Author(s)

D. Gologan

Abstract

Flocculants are chemicals that speed up the aggregation of destabilized particles by increasing the efficiency of their removal. Due to the impact that residual substances which are found in water treatment reagents has on consumers’ health, replacing polyacrylamide flocculants has become a priority. In order to address this issue, a polysilicate type flocculant was evaluated in two steps. The first step was performed in laboratory conditions, on raw surface water, along with four types of coagulants: aluminium-sulfate, two different types of polyaluminum-chloride-hydroxide, and polyaluminum-chloride-hydroxyde-sulfate, which is a bi-component coagulant. The second step consisted of studies performed at an industrial level. During these studies, the polysilicate and the polyacrylamide type flocculants were compared, in combination with the polyaluminum-chloride-sulfate type coagulant. The purpose of these studies was to determine which one yielded better results, in terms of reducing turbidity and organic carbon deposits (TOC, DOC, BDOC) contained within raw surface water. The results obtained through these studies clearly showed that for potable water treatment, the polysilicate type flocculant was a superior replacement to the polyacrylamide type.

Keywords

flocculant, aluminum polysilicate, organic substances removal