Study On Combined Process Of Aoagulation-Flotation-Biological Treatment Of Abs Resin Wastewater

ABS resin is an important synthetic polymer, which has a large production and wide application field. During the production process, a large quantity of organic wastewater containing high concentration of nitrogen and phosphorous was produced. The components of the wastewater are complex, and the wastewater contains latex, resin powder as well as high concentration of organic nitriles and aromatic organic matter. Therefore, the wastewater is difficult to treat. The existing treatment processes for ABS resin wastewater can remove most organic contaminants in the wastewater, but lack of in-depth research on the total phosphorus(TP)remove effects, and the chemical oxygen demand(COD), the total nitrogen(TN) and the ammonia nitrogen are still at a high level. Therefore, against the quality characteristics for ABS resin wastewater, this study investigated the coagulation agent which having both high emulsion breaking and high phosphorus removal efficiency, and optimized the application parameters. The effluent of aoagulation-flotation treatment entered an integrated bioreactor. The effect of aoagulation-flotation on the COD and TP in effluent of biological treatment, as well as the effect of dissolved oxygen(DO) on integrated bioreactor, were investigated.Coagulation agents were selected and combined, and the parameters of the process were optimized. The results indicated that the combination of aluminum sulfate and ferric chloride is better. Optimum conditions were p H=8, temperature 25~45℃, mixing speed 200~400r/min, mixing time 1~3min, flocculation stirring speed 20~80 r/min, flocculation mixing time 5~15min.The performance of the coagulation-flotation treatment had significant influence on the effluent quality of bioreactor. When the performance of coagulation-flotation was poor, it would lead to high SS, COD and TP concentration of the bioreactor effluent, especially during impact load periods; which would lead to a significant increase of pollutant concentration in the effluent. When the performance of coagulation-flotation was good, the effluent of bioreactor went to SS<20mg/L, average COD = 60.2mg/L, average TP = 1.3mg/L.DO had a significant effect on effluent quality of the bioreactor. Under the optimized conditions, integrated bioreactor in A/O mode(DO 1~2mg/L in the aerobic zone) and micro-oxygen mode(DO 0.67mg/L in the aerobic zone, DO 0.21mg/L in the influent zone) both achieved good performance of nitrogen removal.The TN and NH4+-N concentrations of effluent complied with Discharge Standard of Pollutants for Synthetic Resin Industry(GB 31572-2015).