Biohydrogen and biomethane production from cassava wastewater in a two-stage anaerobic sequencing batch biofilm reactor

Abstract

The objective of the present study was to determine the energetic potential from cassava starch wastewater in a two-stage system (BioH2 + BioCH4) composed by anaerobic sequencing batch biofilm reactors (AnSBBR). Included in this general objective, the behavior of the methanogenic AnSBBR regarding organic matter removal and biomethane production will be investigated. The acidogenic AnSBBR was operated with organic loading rate (OLR) of 14 gCarb.L−1.d−1, influent concentration of 5 gCarb.L−1 and cycle time of 4 h. The methanogenic AnSBBR was submitted to OLR increase (3.7–12 gCOD.L−1.d−1), provided by arrangements between influent concentration (2.8; 4.0 and 6.0 gCOD.L−1) and cycle time (6; 8 and 12 h). For the evaluated condition, the acidogenic reactor presented productivity of 0.7 LH2.L−1.d−1 and yield of 1.1 molH2.kg−1Carb. The methanogenic reactor presented stable methane production (%CH4 > 78) during the 260-days operating period. The maximum methane productivity (2.71 LCH4.L−1.d−1) and yield (0.263 LCH4.g−1COD) were obtained at OLR of 12 gCOD.L−1.d−1 and cycle time of 6 h. The estimated energy production rate in the two-stage system (BioH2 + BioCH4) was 105.2 kJ.L−1.d−1.