A COMBINED ELECTROCOAGULATION-ELECTROOXIDATION TREATMENT FOR DAIRY WASTEWATER

Dairy industry effluent is characterized by high chemical oxygen demand (COD) and other pollution load. This study addresses the elimination of organic compounds in dairy wastewater using electrocoagulation (EC), electrooxidation (EO) and a synergistic combination of EC and EO. The removal of COD, color and turbidity was investigated at various current intensities by using different electrodes and at various electrolysis times. Results show that EC is a relatively quick process (6 min), which is very effective in removing colloidal and suspended particles, as seen in changes in turbidity and color, but it is effective to eliminate only half of the COD. However, EO reduces 40% of COD in a practical time of about 30 min. To improve the removal of COD we proceeded to combine the two processes. Thus, the coupled process eliminates 60% of COD in a practical amount of time (21 min), removes the colloidal and suspended particles and eliminates color, turbidity, phosphorus, K+ and NTK. The use of the seed toxicity test allows evaluating the quality and effectiveness of the studied effluent treatment system. Seed irrigated with raw waste or treated dairy effluent show no phytotoxicity.