cooling Tower blowdown Treatment and Reuse A ZLD Case History A ZLD Case History

摘要

Introduction The High Desert Power Project, LLC is a large California power generator using microfiltration (MF) technology to treat and reuse cooling tower blowdown in a ZLD (zero liquid discharge) process. In operation since 2003, the process consists of chemical addition to the blowdown water to effect hardness and silica removal by precipitation. The precipitated solids are then continuously removed with microfiltration technology. The MF treated water (permeate) is pH adjusted and directed to a first-stage RO unit, where a portion of its permeate is sent directly to the cooling tower as makeup water and the remainder to a polishing RO with its permeate treated with continuous deionization (CDI) technology for boiler feed. The concentrate stream from the first-stage RO unit is sent to a second-stage RO with its permeate utilized as cooling tower makeup and concentrate dewatered in a crystallizer. The polishing RO concentrate stream is utilized as cooling tower makeup water (see Figure 1).