碱解—微电解工艺对吡虫啉农药生产废水预处理的研究

Study on the pretreatment of imidacloprid pesticide wastewater by alkaline hydrolysis-microelectrolysis process

吡虫啉农药生产废水是一种典型的高浓度难降解有机废水,可生化性差,需采用物化法作为其预处理手段。实验采用碱解—微电解作为吡虫啉农药生产废水的主要预处理工艺,能有效地降低废水中有机物浓度,使预处理出水的可生化性大大提高,保证其后续生化处理的有效进行。实验表明,碱解最佳条件:温度70℃,pH 13,反应时间2 h;微电解最佳条件:pH 3￣4,停留时间3 h。预处理出水的COD总去除率为65%左右,色度的去除率达90%以上,m(BOD5)∶m(COD)提高到0.25以上,可生化性大大提高。

Imidacloprid pesticide wastewater is a kind of typical organic wastewater. Containing the persistent organic pollutants with high concentration, it is difficult to be directly degraded only by bio-treatment, and it needs physico-chemical process as its pretreatment before bio-treatment. In this experiment, alkaline hydrolysis-microele-ctrolysis process is used as main pretreatment technology for this pesticide wastewater. This method could reduce the concentration of organic pollutants effectively; also, it could increase the biodegradability of the wastewater, and create favorable conditions for the subsequent bio-treatment. The optimal conditions of the pretreatment are determined as follows： alkaline hydrolysis-temperature is 70℃, pH 13 and reaction time 2 h; microelectrolysis-pH 3 -4 and reaction time 3 h. After the pretreatment, the removal rates of COD and chroma are about 65% and above 90%, respectively. The ratio of BOD5 to COD is increased to about more than 0.25, and the biodegradability of the wastewater has been improved evidently.