| With the rapid development of urbanization and industrialization process, a sharp increasein urban population and the expansion of urban areas, the volume of industrial wastewater andmunicipal sewage has increased significantly. In order to improve water quality, the Chinesegovernment has invested heavily in the construction of sewage treatment plants. At the sametime, as the byproduct of sewage treatment, the amount of sewage sludge has also increased yearby year. However, the government has ignored sewage sludge treatment. In term of currentsewage sludge treatment, landfill, aerobic fermentation, natural drying, sludge burning andwithout any treatment account for65%,15%,3%,2%,15%, respectively. About80%of sewagesludge is not treated and disposed in a safe and effective manner. These untreated or improperlytreated sewage sludge has polluted the water environment. Beijing is a typical case in this regardin China.Due to its rapid economic and population growth, Beijing’s municipal sewage emissions areincreasing every year. In2010, the city discharged more than1.4billion tons of sewage. Manysewage treatment plants that have been constructed by the Beijing municipal government haveadopted advanced technologies, and the sewage treatment rate increased to80%in2010.However, the amount of sewage sludge has also increased. Sewage sludge is the byproduct ofsewage treatment, and these byproducts pollute the water environment. If this sewage sludgecannot be treated properly,50%of the water pollutants not removed by sewage treatment willreturn to the environment. However, the need for sewage sludge treatment has not beenaddressed by the government. The rate of sewage sludge treatment was less than50%in2010.More than20,000tonsof total nitrogen isdischarged by untreated sewage sludge every year,which accounts for approximately30%of the total nitrogen load in Beijing.Recently, the government has realized the importance of environmental protection.Accordingly, The Twelfth Five-Year Plan of Economic and Social Development requires that allsewage sludge be treated by2015and load of chemical oxygen demand (COD) be reduced by8.7%in2015compared with2010. Therefore, the government has adopted an integrated policythat promotes water conservation, reduction of working capital and the introduction of advancedsewage and sewage sludge treatment technologies. In order to determine the optimaldevelopment plan for Beijing, it is beneficial to use a simulation method to evaluate the regional environmental and economic impacts of adopting advanced technologies for the treatment ofsewage sludge.In this study,a comprehensive optimization simulation model was constructed to simulatesocio-economic and environmental development in Beijing city. The simulation period is from2010to2020. The Simulation model for this comprehensive analysis was performed using Lingosoftware.Based on the comprehensive simulation results, we found out that the integrated policyemphasis on sewage sludge treatment with advanced technology is effective to reduceenvironmental pollutants and achieve economic development. Specifically, in the optimalscenario, the average rate of economic growth from2010to2020is8.03%. Moreover, thereduction rate of T-P, T-N and COD is26%,40%and25%, respectively, in2020compared with2010while keeping the target of8%GRP growth.If the reduction rate of COD is25%in2020compared with2010, the reduction rate ofenergy consumption intensity and GHG emission intensity reaches39%and36%, respectively,both of which can achieve the government’s plan. Moreover, GHG emission reduction potentialby proper treatment of sewage and sewage sludge is1.9million tons for the study period.Additionally the model generates724thousands TCE as byproduct.The optimal budget expenditures for the policy are3.19billion CNY for new sewage plantconstruction and6.81billion CNY for new sewage sludge plant construction for the study period.The optimal sewage and sewage sludge plants construction plan involves eleven new sewageplants featuring the MBR technology and fourteen plants featuring the EMBR technology; ninesewage sludge plants with the A-D-F-I technology, fifteen sewage sludge plants with the A-D-F-II technology and one sewage sludge plant with the F-C-II technology. |
