The National Trend towards Direct Potable Reuse

Transcription

1 The National Trend towards Direct Potable Reuse RMWEA/RMSAWWA JTAC March 19, 2015 Larry Schimmoller/CH2M Hill Global Technology Leader for Water Reuse John Rehring/Carollo Vice President

2 Agenda Introduction Drivers Regulatory Approaches DPR Economics Water Quality Considerations and Implications to Treatment Projects Public Outreach Conclusions 2

3 Water Reuse is the Recycling of Treated Effluent for Beneficial Use Non-Potable Reuse Agricultural Irrigation Landscape Irrigation Industrial Uses Recreational & Environmental Enhancement Water Reclamation Plant Potable Reuse Indirect Potable Reuse: Drinking water source (reservoir, aquifer, etc..) Direct Potable Reuse: pipe to pipe connection Wastewater Treatment Plant Treatment Plant Effluent 3

4 Common Indirect Potable Reuse Approaches De Facto reuse WWTP River WTP Surface water augmentation WWTP AWTP Reservoir WTP Groundwater recharge via spreading basins WWTP AWTP Spreading Basins Groundwater recharge via direct injection 4 WWTP AWTP

5 Direct Potable Reuse Direct Potable Reuse Approaches WWTP AWTP WTP WWTP AWTP 5

6 Potable Reuse Indirect Potable Reuse Recycling of reclaimed water back to the potable water system via an environmental buffer Environmental Buffer provides: Retention time to allow response to upset events Attenuation of contaminants Blending and dilution with other waters Direct Potable Reuse: Recycling of reclaimed water directly into the potable water system Pipe-to-Pipe Connection upstream or downstream of WTP Direct potable reuse can provide equivalent water quality provided the appropriate monitoring and response time is provided 6

7 History of Potable Reuse 7

8 Denver Direct Potable Reuse Demonstration Plant Can wastewater be purified to a level equivalent to Denver s high quality drinking water? Building on experience learned from the South Lake Tahoe and UOSA projects, Denver Water built a 1 mgd potable reuse demonstration plant to test the feasibility of direct potable reuse $30 million project: most comprehensive direct potable reuse feasibility study ever conducted in the world Engineering and construction For 5 years, the demonstration plant is operated in alternative treatment configurations to select the highest performing treatment. For 2 years, the highest performing treatment is subjected to unprecedented water quality and health effects testing for comparison to Denver s drinking water. The final project report is prepared and delivered proving the technical feasibility and public health safety of direct potable reuse. 8

9 Denver Direct Potable Reuse Demonstration Plant the selected treatment was subjected to unprecedented health effects testing $4 million whole animal health effects testing program: A 2-year chronic toxicity and carcinogenic study on both rats and mice was conducted A two-generation reproductive toxicity study was conducted. Notable absence of any negative health effects associated with consumption of either the reclaimed water or Denver drinking water. Findings unequivocally verified the ability of advanced water treatment processes to reliably remove a broad spectrum of pollutants and produce water that satisfies every currently known measure of drinking water safety. 9

10 Denver Direct Potable Reuse Demonstration Plant the demonstration plant was a touring show piece to foster public understanding & acceptance Thousands of people from around the world toured the facility. After learning about water treatment and reuse first hand, acceptance of direct potable reuse generally broke down as follows: 1/3 YES PLEASE 1/3 MAYBE 1/3 NO THANK YOU 10

11 Denver Direct Potable Reuse Demonstration Plant Big Lessons Learned 1. We can technically do it safely 2. The lime clarification system is O&M intensive is there a better way? 3. The Yuck Factor is a social barrier 11

12 Agenda Introduction Drivers Regulatory Approaches DPR Economics Water Quality Considerations and Implications to Treatment Projects Public Outreach Conclusions 12

13 Agenda Introduction Drivers Regulatory Approaches DPR Economics Water Quality Considerations and Implications to Treatment Projects Public Outreach Conclusions 13

14 Drinking Water & Public Health Protection Basis: Caveats for Potable Reuse Drinking water & public health protection guidance and regulations have evolved largely over the past 50 years and have always been founded on the premise that the water supply was either a natural surface water or groundwater source. Potable reuse violates this premise Drinking water and public health principles require modification to assure public health protection when the source of supply is derived from wastewater. 14

15 Drinking Water & Public Health Protection Basis: Caveats for Potable Reuse Higher pathogen concentration in source drives the need for additional treatment Clean Surface Water (USEPA) Dirty Surface Water (USEPA) Ground Water (USEPA) Indirect Potable Reuse (CDPH) Direct Potable Reuse (CDPH?) Virus Log Removal ? Crypto Log Removal Giardia Log Removal ? Minimizing or eliminating sources of industrial and commercial wastewater is prudent and discouraging residential customers from using toilets and sinks as receptacles for disposal of uncommon wastes (drugs, cleaners, paints, etc ) is important 15

16 Water Quality Health Maximum contaminant levels (MCLs) for drinking water must be met Also, consider chemicals on CCL3 (e.g., NDMA) Pathogens multiple barriers required for significant log removal Inorganics (e.g., ammonia, nitrate) Biological nutrient removal to produce low levels of ammonia, nitrate, and phosphorus highly recommended Organics Synthetic organic chemicals (e.g., atrazine); volatile organic chemicals (e.g., benzene) Elevated TOC can form THMs and HAAs in potable distribution system; TOC less than 2-3 mg/l usually required Heavy metals and Radionuclides: Typically not problematic although data analysis is required Chemicals of Emerging Concern No regulations and no known health effects, but multiple barriers typically provided 16

17 Water Quality - Aesthetics Total Dissolved Solids (TDS) Typically, mg/l of TDS added to the drinking water through the domestic cycle USEPA s secondary MCL (nonenforceable) is 500 mg/l; higher levels can cause taste complaints Total Hardness (calcium and magnesium) Between mg/l as CaCO3 is typically targeted for potable water to avoid customer complaints (taste, spotting on glassware) Tasters Scores (Higher is Better) TDS Goal: 400 mg/l A B C D E F G H I Sample TDS (mg/l) 17

18 Regulatory Considerations for Direct Potable Reuse Regulations for Indirect Potable Reuse (IPR) exist in some states in the U.S. and Australia, but there are no regulations for Direct Potable Reuse (DPR) California is currently considering the feasibility of regulating DPR DPR regulations under consideration are highly influenced by existing IPR regulations Texas has approved one DPR project; one other DPR project (Windhoek, Namibia) 18

19 Regulatory Examples for Potable Reuse Parameter California (IPR) Texas (DPR) USEPA (IPR) Total Organic Carbon (TOC) Pathogens < 0.5 mg/l RO required < 2 mg/l (of WW origin) Virus: 12-log LRV Crypto: 10-log LRV Giardia: 10-log LRV MF, RO, and UV required Multiple barriers required (Total Coliform BDL) Nitrogen TN < 10 mg/l None None Chemicals of Emerging Concern (CECs) Reverse Osmosis (RO) and advanced oxidation treatment req d RO required Miscellaneous Drinking water MCLs Drinking water MCLs; 80% min dilution req d None Drinking water MCLs; Turbidity < 2 NTU Note: This table summarizes the most significant parameters. Other requirements exist but are not shown for simplicity. IPR = Indirect Potable Reuse DPR = Direct Potable Reuse 19

20 Operational Potable Reuse Plants Project Location Type of Potable Reuse Year Capacity Montebello Forebay, CA, US Coastal GW recharge via spreading basins Windhoek, Namibia Inland Direct potable reuse mgd Current Advanced Treatment Process mgd GMF + Cl 2 + SAT (spreading basins) O 3 + Coag + DAF + GMF + O 3 /H 2 O 2 + BAC + GAC + UF + Cl 2 (process as of 2002) UOSA, Virginia, US Inland Surface water augmentation mgd Lime + GMF + GAC + Cl 2 Hueco Bolson, El Paso, TX, GW recharge via direct injection Inland US and spreading basins mgd Lime + GMF + Ozone + GAC + Cl 2 Clayton County, GA, US Inland Surface water augmentation mgd Cl 2 + UV disinfection + SAT (wetlands) West Basin, El Segundo, CA, US Coastal GW recharge via direct injection mgd MF + RO + UVAOP Scottsdale, AZ, US Inland GW recharge via direct injection mgd MF + RO + Cl 2 Gwinnett County, GA, US Inland Surface water augmentation mgd NEWater, Singapore Coastal Surface water augmentation mgd (5 plants) Coag/floc/sed + UF + Ozone + GAC + Ozone MF + RO + UV disinfection Los Alamitos, CA, US Coastal GW recharge via direct injection mgd MF + RO + UV disinfection Chino GW Recharge, CA, US GWRS, Orange County, CA, US Inland Coastal GW recharge via spreading basins GW recharge via direct injection and spreading basins mgd GMF + Cl 2 + SAT (spreading basins) 2008 Queensland, Australia Coastal Surface water augmentation mgd (3.1 m3/s) 66 mgd via three plants MF + RO + UVAOP + SAT (spreading basins for a portion of the flow) MF + RO + UVAOP Arapahoe County, CO, US Inland GW recharge via spreading mgd SAT (via RBF) + RO + UVAOP Surface water augmentation SAT (via RBF) + Soft + UVAOP + Aurora, CO Inland mgd (indirect potable reuse) GMF +GAC Direct potable reuse through raw Big Spring,TX, US Inland mgd MF + RO + UVAOP water blending 20

21 Direct Potable Reuse Examples RESERVOIR WATER Windhoek, Namibia (1968 Present) SECONDARY EFFLUENT PRE- OZONATION O3 FERRIC CHLORIDE FLOCCULATION Lahnsteiner et al, Aqua Services & Eng Ltd, 2007 AIR DAF BAC 2 STAGE GAC ULTRAFILTRATION DUAL MEDIA FILTRATION NAOH NAOH KMNO4 CL2 CHLORINE CONTACT MAIN OZONATION O3 POTABLE WATER GAC-based treatment approach Multiple organic barriers: DAF, ozone, BAC, GAC Multiple pathogen barriers: filtration, ozone, BAC, UF, Cl2 21

22 SECONDARY EFFLUENT Direct Potable Reuse Examples Big Spring, Texas MEMBRANE FILTRATION DISTRIBUTION SYSTEM POTABLE REUSE PLANT FILTERS Marlo Berg, TCEQ, 2011 REVERSE OSMOSIS SEDIMENTATION BASINS UV ADVANCED OXIDATION HYDROGEN PERO XIDE FLOCCULATORS RAW WATER RESERVOIR RAPID MIX WATER TREATMENT PLANT THOMAS PIPELINE RO-based plant Multiple organic barriers: RO, UVAOP Multiple pathogen barriers: MF, RO, UVAOP Water treatment plant included downstream for additional pathogen and organics barriers 22

23 Key Considerations for DPR Treatment Train Selection Equalization of flow required to capture diurnal flows, attenuate water quality, and to provide steady flow to advanced treatment processes Multiple barriers to pathogens are required Multiple barriers to organics are required Significant storage of finished water is required to allow water quality monitoring prior to pumping to potable water distribution Questions that may further influence DPR treatment selection: Where in potable water distribution system will water be introduced (Upstream of WTP? Directly into distribution system?) What will regulators require? What will public expect? 23

24 DPR Treatment Train Examples MF-RO-UVAOP WWTP Secondary Eff Potable Water RO- Based Equalization Floc/Sed MF/UF Reverse Osmosis UV AOP Storage & WQ Monitoring MF-NF-UVAOP WWTP Secondary Eff Potable Water NF- Based Equalization Floc/Sed MF/UF Nanofiltration UV AOP Storage & WQ Monitoring FLOC/SED-OZONE-BAC-GAC-MF-UV WWTP Secondary Eff Cl2 Potable Water GAC- Based Equalization Floc/Sed Ozone BAC GAC MF/UF UV Storage & WQ Monitoring 24

25 Treatment Train Comparison Contaminant Log Reduction Credits or Barrier (Y/N) RO-Based NF-Based GAC-Based Enteric Viruses 15-logs 15-logs 14-logs Crypto 14-logs 14-logs 9-logs Giardia 15-logs 15-logs 13-logs Suspended Solids 3 barriers 3 barriers 3 barriers Dissolved Metals 2 barriers 2 barriers 1 barriers Dissolved Organics 3 barriers + 3 barriers 3 barriers (but concerned about high THMs and HAAs) Dissolved Nutrients 2 barriers + 2 barriers 1 barriers Salts 1 barriers + 1 barriers 0 barriers 25

26 Treatment Train Comparison Contaminant Log Reduction Credits or Barrier (Y/N) RO-Based NF-Based GAC-Based Enteric Viruses 15-logs 15-logs 14-logs Capital Costs Crypto 14-logs 14-logs 9-logs $400,000,000 MF/RO/UVAOP Giardia 15-logs MF/RO/UVAOP 15-logs (mech evap) 13-logs (evap ponds) Suspended Solids $350,000,000 3 barriers 3 barriers 3 MF/RO/UVAOP barriers Dissolved Metals $300,000,000 2 barriers 2 barriers 1 (Ocean barriers Disposal) Dissolved Organics 3 barriers + 3 barriers 3 barriers (but concerned $250,000,000 about high THMs and HAAs) Dissolved Nutrients 2 barriers + 2 barriers 1 barriers $200,000,000 Salts 1 barriers + 1 barriers 0 Floc/Sed/O3/ barriers WWTP Improvements No Probably (nitrogen Yes BAC/GAC/UV $150,000,000 (nitrogen Required? removal) removal) Cost Considerations $100,000,000 $50,000,000 $0 CAPEX is most likely similar between all three treatment trains, except at inland locations where treatment/disposal of RO concentrate is required OPEX is most likely the lowest for the GAC-based train and highest 30 for the 40 RO-based 50 train Plant Capacity (MGD) 26

27 Water Quality Monitoring at Critical Control Points is Important CCP #1: TURBIDITY (ON-LINE) TOTAL COLIFORM (DAILY) DEAERATION TANK CHLORAMINE 2.5 m3/s ACID, SCALE INHIBITOR CCP #2: TOC (ON-LINE) CONDUCTIVITY (ON-LINE) 1.9 m3/s HYDROGEN PEROXIDE SODIUM HYPOCHLORITE SODIUM BISULFITE CCP #4: POWER MONITOR (ON-LINE) H202 DOSE (ON-LINE) CALCIUM CHLORIDE, SODIUM HYDROXIDE, CARBON DIOXIDE 1.9 m3/s TO POTABLE WATER LINE MEMBRANE BIOREACTOR (MBR) TO TIETE RIVER 2.0 m3/s RO FEED PUMP REVERSE UVD OSMOSIS CCP #3: POWER ROC TO MONITOR BAUEREI WWTP (ON-LINE) 0.6 m3/s UVAOP WATER QUALITY MONITORING & STORAGE STABILIZATION CCP #5: FREE CL2 (ON-LINE)

28 Typical Water Quality Parameter MBR TSS, mg/l < 1 Parameter RO Permeate ph < 6 Parameter Finished Water BOD, mg/l < 2 Nitrate + Nitrite, mg/l 5 Total Hardness (mg/l CaCO3) Corrosivity < 5 corrosive ph 7-9 Total Hardness (mg/l CaCO3) > 50 Ammonia, mg/l < 1 TN, mg/l < 10 TP, mg/l < 0.5 Turbidity < 1 NTU DEAERATION TANK CHLORAMINE TOC, mg/l < 0.5 TDS, mg/l < 20 TN, mg/l < 1 TP, mg/l < m3/s ACID, SCALE INHIBITOR 1.9 m3/s HYDROGEN PEROXIDE SODIUM HYPOCHLORITE SODIUM BISULFITE CALCIUM CHLORIDE, SODIUM HYDROXIDE, CARBON DIOXIDE Corrosivity 0 to -5 TOC, mg/l TDS, mg/l TN, mg/l < m3/s TP, mg/l < 0.05 TO POTABLE WATER LINE RO FEED PUMP STABILIZATION MEMBRANE BIOREACTOR (MBR) TO TIETE RIVER 2.0 m3/s REVERSE OSMOSIS ROC TO BARUERI WWTP 0.6 m3/s UVD UVAOP WATER QUALITY MONITORING & STORAGE

29 What do Potable Reuse Plants Look Like? Luggage Point AWTP (20 mgd) Flocculation / Clarification Raw Water Storage Membrane & UVAOP Building Chemical Building Thickener and Centrifuge Bldg Finished Water Pump Station WWTP Secondary Eff Potable Water Equalization Floc/Sed MF/UF Reverse Osmosis UV AOP Storage & WQ Monitoring Admin Bldg 29

30 Luggage Point AWTP Flocculation / Clarification Microfiltration Reverse Osmosis UV / Advanced Oxidation 30

31 Public Outreach and Education is Important Lack of knowledge leaves water management issues vulnerable to political exploitation, to stigmatizing language and misinformation Reuse projects are typically rejected due to fear and misunderstanding born from lack of knowledge We fail to tell the public about the water that has been recycled around the world for many decades - water reuse is the water industry s best kept secret We focus on the source of the water rather than its quality We define reuse in a way that scares people 31

32 Recent Research Illustrates that Words and Terminology are very important for Potable Reuse Projects (WRRF-07-03) The least reassuring terms are the ones the industry uses the most 32

33 Conclusions Increasing focus on potable reuse (and DPR) due to drought, population growth, and economics Drought-proof water supply Long history of potable reuse in the U.S. and the world Only two long-term DPR plants currently in operation but more to come Safe water can be reliably produced Multiple treatment barriers and continual monitoring is crucial Public outreach and education is important 33

34 Questions? 34