| Baiyangdian is mainly located in Anxin County,Xiong’an New Area,is the famous"Pearl of North China",which has a great impact on the regulation of the regional ecological environment,and the ecological environment of Baiyangdian will directly affect the overall construction of Xiong’an New Area.In 2020,Baiyangdian Anxin County completed the task of covering rural domestic sewage in 208 villages,and built and operated 157 small sewage treatment stations in 79 villages in the lake and 68 villages outside the lake.This study mainly analyzes the discharge characteristics of domestic sewage in Baiyangdian Dian villages in the lake and villages outside the lake by combining investigation and analysis and on-site monitoring based on the actual operation of 157 small sewage treatment stations that have been operated,and evaluates the suitability of 8 different treatment processes of 157 sewage treatment stations,and puts forward corresponding improvement countermeasures according to the evaluation results.The main findings are as follows:(1)In 2022,the actual influent scale and service population of 157 sewage treatment stations were investigated and statistically analyzed,and the average per capita domestic sewage discharge in villages in the lake in different seasons was 58.17 L/person·d,76.43 L/person·d,58.07 L/person·d,and 51.84 L/person·d in spring,summer,autumn and winter,of which the annual average was 61.38L/person·d.The average per capita sewage discharge in villages outside the lake in different seasons was 67.29 L/person·d,101.41 L/person·d,72.67 L/person·d and 55.51 L/person·d,respectively,and the annual average was 74.22 L/person·d.It can be clearly seen that both the villages in the lake and outside the lake show the characteristics of summer domestic sewage discharge being greater than other seasons,and the winter discharge is the lowest;In addition,the per capita discharge of domestic sewage in villages outside the lake is higher than that in villages in the lake every season,which is closely related to the incomplete water supply facilities of villages in the lake and the supply of water at different times,which is in line with the actual situation.(2)After monitoring and analyzing the influent water quality of domestic sewage treatment stations in villages in the lake and villages outside the lake in different seasons in 2022,the statistical results showed that in the four seasons of spring,summer,autumn and winter,the COD in the average influent water quality of domestic sewage in villages in the lake was 175.77 mg/L,147.87 mg/L,99.98 mg/L and 107.51 mg/L,respectively;Ammonia nitrogen was 28.71 mg/L,24.11 mg/L,19.64 mg/L and 20.22 mg/L,respectively.The total phosphorus was 3.41 mg/L,2.39 mg/L,1.78 mg/L and 1.96 mg/L,respectively.The total nitrogen was 35.25 mg/L,27.01 mg/L,21.84 mg/L,and 22.78 mg/L,respectively.The COD in the average influent water quality of domestic sewage in villages outside the lake was 132.92 mg/L,110.54 mg/L,78.91 mg/L and 104.84 mg/L,respectively.Ammonia nitrogen was 22.49 mg/L,16.96 mg/L,12.62 mg/L and 19.14 mg/L,respectively.The total phosphorus was 1.98 mg/L,1.69 mg/L,1.28 mg/L and 1.68 mg/L,respectively.The total nitrogen was 25.56 mg/L,22.16 mg/L,17.75 mg/L and 25.44 mg/L,respectively.The four indicators showed that the water quality data of domestic sewage in villages in the lake in each season were higher than that of villages outside the lake in spring>summer>winter>autumn.(3)Through AHP-entropy weight-fuzzy matter element analysis method,11 indicators in four categories were selected to compare and analyze 157 sewage treatment stations and 12 sewage treatment processes in Baiyangdian,and according to the European closeness of the suitability evaluation results,the process suitability was sorted as A2O+AO+MBBR>A20+MBR>microfilter+conditioning cell+A2O+MBR>two-stage biological+regulation pool+A2O+MBR>A2O+precipitation+multi-media filtration>multi-stage A2O>A2O+ MBBR>A2O+sand filtration>improved A2O+SSLE+sand filtration>A2O+precipitation+micro-nano water purifier +two-stage biological filter>improved A2O+SSLE+composite filtration + sand and gravel filtration>regulating tank+anaerobic+hydrolysis+contact oxidation+sludge sedimentation tank+flocculation precipitation+shallow filtration denitrification.Among them,A2O+AO+MBBR score is higher,and there is a certain gap with the second place.The scores of A2O+MBR are close to those of microfilter+ conditioning cell+A2O+MBR,two-stage biological+conditioning cell+A2 O+MBR scores,which are all treatment processes that conform to the Baiyangdian environment.(4)Through on-site investigation and data collection,the existing sewage station in Baiyangdian has problems such as mismatch between the design scale and the actual scale,too high cost per ton of water,and shortage of operation and maintenance funds.Combined with the results of this research,targeted countermeasures and suggestions such as adjusting the scale of treatment,optimizing the treatment process,strengthening technical research,improving the maintenance mechanism,and broadening the funding channels were put forward.Through the above research,the discharge characteristics of domestic sewage in Baiyangdian rural area are more clarified,the applied treatment technology is evaluated,and corresponding measures are proposed for the existing problems.It provides a theoretical and practical basis for the treatment of rural domestic sewage in the Baiyangdian River Basin in the future. |
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