Circular economy and efficiency to ensure the sustainability in the wastewater treatment plants

Wastewater treatment plants (WWTPs) represent a great opportunity within the framework of the circular economy. Not only are WWTPs an alternative source of water, but they can provide other valuable resources for other sectors such as water and energy. For instance, the nutrients contained in wastewater are of great importance for agriculture, since they can be used as fertilizers. In this sense, evaluating the efficiency of wastewater treatment processes makes it possible to identify those aspects that improve the performance of these infrastructures, thus ensuring their long-term sustainability. Most of the previous studies evaluate the efficiency based on the resources used and the total pollutant removal, this aspect does not consider that the quantity of pollutants that WWTPs are obliged to remove depend on the characteristics of the discharge location. To address this, an advanced efficiency model is applied to differentiate between the amount of pollutants that the Directive 91/271/EEC oblige to remove and the extra quantity of pollutants that WWTPs remove beyond the legal re-quirements. The results show that most of the facilities are able to remove a higher quantity of pollutants and, consequently, generate more resources for the society. The methodology and results of this study are of great interest to WWTP managers and administrations, encouraging the implementation of design-based solutions to maximize by-product collection in the wastewater treatment sector and improve the efficiency of these facilities.

Automated summary

Wastewater treatment plants (WWTPs) have great potential in the circular economy as they can provide alternative water sources and valuable resources for other sectors. Evaluating the efficiency of wastewater treatment processes helps identify ways to improve performance and ensure long-term sustainability. The study introduces an advanced efficiency model that differentiates between mandatory pollutant removal and additional removal, showing that most facilities can remove more pollutants and generate more resources for society.