Cooling Water Recycle by Softening

摘要

Development of a preliminary design methodology for integrating a sidestream softening unit into a cooling water system to achieve zero pollutant discharge is presented. Cooling water discharge is a major environmental problem which the U.S. Environmental Protection Agency (EPA) and Congress aim to eliminate from all industrial facilities within the decade. Current zero blowdown technologies involve sidestream softening (using lime-soda, reverse osmosis, ion exchange and electrodialysis) in which a side-stream of water from the cooling tower is treated to remove potential scale-forming and corrosive material bringing scaling and corrosion to acceptable levels. Basics of softening and scaling related to the adsorption of silica and the kinetics of high total dissolved solids (TDS) reactions involving calcium, magnesium, and silica are investigated.