The aim of this study was to determine selected energy parameters, leachability of heavy metals and phytotoxicity of biomass ash for different types of plant biomass (wheat straw, miscanthus straw, bark and sawdust) and poultry manure, as well as biochars produced from them. Based on data from proximate and ultimate analysis of the investigated materials, fuel value index (FVI) was calculated to determine their suitability for energy production. The ashes were analyzed for both chemical composition and leaching behavior. The phytotoxicity test of aqueous ash extracts was performed for Lepidium sativum L. It was found that the calorific value of biochars was higher on average by 36% than the value determined for feedstocks used in the pyrolysis process. The pyrolysis of organic materials resulted in the reduction of the volatile matter content. The gross calorific value was determined in biochars formed from miscanthus straw and sawdust which were 26.6 and 23.4 MJ kg⁻¹, respectively. Leachability of heavy metals of biomass ash was highly diverse and depended on the analyzed element and the material type. The phytotoxicity analysis showed that, in general, each of the ash extracts tested had a positive effect on the growth of Lepidium sativum L. compared to the control. The use of ash, fertilizer, or sorbents can be an interesting alternative for materials with high ash content. In all these cases, biochars seem to be very attractive materials that can be used not only in energy production. Given the high carbon content of biochar obtained in the pyrolysis process, it has a high-energy potential and can be used as a biofuel.

Knowledge on the fraction of trace elements in the bottom sediments is a key to understand their mobility and ecotoxicological impact. The purpose of this study was to assess the influence of the content of organic matter fractions on the mobility and ecotoxicity of trace elements in sediments from the Rybnik reservoir. The most refractory fraction of organic matter—Cnh (non-hydrolysing carbon)—dominated in the sediments. The content of organic matter fractions are arranged in the following order: Cnh (non-hydrolysing carbon) > Cfa (fulvic acid) > Cha (humic acid) > DOC (dissolved organic carbon). On the other hand, the highest value of correlation coefficients was found for different fractions of trace elements and DOC content in the bottom sediments. A higher content of TOC in the sediments significantly increased the share of elements in the potential mobile fraction and, at the same time, decreased the binding of elements in the mobile fractions. Moreover, in sediments that contain more than 100 g/kg d.m. TOC, no and medium risk of trace element release from sediments was observed. The Cu, Cd and Ni were potentially the most toxic elements for biota in the Rybnik reservoir. However, the correlation between the content of trace elements and the response of bacteria was insignificant. These results suggested that the complexation of trace elements with organic matter makes them less toxic for Vibrio fischeri. The transformation and sources of organic matter play an important role in the behaviour of trace elements in the bottom sediments of the Rybnik reservoir.

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.