Comparison of organic compounds in char and soot from the combustion of biomass in boilers of various emission classes

A case study on microlitter and chemical contaminants: Assessing biological effects in the southern coast of the Gulf of Finland (Baltic sea) using the mussel Mytilus trossulus as a bioindicator

Chemical and microlitter (ML) pollution in three Estonian coastal areas (Baltic Sea) was investigated using mussels (Mytilus trossulus). Polycyclic aromatic hydrocarbons (PAH) in mussel tissues were observed in moderate levels with high bioaccumulation factors for the more hydrophilic and low molecular weight PAH (LMW PAH), namely anthracene and fluorene. Tissue concentrations of polybrominated diphenyl ethers (PBDE) and cadmium within mussel populations exceeded the Good Environmental Status thresholds by more than 200% and 60%, respectively. Multiple contamination at the Muuga Harbour site by tributyltin, high molecular weight PAH, including the highly toxic benzo[c]fluorene and PBDE, coincided with the inhibition of acetylcholinesterase activity and a lower condition index of the mussels. The metabolization and removal of bioaccumulated LMW PAH, reflected in the dominance of oxy-PAH such as anthracene-9,10-dione, is likely associated with the increased activity of glutathione S-transferase in caged mussels. Only a few microplastic particles were observed among the ML in mussel tissues, with coloured cellulose-based microfibers being the most prevalent. The average concentration of ML in mussels was significantly higher at the harbour area than at other sites. The integrated biomarker response index values allowed for the differentiation of pollution levels across studied locations representing high, intermediate, and low pollution levels within the studied area.

Exploratory study on noninvasive biomarker of silicosis in exhaled breath by solid-phase microextraction-gas chromatography-mass spectrometry analysis

BACKGROUND

As a chronic occupational disease, silicosis could cause irreversible and incurable impair to the lung. The current diagnosis of silicosis relies on imaging of X-ray or CT, but these methods cannot detect lung lesions in the early stage of silicosis.

OBJECTIVE

To establish a regular screening and early diagnosis methods for silicosis, which could be helpful for the prevention and treatment of silicosis.

METHODS

A total of 161 subjects were enrolled in the study, including 69 patients with silicosis (SILs) and 92 healthy controls. The exhaled breath samples of the subjects were collected with breath sampler and Tedlar bag. The analysis of volatile organic compounds (VOCs) in exhaled breath was performed by solid-phase microextraction (SPME) combined with gas chromatography mass spectrometry (GC-MS).

RESULTS

After excluding the pollutants from sampling bags and instruments, 86 VOCs have been identified in the exhaled breath. The orthogonal partial least squares-discriminant analysis (OPLS-DA) was employed for the screening of potential biomarkers of silicosis. Those components that related to smoking were also excluded from the biomarkers. Finally, nine possible biomarkers for silicosis were screened out, including 2,3-butanedione, ethyl acetate, chlorobenzene, o-cymene, 4-ethylhex-2-ynal, 3,5-dimethyl-3-heptanol, hydroquinone, phthalic anhydride and 5-(2-methylpropyl)nonane. Based on these biomarkers screened, a predicted model for silicosis was generated with the accuracy of 89.61%.

CONCLUSION

The nine biomarkers in exhaled breath were preliminarily screened out for the early diagnosis of silicosis, which can be helpful to the establishment of a noninvasive screening method for silicosis. Follow-up studies should be conducted to further verify these markers.

The use of polymer compounds in the deposits from the combustion of briquettes in domestic heating as an identifier of fuel quality

The utilisation of waste wood from furniture production brings new problems connected with an incomplete thermochemical decomposition of additives (chemicals for improving properties of plastics) in small heating with the addition of sources. Unique organic compounds produced by the combustion of waste wood allow the identification of the type of fuel. The organic compounds contained in the char deposits were analysed by pyrolysis gas chromatography with mass spectrometry. The deposits from the combustion of briquettes from furniture production contain organic compounds originating by decomposition of phenolic resins, aminoplasts (urea-formaldehyde, resorcinol-formaldehyde and melamine), polyurethanes and wood glue. Additives contained in the deposits include plasticisers such as phthalates (DEHP, dibutyl phthalate and diisobutyl phthalate), flame retardants (2-propanol, 1-chlorophosphate (3:1) and p-terphenyl). Deposits from the combustion of briquettes from virgin wood do not contain these compounds. The total amount of compounds identified in the deposits from the boiler, which do not come from virgin wood combustion, varies in the range between 4.25 and 6.25 g/kg. Phthalates (55.5%) and PVAc adhesives (18.6%) are the main anthropogenic compounds in the deposits from domestic boilers.

Characteristics and Influencing Factors of Polycyclic Aromatic Hydrocarbons Emitted from Open Burning and Stove Burning of Biomass: A Brief Review

To mitigate global warming and achieve carbon neutrality, biomass has become a widely used carbon-neutral energy source due to its low cost and easy availability. However, the incomplete combustion of biomass can produce polycyclic aromatic hydrocarbons (PAHs), which are harmful to human health. Moreover, increasing numbers of wildfires in many regions caused by global warming have greatly increased the emissions of PAHs from biomass burning. To effectively mitigate PAH pollution and health risks associated with biomass usage, the concentrations, compositions and influencing factors of PAH emissions from biomass burning are summarized in this review. High PAH emissions from open burning and stove burning are found, and two- to four-ring PAHs account for a higher proportion than five- and six-ring PAHs. Based on the mechanism of biomass burning, biomass with higher volatile matter, cellulose, lignin, potassium salts and moisture produces more PAHs. Moreover, burning biomass in stoves at a high temperature or with an insufficient oxygen supply can increase PAH emissions. Therefore, the formation and emission of PAHs can be reduced by pelletizing, briquetting or carbonizing biomass to increase its density and burning efficiency. This review contributes to a comprehensive understanding of PAH pollution from biomass burning, providing prospective insight for preventing air pollution and health hazards associated with carbon neutrality.

Environmental risks related to organic compounds from the combustion of paper briquettes in domestic boilers

Environmental risks connected with the combustion of paper/cardboard briquettes are still not sufficiently known. This paper aims to bring attention to the risks related to the utilisation of paper briquettes in local boilers and to characterise these risks by means of the identification of organic compounds in deposits from exhaust flues. The identification of the chemical compounds was performed by pyrolysis gas chromatography with mass spectrometric detection. Paper/cardboard briquettes contain 119 compounds of biogenic origin derived from major biomass components and 53 additives. Additives are used both for improving the properties of paper and in printing inks. By burning the paper briquettes, the same 53 compounds from the additive group were caught in the deposits from the flue gas pathway, occurring in the range of 1-10% of the concentration of individual compounds (additives) contained in the input fuel. Compounds that are very stable during the combustion process have an enrichment factor (EF) >30, which corresponded to approximately 3% of the additive capture in deposits. The highest values were found for plasticisers (phthalates). Many of the primary organic compounds contained in the input raw material do not decompose during combustion and can have adverse effects on human health.

An Influence of the Fuel Type on Element Behaviour in Domestic Boilers with Respect to the Circular Economy

The use of waste from the regional production of waste wood, waste paper, and cardboard in the form of briquettes may be causing an increase in local emissions, both of major elements and trace elements. When burning paper and cardboard briquettes, more than 70% of Mn, Zn, As, and Pb is released into the air from the total content of trace elements in the fuel. The largest amounts of major and trace elements are released when burning paper briquettes (56 g/kg of fuel); half of these amounts are released from burning briquettes from waste wood and coal (23 g/kg of fuel). The pursuit of alternative uses for those cardboard components that are not suitable for recycling cannot be directed to the production of briquettes for residential combustion in the framework of the application of the principles of the circular economy. In particular, the high concentrations of undesirable elements in the emissions released in the gas phase into the atmosphere are an obstacle existing even when the parameters of the PM10 emissions of a boiler are met. This is related to the high ash content of the cardboard (13.5%). Waste paper or cardboard could be added to waste wood at a maximum of 10% to make the pollution produced comparable to the burning of coal briquettes.

Green development challenges within the environmental management framework

Green development of energy, water and environment systems is essential as these three systems represent the basic life needs of humankind. Therefore, environmental problems arising from each of these three systems need to be carefully addressed to preserve the energy, water and environment resources for future generations. This paper discusses some of the latest developments in three main areas of sustainability themes, namely energy, water and environment, that emerged from the 14th Sustainable Development of Energy, Water and Environment Systems (SDEWES) Conference held in 2019. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES 2019 conference.

Spent coffee ground as renewable energy source: Evaluation of the drying processes

Spent coffee ground (SCG) is an environmental nuisance material, but, if appropriately processed it can be converted into pellets, and thus, used as an energy source. The moisture content of the final product should be below 10%, to ensure safe storage, and elimination of microorganism growth (particularly moulds). The present study aims to identify the optimal drying process for removing moisture from SCG and to investigate changes to the composition of SCG due to drying, at temperatures around 75 °C, so that the dried SCG to qualify as renewable energy source. Three drying processes were employed for SCG drying (with initial moisture content of about 65%): oven drying, solar drying and open air sun drying, while SCG samples were placed in aluminium trays with thicknesses of 1.25, 2.5 and 4 cm. Based on the experimental results for SCG samples with thickness 2.5 cm, the open air sun drying process required 10 h to reach final moisture content of 37%, while solar drying achieved 10% moisture content in 10 h and oven drying achieved 7% moisture content in 6 h. The solar drying process proved as the most advantageous, due to low energy requirements and adequate quality of dried SCG. Also, experiments indicated that SCG storage at "normal room conditions" resulted to equilibrium moisture content in SCG of 8%, regardless of the initial moisture content. Furthermore, instrumental analyses of the SCG, revealed changes to its composition for a number of chemical groups, such as aldehydes, ketones, phytosterols, alkaloids, lactones, alcohols, phenols, pyrans and furans, among others. It was also identified that the SCG colour was affected due to the drying process.

Low Emissions Resulting from Combustion of Forest Biomass in a Small Scale Heating Device

The paper concerns the analysis of harmful emissions during the combustion process in households. The subject of the analysis is a low emission heating device with an output of 50 kW for burning biomass of forest origin (low-quality hardwoods or softwoods). The proposed boiler is automatically fed from the connected container by means of a screw conveyor. In this way, the optimum amount of fuel is supplied for maximum heat output (adjustment of the ratio of primary air to fuel). The proposed biomass heating system is equipped with a primary and secondary air supply system and exhaust gas sensors. This ensures optimal regulation of the air mixture and efficient and clean combustion. Proper control of the combustion process, control of the air supply by means of a lambda sensor and power control of the system ensure a low-emission combustion process. The system precisely adjusts to the heat demand. This results in highly efficient heating technology with low operating costs. In the presented work, the emission of exhaust gases from the proposed heating device during the combustion of woodchips and beech–oak pellets were measured. It is demonstrated that the proposed design of the boiler equipped with intelligent control significantly reduces emissions when the biomass solid fuels are used, e.g., CO emissions from beech and oak chips and pellets in the low-emission boiler—18 extract pipes shows the value <100 ppm, which is even lower than when gas is burned in the other boilers; on the other hand, the pine chips show even higher emission when burned in the low-emission burner. Consequently, the choice of biomass source and form of the fuel play some role in the emissions observed.

Recent Advances in Technology, Strategy and Application of Sustainable Energy Systems

The global COVID-19 pandemic has had strong impacts on national and international freight, construction and tourism industry, supply chains, and has resulted in a rapid decline in the demand for traditional energy sources. In fact, research has outlined that urban areas depend on global supply chains for their day-to-day basic functions, including energy supplies, food and safe access to potable water. The disruption of global supply chains can leave many urban areas in a very vulnerable position, in which their citizens may struggle to obtain their basic supplies, as the COVID-19 crisis has recently shown. Therefore, solutions aiming to enhance local food, water and energy production systems, even in urban environments, have to be pursued. The COVID-19 crisis has also highlighted in the scientific community the problem of people’s exposure to outdoor and indoor pollution, confirmed as a key element for the increase both in the transmission and severity of the contagion, on top of involving health risks on their own. In this context, most nations are going to adopt new preferential policies to stimulate the development of relevant sustainable energy industries, based on the electrification of the systems supplied by renewable energy sources as confirmed by the International Energy Agency (IEA). Thus, while there is ongoing research focusing on a COVID 19 vaccine, there is also a need for researchers to work cooperatively on novel strategies for world economic recovery incorporating renewable energy policy, technology and management. In this framework, the Sustainable Development of Energy, Water and Environment Systems (SDEWES) conference provides a good platform for researchers and other experts to exchange their academic thoughts, promoting the development and improvements on the renewable energy technologies as well as their role in systems and in the transition towards sustainable energy systems. The 14th SDEWES Conference was held in Dubrovnik, Croatia. It brought together around 570 researchers from 55 countries in the field of sustainable development. The present Special Issue of Energies, specifically dedicated to the 14th SDEWES Conference, focuses on four main fields: energy policy for sustainable development, biomass energy application, building energy saving, and power plant and electric systems.

Kinetics of the Reactions of Hydroxyl Radicals with Furan and Its Alkylated Derivatives 2-Methyl Furan and 2,5-Dimethyl Furan

Furans are promising second generation biofuels with comparable energy densities to conventional fossil fuels. Combustion of furans is initiated and controlled to a large part by reactions with OH radicals, the kinetics of which are critical to understand the processes occurring under conditions relevant to low-temperature combustion. The reactions of OH radicals with furan (OH + F, R1), 2-methyl furan (OH + 2-MF, R2), and 2,5-dimethyl furan (OH + 2,5-DMF, R3) have been studied in this work over the temperature range 294-668 K at pressures between 5 mbar and 10 bar using laser flash photolysis coupled with laser-induced fluorescence (LIF) spectroscopy to generate and monitor OH radicals under pseudo-first-order conditions. Measurements at p ≤ 200 mbar were made in N₂, using H₂O₂ or (CH₃)₃COOH radical precursors, while those at p ≥ 2 bar were made in He, using HNO₃ as the radical precursor. The kinetics of reactions R1-R3 were observed to display a negative dependence on temperature over the range investigated, indicating the dominance of addition reactions under such conditions, with no significant dependence on pressure observed. Master equation calculations are in good agreement with the observed kinetics, and a combined parametrization of addition channels and abstraction channels for R1-R3 is provided on the basis of this work and previous shock tube measurements at higher temperatures. This work significantly extends the temperature range previously investigated for R1 and represents the first temperature-dependent measurements of R2 and R3 at temperatures relevant for atmospheric chemistry and low-temperature combustion.

Environmental problems arising from the sustainable development of energy, water and environment system

Integration of energy, water and environment systems is essential in the multidisciplinary concept of sustainable development, as they represent the basic life needs of mankind. Therefore, problems arising from the sustainable development concept need to be carefully addressed to preserve the energy, water and environment resources for future generations. This article discusses some of the latest developments in three main areas of sustainability themes, namely energy, water and environment, that emerged from three Sustainable Development of Energy, Water and Environment Systems (SDEWES) conferences held in 2018. As such, it acts as an editorial paper for the virtual special issue of the Journal of Environmental Management, dedicated to the SDEWES2018 conferences.

Assessment of combustion and emission behavior of corn straw biochar briquette fuels under different temperatures

The 350 °C and 700 °C corn straw biochars were used to produce solid fuel briquettes. NovoGro (NG), an industrial by-product, were selected as a binder in the briquetting process. The ratios of the raw material to NG was assumed as 100:1 and 50:1 (denoted as 350NB₁, 350NB₂, 700NB₁ and 700NB₂, respectively). The physicochemical and morphological properties, combustion characteristics and gas emissions of the four briquettes were investigated. The results revealed that the biochars and the NG binder performed a good combination. The low temperature biochar briquettes, especially 350NB₂, had excellent combustion characteristics, including low H/C and O/C ratios (0.17 and 0.82), low gas emissions (104.06 mg/m³ of CO, 157.25 mg/m³ of NO_x and 18.92 mg/m³ of SO₂), optimal resistance to mechanical shock (~90%) and high calorific values (21.48 MJ/kg). Thus, NG is a good binder for the briquetting of biochar. The low temperature biochar was a good feedstock for solid fuel production in the improvement of the combustion and emission quality.

Emission and conversion of NO from algal biomass combustion in O2/CO2 atmosphere

Environmental impacts of NO emissions from biomass combustion have become an important concern. To address NO emission and conversion from algal biomass combustion in O₂/CO₂ atmosphere, three typical algal biomass, Chlorella (Ch), Enteromorpha (En), and Sargassum (Sa), were used to investigate NO emission characteristics in a one-dimensional tube furnace. The effects of the combustion temperature and O₂ concentration (21%, 25%, and 30%) on the NO emission were examined. It was found that the main peaks of NO positively are correlated to the O₂ concentration and combustion temperature. The NO emission trends of each algal biomass are slightly affected by the O₂ concentration at a given temperature. Roughly, the NO yield and conversion rate for each algal biomass increase with increasing O₂ concentration at a given temperature. They first increase with the increasing temperature and then decrease beyond 800 °C with exception for Sa in 30% O₂/CO₂ atmosphere. However, 21% O₂/CO₂ atmosphere is at least effective to reduce NO emission from most algal biomass combustion compared to air-based atmosphere (21% O₂/N₂), by 8.2-62.0%, 4.9-45.6%, and 22.5-59.6% for Ch, En, and Sa, respectively. The possible conversion pathway of fuel-N implies that the NO emission from algal biomass combustion in O₂/CO₂ atmosphere is the result of the combined effect of the NO formation oxidized from N-precursors and NO reduction by CO (converted from CO₂) and other reductive components. These results may provide a positive reference for the control of NO_x emissions from direct combustion or co-firing of algal biomass for energy utilization.

Chemical and Mineralogical Composition of Soot and Ash from the Combustion of Peat Briquettes in Household Boilers

Soot and ash as residues from the combustion of peat briquettes were analysed by chemical and mineralogical methods. The study aimed to characterize combustion in domestic boilers of two different emission classes. Ten samples of soot deposited in exhausting ways of boilers were obtained (five of each emission class). The analyses of organic substances in soot were performed using a combination of the methods for the determination of elemental and organic forms of carbon with analytical pyrolysis. Pyrolysis gas chromatography with mass spectrometric detection (Py-GC/MS) allowed the identification of organic compounds belonging to twenty different groups. The major and minor elements in peat briquettes, char and soot, were determined by X-ray fluorescence spectroscopy. The identification of grains and the chemical character of soot was performed using a scanning electron microscope with energy dispersive X-ray spectrometry. The mineral phases in ash were determined by X-ray diffraction. The behaviour of the inorganic elements in combustion products (ash and soot) was studied by means of an enrichment factor. The analytical results are used for characterizing the technological conditions of combustion. The soot deposits from the more advanced boilers with increased combustion temperature contain more organic compounds which indicate the highly carbonized cellulose (benzofurans and dibenzofurans). The increased combustion temperature is indicated by increased concentrations of heterocyclic and aliphatic nitrogen compounds, while the total concentrations of nitrogen in soot from boilers of both types are comparable.

The Impact of Fuel Type on the Output Parameters of a New Biofuel Burner

Intensified action aimed at reducing CO2 emissions and striving for energy self-sufficiency of both business entities and individual consumers are forcing the sustainable development of environmentally friendly and renewable energy sources. The development of an appropriate class of equipment and production technology is not without significance in this process. On the basis of a proven design for a combustion burner for ecological fuels, a new biofuel burner, also dedicated to prosumers’ energetics, was built. The aim of the study was to determine the effect of the type of biofuel on a burner’s output parameters, especially gaseous emissions, during the combustion of four types of fuels, including three types of biomass. The combustion temperature was measured for lignite, wood pellets, straw pellets, and sunflower pellets. An analysis of exhaust gas composition was performed for lignite and wood pellets. The results of exhaust emissions and combustion temperatures were compared with the burners currently in use. The use of a new burner might contribute to cleaner combustion and reducing the emissions of some gaseous components.