Policy-driven municipal solid waste management assessment using relative quadrant eco-efficiency: A case study in Malaysia.

Despite studies encouraging sustainable waste management, most municipal wastes remain in landfills, particularly in developing countries. Lack of holistic planning and national policy alignment might impair the waste management facility implementation. Policy-driven waste treatment scenarios should be designed to strongly link to the local conditions when assessing the eco-efficiency impacts of the waste management system. Taking Malaysia as a case study, a relative quadrant life cycle eco-efficiency indicator is developed to investigate the eco-efficiency of waste treatment scenarios. The relative quadrant life cycle eco-efficiency indicator depicts the eco-efficiency of various waste management scenarios. Compared with Scenario S1 - business-as-usual (i.e., 71.5% open landfill, 10% sanitary landfill, 1% composting, 17.5% recycling), five waste treatment scenarios (S2-S6) are designed based on Malaysia's existing and future policy targets. Scenario S5 (15.5% sanitary landfill, 22.25% composting, 22.25% anaerobic digestion, 40% recycling) and Scenario S6 (5% sanitary landfill, 22.25% composting, 22.25% anaerobic digestion, 40% recycling, 10.5% incineration) demonstrate that the 40% recycling rate is 32.9-33.6 times more environmentally favorable and 10-20% more economically viable than business-as-usual. Another four scenarios (NS1-NS4) are designed to investigate zero waste in landfills and the need to implement incineration or material recovery. Scenario NS3 suggests increasing incineration capacity to 33% could be an option should incineration is implemented. Adopting home or centralized windrow composting and increasing 2.5-5.5 times of current Feed-in Tariff rates are recommended to improve the eco-efficiency of the waste treatment scenarios. This study could facilitate policymakers to set waste minimization targets and incentives through various scenarios via sensitivity and comparative analyses.

Life cycle assessment of bioelectrochemical and integrated microbial fuel cell systems for sustainable wastewater treatment and resource recovery.

Bioelectrochemical system (BES) is an emerging technology that can treat wastewater via microbial activity while producing energy simultaneously. The system can couple with conventional systems to improve system performance. This study aims to compare the environmental performance of BES and the integrated microbial fuel cell (MFC) systems via a life cycle assessment methodology and identify the major environmental hotspots of the system. Fifteen treatment options are assessed with the ReCiPe 2016 characterization method using SimaPro 9.2 software. The results show double chamber air-cathode microbial electrolysis cell (MEC1) and membrane distillation integrated MFC (MD + MFC) treatment options present as the most environmental favourable among the BES and integrated MFC systems, respectively, due to the offset of the environmental loads from the avoided impacts contributed by their value-added by-product, which is hydrogen fuel for MEC1 and tap water for MD + MFC. Electricity consumption dominates the environmental loads of all the BES options for up to 90% of the global warming impact category. The environmental benefits from the electricity generation of BES are minor (i.e., MFC: 0.01-2% while microbial desalination cell: 0.01-7% of the total environmental impact in a system) to offset the environmental loads incurred by the system. Platinum-based cathode incurs 2.5-24 times higher environmental burdens than non-platinum configurations in MFC under the human carcinogenic toxicity impact category. In line with Sustainable Development Goals 6 and 13, this study provides scientific references to wastewater treatment stakeholders in selecting suitable BES and integrated MFC systems to improve water sanitation and address climate change simultaneously.