Date of Award

Fall 1993

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Civil, Construction, and Environmental Engineering

First Advisor

Zanoni, A. E.

Second Advisor

Crandall, Clifford

Third Advisor

Jones, Harold V.

Abstract

Ion exchange is the most common process for softening both domestic and industrial waters. The brine backwash from this process can adversely impact septic tank and soil absorption systems. Discharge of this waste flow to sanitary sewer systems may be regulated in the future. The research was conducted using city of Milwaukee tap water. The investigation involved setting up a typical cation exchange home water softener in the laboratory. Preliminary test runs were conducted to test the softening capacity of the exchange resin under typical conditions. The volume and salt content of the brine backwash was measured. The concentration and mass of key cations - calcium, magnesium, and sodium in the brine backwash were estimated at various intervals to evaluate the possible reuse of a portion of the brine solution for recharging the water softener. The reuse of a select portion of the waste brine for recharging the resin resulted in a 20% increase in softening capacity when operating the unit at a typical salt dosage level. The resin was operated at various salt dosages and the composition of the key cations present in the brine backwash was determined. The results clearly demonstrated that operating the softener at low salt dosages generated the least amount of salt in the waste brine. Lowering the salt dosage, while at the same time adjusting some of the design features of the exchange unit, has great promise for reducing the future discharge of waste brine flows.

Share

COinS

Restricted Access Item

Having trouble?