Pulp and Papermill Effluent Treatment by Continuous Electrocoagulation

The continuous electrocoagulation (CEC) technique, which uses aluminium (Al) as an electrode material, is examined in this work for the treatment of highly toxic pulp and papermill effluents. The process optimization was done with respect to the flow rates (L h−1) and residence time (τ) of wastewater which resulted in the excellent removal of Total solids (TS), colour and Chemical Oxygen Demand (COD). The removal rate of COD was 94.4 and 93.1% at the optimal flow rates of 0.5 and 1.0 dm3 h−1, correspondingly, whereas the colour removal rate was 91.6 and 83.6%. There was gradual decrease in the pH of the effluent during the process due to the production of aluminium hydroxides in variable oxidation states. Variation in the cell voltage during the electrolysis has also been studied. TDS of effluent was also decreased by a factor of 93% after 4 h residence time at a flow rate of 0.5 dm3 h−1. With a variation in flow rates, electrode degradation and consumption were also examined.