Site suitability analysis of biogas digester plant for municipal waste using GIS and multi-criteria analysis

Solid waste management of urban areas becomes complex to solve. Practically, macro and micro levels geospatial solutions are needed to solve waste management problem in the fastest growing major cities around the world. Dhaka is the capital city of Bangladesh having 16 million of population, expected to reach 20 million by 2020. Due to uncontrolled population, urbanization, industrialization and migration of people, a large amount of waste is generated every day in the city area. Suitable site selection for a biogas digester using anaerobic digestion of municipal organic waste could be a solution for Dhaka City waste management. This study describes the site suitability analysis for the installation of an anaerobic digester for waste management as a potentially effective option for the production of energy from organic waste in Dhaka City. To select the most suitable sites for the biogas digester, a multi-criteria analysis was performed with integration of the geographical information system (GIS) in a zone of Dhaka. To locate suitable sites, three sets of factors, environmental, social and safety, and economics were considered in an analysis using 11 criteria. The criteria were settlement or residence distance, sensitive site distance, river distance, major road distance, local road distance, agricultural land distance, slope, present land use, future urban growth, low land distance, land cost and electrical pole distance. Each criterion was evaluated using a pairwise comparison matrix. The criteria were reclassified in five levels (most suitable, suitable, moderately suitable, less suitable, and not suitable) using spatial analysis in the ArcGIS((R)) environment. The reclassified features were further analyzed using weighted linear combination and analytical hierarchy process. This analysis indicated that 1 most suitable, 6 suitable and 3 moderately suitable sites could be used for a biogas digester plant in the study area. Furthermore, the potential energy production was calculated based on per capita generated organic waste and population growth. The projected simulation results show the energy potential from 2015 to 2025 for methane (CH4). The proposed most suitable site could be able to generate 26-40 MW of electricity from zone 2 of Dhaka City annually. The research proposed a micro-level solution for biodigester sitting location in 1 zone of Dhaka City for anaerobic digestion to utilize waste as energy. The similar approach can be taken for the rest of 10 zones by identifying the most suitable location for sitting biodigester plants to convert waste to energy. GIS plays a vital role in selecting the best place in the capital city. The methodology proposed in this research was very much practical to identify the best sites in one zone of Dhaka City. Therefore, the developed methodology for siting biogas digester can be implemented for other cities, which are overburdened with large generated waste due to a fast growing population.