Abstract
The existing pressure on the waste management chain is faced by every nation nowadays due to increased population growth. Population growth increment, including rapid urbanisation, wealth growth and scarcity of resources, has re-established waste-to-energy (WtE) as an attractive technology option in the broader waste hierarchy. That supports low carbon growth, socio-economic growth, and environmental protection alongside other renewable energy technologies. It is also a proven process that sustainably provides energy and other resources. However, Nigeria is also facing a critical waste-related environmental problem. Using municipal solid waste (MSW) as a renewable energy resource in Nigeria can be developed as an essential integrated solid waste management (ISWM) strategy. At the same time, it generates resources that can reduce fossil fuel use and greenhouse gas (GHG) emissions. Nevertheless, the essential and common means of MSW management is the open dumping of mixed waste in Nigeria.
However, this study explores the use of MSW as a renewable energy resource in a way that will contribute to sustainable and reliable energy in the Bauchi metropolis and serve as a holistic ISWM approach. The main aim of this study is to explore the opportunities for a sustainable and reliable WtE technique to contribute significantly to the Bauchi metropolis in Nigeria. The study is based on simulations of the impacts of various waste management treatment options and technologies. The open dumping of mixed waste is considered as a baseline scenario (Business-as-usual). It is used as a reference to other developed scenarios (SC) in this study. The remaining SCs were developed based on ISWM treatment technologies. Hence the alternative SC include SC1 (incineration), SC2 (anaerobic digestion, and landfilling), SC3 (anaerobic digestion and recycling), SC4 (composting, incineration, and landfilling), SC5 (anaerobic digestion, incineration, recycling, and landfilling), and SC6 (composting, gasification, and recycling). A life cycle assessment (LCA) framework (ISO14040 and 14044) was adopted to achieve the aim, which served as a sustainability assessment tool.
The LCA findings show that negative values in the scenarios reflect a decrease in environmental burdens. The positive impact categories demonstrate the environmental burdens associated with the treatment technologies. Hence, the optimal scenario is one in which anaerobic digestion is used to generate biogas from biowaste of 62.4 % of the 1 ton of the collected waste—maximising the reprocessing of recyclable materials of 37.6% that includes plastic, glass, sand, and metal. The avoidance in the various impact categories is (-86 kg CO2 eq./t) in Global Warming Potential (GWP), (-13 kg SO2 eq./t) in Terrestrial Acidification Potential (TAP), (-0.3 kg NOX eq./t) in Ozone Formation Human Health Potential (OFHP), (-0.14 kg P eq./t) in Freshwater Eutrophication Potential (FEP), (-12 kg 1,4-DCB eq./t) in Human-carcinogenic Toxicity Potential (HTP), (-5 m3/t) in Water Consumption (WC), (-0.00014 kg CFC-11 eq./t) in Stratospheric Ozone Depletion Potential (SODP) and (-729 kg 1,4-DCB eq./t) is revealed in the Terrestrial Ecotoxicity Potential (TETP).
The most significant result is that using recyclable materials as replacements for raw materials and biowaste for the generation of renewable energy helps alleviate the direct and indirect burdens associated with the whole life cycle of resource generation.