Cyanotoxin Evaluation and Treatment in the New York State Finger Lakes Region Pennsylvania AWWA Annual Conference

Transcription

1 Cyanotoxin Evaluation and Treatment in the New York State Finger Lakes Region Pennsylvania AWWA Annual Conference Stephen Waldvogel, P.E. Teresa Misiti, Ph.D.

2 The Finger Lakes Region Raw Water Supply for Multiple Communities 2

3 Harmful Algal Blooms Cyanobacteria Blooms Cyanotoxins are produced by cyanobacteria, sometimes referred to as harmful algal blooms Cyanobacterial blooms have been detected for several years in the Finger Lakes Blooms can vary significantly each year based on environmental factors such as sunlight, temperature, surface mixing, nutrient loading, etc. 3

4 Harmful Algal Blooms Cyanobacteria Difficulties for Water Operators Cyanobacteria can cause problems for water utilities including: Taste and odors Reduced treatment performance Disinfection by-product precursors Production of cyanotoxins 4

5 Harmful Algal Blooms Cyanobacteria Toxins Cyanotoxins are produced within the bacteria (intracellular) and released when the bacteria are lysed (extracellular) In a typical bloom, 60 90% of cyanotoxins are intracellular 5

6 Harmful Algal Blooms Cyanobacteria Toxins 6 AWWA & WRF A Water Utility Manager s Guide to Cyanotoxins

7 A Growing Public Health Concern Microcystin Emerging, Unregulated Contaminant Microcystin causes serious liver damage and is especially harmful to infants, pregnant women, the elderly and immunecompromised individuals No US water quality criteria or regulations for cyanobacteria or any cyanotoxins In 2015, USEPA issued a microcystin health advisory limit of 0.3 μg/l (children <6yrs) WHO recommended guideline is 1.0 μg/l for microcystin-lr EPA has included it on its CCL4 7

8 Cyanotoxin Treatment Available Treatment Technologies Cyanotoxins can be treated using a variety of physical and chemical methods a combination is typically required to achieve highest removal rates Whole Cell / Intracellular Toxin Removal Extracellular Toxin Treatment Conventional Water Treatment Dissolved Air Flotation Pretreatment Oxidation Microfiltration Ultrafiltration Powder Activated Carbon Granular Activated Carbon Chemical Oxidation Ozone UV/AOP Nanofiltration Reverse Osmosis Alternatives might include purchasing water from an alternative provider or relocating the raw water intake 8

9 Cyanotoxin Treatment New York State Communities Since 2016, GHD has completed cyanotoxin treatment projects in City of Auburn Powder Activated Carbon Town of Owasco Granular Activated Carbon Village of Skaneateles Sodium Hypochlorite City of Syracuse Sodium Hypochlorite Oxidation Wells College Granular Activated Carbon In 2017, all 11 Finger Lakes had confirmed cyanobacterial blooms (many with high toxins detected in the Lake) Finger Lake Otisco S C Skaneateles HT Owasco HT HT HT HT HT Cayuga C C HT Seneca HT HT HT Keuka HT Canandaigua HT C HT Honeoye S HT HT HT C C Canadice C Hemlock C Conesus S C C S = suspicious, C = confirmed, HT = confirmed, high toxin Source: 2017 Finger Lakes Water Quality Report, NYSDEC 9

10 Beat the Bloom Race to Implement Temporary Treatment NYS Governor Andrew Cuomo signs $2million funding authorization for emergency improvements 10

11 Beat the Bloom Race to Implement Temporary Treatment Emergency Declaration legal authorization to bypass some normal procurement policies/steps Pre-procurement of Equipment Owner directly procured long lead time equipment Rolling Design & Informal Bidding Worked with a select group of contractors throughout design to achieve rapid bids/quotes and award 11

12 Extracellular Toxin Removal Activated Carbon Powder activated carbon (PAC) and granular activated carbon (GAC) are adsorbents created from various carbonaceous materials such as coal, wood, peat, coconut shell, etc. Iodine numbers typically ranging from 400 to 1200 mg/g - indicator of adsorption capacity Adsorption varies by carbon type and source water chemistry - each application is unique Activated carbons must be tested to determine effectiveness Commonly used in drinking water plants for filtration, taste and odor control and removal of contaminants 12

13 City of Auburn Powder Activated Carbon Feed System Original Treatment Process Raw Water Pumping (Avg. Day 4 MGD) Slow Sand Rapid Mix/Coagulation/Flocculation Settling Filtration Chlorination Process Change Retrofitted Raw Water Pumping Station with bag feeder system PAC is mixed with motive water and injected into the raw water line minutes of contact time with PAC Settle out PAC Filter out any PAC carry over 13

14 Beat the Bloom Race to Implement Temporary Treatment City of Auburn PAC Bag Feeder System 14

15 Town of Owasco Granular Activated Carbon Contact Vessels Original Treatment Process Raw Water Pumping (Ave day 0.4 MGD, Max day 0.8 MGD) Up-flow Clarification (w/ Polymer) Anthracite/Sand Filtration Chlorination Three Clearwell Chambers provide CT Process Change Two pressurized GAC vessels added containing 20,000 lb of GAC Rated to treat 800,000 gpd at 15+ minutes empty bed contact time (EBCT) Isolated First Two Clearwell Chambers Pump unchlorinated finished water through GAC unit 15

16 Beat the Bloom Race to Implement Temporary Treatment Town of Owasco Low Pressure GAC Units 16

17 Emergency Demonstration Project Pre season and in season laboratory analysis completed to: Select PAC and GAC type Optimize doses and contact times Verify there was no arsenic leaching or major corrosion control water chemistry changes Full scale system testing included: Microcystin sampling throughout WTP processes General water quality monitoring Arsenic and corrosion control sampling 17

18 2017 Microcystin Project Auburn Full Scale Efficacy Demonstration Concentration (mg/l) GHD Raw DOH Raw Low Lift Pump Well GHD Finished DOH Finished EPA 10-day HA Microcystin 0 8/23/2017 9/2/2017 9/12/2017 9/22/2017 Date 10/2/ /12/ /22/ /1/ /11/2017

19 Conclusions PAC and GAC systems were installed prior to the 2017 bloom and successfully protected both communities from finished water detections The 2017 cyanobacterial bloom was mild No arsenic leaching or corrosion issues Both systems have been purchased and are / will be made permanent The 2018 season was very mild and there were no finished water drinking detections Systems will be operated throughout future seasons to protect both communities from cyanotoxins 19

20 HABs - Where Are We Heading? The new normal? Apparent trends indicate HABs are here to stay HABs were observed at high levels in all finger lakes and great lakes last year Many NE communities will face similar raw water quality concerns How do we best protect public health? Are we ready? Recommendations Start proactive monitoring Develop a response plan Evaluate optimizing existing treatment Consider supplemental treatment if required 20

21 Thank you! Questions?