Zero-Liquid Discharge: Desalination of Waters with High Organic Content

Abstract

A Water Research Foundation Tailored Collaboration project is being conducted to evaluate zero-liquid discharge (ZLD) desalination of waters with high concentrations of natural organic matter (NOM). The technical approach involves treating reverse osmosis (RO) or nanofiltration (NF) membrane concentrate to reduce fouling potential so the concentrate can be desalinated in a second membrane application. Concentrate generated from waters with high organic content must be treated to remove total organic carbon to prevent organic fouling and calcium, sulfate, and silica to prevent inorganic fouling. The research consists of three phases: preliminary analysis to identify concentrate treatment goals, evaluation of concentrate treatment options, and evaluation of the selected treatment approach. The processes evaluated for concentrate treatment were chemical softening, fluidized-bed crystallization, activated alumina, coagulation, ion exchange, and electrodialysis metathesis. Testing was conducted on five water sources. Results for one water source are reported here. The final Water Research Foundation report will be published in November 2010.