Economical Analysis Of Sewage Collection And Treatment System In Small Towns

By the end of2013, there are32929towns (townships) in China, coupled with asteady increase in the population density of small towns, large amounts of sewage isemitted every day, water pollution problems become more and more serious in thesmall town areas. For the water pollution control, the sewage collection and treatmentsystem construction needs huge funds，so that it is imminent to research sewagecollection and treatment system planning optimization technology.Sewage collection and treatment system in small towns can be divided into twomodes: centralized sewage collection treatment system and decentralized sewagecollection and treatment system. For a long time, when we consider the sewagetreatment, we always tend to follow the traditional centralized collection and treatmentsystem that big cities often use, but this system for the distribution of the dispersedvillages is not economic. Decentralized sewage collection and treatment system cansubstantially reduce the cost of the pipe network and facilitate sewage reuse, but it isnot easy to manage at the same time as it’s fragmentation characteristics; Centralizedsewage collection and treatment has good treatment effect and easy management, but itis need to build ambitious pipe network project with long construction period and highinvestment，the construction of sewage collection system is often seriously lagging inpractice, so that sewage can’t be treated timely. The domestic and foreign researcheson the decentralized sewage collection and treatment technology shows thatdecentralized sewage collection and treatment has equal importance with thecentralized，and it is an important part of the sewage collection and treatment system.Sewage collection and treatment system from economy condition in small townsis regarded as the research object in this paper, firstly, the characteristics ofdecentralized and centralized collection and treatment system is analyzed, and theselection principle and process of system is proposed; Secondly, the system cost isinvestigated and analyzed; Finally, according to the determinants of system planningcost, small town sewage collection and treatment system economical analysis modelsand optimization algorithms is constructed. The work is done as follows: （1）Through accessing to information, the centralized and decentralized sewagecollection and treatment system is raised according to the actual situation.Decentralized and centralized collection and treatment system selection needs to suitlocal conditions, combined with the actual situation of different regions andeconomic analysis to choose a suitable system.（2）Wastewater collection and treatment systems targeting process includes five parts:analyze the water pollution current situation, forecast the water environment capacity,determine the system objectives, workout the development plan and propose plan toimplement safeguard measures. The collection system cost is greatly influenced by themain design full of degree, diameter, flow velocity, slope design and design depth andother factors. Selection principles are proposed for scheme sewerage and treatmentsystems.（3）Based on a lot of basic research and theoretical analysis，the cost function ofintegration of the currently used sewage treatment technology has been studied;Through the analysis of various components of the network cost function, the pipenetwork cost function has been obtained.（4）Under the premise of meeting water quality and removal requirements, thelow system cost is an important decision-making condition to choose plan. Accordingto the system cost composition and characteristic of small rural water quantity, aregional sewage collection and treatment system cost model has been established，andthe model is programmed and improved computing efficiency. The example fullyproves the rationality and the unique superiority of the model and the program.