The process of composting biological waste is a natural process – in which heat is released. Biological wastes generated in typical households in Poland – are mainly kitchen waste (KW) and green waste from home gardens (GGW – if they are owned). From the ecological point of view – the most advantageous method of their management is their utilization in the place of production. The paper presents a proposal for effective management of bio-waste arising by composting – with the simultaneous use of heat for greenhouse heating in autumn. This is to encourage residents to independently compost bio-waste – and increase the level of recycling of waste generated in Poland by 2020. Calculations for greenhouses were made – in accordance with the energy audit methodology. The obtained thermal balance results were compared with the actual temperature prevailing in the greenhouse in autumn. These calculations were the basis for calculating the amount of KW and GGW enabling effective heating of greenhouses in the autumn so that the internal temperature does not drop below 10ºC. It has been calculated that 22 kg of composted bio-waste (KW and GGW) will suffice to heat the greenhouse in October with an area of 18 m2.
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.