Biogas production from waste food as an element of circular bioeconomy in the context of water protection

Production of food use huge amounts of water. The loss of food leads to the waste of resources such as land, water and energy. Water protection and management of waste food are elements of a circular economy. Numerous studies have shown utilization of food for biogas production. However, much less attention is paid to use different source of waste food and biochar in anaerobic digestion. Utilization of waste food for production of energy career is the answer on societal, economy and environmental needs and helps to protect water. The aim of the research was to assess the possibility of using wasted cheese, spend coffee ground, dessert and rice and biochar for the production of biogas. The tests were carried out in glass reactors. The yield of biogas production was dependent on the chemical composition of a substrate used. Due to the high protein content in cheese, the high amount of biogas was produced (76.00%). Cheese with biochar achieved the highest yield of biogas production. Substrates that contained high amounts of sugar, such as rice and dessert, showed a lower biogas yield. Biochar that was added to the cheese induces an increase on the biogas production of 0.153 Nm3/kg·SV, and an increase of methane production of 0.135 Nm3/kg·SV.