In situ hypochlorous acid generation for the treatment of syntan wastewater

A new treatment process was employed to treat wastewater generated from a factory manufacturing syntan (synthetic tannin). In this treatment process, in-situ production of hypochlorous acid was achieved by the use of an aqueous sodium chloride solution for chlorine production. As the graphite anode and stainless steel cathode zones were kept unseparated, the hypochlorous acid was produced by electrolysis. The hypochlorous acid was utilized for the oxidation of organic matter present in the wastewater. The results showed that for an initial COD concentration of 10,000 mg/l, a turbidity of 277 NTU, a tannin concentration of 4000 mg/l, a temperature of 27 ± 1°C, a current density of 42.5 mA/cm2, a sodium chloride content of 3% and an electrolysis period of 210 min showed an effluent COD concentration of 230 mg/l, a turbidity of 9 NTU, a tannin concentration below the detection limit and a temperature of 37 ± 2°C.