## 6 Proposed WTE Conversion Technology  
Among the various treatment processes mentioned in the preceding section, there are a number of technological challenges in each of the methods. Although landfill is the most common method of waste management in RCC, it is no longer appropriate due to the deficiency of land [17]. Incineration is very common in WTE plants in Asia [39]. However, the main challenges of incineration processes are the implementation of proper flue gas treatment technology and proper carbon dioxide capture and storage technology. They also have high carbon emissions and high emissions of harmful flue gases [40]. Additionally, the drying of wastes in the rainy season is very difficult, which is a great disadvantage of the incineration process and a large amount of fuel is required to execute the incineration process [9]. Though pyrolysis is one of the most common methods for WTE conversion, the major disadvantage is the requirement of a very small particle size for fluidized bed reactors [17]. The main challenge of pyrolysis is the development of the technology to maturity. It is also not suitable for plastic and rubber wastes [40]. Tar removal technology is one of the main technological challenges of the gasification process [40]. The pretreatment process is very costly in the gasification process [5].  
Most (72.29%) of the total wastes have are food and vegetables, which are biodegradable. Thus, anaerobic digestion (AD) can be an attractive energy recovery process to produce electricity, though upgradation of biogas is very challenging for AD. It will not only reduce the landfill waste, but will also meet the high electricity demand in RCC. Another advantage of anaerobic digestion is that it produces both biogas (CH4 and CO2) and digestate (innocuous liquid and solid residues) at the same time [41]. Biogas can be used to generate power, where the digestate can be further modified to compost, that can be used in the land. It has less environmental impact, as the byproducts of this process are modified to produce compost. A schematic of the proposed waste management process in RCC is illustrated in Figure 11.  
Non-recyclable and non-biodegradable wastes are suggested for incineration and landfill. Recyclable wastes, like metals, should be sent for further processing. Plastics, paper and paper products should be reduced through a pyrolysis process, as pyrolysis oil and gas can provide a significant amount of energy [36; 37]. Table 10 shows the energy recovery potential from anaerobic digestion. It has been observed that about 38,850 m\({}^{3}\) of biogas can be generated per day from MSW in RCC, whi  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Treatment Technique** & **Category of Solid Waste** & **Percentage of Total Waste** \\ \hline \begin{tabular}{c} Composting/anaerobic \\ digestion/incineration \\ \end{tabular} & Vegetable and food wastes & 72.29\% \\ \begin{tabular}{c} Landfilling \\ \end{tabular} & \begin{tabular}{c} Dust, ash, mud, brick, concrete, \\ stone, glass, ceramic, etc. \\ \end{tabular} & 10.87\% \\ \begin{tabular}{c} Pyrolysis/gasification \\ \end{tabular} & \
\begin{tabular}{c} Paper, paper product, \\ polyethylene, wood, rubber, etc. \\ \end{tabular} & 10.53–15.6\% \\
\begin{tabular}{c} Recycling \\ \end{tabular} & Metals & 1.24\% \\ \hline \hline \end{tabular}
\end{table}
Table 9: Potential treatment of MSW.  
generation, as well as other uses, such as cooking. In addition, about 65 tons of compost fertilizer can be produced per day from MSW. Considering that the price of compost fertilizer is BDT 6/kg, about BDT 0.39 million can be saved with the produced compost [17].