BIOGEOCHEMICAL AND MECHANICAL CHARACTERIZATION OF THE LANDFILL FRACTION GENERATED BY MECHANICAL WASTE SORTING

As the resource recovery from mixed waste streams are performed, new mixed waste streams are generated. Some of these waste streams does not fit well to existing waste management options, for example, they may hold a to low heating value to sustain combustion and they may have a too high carbon content to be accepted at non-hazardous landfills. Also various health and pollution risks may arise as well as practical handling issues due to the physical properties of such wastes. One such waste is the under sieve fraction generated when recovering metals and fuel from mixed waste streams using mechanical and magnetic separation tools. Such mechanical sorting is typically used for mixed wastes of different properties and particle sizes, such as houshold bulky wastes, construction and demolition waste, and at landfill mining materials. In this work, we examine the properties of one case of mechanical sorting of bulky wastes, including construction and demolition wastes. We analyse a broad spectrum of chemical, physical, and mechanical properties as well as some biological. Based on the data we develop recommendations for landfilling, what potential problems might arise and how to counteract them.

Leaching of Chlorides, Sulphates, and Phosphates from Ashes Formed as a Result of Burning Conventional Fuels, Alternative Fuels, and Municipal Waste in Household Furnaces

The aim of the study was to assess leaching of Cl−, SO42−, and PO43− from ashes formed in household furnaces. The ashes were obtained following the combustion of conventional fuels, namely wood and hard coal, and alternative fuels with various fractions of municipal waste in a household boiler. Aqueous leachates of the ashes were used to determine concentrations of chlorides by titration (Mohr’s method) (21.3–3049.6 mg/dm3), sulphates by the gravimetric method (12.2–244.1 mg/dm3), and phosphates by spectrophotometry (0.01–67.2 mg/dm3). It was found that co-combustion of municipal waste with plastic-coated paper cartons, diapers, or a mixed waste fraction leaves the greatest amount of ashes on the furnace grate. The highest amounts of Cl−, SO42−, and PO43− were leached from ashes generated from burning a mix of wood and coals, or wood alone (different species). The addition of municipal waste to the process of burning the conventional and alternative fuels studied did not significantly increase Cl−, SO42−, and PO43− content in aqueous extracts of ashes, the exception being diapers and plywood. In light of the study results, it was concluded that all the ashes could be reused (as an additive to concrete) except for the ash generated from the combustion of a mixed municipal waste fraction and coal (due to the content of Cl−) and diapers (due to the content of PO43−). It was demonstrated that Cl−, SO42−, and PO43− content in the entire set of samples and in individual ash groups is highly heterogeneous and variable.

Migration of Sulfur and Nitrogen in the Pyrolysis Products of Waste and Contaminated Plastics

The most advantageous way of managing plastics, according to circular economy assumptions, is recycling, i.e., reusing them. There are three types of plastics recycling: mechanical, chemical and energy recycling. The products of the pyrolysis process can be used for both chemical and energy recycling. Possibilities of further use of pyrolysis products depend on their physicochemical parameters. Getting to know these parameters was the aim of the research, some of which are presented in this article. The paper presents the research position for conducting the pyrolysis process and discusses the results of research on pyrolysis products of waste plastics. The process was conducted to obtain the temperature of 425 °C in the pyrolytic chamber. Such a value was chosen on the basis of my own previous research and literature analysis. The focus was on the migration of sulfur and nitrogen, as in some processes these substances may pose a certain problem. Studies have shown high possibilities of migration of these elements in products of pyrolysis process. It has been shown that the migration of sulfur is similar in the case of homogeneous and mixed waste plastics—it immobilizes mainly in pyrolytic oil. Different results were obtained for nitrogen. For homogeneous plastics, nitrogen immobilizes mainly in char and oil, whereas for mixed plastics, nitrogen immobilizes in pyrolytic gas.

Utilization of Waste Paper to Manufacture of Hydrogels

Huge volumes of mixed waste paper (MWP) pollute the environment. Nevertheless, it is an abundant, renewable and inexpensive material, so finding a new way of utilization it is very important. In this article, MWP has been used as initial material for the production of hydrogels. It was found that when MWP is treated with a cold solvent, namely with an aqueous solution of 7%NaOH/12%Urea (N/U), at solvent to initial paper ratio R ≥ 5, complete amorphization of the cellulose component of the paper occurs, as a result of which a hydrogel is formed. In addition, if the alkali of the solvent is neutralized with phosphoric acid, then the resulting hydrogel will contain PN-fertilizer and can be applied in agriculture. Studies have shown that this hydrogel promotes seed germination, increases the water retention of the soil, and then completely decomposes in a short time under the action of enzymes secreted by microorganisms present in the soil.