Assessment of urban drainage and water reuse system schemes with weight uncertainty analysis

In order to choose more sustainable urban drainage and water reuse system scheme, an assessment system with eight indicators was build, taking the economic cost, environmental cost and resource cost into account. The indicator weight was determined through the method of analytic hierarchy process (AHP), in which the weight uncertainty derived from the expert´s preferences on different aspects of system sustainability is quantified. The assessment system was applied to a rebuilding industrial zone in Beijing with three alternatives for its urban drainage and water reuse system. Among eight indicators, the weight of construction cost, COD load and wastewater discharge amount is relatively higher. Based on the weight distribution and scaled indicator value, the weighted average method was used to calculate the assessment result. It showed that the scheme 2, which has the separate discharge of grey water and black water and centralized grey water reclamation, is much better than other two schemes with quite high probability.