Research For The Treatment Of Pesticide Wastewater With High Concentrations Of Phosphorus By Iron And Calcium Compound Method

The pesticide has made an important contribution to the improving crop production. However, it produced large quantities of wastewater in the course of producing pesticide, and the pesticide wastewater containing phosphorus could cause water eutrophication pollution if we outlet it to natural water without any treatment. Water pollution has become a global environmental problem. Therefore, we should strengthen the treatment of pesticide wastewater containing phosphorus. The main phosphor-containing wastewater treatments methods are currently used in our country are not still mature and valid. In this study, according to know the production technology and materials of phosphorous pesticide, we analyzed the characteristics of wastewater, and researched the feasibility using calcium chloride, iron chloride and iron and calcium compound method to deal with the pesticide wastewater. Then we confirmed the relevant operation parameters, the conclusions were as follows:(1)According to the utilization ratio of calcium chloride, it confirmed the best conditions: the pH was 8, dosages of calcium chloride were 5.33 g/L. And in this condition, the content of phosphorus in the supernatant was 2.73 mg/L, the removal efficiency was 99.45%, and the processing cost was 10.80 Yuan/kg phosphorus; When the TP in effluent reaching the first class discharge standard of municipal wastewater treatment plant (GB18918-2002), the dosages of calcium chloride were required to achieve 31.97g/L. And in this condition, the content of phosphorus in the supernatant was can be achieved 0.91 mg/L, the removal efficiency was 99.82%, but the SV% was high, about 90%, and the processing cost was 64.57 Yuan/kg phosphorus.(2)According to the utilization ratio of iron chloride, it confirmed the best conditions: the pH was 7, dosages of iron chloride were 6.50 g/L. And in this condition, the content of phosphorus in the supernatant was 4.58 mg/L, the removal efficiency was 99.08%, and the processing cost was 56.89 Yuan/kg phosphorus; When the TP in effluent reaching the first class discharge standard of municipal wastewater treatment plant (GB18918-2002), the dosages of iron chloride were required to achieve 34.62 g/L. And in this condition, the content of phosphorus in the supernatant can be reduced to 0.83 mg/L, the removal efficiency was 99.83%, but the SV% as high as 90%,and the processing cost was 300.6 Yuan/kg phosphorus.(3) When the pH was 8, the dosages of calcium chloride were 5.33 g/L and the dosages of iron chloride were 60 mg/L, the content of phosphorus in the supernatant could reach to 0.45 mg/L, using iron and calcium compound method. And the removal efficiency was up to 99.91%, increased 83.52% than calcium chloride at the same condition. Meanwhile, the SV% was only 40% and the processing cost was 11.28 Yuan/kg phosphorus. Compared with calcium chloride and iron chloride, iron and calcium compound method had far more superiorities in SV% and handling cost.The features of iron and calcium compound method were as follows: high phosphorus removal efficiency, quick settling rate, dense sludge, small settlement ratio, easy to dehydrating and simplified sludge treatment. Because of it not only utilized calcium chloride turn to undissolved substance, but also expressed iron chlorides'good flocculability and settleability, in the practical application is feasible.