Effects of press- mud pre-treatment on the feasibility of biogas production

In this study, an energetic, economic and environmental feasibility for the anaerobic digestion (AD) of press mud previously pre-treated with liquid hot water (LHW) or thermo-alkaline (TA) methods were assessed. A typical Cuban sugar mill was selected as Case Study. The sugar mill has a potential capacity to process 4,600 t d(-1) of sugar cane and operates 130 days per year. The biogas produced can be used to feed an internal combustion engine to produce electricity and heat. It was assumed that the electricity will be sold to the national electric grid and the heat recovered from the exhaust gases will be used as energy source to supply the thermal demand for press mud pre-treatments. The thermal requirements for pre-treatments (9.4 and 12.1 MWh d(-1)) were energy sufficient by recovering the heat from the engine exhaust. For the alternatives considered, an improvement of the environmental profile with respect to the reference scenario was obtained. The profitability of methane production also increased for alternatives considering pre-treatment. In general, the economical, energetic and environmental assessment showed the best indicators for the AD of press mud using LHW pre-treatment.