Use of Acid‐Treated Sodium Silicate in Coagulation

This article begins by presenting experimental work on the use of acid‐treated sodium silicate in coagulation. It was found that, in a series of tests on coagulation in an experimental filtration plant, acid‐treated sodium silicate used with aluminum sulfate hastened the rate of coagulation and the rate of settling in settling basins. The use of silicate decreased the amount of aluminum sulfate required and strengthened the coagulation to the extent that there was no danger of coagulated materials passing the filter beds. The article discusses the use of acid‐treated sodium silicate for aiding coagulation with aluminum sulfate for a period of a few weeks to about 3 months each year at the South District Filtration Plant, Chicago, Illinois.