In isolated areas, wastewater reuse is a key solution to water scarcity, enabling the completion of the integral water cycle. However, managing sludge from treatment plants in these regions poses significant environmental and economic challenges, particularly due to limited land availability. This study presents a cradle-to-gate comparative carbon footprint analysis of various sludge management pathways, ranging from traditional systems to advanced thermochemical conversion processes. The regional assessment reveals a significantly higher carbon footprint in Fuerteventura (23.0 kg CO2,eq/capita · year) compared to Tenerife (13.2 kg CO2,eq/capita · year). Centralized thermochemical processing shows the greatest decarbonization potential under the studied conditions; specifically, pyrolysis maximizes the reduction to 54% and 40% for Tenerife and Fuerteventura, respectively. This behavior is due to the carbon footprint recovery associated with pyrolysis byproducts. However, these findings are based solely on carbon footprint considerations and are subject to the technical and operational feasibility of thermochemical processing. These results provide a strategic framework for decarbonizing wastewater treatment plants in similar regions, identifying the most efficient pathways toward achieving carbon neutrality in the sludge line.
Díaz et al. (Sat,) studied this question.