Lime and Caustic Soda Softening at Fremont, Ohio

Abstract

This article describes how Fremont, Ohio, treated its sludge accumulation problem by using caustic soda. Following laboratory jar tests, which indicated no adverse effects on the quality of the water treated, Fremont tried several plant‐scale tests of sufficient duration that equilibrium was reached and the results identified. The trials were continued long enough to get identifiable sludge; this was tested for particle size on wet screens and for settling rate. It appeared that, while caustic soda sludge did not settle as fast as lime sludge in the treatment tanks, as long as this property did not interfere with treatment capacity, it could be turned to good use in preventing the building of sludge banks in the receiving stream.