This paper aims to briefly overview gasification technologies of biomass and heterogeneous wastes as a means for syngas production. For this purpose, an overview of the existing technologies, their main advantages, limitations, and costs, as well as commercial plants and projects (lower TRL) operating with these technologies and syngas applications is presented. The type of technology and operating parameters should be selected considering the quality of the syngas as it will dictate its end use. Syngas quality is determined by the combination of feedstock properties, type of technology and process operating conditions, and the scale of operation. For smaller projects with a capacity of up to 10 MWth, fixed-bed technologies have been a recurring choice, while fluidized bed reactors can have an installed capacity above 100 MWth and are, therefore, more suitable for medium- and large-scale projects. Fluidized bed gasification technology supports feedstock flexibility, has scale-up potential, and presents relatively low cost, making it a suitable solution and a frequent choice for heterogeneous waste gasification in medium- or large-scale projects. Commercializing waste gasification technology is already a reality. However, more efforts need to be made so that pilot and demonstration projects can overcome the technological and economic problems and move towards commercialization.

The construction industry is responsible for a large amount of CO₂ emissions and an intensive energy consumption. Cement production is the third largest source of anthropogenic CO₂ emissions and is responsible for about 1.8 Gt of CO₂ emissions into the atmosphere. The use of waste materials to replace a fraction of cement in the mortar makes it more economically and ecologically friendly. In this work, the main objective was to test incorporations of biochar produced at temperatures of 300, 350, and 400 °C, as a partial replacement for cement in the production of mortar. The materials used for the tests were residual lignocellulosic biomass (WBL) and electrical cable insulation waste (WIEC) mixed in a ratio of 1:1. The biochars produced were crushed and sieved after production to reduce the particles. A sample of biochar was used and tested under these conditions and another sample was washed in water and dried before being incorporated; all tests were carried out with a 5% replacement. Waste recovery tests were also carried out without thermochemical treatment. The specimens were studied for compressive strength and water absorption by immersion. All tests were replicated and were analyzed and compared with a control mixture with no incorporation of biochar in the mixture. It was possible to observe that the tests with the incorporation of biochars at 400 °C showed better results, with only a 24% reduction in resistance to compression.

The search for strategies that contribute to circular economy, based on the valorization of by-products of the most diverse industries and processes, is one of the main environmental objectives at present. This study aims to evaluate the possibility of valorizing by-products from the gasification and carbonization of polymeric residues and biomass of natural origin through their application in adsorption processes. The selected residues and carbon by-products resulting from thermochemical conversion by the gasification and carbonization processes, after their physical and chemical characterization, presented improved structural and chemical properties which allow their application in adsorption processes. The characterization of the materials and samples prepared in this work involved a variety of analytical techniques, such as thermogravimetric analysis, polarized attenuated Fourier transform infrared spectroscopy, X-ray fluorescence, ultimate analysis, and nitrogen adsorption at 77 K. It was possible to observe that the material has between 40% and 50% volatile matter, and when carbonized, these values decrease to the range of 5% and 10%. The BET surface area analysis of these chars shows values between 100 and 400 m²g⁻¹. For the chemically activated samples and for the phenol molecule, the samples with the best results are those that were prepared using olive prunings as a precursor. For the physically activated samples and also for phenol adsorption, the samples that showed the most potential were the ones prepared via air activation. Regarding the gasified samples, the best results were achieved with the samples without the incorporation of waste-derived fuel.

Waste insulation electrical cables (WIEC) currently do not have an added value, due to their physical–chemical characteristics. Carbonization is known to enhance feedstock properties, particularly fuel and material properties; as such, this article aimed to study the production and activation of biochars using WIEC and lignocellulosic biomass wastes as feedstock. Biochars were produced in a ceramic kiln with an average capacity of 15 kg at different temperatures, namely 300, 350 and 400 °C. After production, the biochars were further submitted to a washing process with water heated to 95 °C ± 5 °C and to an activation process with 2 N KOH. All biochars (after production, washing and activation) were characterized regarding an elemental analysis, thermogravimetric analysis, heating value, chlorine removal, ash content, apparent density and surface area. The main results showed that the increase in carbonization temperature from 300 to 400 °C caused the produced biochars to present a lower amount of oxygen and volatile matter, increased heating value, greater chlorine removal and increased ash content. Furthermore, the activation process increased the surface area of biochars as the production temperature increased. Overall, the carbonization of WIEC mixed with lignocellulosic wastes showed potential in enhancing these waste physical and chemical properties, with prospects to yield added-value products that activates biochar.

Rural areas can benefit from the development of biorefineries for the valorization of endogenous feedstocks. In this study, a pre-feasibility assessment of an integrated multi-product biorefinery to produce essential oils and biomethane is carried out considering current technical and economic conditions. The proposed concept is based on the steam distillation of forestry biomass for the extraction of essential oils (2900 L/y) followed by biomethane production via syngas methanation using the spent biomass as feedstock (30.4 kg/h). In parallel, the anaerobic treatment of WWTP sludge (5.3 kg/h) is used to produce additional biomethane for mobile applications. The results show that the intended multi-product biorefinery delivers attractive benefits for investors as described by the calculated financial indicators: NPV of EUR 4342.6, IRR of 18.1%, and PB of 6 years. Overall, the pre-feasibility analysis performed in this study demonstrates that the proposed biorefinery concept is promising and warrants further investment consideration via cost and benefit analysis, ultimately promoting the implementation of multi-product biorefineries across Europe.