Abstract:
Most of the distilleries in India and the world over employ bio-methanation of molasses spent wash in a bio-digester plant followed by two-stage aerobic treatment as a treatment strategy. The bio-digester effluent (BDE) generated after this treatment strategy still has a high chemical oxidation demand (COD) and dark brown color which can not be directly discharged into a water body.
In the present study, electrocoagulation (EC) has been employed for the COD and color removal of a BDE in a batch EC reactor using stainless steel (SS) electrode. A central composite (CC) experimental design has been employed to evaluate the individual and interactive effects of four independent parameters namely initial pH ( pH : 3.5-9.5), current density ( j : 39.06-195.31 A/m2), inter-electrode distance ( g : 1-2 cm) and electrolysis time ( t : 30-150 min) on the COD and color removal efficiency. Pareto analysis of variance (ANOVA) showed a high coefficient of determination value (R2 =0.9144) for COD and (R2=0.7650) for Color between the experimental values and the predicted values by a second-order regression model. Maximum COD removal of 61.58% and color removal of 99.17 % was observed at optimum conditions. Detailed physico-chemical analysis of electrode and residues (scum and sludge) of the EC process has also been carried out. A strategy for the disposal of EC residues has been proposed in the present thesis
