The Impact of Harmful Algal Blooms on Public Drinking Water Systems

Transcription

1 The Impact of Harmful Algal Blooms on Public Drinking Water Systems December 11, 2015 OTCO Presentation, Worthington, Ohio Barb Lubberger Ohio EPA Division of Drinking and Ground Waters

2 What we will cover: Impact of HABs on public water systems Occurrence of HABs in Ohio ( ) Detecting HABs PWS strategies for dealing with HABs Test methods Draft HABs rules in development

3 Impacts on PWSs Health concerns - Dermal toxins, neurotoxins, and hepatotoxins Taste and odor problems - Methylisoborneol (MIB) & Geosmin Increased organic carbon load - Concern for water treatment and DBPs Dissolved oxygen dips - Can result in fish kills Nuisance Unsightly, smelly: quality of life is diminished Costs to Communities - Economic impacts from loss of recreation-based tourism - >$200,000/month for extra treatment at PWSs

4 Occurrence of HABs in Ohio (2015)

5 Occurrence - Microcystis Microcystins can be produced by several types of cyanobacteria; the most frequently seen are variants of Microcystis Lake Erie 2011 Microcystins levels exceeded 1000 ug/l Microcystis and Anabaena under microscope

6 Occurrence - Planktothrix Planktothrix under microscope William s Reservoir, Lima November, 2012 Microcystins concentration: 1400 ug/l

7 Occurrence - Aphanizomenon Grand Lake Saint Marys Microcystins levels exceeded 2,000 ug/l Aphanizomenon under microscope

8 Occurrence - Other Cyanotoxins Saxitoxin was detected in 38% of water system source water samples in Cylindrospermopsin was detected in less than 1% of water system source water samples in 2015 (maximum concentration ug/l). Finished water saxitoxins detections at 3 public water systems. No finished water cylindrospermopsin or anatoxin-a detections.

9 Occurrence The Ohio River

10 Occurrence The Ohio River Cincinnati Intake Maysville, KY Ironton

11 Occurrence Levels of microcystins

12 Occurrence Seasonal Distribution Seasonal Variations in Microcystins Concentrations in PWS Source Waters (Microcystins > 1.6 ug/l)

13 Occurrence increasing levels at GLSM Data Source: Celina PWS

14 Occurrence increasing levels in Lake Erie

15 Occurrence - Possible reasons for increase Warmer temperatures Trend for more severe spring storms (runoff) Accumulated phosphorus in sediments

16 Occurrence - More reasons Dreissena mussels (Zebra & Quagga) Glyphosate & other herbicides Establishment of seed cyanobacteria population Source population in lake sediments Less ice cover in winter Increased sampling

17 Detecting HABs Visual detection Phycocyanin probes Remote sensing data Operational parameters --reduced filter run times --filter clogging --high ph --increased chlorine demand Routine sampling and analysis

18 PWS Strategies

19 PWS Strategies Source Control Switch to, or blend with, other sources --additional unimpacted reservoirs --ground water --interconnections with other public water systems Use different intake depths. (Lower intakes typically less impacted) Physically remove scums (manually or with vacuum trucks, etc.), especially scums located in proximity to intake structures. Pump at optimum times (if system does not need to pump 24-7) Microcystis and Anabaena move up and down in the water column, rising in the morning and settling in the evening. However, Planktothrix and Cylindrospermopsis are typically distributed throughout the water column. Apply algaecide*.

20 PWS Strategies Conventional Treatment Treatment optimization should consider whether the toxins are primarily --intracellular --or extracellular (dying or damaged cells may release toxins, a process called lysing) If intracellular, ideally you can remove the intact cells via sedimentation/flocculation If extracellular, the toxin must be neutralized by oxidants (K-permanganate/chlorine, etc.)

21 PWS Strategies Conventional Treatment When toxins are primarily intracellular, the PWS operator should consider the following: Optimize coagulant dose Slow flocculator speeds to minimize cell disruption Increase sludge removal Increase filter backwash frequency Pre-oxidation with chlorine and other oxidants may cause cell rupture and should be avoided (potassium permanganate may be a better option, if pre-oxidation is necessary) Coagulation, sedimentation and filtration remove cells but have minimal effect on cyanotoxins

22 PWS Strategies Conventional Treatment In addition and especially where toxins are primarily extracellular-- the PWS operator should maximize contact time with oxidants. Measures include: Increasing PAC feed at rapid mix Maximizing pre-oxidant and pre-filtration chlorination* to provide maximum contact time. Slowing rate of flow through plant Maximizing post filtration chlorine feed *If DBPs are a concern, potassium permanganate is preferable to chlorine.

23 PWS Strategies - Treatment Effectiveness of Various Oxidants Chlorine Chloramine Chlorine Dioxide Potassium Permanganate Anatoxin-a Cylindrospermopsin Microcystin Saxitoxin Not Effective Not Effective Not Effective at normal levels Effective* Effective (at low ph)* Effective* Somewhat Effective Not Effective Not Effective Data ranges from Not Effective to Possibly Effective Not Effective at normal levels Not Effective at normal levels Effective* Inadequate Information Inadequate Information Not Effective Ozone Effective* Effective* Effective* Not Effective UV/advanced Oxidation Effective* Effective* Not Effective Inadequate Information *dependent on adequacy of dose and contact time

24 PWS Strategies Advanced Treatment Ozone Generally effective at destroying microcystins, nodularin and and anatoxin-a, but not saxitoxin (potential concern with bromate) UV Not effective at typical light intensities. UV-Advanced Oxidation (H2O2) May be effective if contact time sufficient. Membranes RO & NF are effective at microcystin removal. MF & UF not effective at cyanotoxin removal but can remove intact cells. Dissolved Air Flotation (DAF) Effective at cell removal (not extracellular toxin removal). GAC Can be effective, but costly if persistent or severe blooms.

25 Test Methods Screening: qpcr Microcystins: ELISA- Microcystins-ADDA Liquid Chromatography-based methods

26 Test Methods How does PCR work? A water sample is heated to nearly boiling along with a template of (a portion of) the desired toxin gene. The heat separates the DNA strands of template and water sample. Compatible DNA strands in the sample combine with the separated template strands, producing two complete gene portions. By heating multiple times, the original template can be multiplied exponentially --if enough compatible strands are in the sample--to the point that the genes can be detected and quantified.

27 Test Methods - Why qpcr Instead of Other Screening Tools? Lab standards. qpcr has standards that can be used for certifying laboratories. No standard methods exist for other types of cyanobacteria ID/quantification. Toxin production info. Other methods do not provide information on whether a HAB is producing toxins; qpcr does, and one test can be done for all three of the most common cyanotoxins. Quick. Results for all three toxins available within 2-3 hours. Screening and enumerating under a microscope requires a half hour per sample by highly trained technicians. Cost effective (~$100 per test)

28 Test Methods - How Will Ohio EPA Use qpcr Data? Detection of saxitoxin or cylindrospermopsin production genes will trigger cyanotoxin monitoring. May be able to reduce future microcystins monitoring if there is strong correlation between detection of microcystin gene and microcystins concentrations.

29 Test Methods - ELISA Ohio EPA uses the Enzyme-Linked ImmunoSorbent Assay (ELISA) Microcystin- ADDA Method Measures Total Microcystins (all variants) Certified by USEPA Quick (four hours) Relatively inexpensive Does not require high end equipment or expertise to run (can be used in water system lab)

30 Test Methods - Results of Method Comparison Toxicon 104 (2015) (Foss & Aubel): Using the MMPB technique to confirm microcystin concentrations in water measured by ELISA and HPLC (UV, MS, MS/MS)

31 Test Methods Ohio EPA s ELISA SOP Helps ensure consistent sample handling, preparation, and application of analytical method. Labs must demonstrate they can achieve an acceptable level of precision and accuracy. Ohio EPA s lab personnel conduct site visits at labs performing analysis and will provide certification once rules are in place. Increases consistency and confidence in data.

32 Draft HABs Rules - Outline PWS requirements - new rules in OAC Chapter Microcystins action levels in drinking water Monitoring requirements Treatment technique requirements Public notification and Consumer Confidence Report (CCR) requirements Recordkeeping requirements Laboratory Certification requirements New OAC rule and amended rules in Chapter Laboratory certification Analytical techniques Reporting deadlines

33 Draft HABs Rules - Applicability Surface water systems All requirements apply Consecutive (purchased) water systems Routine monitoring and treatment technique requirements do not apply If wholesale water system has an action level exceedance, conduct monitoring at distribution sampling points; may also be required to: issue public notification include in their Consumer Confidence Report keep records Ground water systems Routine monitoring requirements do not apply If samples collected voluntarily by a ground water system or by Ohio EPA exceed an action level, may be required to issue public notification include in their Consumer Confidence Report fulfill treatment technique requirements keep records

34 Draft HABs Rules - Monitoring Requirements Apply to surface water systems Routine weekly monitoring for cyanobacteria screening (raw) Information will be used to determine if monitoring for cyanotoxins other than microcystins needs to be conducted by Ohio EPA (or voluntarily by the PWS) Routine weekly monitoring for microcystins (raw and finished) Year-round Option for a decreased monitoring schedule, after a year of data collection

35 Draft HABs Rules - Microcystins action levels Based on U.S. EPA s health advisory levels Based on oral ingestion of drinking water at these levels for up to ten days Applied to total concentrations of all congeners/variants Includes nursing and pregnant women, individuals with liver disease and those on dialysis Action Level Children under 6 and sensitive populations Children 6 and older and adults Exceedance in a finished water sample will require: Additional monitoring Treatment optimization Potentially other actions (e.g. public notification) Total Microcystins (μg/l)

36 Draft HABs Rules - Timeline Early Stakeholder Outreach completed June 1 to 30, 2015 Interested party review (comments by October 23) Draft rules available at Propose rules to JCARR winter 2015/2016 Adopt final rules by approximately June 2016 Subscribe to our electronic mailing list at

37 Ongoing & Future Activities Develop Cyanotoxin General Plan Guidance Coordinate Reservoir Management Training Continue Participation on National Workgroups Collaborate with Universities and Federal Partners on Applied HAB Research Projects Revise HAB Response Strategy

38 Questions? Contact Information: (614) Ohio s Public Water System Harmful Algal Bloom Response Strategy is available online at: