An Efficiency-CentredHierarchicalMethod toAssess Performance of WastewaterTreatment Plants

An efficiency-centred hierarchical model is developed to assess the performance ofwastewater treatment plants (WWTPs). Specifically, a new treatment performance index (TPI) has been proposed to determine the overall treatment performance of WWTP by analysing the TPI values and the weights of individual treatment phase for overall treatment performance. Three modules have been developed to examine the performance of the primary, secondary, and tertiary treatment units of aWWTP. Themodel is applied to threeWWTPswith different scale, loading rate, capacity, and process phases. The case study results indicate that the developed tool is useful in assessing the WWTP system in terms of treatment efficiency, operating conditions, and costeffectiveness of its management schemes. The model can be also combined with an infrastructure condition rating index model to form a condition rating model for a WWTP, and used as a costeffective tool to evaluate current and future needs in operation and management.