Developing Wastewater Quality Index (WWQI) for treated municipal wastewater with the wastewater reuse approach

Determining the wastewater quality index of municipal wastewater treatment plant for reuse or disposal purposes has always been an important issue. Therefore, developing a wastewater quality index facilitates the investigation and selection of the best option for wastewater reuse or disposal. Thus, determining the important quality parameters and the level of importance of each parameter in terms of the application of the wastewater are essential. In this study, after determining the important quality parameters by Delphi method, the weight of each factor was calculated using the multi-criteria decision making tools in order to develop the wastewater quality index. Then, the matrix for wastewater quality index was presented by defining the sub-indices for each parameter using the standards for wastewater reuse and disposal and by integration methods. Results indicated that the quality parameters including BOD, COD, TSS, TDS, Fecal Coliform, pH, NH4 PO4 are the most important parameters. Also, developing the wastewater quality index through different methods for reuse and disposal and application of various weights for each parameter was found to be a more accurate and reliable method. This method allows for fast and simple evaluation of wastewater in each treatment plant and comparison of different municipal wastewater treatment plants.