Implementing Direct Potable Reuse in the Arid Southwest: El Paso s Advanced Water Purification Facility

Transcription

1 Implementing Direct Potable Reuse in the Arid Southwest: El Paso s Advanced Water Purification Facility Imagine the result July 31, 2015

2 Acknowledgements El Paso Water Utilities: John Balliew Gilbert Trejo Fernie Rico Carlos Dominguez Aide Zamarron ARCADIS Sanaan Villalobos Dan Olson Fred Blumberg Brent Alspach Corin Marron Chelsea Francis George Maseeh Texas Commission on Environmental Quality (TCEQ) UTEP Shane Walker Graduate students

3 Current Drought Conditions in El Paso El Paso has endured drought conditions for several years Combined reservoir storage less than 10% of capacity EPWU has instituted drought support programs to ensure adequate potable water supplies June 2, 1994 July 8, 2013 Courtesy: NASA Elephant Butte Reservoir 3 20 August 2015

4 Long History of Conservation and Reuse 1963: EPWU began delivering reclaimed water for irrigation, industrial, and construction uses. 1985: EPWU began using reclaimed water treated to drinking water standards for aquifer recharge (Fred Hervey WRP) gpcd: Reduced from 225 in the 1970s to 132 in 2013

5 MGD 220 Non-Drought Year River Water Underground Water Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct Supply Peak Water Use

6 MGD 220 Drought Year River Water Underground Water Feb 1-Mar 1-Apr 1-May 1-Jun 1-Jul 1-Aug 1-Sep 1-Oct 20 August ARCADIS Supply Peak Water Use

7 MGD 220 Drought Year Without River Water Underground Water May June July Supply Peak Water Use

8 MGD 220 Drought Year Without River Water Purified Water Underground Water May June July Supply Peak Water Use

9 Project Evolution: Feasibility Assessment and Policy Changes in Initial feasibility assessment completed in 2012 covering IPR, wetlands restoration, and DPR concepts Business case for potable reuse developed May 8, 2013: EPWU Public Service Board approves reprogramming of capital funding from purple pipe projects to potable reuse

10 Indirect Potable Reuse 10

11 More Direct Potable Reuse 11

12 Most Direct Potable Reuse 12

13 Advanced Water Purification Facility Concept Bustamante WWTP with Additional Treatment (29.2 MGD average flow) 10 MGD Advanced Water Purification Facility Distribution System Residuals Handling MF Backwash = 1.0 MGD RO or NF Concentrate = 1.8 MGD Riverside Irrigation Canal 13

14 Why Pipe-to-Pipe DPR? Lack of surface water supplies for blending into raw water at adjacent Jonathan Rogers WTP much of the year Confidence in advanced treatment processes and monitoring/control technologies Close proximity of Bustamante WRP to Rogers WTP distribution infrastructure No regulatory prohibition Direct-to-distribution makes sense for El Paso August 2015

15 Phase I: Concept Development Water quality review and sampling Initial regulatory coordination Alternatives evaluation and conceptual design Independent advisory panel engagements Pilot testing plan Public outreach (continuous) 15

16 Historical Water Quality Data ( ) Bustamante WWTP Effluent Alkalinity (mg/l as CaCO 3 ) Ammonia (mg/l as N) Nitrate (mg/l as N) Nitrite (mg/l as N) ph TDS (mg/l) Min th % , th % ,210 Max ,250 N August ARCADIS

17 Water Quality Sampling Plan General physical and chemical samples (monthly) Microbial contaminants Giardia, Cryptosporidium, E. coli, Total coliform (monthly) Viruses under EPA 1615 (quarterly) Inorganic Contaminants Perchlorate, cyanide, radionuclides, asbestos (biannually) Organic Contaminants MIB, geosmin (monthly) Phase I, II, and V regulated and unregulated volatiles and polychlorinated biphenyls (quarterly) Other organics with MCLs, e.g., herbicides, pesticides, dioxin, diquat, endothall, glyphosate (quarterly) Disinfection Byproducts (monthly in final effluent) Chemicals of Emerging Concern (biannually) August ARCADIS

18 Regulatory Considerations Municipal/ industrial discharges 10 MGD MF Backwash = 1.0 MGD RO or NF Concentrate = 1.8 MGD Project Component Industrial Pretreatment Program Reclaimed Water Permit (210) TPDES Permit for Concentrate Disposal Pilot Test Plan and Report Review APWTP Plan Review (incl. disinfection CT Study) August ARCADIS Permitting Time Frame No permit requirements Minimum of 90 days each New source evaluation over 365 days

19 Water Quality Goals Address both regulatory criteria and public concerns for this DPR project Meet all primary water quality standards Provide multiple barriers for pathogens Provide diverse treatment for chemical microconstituents Meet EPWU specific goals and AWWA Partnership for Safe Water requirements August 2015

20 Effluent NH3 and NO3 Concentration (mg/l as N) Source Water: Bustamante WWTP Screening/ Grit Removal Pre-Aeration Primary Settling Activated Sludge Secondary Settling Cl 2 Discharge to Riverside Canal Return Activated Sludge 10 MGD Denitrifying Filters To AWPF Apr-14 May-14 Jun-14 Jul-14 Aug-14 Sep-14 Oct-14 Effluent NH3 Effluent Nitrate 30 per. Mov. Avg. (Effluent NH3) 30 per. Mov. Avg. (Effluent Nitrate)

21 Simplified Process Schematic Additional Treatment at Bustamante WWTP 1 Advanced Water Purification Facility 2 Secondary Clarifier Effluent MF/UF NF/RO Cl 2 Disinfection Denitrifying Filters Backwash Concentrate UV AOP GAC for H 2 O 2 Quenching Clearwell 1 Additional treatment at Bustamante WWTP includes improvements to achieve full nitrification and prevent ammonia breakthrough. 2 Potential ozone and/or coagulant addition locations and dosages will also be considered during pilot testing for potential application during full-scale. 21

22 Simplified Process Schematic Additional Treatment at Bustamante WWTP 1 Advanced Water Purification Facility 2 Secondary Clarifier Effluent O 3 MF/UF NF/RO Cl 2 Disinfection Denitrifying Filters Backwash Concentrate UV AOP GAC for H 2 O 2 Quenching Clearwell 1 Additional treatment at Bustamante WWTP includes improvements to achieve full nitrification and prevent ammonia breakthrough. 2 Potential ozone and/or coagulant addition locations and dosages will also be considered during pilot testing for potential application during full-scale. 22

23 Secondary Clarifier Effluent MF/UF NF/RO Cl 2 Disinfection Denitrifying Filters Backwash Concentrate UV AOP GAC for H 2 O 2 Quenching Clearwell Denitrifying Filters MF/UF NF or RO UV/AOP GAC Cl 2 Particulates Range of Treatment Effectiveness Primary removal mechanism; >90% effectiveness TOC Nutrients TDS (Hardness) TDS (Chloride) Microconstituents Pathogens Viruses Additional removal mechanism; >90% effectiveness 75 to 90% effectiveness 50 to 75% effectiveness 25 to 50% effectiveness None to <25% effectiveness August 2015

24 TCEQ Microbial Treatment Requirements for Potable Reuse Projects Site-specific requirements for treatment based source water quality Treatment requirements set to meet EPA goals to minimize exposure to pathogens (10-4 risk of annual infection from Giardia, Cryptosporidium or viruses) Source water quality Treatment for Potable Reuse Target finished water quality August 2015

25 Microbial Barriers Secondary Clarifier Effluent MF/UF NF/RO Cl 2 Disinfection 20 August 2015 Denitrifying Filters Unit Process Backwash Concentrate UV AOP Anticipated TCEQ Log Removal / Inactivation Credits Crypto Giardia Viruses Denitrification Filters MF/UF NF/RO UV AOP GAC Cl Total TCEQ Requirement Example Based on site-specific microbial water quality for Big Spring, TX project. GAC for H 2 O 2 Quenching Clearwell

26 Pilot-Scale Online Monitoring TOC, Ammonia, & Nitrate Turbidity, Pressure Decay, Flow, & Temperature Chloramines, TOC, Turbidity, Conductivity, Pressure, Flow, Temperature, & ph Secondary Clarifier Effluent O 3 MF/UF NF/RO Cl 2 Disinfection Denitrifying Filters Backwash Concentrate UV AOP GAC for H 2 O 2 Quenching Clearwell TOC, Turbidity, Ammonia, Nitrate, & Nitrite UVT, Reactor Power Level, & UV Intensity Flow & Pressure August 2015

27 Testing Plan Approval We find the pilot study protocol acceptable with amendments to include additional data and information in the final pilot study report. TCEQ Approval Letter April 17,

28 Pilot Testing Objectives 1. Meet all TCEQ requirements for pilot testing 2. Demonstrate that the treatment train under consideration meets all water quality goals 3. Establish process design criteria 4. Demonstrate stable and reliable performance 5. Characterize the waste streams to facilitate permitting and design of residuals handling components 6. Determine the best options for online monitoring, alarms, and controls 28

29 Denitrification Filters 29

30 Membrane Filtration 30

31 NF/RO Membranes 31

32 UV-AOP & GAC 32

33 Summary Potable reuse projects can help diversify water supply portfolios with a local, drought-proof, sustainable supply. Advanced technology makes purified water safe to drink. Source water control is a critical component; upgrading WWTPs can be a first step for a smooth transition to potable reuse 33

34 Imagine the result August ARCADIS

35 El Paso has been a leader in water reuse for decades. Advanced technology makes purified water safe to drink. Purified water is a local, drought-proof, sustainable supply for our community. H2OTOGETHER.ORG 35

36 Residuals Handling Residuals Handling Options Recycle to head of Bustamante WWTP Discharge NF/RO concentrate and MF/UF backwash directly to Riverside Canal Blend NF/RO concentrate with Bustamante WWTP effluent for discharge under current TPDES permit Deep well injection 1 Permitting Timeframe Falls under Pretreatment Program 330 days or less 330+ days Dependent on injection well classification Considerations: Regulatory feasibility Permitting time frame Costs Land availability Hydrogeology Evaporation Pond + Beneficial Reuse General permit 1 Current injection wells for KBH are Class V. Classification dependent upon TDS concentration in injection zone August ARCADIS

37 TDS (mg/l) Sodium Adsorption Ratio (SAR) Concentrate Water Quality 6000 Riverside Irrigation Canal Screening Number= 6,000 mg/l TDS 5000 TDS SAR Haskell St WWTP SAR Limit = Full-Stream RO Partial-Stream RO Full-Stream NF Partial-Stream NF August ARCADIS

38 Test Program Nine-month pilot testing program Simulate ultimate full-scale AWPF Four stages of testing: Stage 1: Optimization Stage 2: Demo Testing Stage 3: Ext. Operation Stage 4: Additional Testing Denitrifying filter acclimation Optimization testing for the unit processes Formal 30-day testing window under optimized conditions Continued testing under optimized conditions (following CIP) Potentially assess coagulant addition Challenge testing

39 Key Elements to Testing Approach Pilot- Scale Testing Secondary Clarifier Effluent Denitrifying Filters O 3 MF/UF Backwash NF/RO Concentrate UV AOP GAC Bench- Scale Testing Coagulation evaluation Corrosion/pipe loop testing 39