Dynamic Simulation Of Tianjin’s Reclaimed Water Utilization And Its Impacts On Environment And Economic Development

Currently, due to water shortages and pollution, we have been spurred to use reclaimedwater as an additional source of water. Utilization of reclaimed water is an efficient way toimprove water environment. Water reclamation and reuse can enable society to strategically linkthe use of locally available water resources with the distribution of detail water quality andquantity. Reclaimed water has been used widely in areas where water resources are scarce, waterpollution is serious, and population and economic growth are rapid. Tianjin city in China istypically one of them.Tianjin has experienced high economic development with annual growth rate more than10%with urbanization process. In2010, the water resource utilization was totally2,242million m3, or190m3per capita (which is only1/4of China average amount). It is still growing and seriouswater shortage has occurred. Moreover, the depending ratio of water supply on water transferredfrom the southern part of China and other provinces is30%, which does not guarantee furtherwater supply to be able to meet increase in water demand along with continued high economicdevelopment and high population growth. Sanitation coverage is only82%, and the reclaimedwater reuse rate is only3%in2010in Tianjin.These situations necessitate research on water reclamation and reuse in Tianjin city whichascertain if utilization of potential reclaimed water can solve water environment problems andencourage continued economic development. The purpose of this study is to comprehensivelyanalyze effects of water management policies including utilization of reclaimed water onimproving trade-off between water environment and economic development by solving watershortage problem.A comprehensive simulation model was constructed in order to evaluate effects ofintroducing developed water reclamation technologies up on water environment and economicdevelopment in Tianjin city. The model contains3sub-models: a socio-economic model, areclaimed water cycle model, and a water pollutant flow balance model. The computersimulation was conducted by using LINGO, a dynamic linear programming language. Adevelopment plan for utilization of reclaimed water was proposed based on the simulation resultsfrom2010to2020. The simulation shows that the maximum reclaimed water rate (rate of the amount ofreclaimed water utilization to the total amount of sewage emission) is56%when the totalemission of water pollutant is reduce by15%in2020compared to2009. This can effectivelysaves22%of clean water resources, and reduces water resource fees profoundly. It is proved thatutilization of reclaimed water is cost effective compared to other water resources. Subsidy of3,875million CNY, for water management system construction and reclaimed water promotionwill be needed to improve the water environment. The simulation has shown that the Tianjingovernment plans for reclaimed water promotion and water pollutants reduction are achievable.The simulation results show that water pollutants can be reduced by25%in2020compared with2009by introduction of new advanced water reclamation technologies.Based on consideration of trade-off between improvement of water environment andeconomic development, we specify the optimal case in which water pollutants are reduced by15%in2020along with introduction of new technology and comprehensive policies. The simulationsuggests significant economic development is achievable: with a total discounted present valueof GRP of13,677billion CNY, the annual growth rate of GRP is6.45%from2010to2020.Industrial structure will shift its major emphasis from secondary industry to tertiary industry forits high added value and low water pollutants emission intensity. In2020, the simulation resultsshow that share of the contribution to GRP by the primary, secondary, and tertiary industry’sstructure will be changed to0.5:30.5:69.0. Economic development can be guaranteed alongwith water environment improvement.This research has shown the utilization potential of reclaimed water as well as suggested apractical approach to accomplish the optimal case by showing estimate of government financialsupport necessary, introduction of technology, and incentive policies. An annual plan forutilization of reclaimed water region by region was proposed based on the simulation resultsfrom2010to2020.