Metro - ECCV Zero Liquid Discharge Pilot Study_Application

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. Evaluate membrane treatment technologies in order to characterize their residuals streams in terms of quality and quantity. . Catalogue current membrane treatment technology facilities in Colorado and describe their current treatment and disposal practices. . Evaluate membrane residuals treatment and disposal options in terms of costs and feasibility for different treatment capacities. . Document and report on regulatory strategies utilized by other states with respect to permitting membrane treatment facilities and their produced residuals. . Evaluate the feasibility, cost, and environmental/public health protection concerns associated with: 1) permitting discharges of brine to surface waters; 2) beneficial reuse of water resources and dissolved solids recovered from membrane water treatment waste streams; and 3) land disposal of residual solid evaporates from brine waste streams. . Propose a pilot program that includes a proposed regulatory framework to address membrane water treatment and proper management of brine residuals in a specified drainage area (e.g., one or more water body segments where there are communities with existing and/or proposed membrane water treatment systems). A workgroup website is available at http://www.coloradowateroualitV.com/ro/index.htm. 3.0 Drivers of Membrane Treatment Membrane treatment was first identified as a viable method for treating drinking water in the 1960's. Over the years, membrane treatment plants have become more affordable to construct and operate. Conversely, the cost of freshwater water supplies for municipal use has increased sharply due to a dramatic decrease in available water supplies. In the South Platte River Basin, as well as other parts of the state, public drinking water utilities have become increasingly reliant on lower quality source waters that typically require a greater degree of treatment than pristine sources. Up until now, potential impacts associated with the use of RO/NF treatment have not been fully evaluated. Water suppliers have routinely assumed that RO treatment addresses issues surrounding the production of drinking water that meets public health requirements but have overlooked the issue of brine concentrate disposal. This is primarily an artifact of dealing with residuals from conventional processes. Historically, conventional water treatment residuals have been easily addressed in a the design of a treatment facility. Conversely users of water and regulatory issues have not adequately addressed the impact that activities such as urban growth, non-point source, agricultural return flows, and increased use of reclaimed water have had on water supplies available for drinking water use. Reducing nitrate, TDS, and other natural and man-made concentrations in source waters represents a particularly difficult challenge for drinking water suppliers. Circumstances as described above has resulted in a greater number of drinking water utilities choosing to implement membrane treatment to address Safe Drinking Water Act requirements and aesthetic issues resulting from lower quality source water supplies (refer to Appendix B for information on current and proposed RO facilities in Colorado), 5