再生水项目国民经济评价体系研究

National Economic Evaluation of Reclaimed Water Project

随着水资源供需矛盾加剧,再生水回用已成为缓解水资源供给压力和改善环境的重要手段,而再生水项目国民经济评价是项目投入的先决条件。首先,结合再生水项目特点,采用有无对比法构建了包括经济效益、环境效益和社会效益的再生水项目国民经济评价体系;其次,运用机会成本法、当量因子法对西安市污水处理厂的外部效益进行测算;再次,引入社会折现率、影子价格、影子工资等国民经济评价参数对再生水项目的费用效益进行调整;最后对其进行了国民经济评价。结果表明,该再生水项目的静态投资回收期1.20 a,动态投资回收期1.32 a,净现值9.13亿元,效益费用比达到8.15,而只考虑其直接经济效益的动态投资回收期则为8.67 a,表明该项目具有较好的国民经济效益,同时,对其评价时应重点考虑再生水回用带来的外部效益,并为其他项目环境经济评价提供了参考。

With the intensification of the contradiction between the supply and demand of water resources, reclaimed water reuse has become an important means to ease the pressure on water supply and improve the environment. The national economic evaluation of reclaimed water projects is a prerequisite for project investment. The paper, firstly, combined with the characteristics of reclaimed water projects, a national economic evaluation system for reclaimed water projects including economic benefits, environmental benefits, and social benefits was constructed using the contrast method. Secondly, the paper uses the opportunity cost method and the equivalent factor method to measure the external benefits of Xi’an sewage treatment plant. Thirdly, this paper introduces national economic evaluation parameters such as social discount rates, shadow prices, and shadow wages to adjust the cost-effectiveness of recycled water projects. Finally the paper conducted a national economic evaluation. The results show that the static investment recovery period of the reclaimed water project is 1.20 years, the dynamic investment recovery period is 1.32 years, the net present value is 913 million yuan, and the benefit-cost ratio reaches 8.15,while the dynamic investment recovery period only considering its direct economic benefit is 8.67 years, which indicate that the project has good national economic benefits, and at the same time, the external benefits brought about by reuse of recycled water should be taken into consideration when evaluating the project. The study would provide a reference for the environmental economic evaluation of other projects.