Energetic use of biogas from the anaerobic digestion of coffee wastewater in southern Minas Gerais, Brazil

This study analyzed biogas production from the anaerobic digestion of Coffee Wastewater (CWW), in Brazil. Physicochemical analyzes of CWW were performed before and after biodigestion. Four bio-digesters B1, B2, B3, B4 maintained at 37 degrees C +/- 2 degrees C were connected to a gasometer. 1.35 L of CWW and 0.15 L of inoculum (sludge from an Upflow Anaerobic Sludge Blanket) were fed into biodigesters B3 and B4, resulting in a total substrate level of 1.5 L for each one. Biodigesters B1 and B2 were fed 1.5 L of CWW that was pH adjusted to 6-8 in all four biodigesters at the start of the biodigestion. Theoretical estimations were given for the biomethane potential (BMP) arising from the chemical oxygen demand (COD). Given the BMP values, economic feasibility analysis was performed for a biogas system implemented in a coffee roasting production system under three scenarios: I-BMP for CWW COD without inoculum; II-BMP for CWW COD with inoculum; and III-BMP for the minimum required level of CWW COD needed for the system to be economically viable. The highest methane content observed was 11.4% in B4, which had the highest relative methane production to removed volatile solids (17.31 LkgVS(rem)(-1)). (C) 2019 Elsevier Ltd. All rights reserved.