Impacts of Odor Control Chemistries on FM Pumping Efficiency and ARV Emissions Part One New Puzzle Pieces

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Bruce Perry
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1 Impacts of Odor Control Chemistries on FM Pumping Efficiency and ARV Emissions Part One New Puzzle Pieces Matthew Madolora Director of Technology Water Utilities Sector

2 Overview and Objectives Acknowledgments Case Study Adventure FM and ARV Basic Operational Principles Common Odor Control Chemistries Mechanisms Odor Control Total Gas Production

3 Acknowledgements Special thanks to: David Pickard, Fmr Plant Manager, Tampa James Elsey, Premier Magnesia Dr. Alan Bowers, Vanderbilt Cities: Fayetteville, NC; Rome, GA; Ohio WEA

4 Case Study Adventure During an odor control comparison study, a question was asked of me: Can changing odor control treatment chemistry affect FM pumping efficiency and ARV operation? Why do you ask?

5 Case Study Adventure Nitrate Have you seen this before? Is this even possible? Magnesia

6 Case Study Adventure Why do you ask? PS/LS Operation Changes Total Runtimes Total Starts Stops Lead-Lag Operation ARV Operation Changes Frequency Duration Total Volumes Gas Characteristics Metered Flow

7 FM and ARV Basics A brief refresher of force mains and air/relief valves to set the stage

8 FM Force Mains The key elements of force mains are: Pipe Valves Pressure surge control devices Force main cleaning system Pumps

9 FM Force Mains

10 FM Force Mains

11 FM Force Mains Forcemains: Main Purpose is to convey wastewater from point A to point B Must overcome Friction Losses Blockages Head Pressure

12 FM Force Mains Forcemains: Odor Potential Length of Pipe Detention Time Slime Layer Emission Points Subject to changing pressure and chemistry

13 FM Force Mains Forcemains: Typically establish patterns for regular diurnal flow Daily Runtimes (Weekday, Weekend) Daily Start/Stops Duration Frequency Daily Flow

14 FM Force Mains At Peak Flows: Cycle frequency and duration increase Daily Runtimes and #Starts should be relatively consistent

15 FM and ARV Basics Air accumulation can affect pumping efficiency And usually factors into the regular patterns BUT Loss in pumping efficiency is more commonly attributed to: Blockages (FOG, Debris, etc) Pump wear

16 Air Relief Valve Basics A brief review of ARVs from our friends in Ohio How air accumulates in a Force Main (FM) How Air Release, Pressure Release Valves work (ARV)

17 FM and ARV Basics

18 FM and ARV Basics

19 FM and ARV Basics

20 FM and ARV Basics

21 FM and ARV Basics

22 FM and ARV Basics

23 ARV Basics (Combo) ARV Operation

24 FM and ARV Basics But what about gases that may form biologically? And how might gases be affected by various odor control chemistries?

25 ARV Basics Air Accumulation Affects pumping efficiency Odor Generation Increases corrosion potential

26 ARV Basics Biological generation and accumulation of gases ongoing

27 ARV Basics ARV Operation Releases compressed and concentrated sewer gas into atmosphere Odor compounds diluted into atmosphere Carbon or biofilters polish odor causing compounds

28 FM and ARV Basics Mechanical Entry/Release Turbulent Flow Conditions Absent from Sources: Biogenic Gases H 2 S, N 2, CO 2, VOSCs, CH 4, NH 3 Chemical Effects on Gases ph, Chemical Reaction/Reducing Agents

29 Biogenic Gases

30 Biogenic Gases

31 Biogenic Gases CO 2

32 Biogenic Gases NO 3 - N 2

33 Biogenic Gases How they Form: H 2 S Anaerobic Conditions, SRBs H 2 S H + + HS - 2H + + S -2 VOSCs Anaerobic Conditions, SRBs R-HS, DMS, DMDS CH 4 Anaerobic Conditions N 2 Denitrification (Anoxic conversion) 6 NO CH 3 OH 5 CO N H 2 O + 6 OH - NH 3 Organic Waste, Digestion NH 3 + H 2 O NH 4 OH NH OH- CO 2 Aerobic/Anoxic/Anaerobic Respiration, Fermentation, Digestion CO 2 + H 2 O H 2 CO 3 H + + HCO 3-2H + + CO 3-2

34 Biogenic Gases How they Form: H 2 S Anaerobic Conditions, SRBs H 2 S H + + HS - 2H + + S -2 VOSCs Anaerobic Conditions, SRBs R-HS, DMS, DMDS CH 4 Anaerobic Conditions

35 Biogenic Gases How they Form: NH 3 Organic Waste, Digestion NH 3 + H 2 O NH 4 OH NH 4+ + OH -

36 Biogenic Gases How they Form: N 2 Denitrification (Anoxic - NO 3- ) 6 NO CH 3 OH 5 CO N H 2 O + 6 OH - Nitrate limited

37 Biogenic Gases How they Form: CO 2 Aerobic/Anoxic/Anaerobic Respiration, Fermentation, Digestion CO 2 + H 2 O H 2 CO 3 H + + HCO 3-2H + + CO 3-2

38 Biogenic Gases Triggers for Release: Temperature, Pressure and Turbulence N 2 CH 4 Further Subjected to ph CO 2 H 2 S VOSCs NH 3

39 Biogenic Gases

40 400 g gas per kg water at 30 o C Biogenic Gases

41 3 g gas per kg water at 30 o C Biogenic Gases

42 1.5 g gas per kg water at 30 o C Biogenic Gases

43 0.035 g gas per kg water at 30 o C Biogenic Gases

44 g gas per kg water at 30 o C Biogenic Gases

45 0.016 g gas per kg water at 30 o C Biogenic Gases

46 ph > 9 releases significant NH 3 gas Biogenic Gases

47 ph > 8 captures significant H 2 S ph </= 7 releases significant H2S Biogenic Gases

48 ph > 8 captures significant CO 2 ph </= 6 releases significant CO 2 Biogenic Gases

49 Biogenic Gases The volume of gas generated by 1 mg/l of gas that has evolved from 1 MGD of wastewater

50 Common Odor Control Strategies Most Common Chemicals Fe Salts FeSO 4, FeCl 2 Nitrates NaNO 3, Ca(NO 3 ) 2 Reactive Magnesia Mg(OH) 2 Peroxide H 2 O 2 Oxygen

51 Common Odor Control Strategies Most Common Chemicals Fe Salts FeSO 4, FeCl 2 (ph 1-3.5) Excessive depression of ph can release CO 2 and H 2 S, but reduce NH 3 Precipitation of sulfides can reduce gaseous H 2 S

52 Common Odor Control Strategies Most Common Chemicals Nitrates NaNO 3, Ca(NO 3 ) 2 (ph 5-7) Negligible direct ph impact on wastewater Biological processes can produce low solubility N 2 gas and some NOx, and raise ph slightly As nitrates may be limiting in a collection system, added nitrates can translate directly into more N 2 gas, and possibly more CO 2. Longer detention times and higher doses

53 Common Odor Control Strategies Most Common Chemicals Magnesia Mg(OH) 2 (ph ) Excessive elevation of ph can release NH 3, reduce CO 2 and H 2 S Partial solubility and particulate adsorption can capture additional H 2 S and CO 2

54 Common Odor Control Strategies Most Common Chemicals Peroxide H 2 O 2 Oxidation of organics and degradation can produce additional O 2 and CO 2 Oxygen Injection O 2 Additional O 2 and CO 2

55 Common Odor Control Strategies Most Common Chemicals Fe Salts FeSO 4, FeCl 2 (ph 1-3.5) Depression of ph can release CO 2 and H 2 S, reduce NH 3 Precipitation of sulfides can reduce gaseous H 2 S Nitrates NaNO 3, Ca(NO 3 ) 2 (ph 5-7) Negligible ph impact on wastewater Biological processes can produce N 2 gas and some NOx Reactive Magnesia Mg(OH) 2 (ph ) Elevation of ph can release NH 3, reduce CO 2 and H 2 S Caustic and lime typically cause instantaneous release of NH 3 and can lead to scaling of piping systems Peroxide H 2 O 2 Oxidation of organics and degradation can produce additional O 2 and CO 2

56 Common Odor Control Strategies Most Common Chemicals ph changes, high or low, can stunt or alter some biological activity ph changes can promote or reduce gas evolution Strong oxidizers can inhibit biological activity O 2 and NO 3 - facilitates aerobic and anoxic activity

57 Case Study Adventure Nitrate 54% Reduction in pump station Magnesia runtime. 26% Reduction in #Starts, comparing two technologies % reduction versus no treatment

58 Case Study Adventure Nitrate Magnesia

59 Biogenic Gases Magnesium Hydroxide Treatment

60 Case Study Adventure

61 Case Study Adventure

62 Case Study Adventure Force Main with Magnesium Hydroxide Treatment

63 Summary Odor control chemistries can have an effect on Total Gas Production in a FM Fe Salts Uncertain Fe binds sulfide and reduces release of H 2 S Depressed ph can suppress NH 3, release CO 2 and H 2 S Nitrates Increases N 2 and possibly CO 2 Magnesia Reduces CO 2, H 2 S Peroxide Increases O 2 and CO 2

64 Summary What Changed? Assuming flows remained the same Forcemain operation Runtimes and Starts Volumes of gas discharged through ARVs? Changes in ARV discharge frequency? Compositions of total gas at ARV discharge? (N 2, CO 2, H 2 S, etc) More case history needed

65 QUESTIONS? Matt Madolora

USE OF CHEMICALS TO CONTROL ODORS AND CORROSION IN WASTEWATER SYSTEMS

USE OF CHEMICALS TO CONTROL ODORS AND CORROSION IN WASTEWATER SYSTEMS By Robert P.G. Bowker, P.E. Bowker & Associates, Inc. Portland, Maine Florida Water Environment Association Air Quality Workshop February