Metro - WERF_ Zero Liquid Discharge_Quarterly Report08 30 11

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� WERF Water Emvo�ment Research Poundation Coflaboration. /nnovation. Results. Memorandum To: Greg Johnson, Colorado Water Conservation Board Water Supply Planning Section From: 1eff Moeller, P.E., WERF Senior Program Director �%�� Date: August 3Q, 2011 Subject: Quarterly Report (March 18, 2011—July 18 2011) BACKGROUND Increasing demands for potable water in Coforado have forced drinking water utilities to consider utilizing water from lower quality sources. These lower quality sources require the use of advanced treatment technologies such as reverse osmosis (RO) or nanofiltration (NF) membranes to treat the water to a level su+table for human consumption. At present, drinking water utilities have been reluctant to undertake RO or NF membrane projects due to the uncertainty surrounding the availability of feasible disposal options for the concentrate. Zero liquid discharge (ZLD) is a sustainable disposal option that may represent a long-term solution to concentrate disposal for utilities that need membrane treatment to produce safe drinking water. The primary barrier to implementing ZLD is the lack of cost and performance data developed for drinking water systems under conditions unique to Colorado. A pilot test demonstrating ZLD will help address the technical and financial uncertainties which currently hinder its implementation. Pilot testing will occur at two existing RO plants, one in Brighton, Colorado and another in La Junta, Colorado. The Brighton plant treats groundwater adjacent to the South Platte River and has an average concentrate TDS of 4,260 mg/L. Based on RO modeling of the existing brine, the constituents that will limit the recovery of Brighton's concentrate are silica and calcium phosphate. 7he La Junta plant treats groundwater adjacent to the Arkansas River and has an average concentrate TDS of 7,420 mgjL. Based on RO modeling of the existing brine, the constituent that will limit the recovery of La Junta's concentrate is calcium sulfate. RESEARCH PROJECT PROGRESS The structure for managing and administering the membrane ZLD demonstration project will be composed of several inter-related components including WERF, a Steering Committee, a Project Subcommittee, a Contractor (HDR), Project Test Sites, and the Membrane Treatment Workgroup (MTW). To date, WERF has entered into an agreement with HDR, and they have subsequently entered into agreements with their partners on the project such that the all project agreements are currently in place and the project is up and running. The agreement between WERF and HDR took roughly a month to implement, and was executed on April 11, 2011_ Therefore, this first quarterly report covers a four month period to account for the contractual set-up of the project and to align the reporting of subcontractors with WERF reporting to the Colorado Water Conservation Board for the project going forward.