% removal TN

51 Full Scale Operation Regular sampling Sensors: ph, DO, conductivity, NH 3 -N Regular Operation DO range of mg/l (during aeration phase) ph typically 7.0 Avoidance nitrite accumulation Downtimes

52 DEMON Design Requirements Pretreatment Most BOD, TSS removed Pre-storage tank (6-12 hrs HRT) Design parameters Total/soluble COD, TKN, NH 3 -N, Alkalinity, PO 4 -P, TSS, Temperature, ph Flow (aver/max); sludge processing Tank reactor Operates as SBR, but can be continuous flow

53 DEMON Major Components Seed Sludge Aeration System Instruments & Controls Tank Blowers Decanter Mixer Cyclone

54 Comparison Nitrification/Denitrification DEMON -system NH4 NH4 Energy 1.27 kwh/lb N Energy 0.50 kwh/lb N C-source NO3 2.3 lb Methanol/lb N C-source NO2 / NH4 0 lb Methanol/lb N N2 N2 CO 2 emissions > 4.7 t CO2/t N CO 2 reduction -0.4 t CO2/t N

55 Demon Results - Sidestream Heidelberg, Germany 126,000 gal/day; 1,300 mg/l TN

56 PHOSPHORUSREMOVAL

57 Biological Phosphorus Removal Many Process Options Anaerobic Zone key to process Grow Phosphorus Accumulating Organisms (PAOs) Typically achieves <1.0 mg/l High influent Sol BOD/P is required carbon/vfa addition via fermentation Process stability is key. Conditions that favor the right PAO populations are need to be understood

58 Biological Phosphorus Removal Modified (5-stage) Bardenpho UCT Effluent: TP < 1 mg/l OP < 0.5mg/L Modified UCT VIP (Virginia Initiative Process)

59 Chemical Phosphorus Removal Chemical Options Ferric Salts (Ferric Chloride, Ferrous Chloride) Alum Sodium Aluminate Lime Reaction: FeCl 3 & PO 4 FePO 4 & 3Cl Dosage: Theory : 5.24 lbs FeCl 3 / lb P Actual: lbs FeCl 3 / lb P Rate: 3.1 gallons 30% FeCl 3 / lb P

60 Typical Chemical Treatment Opportunities Primary Secondary Tertiary Polish Solids Processing

61 TERTIARYTREATMENT

62 Tertiary Treatment Treatment Goal Remove additional TSS, TN, TP not captured in secondary treatment processes. Simple TSS Removal Tertiary Clarifier Cloth Filter Disk Sand Filter More Complex Membrane Bioreactor Ultra Filtration RO TN Removal Biologically Active Filter (BAF) Submerged Biofilter

63 Questions? Wastewater Design & Best Practices American Meat Institute Conference on Worker Safety, Human Resources and the Environment Kansas City, Missouri Brian Mulinix, P.E. Brian Bakke, P.E. HDR Engineering, Inc. March 20, 2013