Advances in Treatment for Potable Reuse

Transcription

1 Advances in Treatment for Potable Reuse WateReuse LA Chapter December 6, 2016 Steve Alt CH2M

2 Beenyup Advanced Water Recycling Plant (BAWRP) Process Schematic Plant is designed to be expanded from 10 to 20 MGD Preformed chloramines Dow SFD-2880 UF module STAGES 1 AND 2 PRE-FORMED CHLORAMINES PRE-FORMED CHLORAMINES ANTISCALANT SULFURIC ACID REVERSE OSMOSIS SODIUM HYDROXIDE FROM COARSE SCREENS P P P P TO LEEDERVILLE AQUIFER AWRP BALANCE TANK FINE SCREEN ULTRA- FILTRATION RO FEED TANK DEGASSER UV TREATED WATER STORAGE TANK ALK = 8.4 MG/L PH = 7.5 NAOH = 11 MG/L BACKWASH TO RETURN WORKS CONCENTRATE TO OCEAN OUTFALL

3 BAWRP Level of Microbial Removal Equivalent Log Reduction Credits Bacteria Virus Protozoa Wastewater Treatment BAWRP Process Unit Additional Membrane Virus Credits UF with chloramination >1.5 mg/l Reverse Osmosis UV Disinfection at 186 mj/cm Total AWRP ELRC Total Process Virus Credits Total (WWTP & BAAWRP) DoH Requirement Excess credits (safety factor) California Requirement NA 12 10/10

4 Potable Reuse Plants RO-Based (West U.S. and International) vs. GAC-Based (East and Central U.S) Western U.S. uses RO based approach (and SAT) East and Central U.S. uses GAC based approach Singapore uses RO based approach Queensland, WA use RO based approach Fit for Purpose Water: The Cost of Overtreating Reclaimed Water (WRRF-10-01)

5 Tucson Water Pilot Testing Proposed treatment approach utilizes SAT, side stream NF, Ozone and BAC-GAC to provide multiple barriers required for potable reuse and TDS removal CHLORINE SECONDARY EFFLUENT CARTRIDGE FILTER NF CONC. O3 POTABLE WATER TO DISTRIBUTION SOIL AQUIFER TREATMENT ORGANICS CECs PATHOGENS SOLIDS SIDE STREAM NF TDS ORGANICS PATHOGENS CECs OZONATION / BAC- GAC PATHOGENS ORGANICS CECs Pilot testing for WRRF conducted at Tucson, AZ where reuse is being considered for the future FREE CHLORINE PATHOGENS

6 Tucson Water Total Organic Carbon TOC (mg/l) mg/l 91% Reduction after SAT AGUA NUEVA SECONDARY EFFLUENT 45% Reduction after Partial NF SWEETWATER RECHARGE BASINS SOIL AQUIFER TREATMENT ANTISCALANT CARTRIDGE FILTER 40%Q 60%Q SIDE STREAM NANOFILTRATION TOC Detection Limit NF CONC. O3 OZONATION GAC/BAC >40% Reduction after BAC PRODUCT WATER

7 Tucson Water Total Contaminants of Emerging Concern 44 CECs monitored All below the detection limit in finished water Some CECs are recalcitrant to certain treatment, so multiple barriers is important 2015/04/30 Concentration of Trace Organics in ng/l Compounds Category Agua Nueva Well 69B Ozone Influent Ozone BAC C1 (Calgon) BAC C2 (Calgon) BAC C3 (Norit) BAC C4 (Norit) Benzophenone Industry (paint, 129 < 30 < 16 < 30 < 28 < 29 < 30 < 29 Benzotriazole De-icing, < 480 < 480 < 470 < 500 inhibitor, Caffeine stimulant < 4.0 < 5.2 < 4.4 < 5.6 < 3.9 < 4.1 < 3.7 < 3.8 Carbamezapine Anit-epileptic < 1.6 < 1.6 < 1.5 < 1.5 < 1.5 DEET Insect repellant < 6.0 < 4.1 < 4.0 < 3.8 < 3.6 Gemfibrozil cholesterol drug 5.4 < 1.0 < 1.0 < 1.1 < 0.9 < 0.9 < 0.9 < 0.9 Ibuprofen anti-inflamatory, < 2.8 < 3.7 < 3.5 < 4.9 < 3.6 < 3.5 < 3.0 < 3.5 Iopamidol Angiography < 27 < 28 < 26 < 31 Iopromide x-ray contrast 5465 < 24 < 34 < 24 < 27 < 28 < 26 < 31 Meprobamate tranquilizer < 10 < 10 < 10 < 10 PFO A cookware, < 0.8 < 0.8 < 0.7 < 0.7 textiles, clothing, PFO S Stain repellant < < 3.5 < 3.5 < 3.8 < 3.9 Primidone Anit-epileptic < 4.3 < 5.7 < 4.8 < 4.8 Sucralose Artifical sweetner < 220 < 240 < 240 < 250 Sulfamethoxazole antibiotic < 8.0 < 5.0 < 4.9 < 4.5 < 4.9 TC EP Flame retardant < 22 < 22 < 23 < 23 TC PP Flame retardant 715 < < 22 < 22 < 23 < 23 Triclosan soap 44 < 12 < 9 < 13 < 13 < 14 < 13 < 14

8 Ozone Disinfection Byproducts Ozone Dose = mg/l Bromate Bromide concentration in secondary effluent was relatively high (~0.3 mg/l) Formation was significant at higher ozone doses, but Bromate removal by BAC/GAC was significant NDMA Very high in the secondary effluent (sometimes above 200 ng/l) Excellent removal by SAT (< 10 ng/l) Bromate (µg/l) NDMA (ng/l) Bromate Formation and Removal O3 (BAC Influent) O3:TOC = 1.5 O3:TOC = 1.1 O3:TOC = 0.8 BAC - Calgon Bromate MCL = 10 µg/l BAC - Norit NDMA through Advanced Water Treatment Process * * Below Detection Limit (< 0.5 ng/l ) * * Ozone Influent Ozone BAC Influent BAC #2 (Calgon) BAC #4 (Norit)

9 Tucson Water Conclusions Issue Do multiple organics barriers provide suitable water quality? Can TDS goal be met with sidestream NF treatment? Can bromate and NMDA formation be controlled? Are pathogens adequately removed? Is GAC-based train suitable for potable reuse at Tucson? Answer Yes; finished water quality: 1) TOC< 0.25 mg/l 2) All 44 CECs non-detect Yes, TDS < 500 mg/l consistently met Yes, both were well below regulated limits: Bromate < 3 µg/l (MCL = 10 µg/l) NDMA < 0.5 ng/l (CA limit 10 ng/l) Yes, post-sat water was non-detect for viruses and protozoa; >4-log removal of viruses by just SAT Yes and costs are much lower than RObased train The Final Report for WRRF is currently under review and will be published in 2016

10 WE&RF Characterization and Treatability of TOC from DPR Processes Compared to Surface Supplies The goal of the research is to develop a site-specific, feasible, and scientificallydefensible framework for organics removal for utilities pursuing direct potable reuse TOC and COD alone are not able to properly reflect exposure to organics contaminants Is a TOC goal of 0.5 mg/l appropriate? Is a COD goal of 10 mg/l appropriate? A framework will be develop to demonstrate if potable reuse water is comparable in safety to local drinking water based on the concept of Chemical-Associated Toxicity (CAT) PI: Larry Schimmoller/CH2M CO-PIs: Dr. Bill Mitch/Stanford; Dr. Shane Snyder/University of Arizona

11 Hampton Roads Sanitation District (Virginia) HRSD is constructing pilot facilities that include parallel treatment trains for a direct comparison of RO and non RO based treatment

12 Questions=? Thank You

13 13 Potable Reuse Costs: RO-based vs. GAC-based $400,000,000 $350,000,000 $300,000,000 $250,000,000 $200,000,000 $150,000,000 $100,000,000 $50,000,000 $0 Capital Costs MF/RO/UVAOP (evap ponds) MF/RO/UVAOP (mech evap) MF/RO/UVAOP (Ocean Disposal) Floc/Sed/O3/ BAC/GAC/UV Plant Capacity (MGD) Source: Figure taken from WRRF Figures are WateReuse Research Foundation s Intellectual Property GAC-based treatment less expensive High treatment cost for RO-based treatment due to costs for concentrate disposal, especially at inland locations Pretreatment to RO typically MF and also expensive SAT costs (not shown), are site specific but assumed to be reasonable with right geologic conditions