No abstract

Several studies have shown that it is necessary to use a two-stage anaerobic reactor in biogas production with manipueira as a substrate. The objective of this study is to show the possibility of producing good quality biogas from a single-stage anaerobic reactor using manipueira and cattle manure as substrates. Five scenarios of codigestion are simulated in five digesters with different manipueira/manure ratios. The only digester that has a good result is the digester that is fed with 75% of manipueira and 25% of cattle manure. Under these conditions, biogas is produced with an average methane concentration of 62% the hydraulic retention time of the codigestion process is 30 days. The other digesters show that an excess of manipueira acidifies the codigestion process; such acidification can result in the severe inhibition of methanogenesis because of the accumulation of volatile fatty acids. On the other hand, an excess of cattle manure results in mixtures with a high concentration of lignin, cellulose, and hemicellulose mixtures, which, negatively influences the growth rate of methanogenic bacteria. Thus, using manipueira as cosubstrate, it is possible to produce a high-quality biogas in a single-stage anaerobic reactor.

The bioenergy has turned into a good alternative for reducing the emission of pollutant gases. In Brazil, the use of this type of energy has increased in the last decades. Biogas, produced from cassava, appears as an alternative fuel to fossil fuels and, also, becomes economically competitive, since this is a low cost carbon source. Anaerobic biodigesters that use renewable raw materials are known as a technology with great potential for biogas production which is considered a source of clean energy. Biogas produces sustainable energy and consists mainly of methane (60%) and carbon dioxide (35% to 40%). This study presents the biogas potential from the cassava processing residual water for the production of dry flour (manipueira). The results of this study indicated that the biogas potential is 1.389.312 cm 3 per year from a single-stage reactor with a capacity of 60 liters using manipueira as substrate and inoculated with cattle manure, which could provide a generation of electricity of 214 kwh/year.