Catalytic ozonation using Fe2+ in the treatment of dairy effluent in a semi-batch process with recycle

Abstract

This work describes the treatment of dairy industry effluent using catalytic ozonation with Fe2+ as its catalyst in a semi-batch process with recycle. A fractional factorial design 24-1 was used with a reduction percentage of total organic carbon (TOCred) as response. Optimal conditions were obtained by the reaction time of 30 min, ozonator power of 35 W, O2 flow rate of 0.125 L min-1, Fe2+ concentration of 1.0 g L-1 and pH 4.0 for a 2 L raw effluent. TOCred of 64.03% represents a decrease in concentration from 473.0 to 170.1 mg L-1, with an estimate cost of US$ 0.03 L-1 effluent. The treatment performed was not sufficient to discharge it directly on surface water; however, significant reduction of TOCred, among physical and chemical characteristics makes a better product to be proceeded into a biological treatment.