Technical Development And Engineering Practice Of Pesticide Wastewater Treatment From Bisultap Production

Bisultap is one of the China's own R&D pesticides and largely used in today. Wastewater from its production process contains a lot of refractory organic pollutants and salinity. As a result of high concentration of salt and COD, it is difficult to treat it appropriately. Therefore, to seek a comprehensive treatment technology with economic feasibility and stable operation for Bisultap wastewater will have a positive social significance.In this paper, an integrated technology of Fenton oxidation, activated sludge treatment and coagulation was adopted to treat the Bisultap wastewater in laboratory test period, according to its physical and chemical properties.Fenton oxidation was chosen as a pretreatment method. After a series of experiments under different conditons of pH value, Fe2+ and H2O2 concentration and reaction time, the optimal parameters of Fenton reaction for Bisultap wastewater pretreatment were obtained as follows:pH values is 3, the dosages of Fe2+ and H2O2 are 500mg/L and 12g/L respectively, and reaction time is 120min. After pretreatment, the COD concentration was dropped from 27400mg/L to 13900mg/L, as well as 49.3% removal efficiency of COD received, and the BOD5/COD value of wastewater increased from 0.06 to 0.21.Because the salt concentration in wastewater is 178000mg/L, pretreated wastewater was mixed with sewage before biotreatment, for the purpose of reducing the adverse effect from high concentration Cl-.In SBR (Sequencing batch reactor), the ratio of Bisultap wastewater volume/reactor volume is 1/25, and the COD concentration in influent is 920mg/L. After 24 hours biotreatment and subsequent coagulation with FeSO4, the COD concentration was reduced to 460mg/L.On the basis of the results from the laboratory test, the integrated technology process of Fenton oxidation, biotreatment and coagulation was used to treat Bisultap wastewater from a certain pesticide plant. The integrated treatment engineering project was builded through designing, constructing and test runing. The results showed that the COD concentration of wastewater was stably below 500mg/L after treatment, meeting the requirements of discharging wastewater into sewage pipe network in the industrial park.