PRELIMINARY EVALUATION OF THE PERFORMANCE OF NEW PRE-POLYMERIZED INORGANIC COAGULANTS FOR LOWLAND SURFACE-WATER TREATMENT

This paper is concerned with the performance of relatively new kinds o f pre-polymerised inorganic coagulants, poly-alumino-iron-sulphate (PA FS) and polyferric sulphate (PFS). Laboratory experiments were underta ken to evaluate the PAFS and PFS, in comparison with conventional coag ulants such as ferric sulphate (FS) and aluminium sulphate (AS), for t he coagulation of algal-type model waters and a lowland surface water containing algae and natural organic matter (NOM). Experimental result s demonstrated that under the conditions studied, the performance of p re-polymerised coagulants were consistently superior to conventional c oagulants (i.e., FS and AS). This is attributed to the presence of a r ange of pre-formed polymerised species. The coagulation mechanism of P AFS and PFS has been discussed in the paper. (C) 1998 IAWQ. Published by Elsevier Science Ltd.