Synthesis of optimal biogas production system from multiple sources of wastewater and organic waste

Abstract

Biogas is one of the products that can be produced from wastewater or organic waste. Given the input streams for biogas digester can come from multiple sources rich in organic compound, optimization can be performed to maximise the production. In an industrial park with several types of industry, wastewaters and/or organic wastes from the industries or surrounding area can be used as feedstock for biogas production. Compared to conventional industrial park, Eco-Industrial Park (EIP) could be the appropriate platform for implementation as it advocates for industrial symbiosis through materials exchange and minimisation of waste, which are also in-line with the circular economy concept. In this study, a superstructure applicable for an EIP, which consists of multiple biogas sources, biogas digester, biogas upgrading, and biogas demands are developed. The model considers parameters which can affect biogas production quality and quantity such as Chemical Oxygen Demand (COD), Carbon/Nitrogen ratio (C/N ratio), and temperature. It also considers percentage of methane lost, removal efficiency of Carbon Dioxide (CO2), electricity cost, capital cost of the selected biogas digesters as well as the cleaning and upgrading units. The main objective of the mathematical model is to maximise the profit generation from biogas generation for the EIP centralized biogas production plant. The model is solved by using General Algebraic Modelling System (GAMS) software. Case study conducted shows that anaerobic closed lagoon is selected as digester for the industrial wastewaters, while water scrubber is suggested as the biogas upgrading technology. A yearly profit is estimated at USD13,700,000, which is generated from selling of 279nm3 of purified biogas. This may suggest that generating biogas from several sources of industrial wastewater and organic waste could be potentially feasible, thus reducing unnecessary pollutant while capturing the carbon source as an additional revenue stream.