Ozone pre-oxidation of a textile industry wastewater for acute toxicity

Abstract

The present work evaluates pre-ozonation for removal of acute toxicity from a raw textile wastewater sample taken from the process wastewater balancing tank. Toxicity was monitored using Daphnia magna. A low ozone flow rate (9.6 mg/min) was applied at original pH of the wastewater. The effect of pH varying form 5 to 11 and the H2O2 dose of 600 mg/l on ozonation to remove toxicity were also investigated. The samples were filtered through 0.45 mu m membrane filter (Millipore) for measuring toxicity, COD, in APHA Pt-Co (platin-cobalt) unit and absorbance at 450, 500 and 550 nm wave lengths.

A 60% of acute toxicity, 92% of and 50% of total COD removal were obtained at original pH of wastewater by applying ozone for 30 min. Absorbed ozone dose was 105 mg/l with a ozone transfer rate of 3.5 mg/l. Neither H2O2 addition nor varying pH improved toxicity and COD removal. The toxicity control based systematic followed in this study is expected to contribute to the aquatic environment protection.