Feasibility of successive hydrogen and methane production: Effects of temperature and organic loads on energy potential and microbial dynamics

Author(s)

Devens, Kauanna Uyara ; Ribeiro, Alexandre Rodrigues ; Camargo, Franciele Pereira ; Sakamoto, Isabel Kimiko ; Varesche, Maria Bernadete Amancio ; Silva, Edson Luiz

• Document type: Journal article
• Source: INTERNATIONAL BIODETERIORATION & BIODEGRADATION; v. 196, p. 14-pg., 2025-01-01.

Abstract

This study aims to assess the co-digestion of Cassava Wastewater (CW) and glycerol in a two-stage process using fluidized bed reactors (AFBR), verifying the effect of organic loading rate (OLR) and temperature (mesophilic [SMR] and thermophilic [STR]) in sequential reactors on CH4 production. The OLR ranged from 1.2 to 15 g COD. L- 1.d- 1 and the hydraulic retention time (HRT) was set at 20 h. The mesophilic sequential reactor (MSR) (average temperature of 30 degrees C) showed greater tolerance to high OLR and its best MPR was 101.12 mL of CH4. d- 1.L- 1 h-1, obtained at a OLR of 15 g COD.L- 1.d- 1). The maximum yield was 341.10 mL of CH4.g- 1CODcons, found at the OLR of 1.2 g COD.L- 1.d- 1. The sequential thermophilic reactor (STR) showed the maximum yield and MPR of 333.03 mL of CH4.g- 1CODcons (1.2 g COD.L- 1.d- 1) and 58.84 mL of CH4.d- 1.L- 1 h- 1 (12 g COD.L-1. d- 1), respectively. Through the massive sequencing analysis of the 16S rRNA gene, it was possible to observe a greater diversity of microorganisms in the TSR than in the MSR. A predominance of acetoclastic microorganisms was observed, with the genera Methanobacterium, Methanosarcina and Methanobrevibacter being the most abundant in both reactors. The two-stage system composed of mesophilic acidogenic reactor + MSR was more suitable for the co-digestion of CW and glycerol than the acidogenic reactor + TSR. These results support the notion of standard operating conditions at the industrial plant, where the cassava processing process is carried out at room temperature (25-30 degrees C). (AU)

• FAPESP's process: 15/06246-7 - Biorefinery concept applied to biological wastewater treatment plants: environmental pollution control coupled with material and energy recovery
• Grantee: Marcelo Zaiat
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 22/10615-1 - Consolidation of the biorefinery concept applied to the biological treatment of wastewater and solid wastes
• Grantee: Marcelo Zaiat
• Support Opportunities: Research Projects - Thematic Grants