Study On Advanced Treatment Technology Of Waste Water In Wastewater Treatment Plant Based On Surface Water Environment Standard

Liaohe River Basin as a water shortage area,the lack of high quality ecological water supply and sewage treatment plant tail water to improve the river water quality capacity is limited,resulting in a low proportion of river water quality.Therefore,in order to improve the river water quality and reach the standard of IV or III water quality in surface water environment,the experimental study on advanced treatment of waste water from wastewater treatment plant was carried out.The effects of constructed wetland,chemical coagulation and adsorption process on the treatment of tail water from wastewater treatment plant with a water quality index of grade A was studied.The research contents include the effect and analysis of the traditional constructed wetland with gravel as the matrix,the modified constructed wetland with zeolite and steel slag in series,and the effect and analysis of adding the conventional coagulant to treat the tailings.And the effect and analysis wastewater treatment by adsorption coagulation process.The experimental study on constructed wetland technology shows that when the hydraulic load of traditional constructed wetland is 0.5?0.4?0.3m3/(m2 d),the four indexes of COD?NH4+-N?TN?TP can not be reduced to the water quality standard of IV in the surface water environment.When the hydraulic load is 0.2m3/(m2 d),the COD and TP indexes of the effluent from wetland system can reach the IV standard of surface water environment,but the concentration of NH4+-N and TN pollutants can not be treated to V class standard of surface water environment.The improved constructed wetland with zeolite and steel slag as filler in series has good treatment effect onNH4+-N and TP.When hydraulic load is 0.5m3/(m2 d),the removal rate of NH4-N in zeolite section is 64.87,the removal rate of TP in slag section is 70.77;When the hydraulic load of improved constructed wetland is less than or equal to 0.5m3/(m2 d),the three indexes of COD?NH4+-N?TP can be treated to the water quality standard of ? class in surface water environment,but TN can not be treated to V class water quality standard in surface water environment.The results of chemical coagulation process showed that the chemical coagulation process had a good effect on COD and TP treatment in tail water,and a very general effect on NH4+-N and TN treatment,and the removal rate was almost less than 20%.For the low molecular coagulant aluminum sulfate,ferrous sulfate and aluminum chloride,when the dosage is 40mg/L,the COD and TP in the tail water can meet the quality standard of IV class water,and when the dosage is 80mg/L,The COD and TP in the tail water can reach the standard of ? water quality.For polymeric coagulant polyferric sulfate and polyaluminium ferric chloride,the dosage is 20mg/L.The COD and TP in the tail water can reach the standard of ? water quality.The effect of polyaluminium ferric chloride is better than that of polyaluminium chloride and polyferric sulfate.When the dosage is 40 mg/L?60 mg/L?80 mg/L,the COD and TP in tail water reach the standard of ? water quality.Polyacrylamide is not suitable for treating tailings as coagulant alone,and polyaluminium ferric chloride is superior to other coagulants after economic and technical analysis.The experimental study on adsorption and coagulation process showed that the combined effect of modified bamboo charcoal and polyaluminum ferric chloride was better than that of using alone,and NH4+-N in the tail water could be treated to the surface ? water quality standard.The removal rate can reach 66.53;The removal rate of TN can reach 70.78,although it can not reach the water quality standard of V water,but it can reduce the concentration of TN pollutant to 4.134 mg/L,and reach the standard of quasi ? water quality.Through the experimental study on the effect of advanced treatment of tailings by artificial wetland process and chemical coagulation and adsorption process,the effects of these processes on the advanced treatment of tailings are clarified,which provides a reference for the selection of advanced treatment and upgrading process for wastewater treatment plant.