Effect of Chlorine Dioxide Oxidation on Degradation of Methamidophs in Wastewater

Objectives  To investigate the effect of chlorine dioxide (ClO₂) oxidation on the degradation of methamidophos in wastewater.

Methods  Comparing the effects of conventional activated sludge with chlorine dioxide oxidation on the treatment of methamidophos in wastewater. The effect of ClO₂ on methamidophos in wastewater was detected by the change of chemical oxygen demand (COD) value.

Results  The removal of COD in methamidophs wastewater was increased steadily with higher amount of ClO₂ and longer aeration time. The value of COD in 20 mL of influent methamidophs wastewater was decreased from 7 697.31 mg/L to 391.20 mg/L in the effluent when 25 mL of ClO₂ was used and reacted for 5 min; the removal of COD reached 94.92% after treatment with ClO₂. By curve fitting, the regression equation in the treatment of methamidophs wastewater with chlorine dioxide was:y=0.98x³-32.63x²-83.23x+7 626.60,R²=0.98,in which x was the amount of ClO₂ (mL) used and y was the remained COD value (mg/L). When methamidophs wastewater was treated with conventional activated sludge degradation method for 204 h, the COD in the influent wastewater was decreased from 8 230 mg/L to 1 451 mg/L in the effluent. The removal of COD reached 82.37%.

Conclusions  Comparing with the conventional method of activated sludge degradation, the length of reaction time was shorter, the value of COD removal was higher and no chlorinated organic compounds and other secondary containments were produced by using the chlorine dioxide oxidation method. Chlorine dioxide oxidation is a desirable method for the treatment of wastewater polluted by pesticide methamidophos.