The aim of this paper was to investigate the possibility of obtaining oil from spent coffee grounds, which are left behind after the coffee is prepared, as the potential feedstock for biodiesel production. The effect of process parameters, such as are the type of solvent, the ratio of spent coffee grounds/solvent and the extraction time on oil yielded from coffee grounds was examined. The oil was obtained by maceration and extraction in the Soxhlet apparatus. The obtain results show that the spent coffee grounds could be used as an alternative raw material for biodiesel production, because it contains a significant amount of oil that can be extracted. The oil yield depends on the extraction (maceration) process parameters. The maximum oil yield obtained by the Soxhlet extraction with the n-hexane for the period of 5 h was 11.85% (the weight percentage of oil on dry mater), whereas with petroleum ether the oil yield was slightly lower and amounted to 10.44%. The yield of the oil extracted by maceration increases with the decrease of spent coffee grounds/solvent ratio from 1/3 to 1/7 g/cm3, and other parameters being constant. The oil yield increases with the duration of the maceration. Greater oil yield, ranging from 3 to 8.5%, can be obtained with n-hexane compared to the extraction with petroleum ether. Furthermore, n-hexane is less volatile and flammable, compared to petroleum ether, so it is more convenient to use.

Th e poultry farming waste, as a mixture of dropping and bedding material, is usually used as a fertilizer in agriculture because of their richness of mineral materials. However, expanded production of broilers, with decreased availability of agricultural land and potential negative eff ects of long-lasting application of such a material on land, encourage searching for alternative ways for use of this materials. Generally speaking, there are two ways, beside of abovementioned: (1) exploitation of poultry waste in compost production and (2) its use for energy production. Th is paper exposes the overview of state-of-the-art (techniques and equipment) within the fi eld of energetic valorization of poultry waste by direct thermal methods, and discusses various aspects of mentioned practices.

: Great potential in gas production is found in raw materials of organic origin, such as manure, waste sludge, food residues and the like. In order to speed up the process of biogas production, that is, the first stage of hydrolysis, it is necessary to pre-process the substrate. In order to obtain the maximum amount of biogas, the anaerobic digestion process was carried out in mesophilic conditions for 37 days. For the purpose of examining the effects of pretreatment, the substrate was chemically treated with the addition of dehydrated CaO in quantities of 0.75% and 1.5% in relation to the mass of the substrate. The results showed that by treating cattle manure with the addition of 0.75% CaO, higher daily production of biogas with a higher methane content is achieved. The total amount of biogas obtained with the addition of 0.75% CaO was 5247.21 ml, while the highest methane content was 61.24%.