Municipal solid waste (MSW) with high food waste (FW) content requires adequate treatment to achieve sustainable development goals worldwide. Their treatment systems consume a considerable amount of abiotic energy and resource input, which not only incur environmental pollution and loss of valuable natural resources but also contribute to global warming. Hence, the global paradigm has evolved from simple pollution mitigation to resource recovery systems by employing advanced technologies and innovative policies such as the development of an integrated waste management system (IWMS). This is particularly a true case in Hong Kong which faces an imminent issue of MSW and FW management.

To investigate the feasibility of IWMS for Hong Kong, this study comprehensively evaluated several poten...[ Read more ]

Municipal solid waste (MSW) with high food waste (FW) content requires adequate treatment to achieve sustainable development goals worldwide. Their treatment systems consume a considerable amount of abiotic energy and resource input, which not only incur environmental pollution and loss of valuable natural resources but also contribute to global warming. Hence, the global paradigm has evolved from simple pollution mitigation to resource recovery systems by employing advanced technologies and innovative policies such as the development of an integrated waste management system (IWMS). This is particularly a true case in Hong Kong which faces an imminent issue of MSW and FW management.

To investigate the feasibility of IWMS for Hong Kong, this study comprehensively evaluated several potential integrated scenarios for MSW and FW management. The lifecycle-based impact assessment of these scenarios was performed in terms of net greenhouse gas emissions (GHEs) and energy use by applying classified modelling approaches. The baseline results for total MSW management revealed that, compared to conventional landfilling and four other scenarios, an integrated scenario comprising incineration for MSW and combined anaerobic digestion (AD) and composting (ADC) for FW treatment was ranked as the best-case scenario by providing maximum GHEs reduction and energy recovery.

Moreover, the quantitative investigation of impacts of the FW co-treatment with wastewater (WW) was carried out by performing a case-specific plant-wide steady-state modelling (PWSSM) of a local WW treatment plant (WWTP). The PWSSM evaluation delivered optimistic results and feasibility for the practical application. The WWTP’s organic load capacity and performance in terms of organics and nitrogen removal was not significantly degraded. The net energy balance and carbon footprint were improved significantly, while the sludge production was increased by nearly 33%.

Finally, the comparative analysis of six FW treatment scenarios also including the FW co-treatment with WW at biological WWTP was performed. The results revealed that anaerobic co-digestion (AnCoD) of FW with sewage sludge by separate transportation was the most promising scenario in terms of saving abiotic energy use and GHEs. Whereas, the sensitivity analysis of key parameters showed a significant impact on the magnitude of net GHE results and the incredible deviation from the average input data may affect the scenarios rankings. Nevertheless, it is evident that conventional landfilling was the worst-case scenario in terms of both impact categories and all tested scenarios for the development of IWMS were significantly better.