Author(s)

A. Zouboulis, V. Fotini & M. Panagiotis

Abstract

The process of coagulation is a core environmental protection technology, which is mainly used in the wastewater treatment facilities. Research is now focused on the development of new inorganic coagulants. A characteristic example is PFS (polyferric sulphate), a relatively new pre-polymerised inorganic coagulant with high cationic charge. It consists of medium and high molecular weight polymeric chains and it can be described with the chemical formula [Fe2(OH)n(SO4)(6-n)/2]m. In this paper, the role of some parameters including temperature, types of chemical reagents etc in the preparation stages of PFS were investigated. Furthermore, the prepared PFS was characterized based on typical properties such as the percentage of the polymerised iron present in the compound etc. Furthermore, dynamics of coagulation process were examined by means of the Photometric Dispersion Analyzer (PDA). Finally, the coagulation performance of PFS in reducing the turbidity of synthetic kaolinite suspensions was studied. Keywords: coagulation, polyferric sulphate, inorganic polymeric coagulant, prepolymerised coagulant. 1 Introduction The process of coagulation is widely used in the wastewater treatment facilities especially for the destabilisation of colloids suspensions and for the removal of suspended solids along with the removal of phosphate ions. It is known as a core environmental protection technology. Nearly all the colloids found in natural waters carry negative charge and therefore, they remain in suspension, due to the mutual electric repulsions. Therefore, the addition of a cation will result in colloidal destabilisation, as they specifically interact with the negatively charged colloids and neutralise their charge. Highly charged cation, such as Fe3+, is

Keywords

coagulation, polyferric sulphate, inorganic polymeric coagulant, prepolymerised coagulant.