Research On Process Design Of Wastewater Treatment Plant In Longlou Town,Wenchang City

With the development of domestic urbanization and the acceleration of the pace of economic construction with local characteristics,a series of environmental pollution caused by the increasing amount of sewage has become a severe environmental problem that China’s cities and towns generally face.In view of the main problems in the process of centralized sewage treatment in small towns,such as the not-large total amount of sewage water,scattered sewage,and strong uneven drainage,logging sewage pipe network construction,serious network leakage,the influent water quality and water volume of the sewage plant with large fluctuations in the actual operation process,high sewage treatment requirements in accordance with the latest national emission standards,etc.This topic takes the sewage treatment plant in Longlou Town,Wenchang City as an example,combined with the actual situation of the local sewage drainage system,topography,and climate.Research has been carried out on the prediction of sewage water quality and quantity,the determination of sewage treatment technology and sludge treatment and disposal methods,and the overall layout design of the plant area.It has reference significance for the construction of sewage treatment systems in small cities and towns.The main results are as follows:1.In view of the characteristics of the mismatch between the permanent population and the registered population in Longlou Town,Wenchang City,the urban per capita comprehensive water consumption index method and the city classified land use index method were applied to predict the water inflow of the town’s sewage treatment system and determined Longlou Township has a short-term(2020)sewage volume of 10,000 m3/d,and a long-term(2025)sewage volume of 35,000 m3/d.,BOD5≤140 mg/L,NH4+-N≤30 mg/L,TN≤35 mg/L,TP≤5 mg/L,SS≤200 mg/L.2.In the simulation test of AAO reactor,the removal efficiency of COD and BOD5 could reach 80-85%;the sludge load of BOD increased from 0.16kgBOD5/kgMLSS-d at the beginning of the test to 0.23kgBOD5/kgMLSS-d;the COD of effluent increased with the increase of water intake,but the value could still be kept at 65mg/L.The total nitrogen removal rate of the effluent can also reach more than 70%.In the whole operation process of the reactor,the sludge sedimentation performance is good.The dosage ratio of PAC and PAM suitable for sludge coagulation and precipitation is 40:1.3.By comparing the functions of nitrogen and phosphorus removal of different sewage treatment processes,the stability of system operation,technical reliability,and operating costs,it is determined that the main process of sewage treatment in Longlou Town is the"AAO+advanced treatment" process,The process is:industrial wastewater and domestic sewage→coarse grid→lifting pump station→fine grid→cyclone grit tank→AAO tank→secondary sedimentation tank→high-density sedimentation tank→filter cloth filter → ultraviolet disinfection tank→ Baolin River.which can achieve various effluent The indicators meet the first level A discharge standard of "Emission Standard of Pollutants for Urban Wastewater Treatment Plants"(GB18918).4.Considering the sludge characteristics,investment cost,stability,and operation management and other factors,this project chose the sludge treatment plan of gravity concentration and plate and frame filter press compression,and determined the relevant process parameters.When the recent sludge output is small,the compressed sludge is sent to the nearby municipal waste landfill for sanitary landfill;when the long-term sludge output increases,it is sent to the power plant for incineration.