Produção de biohidrogênio em reator anaeróbio operado em bateladas sequenciais com biomassa imobilizada (ansbbr) a partir de água residuária de cervejaria

Abstract

The biological production of hydrogen (bioH2) through anaerobic fermentation of residual carbon sources is an interesting way to combine the environmental adequation of agro-industrial wastewaters to the generation of value-added products. Wastewaters with fermentable carbon sources have high potential to produce bioH2, being possible using different inoculum and biological reactors. It is the case found in brewery wastewater, generated in large amount at Brazil and around the world, and there are only few studies about it. In this context, this work studied the production of bioH2 by an anaerobic reactor operated in sequencing batch with immobilized biomass, AnSBBR, from brewery wastewater, using two inocula: mixed culture from the natural fermentation of synthetic wastewater based on sucrose and pure culture of Klebsiella pneumoniae, immobilized in expanded clay. Were evaluated the effects of influent concentration (2,8 a 7,2 gTRS L-1), volumetric organic load (2,6 a 12,6 gTRS (L day)-1) and cycle time (12 h e 24 h), in assays taking from 9 to 16 cycles. The inocula gotten through natural fermentation showed potential to produce bioH2 in preliminary experiments (shaken bottles, 0,5 L) but, in the tests on the reactor the production was low, instable and brief (less than 7 days). The pure inocula K. pneumoniae showed a good adaptability to the residue, in activity through the whole experiment. The raise in the volumetric organic load (VOLc) up to 12,6 gTRS (L day)-1 and the reduction of the cycle from 24 h to 12 h had a positive effect in the production and, under those conditions, the best values for the evaluation parameters ahead were obtained: volumetric productivity average of 0,9 LH2 (L day)-1, molar flow rate up to 10,8 mmolH2 h-1, molar yield average de 3,9 molH2 KgTRS-1, with H2 content in biogas between 18 and 42% and TRS and COD removal efficiency of 89% and 23%, respectively, with a predominance of acetic and butyric pathways. Those results indicate a promising production of H2 from brewery wastewater using K. pneumoniae as inocula in AnSBBR reactor, contributing to the development of the bioH2 technology by the proposal of a new inocula to achieve a higher use of this wastewater potential.