| At present,the domestic sewage treatment patterns in rural river networks in the eastern part of China mainly include three modes:centralized,distributed-centralized and decentralized.In this paper,Chongming District of Shanghai,a typical village of the eastern river network and estuarine islands,was selected as the research object to investigate the social conditions of the rural communities in the county,especially the water supply and drainage conditions.The representative sites were selected for sampling and analysis the influence of different drainage patterns on rural water environment,and then the paper analyzes the main difficulties of domestic sewage treatment in eastern China and puts forward relevant countermeasures.This project sampled in winter?December 2016?,spring?March 2017?and summer?June 2017?,and the water quality analysis was conducted to test physical indexes such as dissolved oxygen and pH,indicators of organic pollution,nutrients Indicators,Eclox toxicity indicators and six categories of 12 kinds of antibiotics.The main results of this thesis wre as follows:?1?In terms of water supply,Chongming County has fully popularized tap water and supplied water to all villages and towns in Chongming by"one reservoir and four plants".The sources of water are stable and the water supply conditions are good.;In terms of drainage,the current sewage treatment in Chongming rural is divided into two modes,respectively,centralized and decentralized-centralized.?2?The physical indexes of the receiving water body under the two modes are not obvious,but the concentration of dissolved oxygen in the direct discharge mode is significantly decreased.Compared with the organic pollution in the two drainage modes,the direct mode was 25%higher than that of the decentralized collection and treatment area.Further analysis of nutrients shows that even for distributed sewage treatment have no decarbonization and dephosphorization,their total nitrogen and total phosphorus reduction is still 50%and 40%.?3?The analysis of biological toxicity showed that the inhibitory rates of fluorescence microorganisms in the two drainage modes were less than the toxicity limit line,but the highest inhibition rate in the direct mode was close to the toxicity limit,the model poses a certain potential environmental risk to the receiving water.?4?The total content of antibiotics in water under both drainage patterns decreased significantly with the seasons,with the highest in winter and the lowest in summer.The decentralized centralized domestic sewage treatment could help to reduce the concentration of higher antibiotics in the water body environment,and the reduction rate reached 35%-45%;Most of the detection rates of antibiotics are high,indicating that antibiotic residues is still a common phenomenon the region.The overall concentrations of antibiotics ranged from ND?not detected?to 400 ng·L-1,of which lactams,especially their penicillins,were highly detectable in spring and winter.?5?The capital key factors for the development of rural wastewater treatment in our country are investment and the operation and management of the sites.n comparison with the operation effect,under the"Chongming Mode"in which the rural sewage stations were entrusted to the professional management company,the operation of rural sewage stations is obviously better than that entrusted to the village committees and government.The construction of rural domestic sewage information project includes three aspects:front-end data collection,mid-end information transmission and comprehensive supervision platform construction.The completion of this project will realize the real-time collection of data of all sewage treatment stations in villages and towns in Chongming District,the comprehensive grasp of the effect of sewage treatment,and the operation and maintenance management. |
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