Municipal Solid Waste Incineration with Advanced Emissions Treatment

Abstract

The annual solid waste generation worldwide is estimated to be 2.01 billion tonnes, however, this is expected to increase to about 3.4 billion tonnes by the year 2050. Again, the estimated per capita waste generation in Ghana per day is 0.47 kg, which translates to over 5 million tonnes of Municipal Solid Waste (MSW) generation annually. The disposal and management of this huge amount of MSW generation has been challenging globally. In Ghana, this is evident with the creation of unsanitary open dumpsites scattered across most communities throughout the country. The indiscriminate dumping of MSW has been attributed to causing flooding in most areas of the country. The use of waste incineration is a matured waste-to-energy technology which has become attractive for the disposal and management of MSW. Meanwhile, Ghana has been struggling to meet the electricity demand in the country. The electricity generation capacities of waste incineration facilities in the USA are about 2700 MW, 1925 MW in Germany, 925 MW in the UK, and 876 MW in Sweden. Major drawbacks with this technology include its high cost, and the release of huge volumes of emissions (including acidic gases), which may be detrimental to the environment. Due to the heterogenous composition of MSW as fuel, a simple import of the waste incineration technology to different locations is not usually successful, as such there is a need to perform a techno-economic assessment of the proposed waste incineration facility to be adopted in Ghana and improve on its emissions treatment. The technical assessment carried out in this study involves the determination of the amount of electricity that can be generated in proposed waste incineration facilities. Again, various models of the proposed waste incineration plant were developed and simulated using Aspen Plus® software to assess the performance of various particulate matter separation devices, as well as cleaning acidic gases from the flue gas streams using wet scrubbing and subsequently treating the generated wastewater using membrane distillation. The economic assessment carried out involves determining key economic indicators; the Net Present Value (NPV), and Levelized Cost of Energy (LCOE) for the proposed waste incineration facilities. Results indicate that a total of about 400 MW of electricity can be generated from the total MSW generated in Ghana annually, which can meet the electricity demand of about 8 million inhabitants in the country. The membrane distillation incorporated in the treatment of wastewater produced in the wet scrubbing during acidic gas cleaning had cleaning efficiencies of over 99 % and 95% for sulphuric and hydrochloric acids respectively. The NPV for a proposed 35 MW waste incineration facility was US$ 166,410,969.24 with an LCOE of US$ 0.19/kWh. It can be concluded that waste incineration facilities are not economically viable ventures in Ghana, and its implementation would therefore need government support in the form of subsidies and tax rebates.