Life cycle assessment of municipal solid waste management in Kathmandu city, Nepal - An impact of an incomplete data set

Few studies have been done about engineered facilities related to waste collection, treatment, and disposal in the waste management sectors across Nepal. The decision support system is not well established, resulting in poor planning and execution of waste management. Available data for performing a life cycle assessment (LCA) is limited. We used an LCA model to investigate waste management options for Nepal's capital, Kathmandu. We also tested the hypothesis that exclusion from the LCA model of variables for which there was no data would make no difference in the management rankings. The assessment was based on three scenarios: business as usual, including collection, transportation, and landfilling; recycling; and conjunctive disposal comprised of composting and landfilling. The LCA methodology we used includes detailed unit processes and quantified values of various resources and emissions to compute the impact level on the environment. The contribution of the collection, transportation, landfilling, and recycling was calculated as global warming potential, acidification potential, eutrophication potential, and fuel energy consumption for each scenario. Scenario 3 ranked higher than scenarios 1 and 2 based on available data. The results were based on the environmental burden of metric tons of municipal solid waste handled at landfills, regardless of what was recycled and composted. Scenario 3 yielded minimum environmental impacts and was a cost-efficient option. Using a range of literature values for the missing variables, it was shown that the excluded variables made no difference in the scenario rankings. The study successfully employed the LCA as a decision-making tool in waste management in Kathmandu, which can be useful for other cities in developing countries.