REMOVAL OF PESTICIDES FROM SURFACE WATERS BY COMBINED PHYSICOCHEMICALPROCESSES .1. DODINE

The simultaneous action of powdered activated carbon and several coagu lant agents on the removal of the fungicide dodine from spiked distill ed water, was studied. As coagulants, ferric chloride (FeCl3) and basi c polyaluminium chlorosulfate ([Al(OH)(x)Cl-y(SO4)(z)](n)) were examin ed, using polyacrylamide, in certain cases, as coagulant aid (polyelec trolyte). The efficiency of dodine removal was investigated with respe ct to the added amount of powdered activated carbon (PAC), the pH valu e, as well as the type and dose of coagulant and polyelectrolyte. The experiments were performed applying the standard jar-test procedure. T he initial concentration of dodine was 250 mu g/L. At this concentrati on and pH range 5-8 it was found that a dose of 100 mg/L PAC was neces sary to achieve more than 98% removal of dodine, whereas lower removal (91-93%) was obtained applying half the dose of PAC under the same co nditions. However, when 10-100 mg/L FeCl3 were simultaneously added wi th PAC, the removal efficiency increased to >98%, even with the half P AC dose.