Factors affecting technology selection, techno-economic and environmental sustainability assessment of a novel zero-waste system for food waste and wastewater management

Abstract

To provide food waste energy recovery, sludge management and building wastewater recycling with the primary goal of achieving zero-waste discharge, a novel integrated single-stage anaerobic co-digestion and moving bed biofilm reaction membrane bioreactor system has been developed. The acceptability of the technology and the sustainability of the zero-waste system were assessed by a proposed stepwise evaluation approach that included the factors affecting its usage, technical performance, environmental sustainability and economic feasibility. Based on the three experimental cases of the system prototype, the anaerobic co-digestions of food waste and wastewater sludge (Cases 2 and 3) provided slightly higher methane generation rates than was achieved from the mono-digestion of food waste (Case 1). Average methane yields from the anaerobic co-digestion (Cases 2 and 3) were in the range of 0.352–0.353 L/g TVS. The ratios of VFA/Alk of all the experimental cases were lower than 0.25, indicating the stable anerobic co-digestion performances. The MBBR-MBR was able to achieve ammonia removal rate in the range of 0.34–0.77 g NH4/m2-day. The co-treatment of combined wastewater was able to provide good reclaimed water that was suitable for landscape use. Life cycle assessment results showed that the proposed zero-waste system could reduce the impacts of climate change, eutrophication, acidification, and fossil resource depletion compared to conventional waste treatment. The economic Internal Rate of Return, Net Present Value, and Benefit/Cost of the system were around 9%, 2222 USD, and 1.44, respectively. The challenges and opportunities from implementing the system were discussed.