The progressing degradation of the natural environment taking place over the last few decades and resulting from the systematically growing production of synthetic polymer materials led to the search for technological innovations aimed at producing environmentally friendly materials. Moreover, the increasing importance of sustainability promotes the development of bio-based and biodegradable polymers, sometimes misleadingly referred to as "bioplastics". Inability to degrade synthetic polymer materials and the problem of their persistence in the environment even for hundreds of years have caused the production of polymer materials with the addition of components that may accelerate their degradation more and more important in recent years. Additionally, the growing interest in environmental issues makes the requirements for new materials that will not significantly burden the environment higher. In Poland 29.1% and 26.8% of post-consumer polymer materials, respectively, were recovered and recycled, which means that up to 44.1% of post-consumer polymer materials were sent to municipal landfills. In 2017, for the first time in Poland, more plastics were recovered (55.9%) than stored (44.1%). However, by 2020, the level of energy recovery and recycling of post-consumer polymer materials in Poland should cover a total of 84.5%. When looking at the average values for Europe (recycling 31.1%, recovery 41.6%, storage 27.3%), it should be noted that Poland has much to catch up in this area and decisive actions should be taken to actually solve this problem. For this reason, it is extremely important to know the mechanisms responsible for the degradation of polymer materials and understand the interaction between these materials and abiotic and biotic factors that cause structural changes in polymers. Recent studies show that knowledge of the conditions determining the decomposition of polyethylene polymer materials and their impact on the natural environment is still insufficient. The literature reports reveal many contradictory theories, especially those that relate to the degradation of polymer materials in the soil environment. This study constitutes a comprehensive review of researches on (bio)degradation of polymer materials over the last decades, various methods of polymer structure modification to increase the degree of their degradability, as well as methods of recycling post-consumer polymer materials. Because there is a need to assess the performance of polymer innovations in terms of their biodegradability, especially under realistic waste management and environmental conditions, to avoid the unwanted release of plastic degradation products to the environment.
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.
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