Impact of Coffee Grounds Addition on the Calorific Value of the Selected Biological Materials

The objective of the paper was, inter alia, to determine the impact of coffee grounds on the heat of combustion of their combination with other biological materials. Research on the heat of combustion and calculations of the calorific value were carried out with the use of a KL-12 Mn calorimeter according to the technical specifications and standards PN-81/G–04513 i PN-ISO 1928:2002. Coffee grounds, tea grounds, pine wood and yellow wheat straw were used in the research. The heat of combustion of particular substrates was determined and then their mixtures with coffee grounds in the following proportion were prepared: 75% substrate – 25% coffee grounds, 50% substrate – 50% coffee grounds, 25% substrate – 75% coffee grounds. Calorific value of particular substrates was increasing with the amount of added coffee grounds. Their biggest flow was reported in the mixture of 50%/50% of coffee grounds and wheat straw and the smallest in case of coffee grounds and wood on account of a similar calorific value of both substrates.