Biological removal of diazinon in a moving bed biofilm reactor – process optimization with central composite design

Abstract

Diazinon is one of the most widely used organophosphate pesticides classified by the World Health Organization (WHO) as “moderately hazardous” Class II, and its removal from water is of unquestionable importance. The aim of this study was the optimization of diazinon biodegradation from synthetic wastewater by moving bed biofilm reactor (MBBR) using the response surface methodology (RSM). The variables such as initial diazinon concentration (10–50 mg/L), hydraulic retention time (HRT) (12–36 h) and a filling fraction (25–75%) were studied according to the RSM. The highest diazinon removal efficiency using the biological process was 97.66%, under the conditions, i.e. (HRT= 36 h, filling fraction= 75% and diazinon concentration = 10 mg/L). The quadratic model was well fitted with test results (R² = 0.986). Moreover, the kinetics of the biological process showed that removal of diazinon from synthetic wastewater adhered to the second-order model (Grau) with a high correlation coefficient (R² = 0.97). The results showed that the MBBR process can be effectively used as a biological process to remove diazinon and similar pesticides.

Keywords:

• Biodegradation
• diazinon pesticide
• MBBR process
• kinetics modeling
• response surface methodology

Disclosure statement

No potential conflict of interest was reported by the authors.