TREATMENT OF ACIDIC EFFLUENT FROM ELEMENT CHLORINE-FREE BLEACHING BY ELECTROLYTIC FLOCCULATION

The application of electrolytic flocculation to treat acidic effluents from ECF bleaching was investigated by changing the feed pH of the ac idic effluents. The present results indicate that 85 to 90% of the col our can be removed by this technique.The removal efficiency was found to be better, the longer the retention time. Correspondingly, the remo val efficiency of COD was 35 to 70%. The best results were achieved wi th the original feed pH of the effluent. The maximum removal efficienc ies of the transition metals iron end manganese were found to be about 99%, being better, the longer was the retention time while the feed p H was set neutral. The corresponding maximum removal efficiencies of c alcium and magnesium were over 99%, while no effect was found on the r eduction of univalent ions (K+ end Cl-). The total operating costs of electrolytic flocculation in the tests varied from 3 to 25 FIM/m(3) of treated effluent.