New Drinking Water Issues

Transcription

1 New Drinking Water Issues George C. Budd CS AWWA Seminar March 30, 2011

2 Background on Regulations B&V - 2

3 Evolution of Regulations US EPA required to examine up to 30 new contaminants once every 6 years Not required to regulate. No new contaminants in recent years. Recent regulations have come from older intiatives GW and SW Rules DBPs Chemical Contaminants B&V - 3

4 Impetus of for New Regulation Candidate Contaminant List Reviews by Scientific Panels EPA Science Advisory Panels National Academy of Science Drinking Water Advocacy Groups Environmental Working Group National Resources Defense Council B&V - 4

5 Impetus of for New Regulation Candidate Contaminant List Reviews by Scientific Panels EPA Science Advisory Panels National Academy of Science Drinking Water Advocacy Groups Environmental Working Group National Resources Defense Council NO NEW CONTAMINANTS IN SEVERAL REGULATORY REVIEW CYCLES B&V - 5

6 Unregulated Contaminant Monitoring B&V - 6

7 Unregulated Contaminant Monitoring Obtain data on presence of contaminants to determine need for regulation. Two cycles since 2001 List for third cycle 7 Hormones (Significant impetus from Environmental Groups) 9 Carcinogenic VOCs 6 Perfluorinated compounds 1,4 Dioxane 4 Inorganics (Cobalt, Strontium, Molybdenum, Vanadium) Chlorate 2 Viruses (Norovirus and Enterovirus) B&V - 7

8 Other Contaminants/Issues B&V - 8

9 Other Contaminants Chromium VI (Significant Impetus from Environmental Groups) Fluoride Perchlorate (Rule forthcoming) Revisions to Lead/Copper Rule Modifications to Coliform Rule B&V - 9

10 Characteristics of Groundwater and Surface Water B&V - 10

11 Ground Water Characteristics Water is confined in aquifers. Limited access to oxygen. Insulated from microbial contamination. General characteristics determined by geochemistry. Flow is confined. B&V - 11

12 Ground Water vs. Surface Water Surface water Directly exposed to surface discharge. Waterborne disease most important risk. Focus on larger pathogens that are difficult to disinfect. Particle removal as a component of a multiple barrier approach to these pathogens Treatment infrastructure in surface water is focused on protecting against pathogens High rate of flow Chemical contaminant concentrations lower Chemical quality of concern, but not as great. B&V - 12

13 Ground Water vs. Surface Water (Cont.) Surface water treatment Focus is on removal of particles and disinfection B&V - 13

14 Ground Water vs. Surface Water (Cont.) Ground Water Exposure to surface influx reduced Waterborne disease risk for larger pathogens generally not addressed in treatment managed by wellhead protection. 4-log virus inactivation/removal required by Ground Water Rule if deficiencies found. Generally achieved by chlorination or other chemical disinfection. Chemical quality generally determines the treatment infrastructure. Dissolution of minerals determine general characteristics. Lower rate of flow Influence of geochemical processes greater. Chemical leaching not easily removed. B&V - 14

15 Factors that Determine Ground Water Treatment Infrastructure Particulate Removal Not as Critical or High Degree of Disinfection Contact Disinfection generally can be met within minutes. Piping, tankage for other processes, and/or storage often can be used. Requirement of GWR for disinfection if applicable Which Chemicals Are Present. Wide range of potential processes. B&V - 15

16 Ground Water vs. Surface Water (Cont.) Ground Water treatment Focus is on removing chemical constituents Chemical Removal Process B&V - 16

17 Key Regulations that Affect Groundwater Supplies B&V - 17

18 Ground Water Rule Promulgated in October 2006 to Address Risks of Fecal Contamination in Groundwater Supplies. Compliance in December B&V - 18

19 Ground Water Rule (Cont.) Requirements of Rule Periodic Sanitary Survey (Every 3 years for community system). 8 areas of evaluation Sensitivity assessment. Source Water Monitoring. Triggered Monitoring (Systems without 4 log virus inactivation/removal plus TCR coliform positive.) Must have sample location prior to treatment. Assessment Monitoring (At discretion of State to identify high risk systems.) Corrective Actions. Can include requirement for 4-log virus inactivation/removal Requires compliance monitoring to assure proper application of treatment. Compliance Monitoring. B&V - 19

20 Other Key Regulations for Ground Water Systems Total Coliform Rule (Changes being Considered) Lead and Copper Rule (Changes being Considered) Corrosion Control Aesthetics Tastes and Odors Discoloration Rules that Govern Chemical Contaminants Existing Rule Future Rules CCL Process B&V - 20

21 Types of Chemical Constituents in Ground Water Mineral dissolution. Leached contaminants B&V - 21

22 Sources of Constituents Low dissolved oxygen leads to reducing conditions Reduced/soluble forms of iron/manganese (Fe +2 /Mn +2 ) Sulfide formation (H 2 S) Nitrogen in ammonia form (NH 4+ ) Other constituents from geochemical processes Hardness Sulfate Fluoride Chloride Arsenic Chromium Radionuclides Carbon Dioxide B&V - 22

23 Sources of Constituents (cont.) Leaching Nitrate Pesticides Industrial contaminants VOCs Perchlorate Chromium Landfills Other B&V - 23

24 Ground Water vs. Surface Water (Cont.) Ground Water treatment Focus is on removing chemical constituents Chemical Removal Process B&V - 24

25 Nature of Contaminants Affects Treatment Strategy Constituents subject to oxidation Reduced iron (Fe +2 Fe +3 ) Reduced manganese (Mn +2 Mn +4 ) Sulfide (S -2 S or SO 4-2 ) Constituents that readily precipitate (Precipitation/Filtration) Oxidized iron Fe H 2 0 = Fe(OH) H + Oxidized manganese Mn +4 + O 2 = MnO 2 Hardness Ca 2+ + CO 3-2 = CaCO 3 Mg H 2 O + Mg(OH) 2 B&V - 25

26 Nature of Contaminants Affects Treatment Strategy (Cont.) Constituents subject to volatilization (Air Stripping) Sulfide (H 2 S) Volatile organics Carbon Dioxide (CO 2 ) Ionic constituents (Ion Exchange/Membranes) Chloride (Cl - ) Sulfate (SO -2 4 ) Nitrate (NO 3- ) Naturally Occurring Organics B&V - 26

27 Nature of Contaminants Affects Treatment Strategy (Cont.) Constituents that can be adsorbed Arsenic Chromium VI Soluble Mn Naturally Occurring Organics Particulates Coagulation/Filtration Membrane Filtration B&V - 27

28 Selected Emerging Contaminants B&V - 28

29 Pharmaceuticals and Personal Care Products, etc. Example of Issue Driven by Advocacy Groups B&V - 29

30 Phenol, Alkylphenols (nonionic surfactants) U of CT

31 Ingested additives/sterols/metabolites 3 tert 4 BHA Cotinine

32 Fragrance/Flavor compounds AHTN Benzophenone HHCB

33 Flame Retardants Tris 2 chloroethyl phosphate Tris 2 butoxyethyl phosphate

34 Polycyclic Aromatic Hydrocarbons U of Wisconsin

35 Pesticides/Repellents Bromacil DEET Pentachlorophenol

36 Plant A Sample 1 Raw Water Screening Recycle Raw Water Pumps KMnO 4 NaOH or H 2 SO 4 FeSO 4 High Rate Ballasted Clarification Microsand Sample 2 Settled Effluent Ozone Polymer Ozone Contact H 2 O 2 Sample 3 Ozone/Peroxide Effluent NaOCl NaOH GAC Filters PACl Sample 4 GAC Filter NaOCl Clearwell Sample 5 Finished Water To Distribution

37 May Sampling Plant A 1.0 Tris(2-chloroethyl) phosphate Tris(2-butoxyethyl) phosphate 0.9 Triethyl citrate Tributyl phosphate 0.8 Pyrene Phenanthrene 0.7 Naphthalene Methyl salicylate Concentration, ug/l Isophorone HHCB Fluoranthene Cotinine Carbamazepine Caffeine 0.3 Benzophenone 9,10-Anthraquinone 0.2 Prometon p-cresol 0.1 Metolachlor DEET 0.0 Raw Water Settled Effluent Ozone/Peroxide Effluent GAC Filter Effluent Finished Water Carbazole Camphor Field Blank clean

38 Plant B Sample 1 Raw Water Pumping Aeration Sample 2 Post Aeration Sludge Supernatant Decant Tank Flash Mix Coagulation Alum Polymer Sedimentation Sample 3 Post Sedimentation Sand/Anthracite Filters Sample 4 Post Filter Balancing Tank Sample 5 GAC Effluent Sample 6 Finished GAC Filters To Storage NaOCl

39 May Sampling Plant B 1.0 Concentration, ug/l Tris(2-chloroethyl) phosphate Tris(2-butoxyethyl) phosphate Triethyl citrate Tetrachloroethene Fluoranthene Cotinine Carbamazepine Caffeine Acetaminophen 9,10-Anthraquinone Metolachlor DEET Carbazole Camphor Field Blank clean 0.0 Finished and Chlorinated GAC Effluent Post Filter Post Sedimentation Post Aeration Raw Water

40 May Sampling Plant C Concentration, ug/l Tris(2-butoxyethyl) phosphate Naphthalene Methyl salicylate Cotinine Carbamazepine Caffeine Prometon DEET Camphor Field Blank clean 0.0 Finished and Chlorine Post Filter and Chlorine Post Flocculation/Sedimentation and Chlorine Mix1 and Chlorine Post Aeration and Seasonal Chlorine Dioxide Raw River and Reservoir

41 May Sampling Plant D Concentration, ug/l Tetrachloroethene Isophorone HHCB Cotinine Caffeine Acetaminophen p-cresol Field blank clean Finished and Chlorine Post Filter and Chlorine Post Chlorine Post DAF Post Ozone Raw Water Reservoir

42 Recalcitrant Compounds Dehydronifedipine Flame retardants DEET Cotinine

43 Chromium VI (Hexavalent Chromium) MCL for Total Chromium = 0.1 mg/l Possible Interest in Cr VI at Levels less than 0.1 ug/l; CA limit is 0.06 ug/l Example of Issue Driven by Advocacy Groups B&V - 43

44 Treatment Technologies for Cr VI Chemically reduce to Cr III and precipitate. Followed by Coagulation and Filtration. Anion exchange Iron based adsorbents Membrane processes B&V - 44

45 Fluoride Present MCL = 4.0 mg/l Present Secondary Standard = 2.0 mg/l Health and Human Services Recommendation = 0.7 mg/l Example of New Concerns for an Established Contaminant B&V - 45

46 Treatment Technologies for Fluoride Lime precipitation (form CaF) Ion exchange Activated alumina Reverse Osmosis B&V - 46

47 Carcinogenic VOCs Example: TCE (trichloroethylene) MCL = mg/l Possible Reduction Example of New Concerns for an Established Area of Regulation B&V - 47

48 Treatment Volatile compound Treatment processes Air stripping. GAC. Bioremediation possible. B&V - 48

49 Radionuclides Example of Regulation that has been Slow to Develop B&V - 49

50 Regulated Radionuclides Beta/photon emitters 4 mrem/year Gross alpha particle 15 pci/l Radium-226 and Radium pci/l Uranium 30 ug/l A list of 179 beta particles and photon emitters are used for calculating the dose. B&V - 50

51 Radon A Rule in Flux Health effects reviewed in NAS study in EPA published Health Risk Reduction and Cost Analysis. Radon Rule proposed by EPA in November, MCL 300 pci/l Alternative MCL based on multimedia mitigation 4000 pci/l EPA deadline for final rule was August, 2000; delayed by evaluations for Arsenic Rule. Final rule yet to be published. B&V - 51

52 Removal Technologies for Beta and Photon Emitters Ion Exchange Reverse Osmosis Point of Use IE or RO B&V - 52

53 Removal Technologies for Radium-226 and Radium-228 Ion Exchange Reverse Osmosis Lime Softening Green Sand Filtration Co-Precipitation with Barium Sulfate Electrodialysis Hydrous Manganese Oxide Filtration Point of Use IE and RO B&V - 53

54 Removal Technologies for Gross Alpha Particles Reverse Osmosis Point of Use Reverse Osmosis B&V - 54

55 Removal Technologies for Uranium Ion Exchange Reverse Osmosis Lime Softening Activated Alumina Enhanced Coagulation/Filtration Point of Use IE and RO B&V - 55

56 Radon Removal Radon is highly volatile. Removal by air stripping. B&V - 56

57 Disposal of Waste Disposal of solid and liquid waste streams is a critical consideration. EPA is developing guidance. Regulation presently left to States B&V - 57

58 Nitrosamines Example of Expanding Scope for an Existing Area of Regulation. B&V - 58

59 NDMA and other Nitrosamines NDMA can occur in plants that use either chlorine or chloramines. Some ion exchange monomers may be precursors Some coagulant aid polymers that contain nitrogenous components can serve as precursors. Preoxidation and Biological Filtration may minimize Conditions of formation can be managed (Minimize dichloramine range, lower ph) Page - 59 July 29, 2010

60 Summary B&V - 60

61 Summary Range of Emerging Issues New Considerations for Contaminants of Long Standing Concern New Contaminants of Concern. Possible Changes in Future. B&V - 61