Multi-criteria decision analysis of waste-to-energy technologies for municipal solid waste management in Sultanate of Oman.

The Sultanate of Oman faces challenges, like rapid growth of waste generation, which calls for an optimum waste management strategy. Oman has witnessed the production of 1.5m t of municipal solid waste in 2012, which is expected to elevate to 1.89m t in 2030. This rapid increase needs to be tackled to reduce the generation rates along with the environmental impacts. Currently, there are no treatment facilities in Oman other than limited recycling, and therefore dumping waste into the landfill is the only ultimate way to dispose solid waste. Hence, this study is an initiative to improve the waste managing system in Oman by proposing optimum waste-to-energy technology using an analytical hierarchy process, manually and through expect choice software as well. In the present study, the identified important parameters were considered in an analytical hierarchy process model to rank the waste-to-energy technology alternatives. Based on the survey conducted, the most important criteria were environmental and economic, with the local priority vector of 0.400 and 0.277, respectively. This research concludes that the most suitable waste-to-energy technology for Oman, on the basis of the identified criteria, is anaerobic digestion followed by fermentation and incineration, which will help to reduce the amount of waste, greenhouse gas emissions and developing and maintaining costs of landfills.

Economic and environmental benefits of landfill gas utilisation in Oman.

Municipal solid waste disposed in landfill sites decomposes under anaerobic conditions and produces so-called landfill-gas, which contains 30%-40% of carbon dioxide (CO2) and 50%-60% of methane (CH4). Methane has the potential of causing global warming 25 times more than CO2 Therefore, migration of landfill-gas from landfills to the surrounding environment can potentially affect human life and environment. Thus, this research aims to determine municipal solid waste generation in Oman over the years 1971-2030, to quantify annual CH4 emissions inventory that resulted from this waste over the same period of time, and to determine the economic and environmental benefits of capturing the CH4 gas for energy production. It is found that cumulative municipal solid waste landfilled in Oman reaches 3089 Giga gram (Gg) in the year 2030, of which approximately 85 Gg of CH4 emissions are produced in the year 2030. The study also found that capturing CH4 emissions between the years 2016 and 2030 could attract revenues of up to US$333 million and US$291 million from the carbon reduction and electricity generation, simultaneously. It is concluded that CH4 emissions from solid waste in Oman increases enormously with time, and capture of this gas for energy production could provide a sustainable waste management solution in Oman.