The adverse effects of atmospheric particulate matter (PM) on health and ecosystems, as well as on meteorology and climate change, are well known to the scientific community. It is therefore undeniable that a good understanding of the sources of PM is crucial for effective control of emissions and to protect public health. One of the major contributions to atmospheric PM is biomass burning, a practice used both in agriculture and home heating, which can be traced and identified by analyzing sugars emitted from the combustion of cellulose and hemicellulose that make up biomass. In this review comparing almost 200 selected articles, we highlight the most recent studies that broaden such category of tracers, covering research publications on residential wood combustions, open-fire or combustion chamber burnings and ambient PM in different regions of Asia, America and Europe. The purpose of the present work is to collect data in the literature that indicate a direct correspondence between biomass burning and saccharides emitted into the atmosphere with regard to distinguishing common sugars attributed to biomass burning from those that have co-causes of issue. In this paper, we provide a list of 24 compounds, including those most commonly recognized as biomass burning tracers (i.e., levoglucosan, mannosan and galactosan), from which it emerges that monosaccharide anhydrides, sugar alcohols and primary sugars have been widely reported as organic tracers for biomass combustion, although it has also been shown that emissions of these compounds depend not only on combustion characteristics and equipment but also on fuel type, combustion quality and weather conditions. Although it appears that it is currently not possible to define a single compound as a universal indicator of biomass combustion, this review provides a valuable tool for the collection of information in the literature and identifies analytes that can lead to the determination of patterns for the distribution between PM generated by biomass combustion.

The combustion of biomass is a process that is increasingly used for the generation of heat and energy through different types of wood and agricultural waste. The emissions generated by the combustion of biomass include different kinds of macro- and micropollutants whose formation and concentration varies according to the physical and chemical characteristics of the biomass, the combustion conditions, the plants, and the operational parameters of the process. The aim of this work is to evaluate the effect of biomass moisture content on the formation of volatile organic compounds (VOCs) during the combustion process. Wet and dry poplar chips, with a moisture content of 43.30% and 15.00%, respectively, were used in a cogeneration plant based on a mobile grate furnace. Stack’s emissions were sampled through adsorbent tubes and subsequently analyzed by thermal desorption coupled with the GC/MS. The data obtained showed that, depending on the moisture content of the starting matrix, which inevitably influences the quality of combustion, there is significant variation in the production of VOCs.

Agro-industrial activities generate a great amount of bioproducts as biomass residues containing energy and with potentially useful applications in the thermochemical conversion process. The management of this feedstock as uncontrolled combustion (“open burning”) can often be a problem within the supply chain for disposal practices, both in environmental and economic aspects. The residual matrices from agroforestry biomass processing can be treated to increase their energy levels and economic value. A widespread practice for sustainable disposal is the production of pellets from residual biomass, such as pruning. The aim of this study is to explore the combustion of pellets obtained from olive and citrus pruning, and their emissions into the atmosphere. This study confirms the possibility of using waste biomass to obtain a high-energy biofuel that is usable in a controlled combustion system and to monitor the process and its related emissions (CO, CO₂, NO_x, SO₂, PM). Three different pellets (olive pellet, citrus pellet and a pellet obtained from a mix of olive and citrus) were characterized to determine their physicochemical properties and burned in an 80 kW_th boiler equipped with multicyclone filter bags as an abatement system to evaluate relative emission. The characterization results show that citrus pellet has a higher ash content, moisture content and lower energy value than mixtures of olive pellet. The emission results suggest that, during combustion, higher emissions of CO and SO₂ were monitored from mixtures of citrus pellet compared to burning only olive pellet.

Today, in Europe, there is still no industrial process to favor the distribution of exhausted extinguishing powders (EEP). Extinguishing powders (EP) are the most common extinguishing agents and are composed of very fine particles (90% is less than 0.250 mm, with at least 40% less than 0.040 mm). Illegal processes of disposal or reuse of EEP are currently taking place throughout Europe. In fact, often maintenance companies illegally dispose of and/or reuse spent extinguishing powders with enormous environmental damage. This is partly due to prohibitive costs, of which a large part is due to transport. The demand for fertilizers is increasing; phosphorus is a key raw material, and a possible solution could be mixing it with compost and other organic biomass and agricultural residues. In general, both compost and EEP powder have a low density and can take up a great deal of storage volume, so thickening this compost would help reduce the required storage capacity. Furthermore, a danger represented by the handling of compost and EEP is the dispersion of dust that can potentially carry pathogens and toxic organic substances which, if inhaled, could cause respiratory problems during distribution and handling. The aim of this study was to produce compost pellets using exhausted EP in different formulations and to observe the quality of different compost pellet products with respect to different factors affecting handling, storage, and distribution. For the first time, the pelletizing of EEP with compost was performed successfully using five different blends, each with different properties. The results showed that qualitative variables could be controlled to optimize production efficiency and improve the quality of the finished product depending on the type of distribution, handling, and storage. The five compost mixes could be applied in different agricultural crops as fertilizer. Furthermore, this use of exhausted EP allows for positive ecological and economic effects, avoiding the disposal costs required by specialized companies.

The relevance of selecting an appropriate bed material in fluidized bed gasification is a crucial aspect that is often underestimated. The ideal material should be economical, resistant to high temperatures and have small chemical interaction with biomass. However, often only the first of such three aspects is considered, neglecting the biomass–bed interaction effects that develop at high temperatures. In this work, olivine and K-feldspar were upscale-tested in a prototype fluidized bed gasifier (FBG) using arboreal biomass (almond shells). The produced syngas in the two different tests was characterized and compared in terms of composition (H₂, CH₄, CO, CO₂, O₂) and fate of contaminants such as volatile organic compounds (VOCs), tar and metals.. Moreover, the composition of olivine and K-feldspar before and after the biomass gasification process has been characterized. The aim of this work is to show which advantages and disadvantages there are in choosing the most suitable material and to optimize the biomass gasification process by reducing the undesirable effects, such as heavy metal production, bed agglomeration and tar production, which are harmful when syngas is used in internal combustion engines (ICE). It has been observed that metals, such as Ni, Cu, Zn, Cd, Sn, Ba and Pb, have higher concentrations in the syngas produced by using olivine as bed material rather than K-feldspar. In particular, heavy metals, such as Pb, Cu, Cd, Ni and Zn, show concentrations of 61.06 mg/Nm³, 15.29 mg/Nm³, 17.97 mg/Nm³, 37.29 mg/Nm³ and 116.39 mg/Nm³, respectively, compared to 23.26 mg/Nm³, 11.82 mg/Nm³, 2.76 mg/Nm³, 24.46 mg/Nm³ and 53.07 mg/Nm³ detected with K-feldspar. Moreover, a more hydrogen-rich syngas when using K-feldspar was produced (46% compared to 39% with olivine).

Agricultural activities lead to the production of large quantities of pruning and residual biomass, the correct disposal of which is a topic of great interest. Unfortunately, although it is an environmentally unacceptable practice, disposal often takes place with uncontrolled combustion in field (open burning). Disposal using biomass boilers produces energy from controlled combustion and the use of abatement systems reduces emissions that are inevitably generated in the combustion processes of solid fuel (CO, CO₂, NOx, SO₂, PM, etc.). Among the pollutants produced in combustion processes, Persistent Organic Pollutants (POPs) are one of the most relevant groups of chemicals that must be monitored for their effect on human health and the environment. This paper reports the data obtained for the emissive characterization of POPs of three different wood biomass prunings (Olive, Citrus and Grapevine) focusing on VOCs, PAHs, PCBs, PCDD/Fs. Emissions samplings were performed at the stack during combustion in a 30 kW_th boiler equipped with a multicyclone filter bag for PM abatement in an isokinetic mode in accordance with the CEN and ISO standards methods. Through this work, a complete emission profile of VOCs, PAHs, PCBs, and PCDD/Fs of three different biomass types is provided for the first time, showing that the use of biomass boilers produces quantities of pollutants below the regulatory limits and still lower than those produced by open burning phenomena. Citrus has shown, regarding the other two essences, elevated concentrations in terms of Σ PAH = 174.247 ng/m³, while Olive gave higher results in terms of PCBs and PCDD/Fs (respectively, 39.769 and 3390.63 TEQ pg/Nm³). This is probably due to the high concentration of iron in this biomass (711.44 mg/kg), which during combustion is a catalyst (together with copper) of PCDD/Fs.