"Report date December 1971." United States Environmental Protection Contract No. Contract Number: 14-12-599.

The feasibility of wastewater demineralization by ion exchange procedures was successfully demonstrated by pilot plant studies conducted on sewage effluent from an activated sludge treatment plant. A pretreatment unit consisting of lime clarification, dual media filtration, and granular activated carbon filtration was operated in series with the ion exchange system. Phosphate reductions were achieved by lime clarification at pH 10.0, but identical reductions were achieved by ion exchange alone. In addition ion exchange treatment without lime was cheaper. Ion exchange processes using strong acid cation exchange resin and weak base anion exchange resin can be readily applied to wastewater demineralization. Design of treatment plants for such a process applied to wastewater containing as much as 500 mg/l of ionizable solids can use established design parameters. Disposal of sludges and saline liquids must be considered.