Emerging Waste Valorization Pathway with Aerobic Granular Sludge: Prospective Life Cycle Assessment for Türkiye

Abstract

To address the environmental burdens of wastewater generation and fossil-based economy, application of aerobic granular sludge (AGS), which entails bio-resource recovery and wastewater treatment can be promising. Recognizing AGS technology as a sustainable waste management solution requires a robust assessment of its environmental performance relative to conventional pathways. Prospective environmental impacts of two AGSbased wastewater treatment configurations were evaluated in the context of Türkiye: (1) AGS with primary settling and an external membrane (PS-AGS-EM), (2) AGS with an external membrane (AGS-EM), where both enable recovery of polyhydroxyalkanoates, extracellular polymeric substances and biogas. From a consequential assessment perspective, operation of AGS configurations with an average of-0.3 kg CO2eq. per m3 wastewater demonstrated to be more favorable compared to the activated sludge and membrane bioreactor with 1.26 kg CO2eq. and 0.8 kg CO2eq. per m3 wastewater, respectively. Consumption of electricity was the major hotspot in both AGS configurations, especially for AGS-EM with almost 50% contribution to global warming potential and freshwater eutrophication potential categories. Under a wastewater management functional unit and assuming high substitution rates of conventional polymers by recovered biopolymers, AGS-EM configuration demonstrated superior environmental performance despite higher energy and chemical demands. Conversely, when EPS production was considered as the functional unit, PS-AGS-EM performed more favorably due to its lower energy and chemical requirements and higher biogas recovery potential. In the endeavors towards sustainable phasing out of fossil-based polymers and efficient water treatment strategies, the outcomes of the present AGS resource recovery study can provide an environmentally enlightening guideline.