WASTE-TO-ENERGY: BIOGAS EFFICIENCY OF WASTE FROM THE COFFEE PRODUCTION AND CONSUMPTION

The generation of waste is an indispensable process related to the production and consumption of coffee. One of the wastes associated with the production of coffee is the husk, which separates from the beans when it is roasted. Another waste related to the consumption of coffee are spent coffee grounds generated during the coffee brewing process. The study aimed to determine the possibility of using waste generated during coffee production and consumption in the anaerobic digestion process. The tested parameters were i.a., biogas efficiency, methane efficiency, and methane conctent in biogas. The experiment was carried out under anaerobic digestion conditions at the Laboratory in the Department of Biosystems Engineering. The biogas and methane efficiency were tested using German norm DIN 38414/S8. The total solids content of the coffee husk was 93.37%, with the organic matter content at the level of 93.34%. The biogas efficiency in terms of fresh matter was 329.50 m(3).Mg-1. The total solids content of all three analyzed grounds samples ranged from 41.27% to 45.72%. The high content of volatile solids, in the range of 97.91-98.41%, confirmed the biogas potential. In all three samples of coffee grounds, biogas efficiency in the range of 225.45-270.97 m(3).Mg-1. The obtained results allow to conclude that analyzed coffee production and consumption waste have a high potential for biogas production.