EVALUATION OF THE CARBON FOOTPRINT IN THE TREATMENT OF URBAN WASTEWATER IN THE CANARY ISLANDS (SPAIN)

Abstract

Wastewater treatment plants play an important role within the urban water cycle to prevent the natural water environment and human health from being negatively affected by human activities. However, wastewater treatment processes, such as effluent discharge and indirect emissions resulting from energy or chemical production, also negatively affect the environment. Footprints have been used to track human influence on the environment in different areas of interest and have been applied to assess the sustainability of wastewater treatment plants. In this article, a comprehensive review of footprint assessment was investigated to evaluate the wastewater treatment process in wastewater treatment plants. The review showed that carbon footprinting was used to assess the sustainability of WWTPs, and that other footprint assessment applications (such as nitrogen and phosphorus footprinting) were also introduced to assess eutrophication of water bodies. To promote the application of footprint assessment, this article regulates the study objectives, frameworks, system boundaries, data processing methods, and the resulting interpretation process. The pros and cons of the footprint assessments were discussed and investigated in detail, examining the CO2 production on each island of the Canary archipelago, and several suggestions were proposed to improve the footprint assessments. Analysis of footprint assessments at different wastewater treatment plants revealed that wastewater treatment technologies and scales had a significant impact on footprints. Furthermore, research hotspots identified using a keyword network diagram showed that the water-carbon-energy nexus was a promising direction for future studies. The purpose of the study is to improve the reduction of the carbon footprint both at the level of direct and indirect emissions factors using new tools and methodologies.