USEPA s Pursuit of New Ambient Water Quality Criteria for Bacteriophage:

Transcription

1 USEPA s Pursuit of New Ambient Water Quality Criteria for Bacteriophage: What it means to you and your WRRF Brian Hilts, P.E. February 6 th, 2017

2 Outline Current AWQC NYS Disinfection Survey NYS Regulations Proposed AWQC Updates Coliphage? Lower TRC Limits Questions 2

3 Current AWQC Regulatory Background Clean Water Act requires USEPA to develop AWQC to protect uses (e.g. fishable/swimmable) in receiving waters Covers a multitude of pollutants Pathogens fall under AWQC The BEACH Act of 2000 resulted in studies & revision of indicator criteria recommendations Federal Recreational Water Quality Criteria Protect people from water borne pathogens States can adopt the RWQC or use as guidance for their own criteria Based upon BEACH Act, RWQC were updated in 2012 and

4 Current & Proposed AWQC Regulatory Background USEPA 2012 RWQC, reviewed in 2017 Based upon NEEAR definition of Gastro Intestinal (GI) Identify magnitude, duration and frequency for two illness rates 4

5 Current AWQC Regulatory Background Geometric Mean 1 2 Multiple the numbers and take the nth root Quite forgiving Statistical Threshold Value Uses the 90 th percentile of the values Replaces 7 day Geometric Mean E. Coli in Disinfected Effluent Week 1 Week 2 Week 3 Week 4 Monday , Tuesday Wednesday Thursday Friday Geo Mean is 28.9 CFU/100 ml STV is CFU/100 ml 5

6 NYS Regulations NYWEA Disinfection Task Force DEC considering how to proceed NYWEA sponsored Disinfection Survey General information on Disinfection (50 WWTP ~10% of WWTP in NY) Capital and O&M costs Technology used Indicating organism 100% of WWTP measure Fecal Coliform 4.3% of WWTP measure E. coli 21.7% of WWTP measure Enterococcus Evaluate WWTP sampling data for bacteria correlations Fecal Coliform vs. E. coli vs. Enterococcus 6

7 NYS Regulations NYWEA WWTP Survey Disinfection Season None, 8% Other, 2% Disinfection Process None, 2% Microfiltration, 8% Chlorine Gas, 5% Seasonal, 30% Year Round, 60% UV, 37% Sodium Hypochlorite, 48% PAA, 0% 7

8 NYS Regulations NYWEA WWTP Survey Disinfection Costs Avg. Capital Cost = $1.25M Avg. Annual O&M Cost = $95,000 Avg. Chlorine Dose = 5.7 ppm Avg. Capital Cost to Dechlorinate = $300,000 Avg. Annual O&M Cost to Dechlorinate = $20,000 8

9 NYS Regulations NYWEA WWTP Survey Data from 23 WWTPs (18 in NY & 5 in NJ) Data E. coli = 74 days Enterococcus = 216 days Fecal Coliform = 742 days Correlation between bacteria pairs Bacteria Type Pair RSQ Log Fecal Coliform Concentration, MPN/100 ml E. coli and Enterococcus E. coli and Fecal Coliform 0.71 Enterococcus and Fecal Coliform Log E. coli Concentration, MPN 100/ ml 9

10 NYS Regulations NYWEA WWTP Survey Data Analysis Small sample set Few correlations When FC > 200 MPN/100mL; Enterococcus > 35 MPN/100mL However, same is not true in reverse Several instances where FC < 200 MPN/100mL; Enterococcus > 35 MPN/100mL Additional data is needed More data for disinfected bacteria Need undisinfected bacteria data to determine Enterococcus disinfection capacity Disinfection dose Results of both survey presented to DEC 10

11 NYS Regulations Indicating Organisms Moving towards RWQC based organisms for Coastal Recreational Waters E. coli for the Great Lakes Enterococcus for marine waters Most others will stay with Fecal Coliform Limits remain Shell fish waters will continue to utilize Total Coliform Long term goal Everyone utilizing E. coli and Enterococcus 11

12 NYS Regulations Indicating Organisms No mixing zone for bacterial standards Statewide Disinfection ~135 WRRF do not disinfect now (25 > 1 mgd) in year plan permit modifications permit modifications 2019 ~ 50 permit modifications Engineering Planning Grants available for disinfection 12

13 Proposed AWQC Transitioning to Viral Indicator Historically bacteria were thought to cause majority of water borne illness QMRA & various studies indicate pathogenic enteric viruses (adenovirus, enterovirus, and norovirus) cause majority of illnesses Culturable bacterial indicators may not be predictive of viral illnesses USEPA has been investigating the use of coliphage as an indicator for waterborne illnesses, and is developing a new AWQC Other studies have reported no clear epidemiological evidence linking GI to exposure to waters that do not meet the fecal indicator bacteria criteria Desire to come in line with indicating organism being used by FDA for shellfish industry 13

14 Proposed AWQC Timeline of AWQC Development Date Milestone 4/17/2015 Review of Coliphages as Possible Viral Indicators of Fecal Contamination of Ambient Water Quality 10/15/15 Stakeholder Webinar 3/01/16 Coliphage Expert Workshop 7/2016 Coliphage Fact Sheet issued by Office of Water, USEPA 2016 Listening Sessions/Webinars Conferences (New Orleans & Chapel Hill) States Other stakeholders (industry/environmental groups) Winter 2016/2017 Coliphage Expert Workshop proceedings 2017 Analytical method multi lab validation 2018 Drafting of Criteria is moving slowly 14

15 Proposed AWQC What is Coliphage? Monitoring pathogenic enteric viruses directly can be difficult and they pose safety concerns, therefore a viral indicator is needed Coliphage is being evaluated as the viral indicator Coliphage is a virus that only infect E. coli Somatic coliphage Male specific/f+ coliphage (i.e. MS2) 15

16 Proposed AWQC What is Coliphage? NWRI recommends coliphage for evaluating virus removal for water reuse Interstate Shellfish Sanitation Conference & FDA recommend the use of male specific coliphage for shellfish bed closure decisions Advantages Coliphages are common in raw wastewater Physically similar to enteric viruses Similar persistence patterns to enteric viruses No appreciable re growth in ambient waters Non pathogenic 16

17 Proposed AWQC Laboratory Impacts Currently the USEPA has two methods (1601 and 1602) to enumerate coliphage USEPA is developing a new method for coliphage Method passes 2L of sample through an ultra filtration device Allows two agar plates to be generated, one for somatic coliphage and one for male specific/f+ coliphage Incubation period is 24 hours While the existing methods were developed for detecting coliphage in groundwater samples, they have been widely used on water reuse and other sample types. USEPA has undertaken a multi lab validation of the new method for this specific sample type. 17

18 Proposed AWQC Potential Permit Impacts Currently no timeline when new AWQC will be finalized Anticipated coliphage criteria will be developed in 2018 Coliphage criteria in the AWQC will be another tool for regulatory agencies to utilize in protecting public health. Will not replace E. coli or Enterococci. Potential for Mixing Zones Traditional permit limits are set at the end of pipe USEPA lost a court case in Region VII over the use of mixing zones While the USEPA indicates it is prohibited, primacy states may develop mixing zone rules that include the use mixing zones to calculate effluent limits for indicating organisms Mixing zones could have a large impact on how the coliphage limits effect WRRFs A dilution factor of 50 would effectively change a permit limit from 50 CFU/100mL to 2,500 CF/100mL 18

19 Proposed AWQC Potential Permit Impacts How many coliphage are entering disinfection systems is not well understood Site specific log reductions requirements will vary Flow Stream USEPA Lit. Review, PFU/100mL Coliphage Counts HRSD Study, Concentration/100mL Coliphage Counts E. coli Raw Influent Secondary Effluent (HRSD Coliphage Study, 2015) 19

20 Proposed AWQC Impacts on Disinfection Technologies Disinfectants used at WRRFs Ozone Chlorine/Chloramines UV No Disinfection At WWTFs with flow > 0.95 MGD (WERF 04 HHE, 2008) 20

21 Proposed AWQC Impacts on Disinfection Technologies Chloramines Free Chlorine Ultraviolet Light (UV) Peracetic Acid (PAA) 21

22 Proposed AWQC Impacts on Disinfection Technologies Chloramines Disinfection effectiveness is commonly measured via a CT value CT (mg/l*min) stands for Residual Concentration (mg/l) x Time (minutes) A CT value of 20 could mean: Exposure of 20 mg/l for 1 minute (20 x 1 = 20) Exposure of 1 mg/l for 20 minutes (1 x 20 = 20) Exposure of 4 mg/l for 5 minutes (4 x 5 = 20) 22

23 Proposed AWQC Impacts on Disinfection Technologies Chloramines Estimated range of CT values for various levels of inactivation of dispersed bacteria in filtered secondary effluent (ph ~ 7 and T ~20 C) Metcalf and Eddy 4 th Edition E. coli in secondary effluent 100,000 cfu/100 ml Permit limit 100 cfu/100 ml 3 log reduction is required, select a CT of 50 mg/l*min 23

24 Proposed AWQC Impacts on Disinfection Technologies Chloramines Limited amount of data on chloramine inactivation of somatic and malespecific/f+ coliphage Data shows the same inactivation of coliphage with chloramines requires a CT value 2 3 times greater than bacterial indicators, however it is unclear if same inactivation rate is required Options Increase contact time Increase dose, if there is sufficient ammonia present Switch to free chlorine disinfection 24

25 Proposed AWQC Impacts on Disinfection Technologies Breakpoint Curve MEASURED RESIDUALS (mg/l) Initial Chlorine Demand (not illustrated) Chlorine Demand Formation of CRCs and Chloramines Max Chloramine Cl:N ~ 5 Destruction of Chloramines CHLORINE DOSE (mg/l) Breakpoint Cl:N = 7.6 Formation of FRC and CRCs TRC FRC 25

26 Proposed AWQC Impacts on Disinfection Technologies Free Chlorine Limited amount of data on free chlorine inactivation of somatic and male specific/f+ coliphage Data shows that free chlorine is more effective at lower doses than chloramines To implement free chlorine disinfection Ideally, have a nitrification/denitrification secondary treatment process Having a fully nitrified effluent would also work, but there are challenges with nitrogen based chlorine reducing compounds 26

27 Proposed AWQC Impacts on Disinfection Technologies UV Disinfection UV Inactivation Rate E. coli Coliphage (MS2) 1 Log Reduction 5 7 mj/cm mj/cm 2 3 Log Reduction mj/cm mj/cm 2 27

28 Proposed AWQC Impacts on Disinfection Technologies PAA Limited amount of data on PAA inactivation of somatic and malespecific/f+ coliphage PAA & Coliphage Inactivation Log Reduction CT, mg/l*min 28

29 Proposed AWQC Take Aways R E L A X Many unknowns associated with this AWQC update Timing When the final AWQC will be issued, and when state regulators would incorporate them Criteria values Coliphage AWQC Required inactivation rates Disinfection system influent coliphage counts Disinfection effectiveness Chemical disinfectants poorly understood; UV is better understood Possible next steps Monitor USEPA s progress Identify certified lab for new coliphage method Start collecting data 29

30 Lower TRC Limits DEC is pushing Total Residual Chlorine limits down Optimize Chlorine Dose vs. Dechlorinate Depends upon TRC limit > 1.0 ppm Optimize Chlorine Dose 0.5 to 1.0 ppm Challenge to Optimize Chlorine Dose <0.5 ppm Dechlorination Chlorine Dose Optimization Approach Revisit Controls Dechlorination 30

31 Lower TRC Limits Chlorine Dose Optimization Nitrification NH O 2 + Nitrosomonas NO 2 + H 2 O + H + NO O 2 + Nitrobacter NO 3 Chloramines, ammonia plus free chlorine: NH 3 + HOCl NH 2 Cl + H 2 O NH 2 Cl + HOCl NHCl 2 + H 2 O NHCl 2 + HOCl NCl 3 + H 2 O Free chlorine: Quickly reacts with nitrite, organic N, color, etc. Potential for high chlorine demand & DBP formation 31

32 Lower TRC Limits Chlorine Dose Optimization Reasons to sample Nitrification/denitrification upgrades Lower nutrient limits for ammonia or nitrogen NH3 N between 1 to 3 mg/l Can chloraminate Use lower chlorine dose Requires careful attention to dosing control system NH3 N less than 1 mg/l Challenging to chloraminate Form FRC CRCs may exert high chlorine demand 32

33 Lower TRC Limits Chlorine Dose Optimization Sample upstream of disinfection for : ph NH3 N Nitrite ( 1 mg/l reacts with 5 mg/l of chlorine) Nitrate Organic N = TKN NH3 N Concentration of indicator organisms Test chlorination Chlorine demand test Breakpoint curve analysis 33

34 Lower TRC Limits Revisit Controls Revisit instruments TRC analyzers FRC analyzers Oxidative Reduction Potential (ORP) Ammonia analyzers MEASURED RESIDUALS (mg/l) Textbook Breakpoint Curve CHLORINE DOSE (mg/l) TRC SCADA Readout Measured TRC (mg/l) ORP of Various Chlorine Compounds from White's Handbook of Chlorination and Alternative Disinfectants, Black & Veatch (2010) 34

35 Lower TRC Limits Revisit Controls Manual control will not work Flow pacing Compound loop control Continuous ammonia monitoring 35

36 Lower TRC Limits Dechlorination Sulfur Dioxide Gas Sodium Thiosulfate Liquid, not widely used in WW Sodium Bisulfite (SB) 38% Liquid, typically utilized 1 mg/l of TRC is inactivated with 1.46 mg/l of 100% SB Equates to 1 mg/l of TRC requiring 3.87 mg/l of 38% SB 36

37 Lower TRC Limits Dechlorination Good Mixing is critical 30 second contact time at PHF Flow Pacing is utilized along with on line TRC and/or ORP analyzers to determine Sodium Bisulfite dose. Typically overdose by 10%, but use caution as dechlorination compounds are oxygen scavengers Example Dose Calculation: 1.2 mg/l of TRC 1.2 mg/l * 3.87 mg/l of SB *1.1 (10% excess SB) = 5.1 mg/l of SB 37

38 Summary WWTP Disinfection Survey DEC staying the course; ultimately line up with EPA RWQC USEPA is updating AWQC for coliphage Why updating AWQC Timeline Coliphage Permit Impacts Potential use of mixing zones Impacts on Disinfection Technologies Addressing Lower TRC Limits 38

39 QUESTIONS?

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