Photo-Fenton pretreatment of carbofuran - Analyses via experimental design, detoxification and biodegradability enhancement

Abstract

The central composite design (CCD) and response surface methodology (RSM) were employed to evaluate the effect of H(2)O(2) dosage rate (1-10 mg L(-1) min(-1)) and Fe(3+) dosage (1-100 mg L(-1)) in the photo-Fenton treatment of carbofuran and to develop the second-order polynomial equations in terms of carbofuran and dissolved organic carbon (DOC) removals and BOD(5)/DOC ratio with different reaction times. Both H(2)O(2) dosage rate and Fe(3+) dosage have significant effects on the dependable variables. Based on the results of carbofuran removal and BOD(5)/DOC ratio, H(2)O(2) dosage rate of 5.4 mg L(-1) min(-1) and Fe(3+) dosage of 59 mg L(-1) were found to be the favorable reagent dosages for carbofuran degradation. Under these conditions, the toxicity unit measured by Microtox(R) test with 5 min exposure was decreased from 47 to 6 and the biodegradability evaluated by BOD(5)/COD ratio was increased from 0 to 0.76 after 60 min reaction. The results obtained in this study demonstrate that the photo-Fenton process is a promising pretreatment before the application of biological treatment for carbofuran removal from contaminated water/wastewater. (C) 2011 Elsevier B.V. All rights reserved.