November 2015 Technical and Cost Evaluation of Alternative Treatment Trains for Indirect and Direct Potable Reuse Bill Dowbiggin, P.E.; Bruce Chalmers, P.E.; Sheri Smith, P.E Annual Conference Raleigh, NC

Indirect Potable Reuse Includes an Environmental Buffer like a Reservoir, River or Aquifer Between the WWTP and the WTP

NC has lots of Indirect Potable Reuse (IPR) – at each WTP with intake downstream of one of the major NPDES discharges below (each colored area is a river basin). This is termed De Facto or Unplanned IPR. 3

 Microfiltration, reverse osmosis, advanced oxidation process (MF/RO/AOP)  Why look for alternatives to MF/RO/AOP?  Primary reason is the cost  Second reason is brine disposal  Lack of operator experience  Existing tertiary facilities  Abundant surface recharge capacity  Good water quality  Demineralization isn’t necessary  Nitrogen reduction isn’t necessary What is the California Approach?

What Else is There?  Treatment capabilities: depends on treatment process used, some removal is possible for nutrients (e.g. total nitrogen and total phosphorus, TN and TP), total dissolved solids (TDS), total organic carbon (TOC), and contaminants (or constituents) of emerging concern (CEC)  Treated water quality will depend on selected alternative treatment process and the wastewater influent quality AlternativeTreatment Method 1Tertiary recycled water 2MF/RO Blend 3GAC or Ozone/Biologically-Activated Carbon (BAC) 4Nanofiltration 5Electrodialysis

California Model MF/RO/AOP  MF/RO/AOP to produce highest quality water  AOP often with UV-peroxide  Pre-approved by CA as part of 2013 draft GWR Regulations for surface and subsurface application  Recharge facilities: Surface spreading and groundwater injection  Treatment capabilities: nutrient, TDS, TOC, CEC removals  Recycled Water Contribution (RWC): start at 75%-100%, lowest blend water requirements  RWC will vary by project and regulator  Simplifies operations because of less reliance on blend water

California Model MF/RO/AOP To WWTP WWTP

California Model MF/RO/AOP Advantages  Approved by CA for surface percolation and injection wells  Best Available Technology  Numerous existing facilities  Produces highest-quality water  Removes TOC, TDS, TN & CECs  Accepted by the public  Shorter travel time/lower initial diluent requirement  Potential elimination of diluent water Disadvantages  Expensive to construct  High O&M cost for power and chemicals  Brine management required

Alternative Treatment Alternative 1 - Tertiary Filtered Recycled Water  Disinfected tertiary recycled water  CA Recharge facilities: Surface spreading only  Treatment capabilities: no nutrient, TDS, CEC removal, some TOC  RWC in CA: start at 20% RWC, blending req’d  Montebello Forebay: permitted at 35% RWC, TOC reduction to increase to 50% RWC  Chino Basin (IEUA): permitted RWCs range from 25 to 45%

Alternative Treatment Alternative 1 - Tertiary Filtered Recycled Water

Advantages  Approved by CA for surface spreading  Meets T22 (CA reg for reuse water) water quality  Less expensive to construct  Many WRPs already have tertiary effluent facilities for discharge  No brine management required  Proven history (Montebello Forebay since 1962) Disadvantages  Percolation only  May not meet basin plans for TDS and TN  Requires extensive amounts of diluent water  Requires long travel time (> 6 months)  CEC, TN removal by Soil Aquifer Treatment (SAT) only

Alternative Treatment Alternative 2 – Blend of Tertiary Recycled Water/Reverse Osmosis Permeate  Blend of tertiary effluent and RO permeate  Partial advanced wastewater treatment (AWT) train with MF/UF and RO  Phased AWT train with tertiary effluent (TE) initial phase followed by MF/RO phase  Combined or separate disinfection or disinfection/AOP  Recharge facilities: Surface spreading only  Treatment capabilities: Partial nutrient, TDS, TOC, CEC  CA RWC: Begin at 20% RWC because of tertiary component  Higher RWCs than tertiary effluent alone  RO Capacity  RO capacity determined for TOC reduction for desired RWC  RO capacity can also be sized for TDS reduction

Alternative Treatment Alternative 2 – Blend of Tertiary Recycled Water/Reverse Osmosis Permeate 5 mgd 11.6 mgd 0.8 mgd 15 mgd 10 mgd 16.6 mgd 0.8 mgd To WWTP

Alternative Treatment Alternative 2 – Blend of Tertiary Recycled Water/Reverse Osmosis Permeate Advantages  Good water quality  Removes some TDS, TOC, TN & CECs  Requires diluent water (but not as much as TE)  Implementation can be phased  AOP not required  Less expensive than MF/RO/AOP Disadvantages  More expensive to construct than tertiary effluent  Moderate O&M cost for power and chemicals  Some brine management required  Percolation only

Alternative Treatment Alternative 3 – GAC or Ozone-BAC  Ozone & BAC in various configurations to produce high quality water  Processes: Ozone, BAC, optional MF/UF polishing, disinfection  Recharge facilities: Surface spreading only in CA  Treatment capabilities: No nutrient or TDS removal, some TOC removal, CEC removal Filtered WW Disinfection Percolation Pond or Raw Water Reservoir

Alternative Treatment with GAC or Ozone-BAC  Existing Facilities:  Goreangab WTP (Windhoek, Namibia) – Ozone-BAC, direct potable reuse  Fred Hervey WRP (El Paso, TX) – Ozone-BAC, indirect potable reuse, irrigation and cooling water  F. Wayne WRP (Georgia) – Ozone-BAC, indirect potable reuse into Lake Lanier  UOSA (Virginia) – GAC (pilot testing Ozone-BAC), indirect potable reuse into Occoquan Reservoir Pathogen CDPH Reqmt WWTP Title 22 Treatment OzoneBACUV Travel Time/ SAT Total Virus122 Up to 5 total 6006>12 Giardia >0 TBD >10 Crypto- sporidium >0 TBD >10

Alternative Treatment Alternative 3 – GAC or Ozone-BAC (optionally with Sidestream MF/RO) 3.4 mgd 0.24 mgd 2.9 mgd 15.5 mgd 15 mgd 0.26 mgd To WWTP

Alternative Treatment Alternative 3 – GAC or Ozone-BAC  Advantages:  Removes some TOC so less blend water  Effective at removing CECs  Elimination of concentrated brine stream  Potential for reduced energy requirements  Disadvantages:  Must be permitted as an “Alternative” process to increase RWC for initial operation above 20% in CA  Does not reduce TDS or chlorides  Limited removal of nitrogen and phosphorus compounds  Does not remove as much TOC as MF/RO/AOP, higher blending water require  Potential to form bromate when high bromide in source water

Ozone-BAC Pilot Testing Projects are Underway for Gwinnett County GA and UOSA VA

Alternative Treatment Alternative 4 – Nanofiltration  Produces high quality water  Processes: MF/UF, NF, UV-AOP (NF replaces RO)  Recharge facilities: surface spreading, potential for groundwater injection if CA approved “Alternative”  Treatment capabilities: No nutrient removal, some TDS removal, TOC & CEC removal

Alternative Treatment Alternative 4 – Nanofiltration  Advantages  Potential lower power cost than RO  Removes TOC nearly as well as RO  Better water quality than T22, CA might allow subsurface injection  Disadvantages  Power savings may be temporary  Less TDS removal than RO  No reduction of concentrate compared to RO  No MF/NF/UV-AOP installations in California for IPR  Poor removal of inorganic nitrogen  No capital cost savings

Alternative Treatment Alternative 5 – Electrodialysis Reversal (EDR)  Process uses  Replacement for RO for TDS removal  Sidestream TDS reduction  Zero liquid discharge (ZLD) process  Existing Facilities  North City WRP (San Diego, CA)  TDS reduction for irrigation  Design/build: EDR vs RO  6 mgd  Fort Irwin 2014 (Barstow, CA)  EDR is proprietary with GE as the main manufacturer

Alternative Treatment Alternative 5 – Electrodialysis Reversal  Advantages  Slightly higher recovery than MF/RO/AOP at 85%  Can reduce TDS and TN  Can be used for ZLD  Disadvantages  Not a barrier process  No TOC or CEC reduction  Few full size installations with no CA-permitted IPR facilities  Time-consuming manual membrane maintenance  Potential electrical and leakage problems

How to Decide?  Influent and product water quality are critical to determining which treatment process to use:  Primary focus is on TOC/COD reduction in CA and some other locations  Secondary focus is on TDS, Nutrients and CEC reduction  Consider whether current TDS and NO 3 concentrations are acceptable for example  Consider what brine management options are available  How much diluent water is available and at what cost?

How to Decide?  Has the process been permitted for IPR?  Consider sidestream treatment if needed:  South Bay Water Recycling Project – MF/RO to reduce TDS  Consider phasing of treatment:  Reduces initial costs  Helps meet water quality requirements  Extends time for brine management technologies  Impact of future regulations:  Will facilities be applicable to DPR?

How to Decide? CA Example EvaluationObjectiveSub-objective Maximize Cost-Effectiveness Initial Net Present Value (NPV) Build-out Net Present Value (NPV) Maximize Reliability Water Supply/Discharge Benefit Negative Impact on GW Wells Minimize Environmental Impact Environmental Permitting Complexity Environmental Value /Stewardship (Sustainability) Maximize Implementation Permitting Complexity Public Acceptability Improve Groundwater Basin Water Quality Basin Salt Concentration Minimize Operational Complexity Integration/Operational Complexity Reliability of Technology Compliance Sampling Frequency

Tertiary Filtration Ozone – BAC Partial MF/RO MF/RO/AOP Phased TE And MF/RO How to Decide? CA Example Evaluation (NF & EDR already eliminated) Cost EffectivenessReliability Environmental ImpactImplementation Groundwater QualityOperations

Cost of Alternative Treatment Trains for a 10 mgd facility ProcessCapital Cost RangeO&M Cost Range MF/RO/AOP*$ 7-10/gpd$ 1-2.5/thou gal Ozone/BAC$ 2.5-4/gpd$ /thou gal *Assumes ocean outfall available for RO

Conclusions  MF/RO/AOP is still a popular and viable alternative in CA  MF/RO/AOP is the only proven process for injection wells  “Alternative” treatment processes should be investigated  Partial or phased MF/RO offers advantages of less cost and lower brine production  Ozone-BAC can be less expensive and requires less blend water but may need sidestream TDS and TN reduction  Ozone-BAC use is increasing outside of CA due to cost- effectiveness for the quality and sustainability factors  Nanofiltration may have lower O&M costs than RO  EDR is not a barrier but can work as a sidestream or part of a zero liquid discharge brine treatment process

Questions William B. Dowbiggin, P.E., BCEE CDM Smith (919)