Energy and Environmental Engineering 5(2): 37-53, 2017 http://www.hrpub.org DOI: 10.13189/eee.2017.050202 Design Models for Anaerobic Batch Digesters Producing Biogas from Municipal Solid Waste Asinyetogha Hilkiah Igoni * , Ibiye Sepiribo Kingnana Harry Department of Agricultural & Environmental Engineering, Faculty of Engineering Rivers State University of Science and Technology, Nigeria *Corresponding Author: ahigoni@yahoo.com Copyright©2017 by authors, all rights reserved. Authors agree that this article remains permanently open access under the terms of the Creative Commons Attribution License 4.0 International License Abstract Models for the design of anaerobic batch digesters producing biogas from municipal solid waste (MSW) in Port Harcourt metropolis, Nigeria have been formulated. Experimental and field data were used to determine relevant design parameters for the batch digesters, especially the bio-kinetic behavior of MSW. The research data were analyzed using material balance analysis. The anaerobic digester was then designed and simulated for fractional conversion values of 0.2 ≤ α ≤ 0.8 and percentage total solids (PTS) concentration of 10-30%, using Microsoft Visual Basic Version 6.0 computer program. The simulation results were interpreted with Microsoft Chart Editor. The evaluation of research results showed that an empirical optimum PTS concentration of 20% was best suited for the batch digester processing the MSW for biogas generation. At this level of PTS concentration, the MSW digestion was most effective in terms of digester sizing, time of digestion, volume of biogas produced and overall cost of the digester, for the same level of percent stabilization. Keywords Anaerobic Batch Digester, Biogas Production, Municipal Solid Waste, Batch Digester design, Optimal Digester Performance 1. Introduction The menace of municipal solid waste (MSW) in Port Harcourt metropolis, Nigeria has led to the development of several proposals on the best possible option to manage it. One veritable option is the introduction of a treatment component, which has been lacking, using anaerobic digestion. This reduces the waste volume and its pollution potential before final disposal. In anaerobic digestion, a useful by-product is biogas. Igoni et al [1] showed that MSW in Port Harcourt has the potential to be used as a source of biogas. For Nigeria, with large quantities of MSW generated, huge energy demand and a current inability to satisfy the energy needs of the citizenry, this option is attractive. 1.1. Municipal Solid Waste Generally, waste is a useless and unwanted material. In contemporary times when alternative uses have been discovered for materials regarded as waste, there are now various and varied definitions of waste. Byrne [2] says waste is material, which has no direct value to the producer and so must be disposed of. Similarly, Bailie et al [3] explain that “for practical purposes, the term waste includes any material that enters the waste management system”. A waste management system being organized programs and central facilities established not only for final disposal of waste but also for recycling, reuse, composting and incineration. They say “materials enter a waste management system when no one who has the opportunity to retain them wishes to do so”. Therefore, a material that is considered waste and disposed by someone could be valuable to someone else. Waste is classified according to the state of matter in which it occurs. Sincero and Sincero [4] say a gas that is wasted is a gas waste, such as polluted air from a process that is vented into the atmosphere; a liquid that is wasted, such as the polluted water of wastewater, is called a liquid waste; and a solid that is wasted is a solid waste. Hence, Ogunbiyi [5] states that solid waste is a non-fluid type of waste, which makes its handling and management relatively difficult, compared to the types of waste that can flow from one location to another, or even vaporize. According to Bailie et al [3], solid waste refers to all waste materials except hazardous waste, liquid waste and atmospheric emissions; and Kiely [6] says solid wastes are those wastes from human and animal activities including liquid wastes like paints, old medicines, spent oils etc. Therefore, it is possible to have solid waste intermixed with liquid waste. So, solid waste is essentially non-flowing. Igoni [7] enumerated various difficulties posed by solid waste arising from its non-flowing character. He listed such problems as offensive odours, obstruction of traffic flow, blocking of waterways/drain channels, leading to flooding of an area, destruction of environmental aesthetics and pollution of the air we breathe, with the concomitant unfavorable effects on public health. An effective way to describe the relative toxicity of solid