Potential to use out-of-date food waste, including animal waste, to produce substrates for biogas plants — a comprehensive system

The problem of food waste is one of the most significant global problems that negatively affects many environmental elements. Out-of-date food products, particularly category III animal waste, contribute to this problem. The thermal treatment of these is different from the waste hierarchy. On the other hand, using agricultural products as substrates for biogas plants can reduce biodiversity in farming areas and is problematic due to seasonal fluctuations. This paper presents the practical possibility and potential of using out-of-date food waste, including category III animal waste, to produce an innovative substrate for biogas plants. Research has demonstrated the feasibility of using sterilization methods and available equipment to make a substrate for biogas plants based on expired category III animal waste and plant material. The study aimed to analyze basic physicochemical parameters, perform microbiological tests, conduct a model analysis in terms of biogas yield, and examine the methane potential of animal and plant substrate samples that had been previously subjected to radiation, UV radiation, and pasteurization processes. The results show that after converting 1 m³ of these substrates into electricity, the following values can be obtained: 80,41 kWh for the thermally sterilised sample, 210,24 kWh for the UV-sterilised sample, and 168,61 kWh for the radiation-sterilised sample, with a cogeneration engine efficiency of 40%. Establishing clusters of food producers and supermarkets would enable the construction of a network of such plants that produce substrates for biogas plants available throughout the year, based on the proposed technological line.