Issam Najm, Ph.D., P.E., BCEE. Gurpal Deol Lyda Hakes Peter Zhou

Transcription

1 Issam Najm, Ph.D., P.E., BCEE Gurpal Deol Lyda Hakes Peter Zhou Annual Fall Conference CA- NV AWWA Sec3on October 26 29, 2015 Water Jill Duerig Zone 7 Water Agency Steve Peterson Alameda County Water District Bruce Cabral Santa Clara Valley Water District WQTS Brian Gallagher Dan Askenaizer 1

2 SBA Water 3 u South Bay Aqueduct (SBA), built in the 1960 s, conveys water from the Sacramento- San Joaquin Delta to Alameda and Santa Clara CounIes u 10.8 miles of canal, 32.1 miles of pipeline, and 1.8 miles of tunnel u Open reservoirs along the SBA include Dyer Reservoir, Pa^erson Reservoir, and Lake Del Valle ACWD Zone 7 SCVWD 4 2

3 u How would the plants treaing SBA water handle a potenial cyanotoxins bloom in the SBA or upstream reservoirs? u To answer the quesion, the three SBA water agencies pooled resources and funded this bench- scale study u The informaion would also be used to respond to potenial quesions or concerns from policy makers and the public about cyanotoxins in the drinking water 5 PAC (opional) DAF Chlorine CausIc Ammonia PAC(opIonal) Overflow Structure Storage Super- Pulsator Anthracite/Sand Filters to System 6 3

4 Chlorine & Ammonia Ozone Chlorine CausIc Ammonia Clearwell Storage Pre- Ozone Floc/Sed. Anthracite/Sand Filters to System 7 H 2 O 2 (OpIonal) PAC (opional) Ozone Chlorine CausIc Ammonia Clearwell Storage Floc/Sed. Intermediate Ozone Anthracite/Sand Filters to System 8 4

5 Parameter Raw SBA Water Se5led DVWTP (1),(2) Se5led PWTP (1),(2) Alkalinity, mg/l as CaCO Hardness, mg/l as CaCO Bromide, mg/l TOC, mg/l ph UV- 254 (filtered), cm ConducIvity, µs/cm (1) SeRled water samples collected on different days. (2) DVWTP adds 50 to 60 mg/l ferric chloride, while PWTP adds ~30 mg/l alum 9 5

6 1. DestrucIon with ozone addiion to raw water (pre- ozone) 2. DestrucIon with ozone addiion to se^led water (intermediate ozone) 3. DestrucIon with chlorine addiion to se^led water 4. DestrucIon with chloramine addiion to se^led water 5. Removal with PAC addiion to raw water 11 u Collected water samples from raw SBA water and se^led water from the full- scale plants u All waters were filtered through 1 µm filter paper to eliminate effect of pariculate ma^er u Water samples were spiked with four toxins at a target of 10 µg/l of each of: u Anatoxin- a u Cylindrospermopsin u MicrocysIn- LA u MicrocysIn- LR 12 6

7 u Evaluated Doses ranging from 1 to 3 mg/l u Contact Ime was set at 10 minutes to simulate full- scale ozone contactors u Evaluated effect of bromate control strategies: u ph suppression u Pre- chloramine addiion 14 7

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9 17 u Evaluated Doses ranging from 0.5 to 2 mg/l u Contact Ime was set at 10 minutes to simulate full- scale ozone contactors u Evaluated effect of hydrogen peroxide, H 2 O 2, addiion u Evaluated effect of ph adjustment (6.5 vs 7.5) 18 9

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11 21 u Evaluated Doses ranging from 1 to 4 mg/l u Evaluated contact Imes up to 30 minutes u Evaluated toxins destrucion at ph 6.0 and 7.0 u Compared to CT required for Giardia inacivaion 22 11

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13 25 MC- LA MC- LR 26 13

14 MC- LA MC- LR 27 u Used pre- formed monochloramine u Evaluated Doses ranging from 1 to 3 mg/l u Evaluated contact Imes up to 2 hrs u Evaluated toxins destrucion at ph

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16 u Applied it to raw water without coagulant addiion u Evaluated PAC doses up to 40 mg/l u Set contact Ime at 30 minutes u Evaluated toxins destrucion at ph 7.5 and

17 33 Within the context of this s toxins levels and water quality: u Ozone is highly effecive at toxins destrucion to levels well below the HA levels u Free chlorine was ineffecive against anatoxin- a, highly effecive against cylindrospermopsin, and reasonably effecive against microcysins u Chloramine was completely ineffecive against all four toxins u Removal with PAC was significant, but not enough to rely on it by itself, especially for anatoxin- a 34 17

18 Excellent Good Moderate Poor Ineffec3ve Technology Ozone Microcys>ns Cylindrospermopsin Anatoxin- a Free Chlorine PAC AdsorpIon Chloramine 35 Issam Najm Issam.Najm@WQTS.com 18