Evaluation of Biogas Energy from Co-Digestion of Organic Urban Solid Waste with Lime Mud

Abstract

The elevated presence of organic material in Brazilian urban solid waste, along with mismanagement of its disposal, can aggravate environmental problems from greenhouse gas emissions to water and soil pollution. In parallel, the paper and cellulose industries consume considerable resources and produce important solid wastes, including lime mud. These urban and industrial realities present common ground, from which a little-studied alternative arises in using biogas electrical energy from the co-digestion of the organic portion of urban solid waste using lime mud. This intersection can reduce the environmental impacts associated with inadequate management and disposal of solid waste, providing industry financial economy resources and contributing to Brazilian energy grid diversification. The current study used economic–financial indicators to evaluate the proposal’s economic feasibility. The obtained results presented a minimum population of 165,200 inhabitants, generating 39,295.77 m3/year of methane, in order to enable a co-digestion proposal. The sensitivity analysis indicated that a population of 185,500 inhabitants would provide a 10-year payback, an energy rate of USD 0.139, and 44,124.49 m3/year of methane to supply the population with power. The net present value was USD 23,336.94, with an internal return rate of 14.71% and a levelized energy cost of 0.103 USD/kWh.