Optimization of Fenton pretreatment for 2-chlorophenol solution

He Zhong-bing(贺仲兵)^{1, 2, 3}, Liu Yun-guo(刘云国)^{1, 2}, Xiao Yu(肖玉)^{1, 2}

(1. College of Environmental Science and Engineering, Hunan University, Changsha 410082, China;
2. Key Laboratory of Environmental Biology and Pollution Control, Ministry of Education
(Hunan University), Changsha 410082, China;
3. Department of Chemistry, Kaili University, Kaili 556000, China)

Abstract:Fenton oxidation was used as the pretreatment of 2-chlorophenol wastewater with the objective of dechlorination, as it was considered that after breakage of aryl—Cl bond, the generated intermediates may be easily biodegraded. Hence, the optimization of pH and the low Fenton reagent doses for dechlorination was investigated. More than 99% dechlorination is obtained at the optimal pH 4 and the Fenton reagent doses of 86 mmol/L H₂O₂ and 2.87 mmol/L Fe²⁺. The corresponding 2-chlorophenol is degraded completely, 80.02% COD is also removed, and the biodegradability, evaluated in terms of the BOD₅/COD ratio, is increased up to 0.41. To test the effect of this pretreatment, the pretreated 2-chlorophenol wastewater was fed to a sequencing batch reactor (SBR). The results show that complete mineralization is achieved. It is demonstrated that, for the treatment of recalcitrant compounds like 2-chlorophenol, the Fenton pretreatment could be quite effective and economical for enhancing the biodegradability in a Fenton-biological coupled system.

Key words:2-chlorophenol; Fenton-biological coupled system; dechlorination; sequencing batch reactor (SBR); biodegradability