Major efforts are currently being made in the research community to address the challenges of greenhouse gas emissions from fossil fuel combustion by using lignocellulosic biomass, agricultural waste, and forest residues as cleaner energy sources. However, its poor qualities, such as low energy density, high moisture content, irregular shape and size, and heterogeneity, make it impossible to utilize in its natural state. Torrefaction, a simple heat treatment method, is used frequently with natural bioresources to improve their thermal characteristics so that they may be used as energy sources in domestic power plants. The quality of the resulting torrefied solids (biochar) is determined by the heat condition settings in the absence of oxygen, and it may be enhanced by carefully selecting and altering the processing parameters. The comprehensive overview presented here should serve as a useful toolkit for farmers, combined heat and power plants, pulp and paper installations, and other industrial plants that use biomass as a substrate for biofuel production. This research focuses on torrefaction product properties, reaction mechanisms, a variety of technologies, and torrefaction reactors. It is impossible to determine which torrefaction technology is superior as each reactor has unique properties. However, some suggestions and recommendations regarding the use of torrefaction reactors are given.

The degradation of bio-based plastic materials in field soil under natural conditions was investigated in this study. Three bio-based plastics materials, which contained polylactide (PLA) with polybutylene adipate terephthalate and additives (PLA_1), PLA-based polyester blend with mineral filler (PLA_2), and polybutylene succinate with mineral filler (PBS_1) in the form of the film, were subjected to soil burial biodegradation processes. The experiments were carried out in a climate with an average annual temperature of 9.4 °C, in winter and summer periods for one year. The degradation of the materials was evaluated by macro- and microscopic observations, weight loss, thermogravimetric analysis, and tensile test. Macroscopic observation indicated that changes in the color of film surface were visible for samples PBS_1 after 12 months of degradation. Using microscopic inspection the erosion of surface samples PLA_1 and PBS_1 after 12 months was observed. Mass loss of samples PLA_1 and PLA_2 after one year of degradation were below 0.6 %. Moreover, for PBS_1 sample, mass loss was equal to 4.3 %. Based on the obtained results of the mass loss, a description of the degradation kinetics was proposed, showing the changes in the thickness of the tested polymer over time. The thermal stability of the samples PLA_1 and PLA_2 decreased during the degradation process by 16.1 and 2.6 °C, respectively, and for PBS_1 increased by 1.7 °C. Tensile strength at break after 12 months of degradation decreased for sample PLA_1 and PLA_2 by 27.3 and 5.8 %, respectively, and increased for sample PBS_1 by 28.2 % compare to unexposed sample.

The depletion of fossil fuels has led to a search for new methods of fuel and chemical production from biomass. One of the methods of converting biomass into valuable products is the process of pyrolysis. This process has been extensively researched in recent years due to the rising prices of energy and chemicals. This work contains basic information on the pyrolysis process concerning the individual components present in the biomass and the types of biomass used in the pyrolysis process. Particular attention was paid to sewage sludge, the management of which is a big challenge. The influence of the most important process parameters (temperature, heating rate, residence time of the solid and vapor, reaction atmosphere) on the pyrolysis products (char, oil, and gas) was presented. The paper presents an overview of the reactors used in the pyrolysis process, from slow to fast pyrolysis, together with their efficiency, advantages, and disadvantages. The analysis of the application of other thermochemical processes for producing the energy used in the process of pyrolysis and in the drying of the biomass was carried out. Two industrial-scale installations for the pyrolysis of sewage sludge were presented.