Two-phase anaerobic digestion of cassava wastewater with addition of residual glycerol for hydrogen and methane production

Digestão anaeróbica em duas fases de águas residuais de mandioca com adição de glicerol residual para produção de hidrogênio e metano

Abstract

Biogas production through co-digestion of two or more waste products has garnered increasing attention from researchers seeking to optimize this process. Biogas and methane production increase with the addition of glycerol to agro-industrial wastes during anaerobic biodigestion. However, the utilization of a two-phase process focused on hydrogen production has not been widely explored. This work aims to evaluate two-phase anaerobic biodigestion of cassava wastewater by adding residual glycerol and swine wastewater to enhance hydrogen and methane production. A pilot-scale biodigester was used during the acidogenic phase at 38.5°C, containing 4% glycerol. The effluent was submitted to methanogenic treatment, and the influence of temperature (36.0 to 39.0°C) and sodium bicarbonate concentration (2.0 to 6.0 g L-1) were evaluated. The results indicated that the optimum conditions during the methanogenic phase were 39.0°C with a sodium bicarbonate concentration of 5.0 g L^-1. The two-phase biodigestion produced 30.8 mL of (H₂) RCOD^-1 and 104.5 mL of (CH4) RCOD^-1. Thus, the substrates and inoculum used were adequate for the anaerobic biodigestion process, increasing the energetic efficiency of the process due to hydrogen production.

Keywords:
anaerobic biodigestion; codigestion; biogas; biomethane; green hydrogen