| Cartap hydrochloride is a derivative nereistoxin which is widely used as pesticide in China. During the manufacturing of the product, a large amount of wastewater containing toxic by-product is emitted. The treatment of this wastewater is difficult, so its effect on environment is of grave concern. In this study, Fenton reagent was utilized for the treatment of an artificial Cartap wastewater. Through this work, the characteristics of degradation and biodegradability, degradation intermediates formed and the degradation pathway of the Cartap were explored during the investigation. A combined process involving iron carbon micro electrolysis-Fenton oxidation-activated sludge was used to treat Cartap wastewater.The degradation of Cartap pesticide wastewater by Fenton’s reagent was investigated. The experiment were carried out to study the effect of the dosage of FeSO4·7H2O and H2O2, initial pH, reaction temperature, the reaction time and bed rotation speed on the degradation of the Cartap pesticide wastewater, respectively. The Cartap pesticide wastewater has a chemical oxygen demand(CODCr) concentration of 676.8mg/L in a sample of 100 mL. The optimum conditions of degradation in Fenton’s reagent system were determined to be 1g FeSO4·7H2O+4mL H2O2, pH 3, bed rotation speed 160 r/min, and reacting for 60 min at 25℃. Under these conditions, the removal efficiency of Fenton’s reagent treatment was 83.9% of CODCr. The biodegradable BOD5/CODCr value of the Cartap pesticide wastewater increased from 0.0746 to 0.9147 after the solution was treated by Fenton’s reagent, it was advantageous to subsequent biodegradation processing.Research of degradation pathways which Fenton oxidation degrade Cartap indicate: HPLC studies indicated that the degradation of Cartap wastewater by the Fenton system degrade completely and quickly. However, CODCr and TOC decrease slowly and it implied that the reaction form intermediates and its mineralization time were longer. IC detection indicated the formation of acetic acid, propionic acid, formic acid, nitrous acid and sulfuric acid in the reaction mixtures. From FT-IR changes of characteristic peaks and functional groups, we can infer formation of intermediates such as alcohol, sulfur dioxide or sulfuric acid, compounds with nitro group, and alkene. It provides further evidence of the part of conclusions of IC. The gas analysis in the process of degradation by flue gas analyzer showed : These studies showed that Cartap rapidly liberates nitrogen monoxide and sulfur dioxide, and find the degradation rule. Furthermore, the GC-MS analysis further demonstrated the formation of oxalic acid, ethanol, and some by-products such as 1-Alanine ethylamide, and benzenesulfonamide. Based on these experiments, the plausible degradation pathways for Cartap mineralization in aqueous medium by the Fenton system were proposed.Further, a method including iron-carbon micro-electrolysis-Fenton oxidationactivated sludge was used for the treatment of Cartap wastewater. The Cartap practical wastewater has a CODCr and BOD5 concentration of 1146.6 mg/L and 183.5 mg/L, respectively. The optimum conditions of degradation in micro-electrolysis system were determined to be Fe/C 1.5:1, pH 2, and reacting for 60 min. Under these conditions, the removal efficiency of micro-electrolysis treatment was 43.8% of CODCr. The biodegradable BOD5/CODCr value of the Cartap pesticide wastewater increased from 0.1612 to 0.4168. The optimum conditions of degradation in micro-electrolysis-Fenton oxidation combined process system were determined to be the molar ratio of H2O2 and Fe2+ 10:1, pH 3, and reacting for 60 min. Under these conditions, the removal efficiency of micro-electrolysis treatment was 69% of CODCr. The biodegradable BOD5/CODCr value of the Cartap pesticide wastewater increased from 0.1612 to 0.6835. Further, the wastewater was treated by activated sludge, the effluent quality was CODCr 85 mg/L, BOD5 58 mg/L, NH3-N 6.9 mg/L, and attained the targets for pollutant discharge. |
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