Nutrient recovery and biogas production: advancing sustainable wastewater management with hydrothermal treatment – a life cycle assessment

Abstract

This study explores a novel approach to wastewater treatment using hydrothermal treatment (HT) and anaerobic digestion to enhance nutrient recovery and bioenergy production, supporting sustainable wastewater management. A life cycle assessment of four waste-activated sludge (WAS) valorisation scenarios was conducted, assessing impacts such as global warming potential (GWP), eutrophication, and toxicity. The optimal process, combining HT with struvite precipitation and magnetic biochar adsorption, reduced GWP by 26.6%, saved 5,817 m³ of water annually and achieved 70.6% phosphorus recovery, mitigating freshwater and marine eutrophication by 28.7% and 22.9%, respectively. Magnetic biochar reduced toxicity by 37.9% in phenolic compounds, while energy recovery was critical, enhancing GWP reduction by 17.7%. This research highlights the potential of advanced resource recovery to transform wastewater treatment plants into sustainable resource hubs, advocating for supportive policies in Sub-Saharan Africa and globally to foster a circular economy.