Characterization of screenings from urban wastewater treatment plants: Alternative approaches to landfill disposal

Increasingly, wastewater treatment plants are laying the foundation for a circular economy. A novel approach to operating these plants is to redefine them as biorefineries to produce energy and move toward zero waste. To this end, an analysis of wastewater screening was carried out, as this is the only waste that does not yet have a valorization route, being generally disposed of by landfill. This process causes economic and environmental costs and will be restricted in the coming years, so it is necessary to search for alternatives. Sampling was carried out at the South Biofactory (Granada, Spain). The screening composition was mainly composed of sanitary textiles (52.1%) and other fractions such as paper and cardboard, vegetables, plastics, and other fine particles, similar to the rejects from mechanical biological treatment. The samples showed a high lower calorific value (24.29 MJ/kg dry sample), which was reduced by the moisture content of the waste (77.3%). The lower calorific value results, and the chlorine and mercury contents, met the requirements for the potential production of solid fuel recovered from the screening. Consequently, this alternative could be developed for energy recovery in thermochemical processes.