Engineering Design Of Sewage Treatment Plant In Nanchuan Industrial Zone

Located in the east of Nanchuan region of Chongqing Municipality, the11.58square kilometers Nanchuan Industrial Zone, an integral part of the “ChongqingOne-Hour Economic Rim”, is within45-minute-drive from downtown Chongqing.The construction of the industrial zone is divided into phases. The currentconstruction phase (up till2015) is dedicated to construction projects in aluminumindustry, light textile industry, chemistry industry, light industry and foodmanufacturing. In the later phase (up till2020), the focus will be shifted to high-techindustries and resources with relatively low pollutions as well as industrial districtswith high energy consumptions.The Sewage Treatment Plant of Nanchuan Industrial Zone was constructed witha planned treatment capacity of40,000m3of sewage per day. This thesis based itsdiscussion on a relatively small sewage treatment plant with a treatment capacity of20,000m3per day. In view of the project specifics and preliminary analysis of thelocal natural resources, climate and geography, the suitable techniques to be adoptedmust have high operational stability and high adaptability to changes in inflow qualityso as to ensure the effluent quality. This thesis shall analyze the suitability of thesewage plant site selection and wastewater treatment process by methods ofcomparison. Ultimately,“A/A/O process” stands out as the technique of choice forNanchuan Industrial Zone’s sewage treatment plant in terms of inflow quality, itsattribution of lower C/N and strict effluent requirement for phosphorus removal rate.Conventional A/A/O process has very high operational stability. ImprovedA/A/O and inversed A/A/O are designed to facilitate the removal of nitrogen andphosphorus. Both of them possess strengths that are suited for different environmentsand working conditions. To aggregate the strengths of different techniques, theconstruction design has adopted a “multi-mode A/A/O biological nitrogen andphosphorus removal” technique with multiple water inlets, which allows theadjustment of operational mode according to inflow volume, water quality andenvironmental changes so as to achieve desired effluent quality.The completion of Nanchuan Industrial Zone’s sewage treatment plant isexpected to greatly alleviate urban water pollution. It is estimated to reduce the yearlyconsumption of BOD5,COD, SS, TN and TP to1296tons,3168tons,1656tons, 252.5tons and29.2tons respectively. The associated decline in water pollutants isalso expected to be a reliable measure in preserving and preventing pollution of watersources. In the meantime, it can create a conducive environment in NanchuanIndustrial Zone to attract investment and stimulate sustainable economicdevelopment.