Environmental and economic assessment of zero waste management

Abstract

The waste management (WM) approach for the protection of resources known as "zero waste" (ZW) has become popular in recent years. A number of measures have been taken and facilities have been installed to facilitate improved management of municipal solid waste (MSW). ZW to landfill targets have gained significant traction worldwide, including in Turkiye. The aim of this thesis is to assess the environmental and economic results of WM pathways within the context of an increasingly applied ZW approach.This study evaluates the sustainability of municipal solid WM through the ZW goal on multiple scales (Istanbul and Ayazağa Campus). The thesis provide a framework that enables institutions to develop a goal-oriented WM strategy using material flow analysis (MFA) and life cycle assessment (LCA). In addition to presenting the framework, a case study was conducted on a campus scale by using primary and secondary data. The framework assumes that no prior data is available, and the study will begin by collecting primary data on campus. For providing primary data; waste characterization and recycling potential of the Istanbul Technical University (Turkiye) Ayazağa Campus before (2019) and after (2022) the ZW management strategy the campus was divided into four distinctive groups, which are (i) academic (ii) administrative (iii) residential/dormitory and (iv) cafeteria. First, initial field study was conducted afterwards (for waste characterization and recycling potential), the new containers were placed. Students and campus personnel have been trained in within the scope of ZW management practices through both in-person and online seminars. The final phase of the study, the second field work, was completed. The results demonstrate that the waste generation rate in the pilot areas fluctuates between 0.045-0.190 kg/cap/day, but it decreases to 0.011-0.117 kg/cap/day in the second field study. The first field study had a potential recycling rate of 76.3%, but then it dropped to 68.2% in the second study. The MFA results indicate that landfill diversion ranges between 29.8% to ~99-100%, some residuals or ash from the incineration plant will still be disposed in landfill. Furthermore, simply diverting waste from landfill does not necessarily lead to circularity or directly address sustainable consumption and public attitudes towards ZW goals. The study framework aims to address potential challenges in campus-based, goal-oriented WM studies. Future case studies from other institutions and their campuses could help validate and improve this methodology. Based on the Ayazağa waste characterization results, the efforts to establish a ZW management system also led to a reduction in waste generation and increase in recycling performance. However, further studies are still required to assess the ZW's public awareness activities. In addition, a case example was developed based on ITU Ayazağa campus, Turkiye, with annual separated food waste of 577 tonne per year to provide a more circular and decarbonised economy. A LCA was conducted using the EASETECH software. Four scenarios were evaluated: anaerobic digestion, composting, incineration, and landfill. Of these, incineration resulted in the highest CO2-eq savings (-192 kg CO2-eq/tonne FW), but lacked decoupling and circularity of resources. Conversely, anaerobic digestion demonstrated the highest circularity and lowest toxicity. Based on these findings, anaerobic digestion was selected for further investigation. Economic transactions for the anaerobic digestion system's business models were analysed,including revenues, municipality fees and operating costs. The new economic model is expected to align with circular economy strategies and promote stakeholder collaboration as a significant social outcome.