Pollution and Sustainability Indices for Small and Medium Wastewater Treatment Plants in the Southwest of Spain

Abstract

Two indices have been defined in this work to measure the pollution load that a Wastewater Treatment Plant (WWTP) receives and the efficiency of the process it carries out from the overall perspective of pollution removal and energy efficiency. The aim is to provide two performance parameters which could be used to characterize both the working conditions of a WWTP and how well it treats the pollution it receives. In this way, they may be used to compare the behavior of different plants in a certain geographical area. Forty-five WWTPs in the Southwest of Spain were studied to find out the most significant information that is to be used to identify and define both indices. Seven of the variables recorded were used to define each one. Their values were calculated for the whole set of plants studied. The results showed that most of the plants received a low pollution load. Only six of them suffered from a high pollution load, probably because of farms and food industries located in their surroundings. Only three plants showed a poor efficiency, while 23 of them presented a very good one.