OPTIMIZATION OF COAGULATION-FLOCCULATION AND OZONATION PROCESSES FOR THE TREATMENT OF KRAFT PULP MILL EFFLUENT

Abstract

A study on the effect of ozonation and coagulation- flocculation processes on kraft pulp mill effluents has been carried out. The objectives were to determine (1)best chemical combination for coagulation-flocculation, (2)optimum pH for ozonation and to evaluate (3)suitability of ozonation as pre and post treatment of coagulation-flocculation. Removal efficiencies of color, turbidity and phenolic compounds were investigated under different conditions. Results indicated that initial acidic pH in the effluent is more favorable for ozonation at the experimented O3 flow rate. Use of 0.1g/L AlCl3.2H2O with 0.05g/L polyacrylamide gives the maximum reductions of color, turbidity and phenolic compounds in the effluent. Coagulation-flocculation followed by ozonation is a better system for the treatment of kraft pulp mill effluent. This system can reduce all the three parameters by about 90%.