Hidrólise enzimática e digestão anaeróbia do bagaço de cana-de-açúcar para aproveitamento energético.

Abstract

About 570 million tons of cane sugar were processed in the 2008/2009 harvest in the sugar plantations of the Brazilian sugar mills generated approximately 188 million tons of bagasse. It is mostly burnt in boilers to use the heat for electrical energy generation, to supply the industrial and agricultural power demands in the mills. However, this operation has a low yield. Aiming to maximize the energetic output from the bagasse, this research evaluated the enzymatic hydrolyses and anaerobic digestion of sugarcane bagasse, stressing the technical viability analysis of the power production potential from this raw material. Three enzymatic hydrolysis reactors (RHI, RH2 and RH3) and three UASB reactors (Ri, R2 and R3) for hydrolysed bagasse anaerobic digestion were operated. The raw material for all the treatments were vapor exploded bagasse (thermally treated material). The enzymatic hydrolysis reactors were distinctly operated: RHI reactor (without enzymes), RH2 (simultaneously feeding and enzyme application) and RH3 (exploded bagasse with pre-enzyme treated under thermophilic condition). The hydrolysed and lixiviated materials were digested in anaerobic reactors. Reactor RH3 presented the best efficiency for the exploded bagasse hydrolysis, while reactors RHI and RH2 presented smaller r, hydrolysis efficiency. Analysing the anaerobic digestion efficiency of the hydrolysed materials, the reactors UASB all three investigated reactors presented high digestibility efficiency with values ranging form 70 to 90 %. Considering all the Brazilian sugarcane production and the chemical energy within throughout bagasse generated, the potential power generation from hydrolysis and anaerobic digestion of the bagasse in the RH3-R3 system would be of 50 Twh/year, almost 12% of the Brazilian electrical energy demand. For the RH2-R2 system, the potential electrical energy generation would be of 46TWh/year, and for RHI-RI system, 26TWh/year, which represent 11% and 6% of Brazilian electrical energy demand. Thus, with this research, it can be concluded that it is technically viable the electrical energy production from the methane which was generated in the built systems with enzymatic hydrolysis reactors followed by UASB reactors.