Study On Advanced Treatment Technology Of Tail Water Of Sewage Plant In Liaohe Basin Based On Section Standards

The"Water Pollution Control Action Plan"for short referred to as"Water Ten"proposed that by 2020,the proportion of excellent water quality in the country（being at or better than Class III）will generally reach more than 70%.However,there are still many problems in the Liaohe River Basin:insufficient carrying capacity of water resources and water environment,saturated environmental capacity,and fewer healthy water bodies in the basin as a whole;ecological water is scarce,and the incoming water is dry and the total amount is small.As the main source of urban river water,Tailwater of the first-stage A discharged from urban sewage treatment plants does not have the ability to improve the water quality of the river.Therefore,in the face of the urgent water quality improvement requirements of the river section,it is necessary to develop a point source discharge for the sewage plant.After the treatment of the sewage water from the sewage plant and the surface water standard,an experimental study was conducted to prevent pollutants from entering the heavily polluted river from an external source.In this paper,the primary research object is the first-stage A tailwater of urban sewage treatment plants.The treatment effect of chemical coagulation,artificially enhanced ecological filter bed and algae stabilization pond on the first-stage A tailwater is investigated,and the first-stage A tailwater quality is explored The feasibility of linking with surface water quality standards,and applying the research results to the compliance of the Wangjia shack section of the Daling River..The chemical coagulation test research shows that when using inorganic and organic flocculants to mix and treat the first-stage A tail water,it is better to add the inorganic flocculant PAFC and then the organic flocculant CPAM.The best dosage interval is 30～40 s.The best dosage ratio is:PAFC dosage of 40 mg,CPAM dosage of 60 mg,and dosage interval of 40 s.At this time,the NH₄⁺-N removal rate of sewage reaches 29.11%.COD and TP meet the standard of surface water class III.The experimental research results of artificial aerated ecological filter bed show that the increase of hydraulic retention time can improve the treatment effect of artificially enhanced ecological filter bed,especially for COD and NH₄⁺-N.When the HRT is 0.5 d,1.0 d,and 1.5 d,the COD effluent water quality can stably reach the standards of classⅤwater,Ⅳwater,andⅢwater respectively,and the NH₄⁺-N effluent water quality can reachⅤwater andⅣwater respectively.Water standard,TP effluent water quality can stably reach Class V water standard.After combined with steel slag filler,TP effluent water quality can be improved to aboveⅢ.The results of algae stabilization pond tests showed that the algae bacteria ratio had an effect on the removal effect.When the algae liquid was added in the same amount,activated sludge or aerobic bacteria accounted for a relatively high proportion,which promoted the removal of COD,but it also promoted the removal of TP.The removal effect is weakened,and the removal of NH₄⁺-N is promoted first and then suppressed.When the algae ratio is appropriate,the extension of the hydraulic retention time is beneficial to the removal of COD,TP and NH₄⁺-N in water.When the HRT is 3 d,4 d,and 5 d,respectively,the COD can reach the water standards of class V,IV,and III,the TP can reach the water standards of class IV,III,and III,and the NH₄⁺-N can reach Category V,III and II water standards.Through the experimental research on the effects of the above three processes on the treatment of tail water,it is clear that these three processes treat the first-level A tail water treatment effect,and it has also achieved the improvement of the quality of the sewage from the point source in the application of the Wangjiawo section of the Daling River.Furthermore,the purpose of promoting the cross-section water quality standard has reference significance for more improvement projects that require cross-section water quality standard.