Produção de hidrogênio a partir do melaço de cana-de-açúcar em reator anaeróbio de leito fluidificado

Abstract

Hydrogen is one of the most studied energy sources nowadays. It can be produced in a number of ways, among which its organic production from renewable sources, such as industrial and household waste rich in carbohydrates, stands out. In this context, sugarcane molasses, a byproduct generated in the production of sugar, contains a large quantity of organic matter and, therefore, when passing through the process of anaerobic digestion, can be converted into hydrogen. Thus, the objective of this study was to use an anaerobic fluidized bed reactor (AFBR) at room temperature to produce hydrogen from sugarcane molasses fed at 25 gDQO.L-1. The total volume of the reactor was 1.2 L.The support material employed to ensure microbial adhesion was the crushed tire and the source of microorganisms consisted of sludge collected from a sludge blanket reactor (UASB) used in a sewage treatment plant. Different volumetric organic loads (VOL) and hydraulic retention times (HRTs: 12, 6, 4 and 3 h), obtained from the variation of the system flow, were analyzed. A maximum hydrogen production rate (HPR = 1.44 LH2.L-1Reactor.h-1) was achieved at HRT of 4 h with a energy production rate (EPR-H2) of 373.25 kJ.L-1Reactor.d-1. The highest hydrogen yield (HY = 3.07 molH2.mol-1glucose) was obtained at optimal HRT of 6 h. The hydrogen content in the biogas reached 25.95% H2 (HRT 6 h). The main metabolites produced were ethanol and acetic acid, from ethanol type fermentation. PCRDGGE analysis revealed that the bacterial community of the reactor underwent structural changes along the decrease of HRT, which were reduced until obtaining an 88% similarity between HRTs of 4 h and 3 h.