OBSERVATIONS OF THE COMPARATIVE HYDROLYSIS PRECIPITATION BEHAVIOR OF POLYFERRIC SULFATE AND FERRIC SULFATE/

The hydrolysis/precipitation behaviour of polyferric sulphate (PFS) an d ferric sulphate (FS) under conditions typical for coagulation and fl occulation in water treatment are investigated by studying the rate of floc size development; the zeta potential and chemical structure of p recipitates and the iso-electric point of re-suspended precipitates. T he results detailed in this study strongly suggest that, under the tes t conditions, the hydrolysis behaviour of PFS was significantly differ ent from that of FS? with evidence of a relatively Io ir er rate of fl ee size development and colloid charge reversal in the investigated Fe (III) dose range and a different chemical structure of the precipitate s formed from PFS and FS. (C) 1998 Published by Elsevier Science Ltd.