Thermal desorption is widely used for remediation of soil contaminated with volatiles, such as solvents and distillates. In this study, a soil contaminated with semivolatile polychlorinated biphenyls (PCBs) was sampled at an interim storage point for waste PCB transformers and heated to temperatures from 300 to 600 °C in a flow of nitrogen to investigate the effect of temperature and particle size on thermal desorption. Two size fractions were tested: coarse soil of 420-841 μm and fine soil with particles <250 μm. A PCB removal efficiency of 98.0 % was attained after 1 h of thermal treatment at 600 °C. The residual amount of PCBs in this soil decreased with rising thermal treatment temperature while the amount transferred to the gas phase increased up to 550 °C; at 600 °C, destruction of PCBs became more obvious. At low temperature, the thermally treated soil still had a similar PCB homologue distribution as raw soil, indicating thermal desorption as a main mechanism in removal. Dechlorination and decomposition increasingly occurred at high temperature, since shifts in average chlorination level were observed, from 3.34 in the raw soil to 2.75 in soil treated at 600 °C. Fine soil particles showed higher removal efficiency and destruction efficiency than coarse particles, suggesting that desorption from coarse particles is influenced by mass transfer.

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Waste can be converted into energy and value-added products by thermochemical processes. Pyrolysis represents the thermal degradation of the material under a non-oxidant atmosphere leading to generation of three products: charsolid, oil-liquid and pyrolysis gas. Pyrolysis process means a complex mechanism of reactions, endothermic and/or exothermic chemical reactions that occurs simultaneously and/or subsequently. The use of lignocellulosic and plastic waste for energy purposes leads to the production of solids that could replace much of the conventional fuels once energy conversion technologies will prove profitable. In this chapter the authors proposed to describe, analyze and apply analytical methods for the heating value estimation of the solid products generated by pyrolysis of different wood and plastic materials. Our results obtained by experimental studies and empirical formulas will be evaluated and compared. The impact of the thermochemical process operational conditions on the variation of chars and biochars heating value will be also discussed in this chapter.

The present research proposes two scenarios for the biomass conversion into valuable products within the integrated management of bio-resources. The scenarios have been developed considering: the biomass availability, material and by-products characteristics and the comprehensive combination of the primary technologies used for the conversion of the biomass mixtures into energy. In scenario 1 the biomass waste valorisation is made via integrated pyrolysis and combustion treatment, while in scenario 2 the biomass conversion in done considering the integration of the pyrolysis, gasification and combustion treatments into the conversion chain. The results revealed that all analysed scenarios purposed are self-independent from the energetic point of view.

The study, presented in two parts, puts in discussion the experimental results of low and high temperature pyrolysis on agricultural residues using a tubular batch reactor. During the experiment, nitrogen was used both as reaction environment and gas products carrier. The work focusses mainly on the pyrolysis gas analytical composition resulted from the process. The first part of the research is dedicated to the effect of process low temperature on rape straw pyrolysis. The experiments were conducted at 300°C, 400°C and 500°C to observe the solid – gas transformation at relative low temperatures. The main results revealed that, by balancing the amount of the nitrogen, the rape straw pyrolysis gas distribution varies by average between: 72%-77% CO2, 22%-24% CO, 1%-4% H2. The density of the gas in the devolatilization stage varies by average between 1.6-1.7 kg/m3, while its higher heating value ranges from 4 MJ/Nm3 - 8 MJ/Nm3.

The results presented in the following paper are making the aim of a broadly research concentrated to investigate the temperature effects on agricultural waste pyrolysis performed in a batch reactor. Briefly, the motivation along with experimental features and main results generated from the rape straw low temperature pyrolysis (300°C-500°C) have been offered in the first part submitted at the MSE 2019 conference, with the title: Bio-gaseous fuels from agricultural waste pyrolysis (Part I). The current section (second part of the study) presents the results obtained in case of the rape straw high temperature pyrolysis (600°C-800°C). Overall, as expected, the augmentation of the operating temperature, inhibits the bio-oil and biochar formation, enhancing the pyrolysis gas production. The distribution of gaseous components varies depending on temperature and residence time. The transition stages and the formation of the main pyrolysis gaseous species are also presented and discussed. The most dominant chemical element from the pyrolysis gas is N2, due to its constant presence as non-oxidant agent in the process. Considering the same premise, the rape straw pyrolysis gaseous species distribution in the temperature range of 600°C-800°C varies between: 47%-58% CO2, 18%-28% CO, 14%-35% H2, while the pyrolysis gas density 1.1-1.4 kg/m3 and higher heating value 23-52 MJ/kg.

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