Effects of Feedwater Salinity and Composition on Industrial Zero Liquid Discharge Process Performance and Costs

This presentation focuses on research results from two projects, the Bureau of Reclamation project: Treatment of Concentrate and the Joint Water Reuse and Desalination Task Force report: Survey of High Recovery and Zero Liquid Discharge Technologies for Water Utilities. As part of the research the treatment of concentrate by the 5 general ZLD processing schemes that have been used in the industry were studied. Variables included plant size (1, 10, and 20MGD), salinity (4,000, 8,000, and 12,000 mg/L), and concentrate composition (various levels of major ions and silica). Capital, operating, and annualized costs were developed for the 5 ZLD process schemes as a function of the variables. Results indicate a strong dependence of process cost on salinity and composition and reveal system performance and cost trends, individual process step contributions to costs, and identify major cost factors.