Electrocoagulation vs. Integrate Electrocoagulation-Natural Zeolite for Treatment of Biowaste Compost Leachate—Whether the Optimum Is Truly Optimal

Abstract

Natural zeolites are well-known materials widely applied in the environmental remediation treatment process. However, the integration of various treatment methods is exceedingly investigated for achieving satisfactory effluent quality. In this paper, the integration of electrocoagulation and natural zeolite was evaluated in the treatment of biowaste compost leachate in a single step. The influence of different distances of electrodes (1.5, 3, and 4.5 cm), stirring speed (70, 200, and 400 rpm), the addition of natural zeolite and electrolyte NaCl on the efficiency of treatment of biowaste compost leachate has been carried out. Process efficiency was evaluated by measuring the change of pH value, electrical conductivity, temperature, turbidity, chemical oxygen demand (COD), total Kjeldahl nitrogen (TNK), total solids, and sludge settling test. The Taguchi method was applied to optimize biowaste compost leachate treatment. Experiments are planned according to Taguchi’s L8 (24 41) orthogonal array. The stirring speed, electrode distance, electrolyte and zeolite addition, solution initial pH adjustment were chosen as controllable factors, and their impact on COD, turbidity, TNK, settling rate, and electrode consumption were studied. Results show that optimal conditions depend on the parameter of interest and that optimal values for a particular parameter are not always the optimum if the desired goal is considered.