Process Design And Optimization Research Of Hefei West Sewage Treatment Plant

Chaohu lake,which is one of the most famous five freshwater lakes in China,is now polluted by nitrogen and phosphorus nutrients and oxygen-consumed organic matters in water.Water in more than 70%of the lake area has been in state of eutrophication for a long time,and this has seriously restricted the basin's sustainable development of society and economy.Building of the sewage treatment plant in the west of Hefei will be conducive to improve and protect the ecological environment of western Hefei,and will help to reduce the downstream pollution load of Chaohu basin.In this paper,under the premise of a stable treatment efficiency of the water plant,a research on different biological and advanced processes'comparison and optimal design was conducted,considering the plant scale,designed in and out water qualities,investment,operation and management difficulties,etc.After confirming conditions of the sewage treatment plant,such as construction scale and water quality factors,analysis of inflow water qualities within the sewage water collection area,and verifying the outflow water quality standards,a study was carried out to find the best method for biological nitrogen and phosphorus removal.Emphatically focused on biological and advanced treatments,the research has contrasted and analyzed several biological processes including series of oxidation ditch,series of A~2O,series of SBR,BAF,MAR,and advanced processes including V-filter,high-efficiency fiber bundle filter,rotary disk filter,continuous sand-filter,deep bed filter and so on,which are all widely used at home and abroad.Based on the above study,two treatment process schemes were proposed to be improved,including Multistage AO combined with Deep Bed Filter and Biological Aerated Filter combined with rotary disk filter.The two schemes have been contrasted and analyzed from several aspects such as technology,economy,operation and management and so on.Finally,the scheme Multistage AO combined with Deep Bed Filter was identified to be more compatible,and was choosed to be the design scheme for the sewage treatment plant.Simulations were conducted for improved multistage AO process to verify the reliability of the process,and help to optimize process parameters such as hydraulic retention time,water distribution ratio,reflux ratio,reflux ratio,etc.Then actual operation situation was further simulated to predict water treatment efficiency.The results can be used as a guidance for the design and operation of the sewage treatment plant and a reference for other similar plants nearby.