Assessing the potential of using water reclamation to improve the water environment and economy: scenario analysis of Tianjin, China

Tianjin City in China is a typical area that suffers from a serious water resource shortage and pollution problems, and this situation has spurred the use of reclaimed water as an additional source of water and an efficient method of improving water quality. This study aims to assess the reclaimed water utilisation amount available and its potential impacts on the water environment and economy, and proposes applicable approaches to establish the optimal development for Tianjin. A water resources-environment-economic management model was constructed, which was accomplished by dynamic linear optimisation. Through scenario analysis, Tianjin's optimal reclaimed water recycle rate can reach 56%, with 475 × 10⁶ tons of reclaimed water amount available (supporting 22% of the water supply), while bringing sufficient environmental and economic benefits, such as reducing 20% of water pollutants and maintaining 6.3% annual economic growth by 2020. This research also suggests that an integrated water management approach is preferable, including a proper introduction of technologies suited to the region's needs, a support system for construction, and control of water pollutant emission sources, especially in agriculture. The originally formulated water management system can be easily applied and extended to solve water issues, especially for water recycling.