Potential use of sisal juice as raw material for sequential biological production of hydrogen and methane

Each kilogram of sisal fiber produced generates around 100 L of wastewater, called sisal juice (SJ). Its high organic matter concentration makes it a potential raw material for biofuel production. Therefore, this work aims to treat SJ and add value to it, producing biohydrogen and methane. The production of biohydrogen, applying the substrate/inoculum ratio of 1:1 (g COD/g VSS), generated 573.2 NmL(H2)/L-medium in 40 h. To produce methane, anaerobic digestion (AD) was performed through a single-step and a sequential process (using the biohydrogen production effluent). After 22 days, the first approach provided 54.0 NmL(CH4)/L.d, 113.9 NmL(CH4)/g-CODadded, and 54.7% of COD removal, whereas the sequential AD, in 12 days, provided 59.3 NmL(CH4)/L.d, 115.6 NmL(CH4)/g-CODadded, and 82.5% of COD removal. The overall energy potentially generated in the sequential process (81.4 cal/g(COD).d) was 85% higher than those of direct AD (44.1 cal/g(COD).d). Thus, the sequential biological production of hydrogen and methane proved to be an efficient strategy for the reduction of organic matter of SJ, generating gases of industrial and energetic interest.

Automated summary

By treating sisal juice (SJ) and adding value to it, biohydrogen and methane can be produced, which efficiently reduces the organic matter of SJ and generates gases of industrial and energetic interest.