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The application of municipal sewage sludge on energy crops is an alternative form of recycling nutrients, food materials, and organic matter from waste. Municipal sewage sludge constitutes a potential source of heavy metals in soil, which can be partially removed by the cultivation of energy crops. The aim of the research was to assess the effect of municipal sewage sludge on the uptake of heavy metals by monocotyledonous energy crops. Sewage sludge was applied at doses of 0, 10, 20, 40, and 60 Mg DM · ha(-1) once, before the sowing of plants. In a 6-year field experiment, the effect of four levels of fertilisation with sewage sludge on the uptake of heavy metals by two species of energy crops, reed canary grass (Phalaris arundinacea L.) of 'Bamse' cultivar and giant miscanthus (Miscanthus × giganteus GREEF et DEU), was analysed. It was established that the increasing doses of sewage sludge had a considerable effect on the increase in biomass yield from the tested plants. Due to the increasing doses of sewage sludge, a significant increase in heavy metals content in the energy crops was recorded. The heavy metal uptake with the miscanthus yield was the highest at a dose of 20 Mg DM · ha(-1), and at a dose of 40 Mg DM · ha(-1) in the case of reed canary grass. Research results indicate that on account of higher yields, higher bioaccumulation, and higher heavy metal uptake, miscanthus can be selected for the remediation of sewage sludge.

The need for organic recycling is justified in the case of poultry waste because after ensuring hygienization there is a chance of obtaining a compost with substantial fertilizer value. Organic recycling of slaughter waste has its justification in sustainable development and retardation of resources. In the research being described, composting of hydrated poultry slaughterhouse waste with maize straw was carried out. Combinations with fodder yeast and postcellulose lime were also introduced in order to modify chemical and physicochemical properties of the mixtures. The experiment was carried out within 110 days in 1.2 × 1.0 × 0.8 m laboratory reactors. Temperature of the biomass was recorded during composting, and the biomass was actively aerated through a perforated bottom.Composting of substrates selected in such a way caused losses of some elements in gaseous form, an increase in concentration of other elements, and changes in relationships between elements. The ability to select substrates influences compost quality. This ability is determined by chemical indicators. Among other things, compost evaluation based on carbon to nitrogen ratio shows the intensity of the composting process and possible nitrogen losses. The addition of slaughter waste to maize straw reduced the content of individual fractions of carbon in the composts, whereas the addition of postcellulose lime intensified that process. The addition of fodder yeast significantly increased the phosphorus content in the compost. Since iron compounds were used in the processing of poultry carcasses, composts that were based on this material had an elevated iron content. The applied postcellulose lime significantly increased the copper, zinc, chromium, nickel, and lead contents. Proper selection of substrates for composting of hydrated poultry slaughterhouse waste allows to obtain a compost with chemical properties that create favorable conditions for natural application of that compost. Addition of large quantities of postcellulose lime to the composting process leads to obtaining an organic-mineral substratum for cultivation or to obtaining an agent that improves soil properties.