Waste Gas Research Articles

Design of a microwave-induced atmospheric-pressure plasma source based on cylindrical resonant cavity TM010 mode

Abstract A microwave-induced low-temperature atmospheric-pressure source based on cylindrical resonant cavity TM010 mode was designed. The microwave power was fed into the cavity from a rectangular waveguide on top of it through a coupling hole. A metal pin with adjustable insertion depth was added to the cavity to tune its resonant frequency. The fed waveguide was connected by a sliding short. By tuning the sliding short, the energy transfer efficiency from the waveguide to the cavity was changed. Experiments showed that it could induce an argon discharge in the resonant cavity at atmospheric pressure with as low as 30 W incident wave power without any extra trigger. The plasma length reached 50 mm when the incident wave power was 200 W. By exciting the argon with an extra ignitor in the feeding waveguide, the length of the plasma plume could be extended to 260 mm when the incident wave power was 800 W. The plasma generated by this device was filamentous for both cases. The emission spectrum proved the uniformity of the plasma along its length. This work will be helpful in providing a new alternative microwave plasma device for waste gas treatment or chemical reactions that require plasma catalysis.

Energy efficiency of waste gasification plants in the national municipal waste management system

To achieve high levels of municipal waste recovery through a system employing mechanical-biological waste processing technologies, effective management of the over-sieve fraction of mixed municipal waste (preRDF) is crucial. This preRDF cannot be landfilled due to its combustion heat exceeding 6 MJ/kg. Therefore, thermal treatment of waste and subsequent energy recovery become pivotal in the national waste management system, particularly amidst energy crises and fluctuating energy prices. Waste-derived energy can serve as a valuable renewable energy source. To ascertain the true efficiency of the plant in terms of energy, environmental impact, and economics, it is vital to organize the concepts of energy efficiency for thermal waste treatment plants. The energy efficiency of a waste gasification plant should be comprehensively assessed from three standpoints: energy efficiency of thermal waste treatment (i.e., energy efficiency index), energy efficiency of recovering chemical energy contained in waste (actual energy efficiency of the plant), and the efficiency of renewable energy production. A thermal waste processing plant qualifies as a renewable energy source, when it generates electricity and heat from the biodegradable fraction of waste. This article endeavours to determine the potential contribution of chemical energy from the biodegradable waste fraction, relying on preRDF fraction test results..

Quantitative physiology and biomass composition of Cyberlindnera jadinii in ethanol-grown cultures

BackgroundElimination of greenhouse gas emissions in industrial biotechnology requires replacement of carbohydrates by alternative carbon substrates, produced from CO2 and waste streams. Ethanol is already industrially produced from agricultural residues and waste gas and is miscible with water, self-sterilizing and energy-dense. The yeast C. jadinii can grow on ethanol and has a history in the production of single-cell protein (SCP) for feed and food applications. To address a knowledge gap in quantitative physiology of C. jadinii during growth on ethanol, this study investigates growth kinetics, growth energetics, nutritional requirements, and biomass composition of C. jadinii strains in batch, chemostat and fed-batch cultures.ResultsIn aerobic, ethanol-limited chemostat cultures, C. jadinii CBS 621 exhibited a maximum biomass yield on ethanol (YX/Smax) of 0.83 gbiomass (gethanol)−1 and an estimated maintenance requirement for ATP (mATP) of 2.7 mmolATP (gbiomass)−1 h−1. Even at specific growth rates below 0.05 h−1, a stable protein content of approximately 0.54 gprotein (gbiomass)−1 was observed. At low specific growth rates, up to 17% of the proteome consisted of alcohol dehydrogenase proteins, followed by aldehyde dehydrogenases and acetyl-CoA synthetase. Of 13 C. jadinii strains evaluated, 11 displayed fast growth on ethanol (μmax > 0.4 h−1) in mineral medium without vitamins, and CBS 621 was found to be a thiamine auxotroph. The prototrophic strain C. jadinii CBS 5947 was grown on an inorganic salts medium in fed-batch cultures (10-L scale) fed with pure ethanol. Biomass concentrations in these cultures increased up to 100 gbiomass (kgbroth)−1, with a biomass yield of 0.65 gbiomass (gethanol)−1. Model-based simulation, based on quantitative parameters determined in chemostat cultures, adequately predicted biomass production. A different protein content of chemostat- and fed-batch-grown biomass (54 and 42%, respectively) may reflect the more dynamic conditions in fed-batch cultures.ConclusionsAnalysis of ethanol-grown batch, chemostat and fed-batch cultures provided a quantitative physiology baseline for fundamental and applied research on C. jadinii. Its high maximum growth rate, high energetic efficiency of ethanol dissimilation, simple nutritional requirements and high protein content, make C. jadinii a highly interesting platform for production of SCP and other products from ethanol.

Kesadaran Pengelolaan Limbah B3 Sesuai Peraturan Perundangan

According to legal regulations Republic of Indonesia No. 32 2009 concerning Environmental Protection and Management, it states that waste is the remaining results of activities or businesses whose reprocessing requires more effort and if the storage is not carried out properly it will pollute the environment. Hazardous and toxic waste is classified into three types based on its nature: liquid waste, solid waste, and gas waste. According regulations No. 74, 2001 concerning the Processing of Hazardous and toxic Materials, Hazardous and toxic Waste is the remainder of a business and/or activity that contains hazardous and/or toxic materials which due to their nature and/or concentration and/or quantity, either directly or indirectly, can pollute and/or damage the environment, and can endanger the environment. The implementation of Community Service activity focus on increase Awareness of Hazardous and toxic Waste Management in accordance with laws and regulations, To store and manage Hazardous and toxic Waste in the workplace. The implementation of this Community Service activity was carried out online in August 2023 inviting workers and prospective fresh graduates who were interested in fulfilling aspects of Hazardous and toxic waste management. The results of this activity the pre-test and post-test showed that webinar participants, increase in knowledge about Hazardous and toxic waste of 72%. A significant increase in knowledge is expected to improve community behavior regarding Hazardous and toxic waste.

Organic Molecule Functionalization Enables Selective Electrochemical Reduction of Dilute CO2 Feedstock

AbstractThe electrochemical conversion of low‐concentration CO2 feedstock to value‐added chemicals and fuels is a promising pathway for achieving direct valorization of waste gas streams. However, this is challenging due to significant competition from the hydrogen evolution reaction (HER) and lowered CO2 reduction (CO2R) kinetics as compared to systems that employ pure CO2. Here we show that terephthalic acid (TPA) functionalization can boost selectivity towards CO2R and suppress HER over a range of catalysts including Bi, Cu and Zn. For instance, TPA functionalized Bi attained a formate Faradaic efficiency (FEHCOO‐) of 96.3 % at 300 mA cm−2 with pure CO2 feedstock. Density functional theory simulations indicate that this is because TPA functionalization modulates the binding energies of the key reaction intermediates *OCHO and *H. With low‐concentration feedstock (15 % CO2) at 100 mA cm−2, we achieved a high FEHCOO‐ of 85.8 %, which was double that of an unmodified Bi catalyst. Using an electrolyzer with a porous solid electrolyte layer, we successfully showcase 30 h of continuous high‐purity formic acid production with a 5 % CO2 feed. Taken together, our findings demonstrate that molecular tuning of a catalyst can be an effective strategy for enabling selective CO2R using low‐concentration feedstock.

Non-submerged attached growth process for low-concentration methane emission treatment using downflow hanging sponge

The gas-liquid mass transfer issue has always been a challenge in the biological oxidation of methane waste gas treatment. Therefore, this study aims to apply the Downflow Hanging Sponge (DHS) that widely used in wastewater treatment, to mitigate the gas-liquid mass transfer obstacles on methane waste gas treatment. The comprehensive experimental results indicate that among the three sponge carriers, the Melamine Foam (MF) exhibits the strongest wettability, characterized by smaller pore size and a uniformly arranged pore structure. And it demonstrates excellent performance in methane degradation. (maintaining methane degradation efficiency above 5 mol·h−1m−3 in the third phase.) Furthermore, the combined analysis of microbial QPCR and KEGG reveals that the MF sponge possesses a more diverse microbial population and superior methane oxidation capability compared to the other two sponges. This study confirms the superiority of the MF sponge as a biological carrier, capable of enhancing the efficiency of DHS treatment of methane waste gas and providing valuable suggestions for carrier selection and modification.

Providing a new route for chemical recycling of plastics by aspen plus simulation, energy, and its carbon dioxide emissions analysis

In this research, a new complex is proposed for chemical recycling of plastic. After determining the plastic waste entering this process, the sections in which chemical reactions occur have been simulated through aspen plus, such as: gasification of plastic waste and purifying, methanol production, methanol decomposition to various chemicals such as ethylene, propylene, and methane, separation processes for these products, methane decomposition to benzene and the separation of the products of this part, single-step production of styrene from benzene and ethylene, and the polymerization processes. Furthermore, the impacts of this complex on issues such as plastic recycling, energy consumption, and carbon dioxide emissions are studied and compared to conventional methods of plastic production. Results indicate that plastic waste recycling will be more than 98% in the proposed model. Energy consumption is decreased by 29%, carbon dioxide in this part is decreased by 53% by using renewable energy for its power consumption. These results show the sustainability, and circularity of the proposed model.

Design and operation of a demonstration plant for fluidized bed low-temperature gasification of alternative fuels applied to cement production

A fluidized bed low-temperature gasification technology for solid waste treatment is proposed, which provides an effective solution for energy saving and carbon reduction in the cement industry. A demonstration plant was designed and constructed, which is a fluidized bed low-temperature gasifier coupled to the calciner, capable of treating more than 4,000 kg/h of solid waste. The project involved detailed equipment configuration to ensure stable operation. Commissioning tests for rice husk and textile waste gasification assessed system reliability and gasification performance, with a thermal substitution rate (TSR) of 53.10 % for the calciner. At the same time, targeting a clinker production capacity of 2500 t/d, the gasification plant could achieve an annual net profit of at least 753,100 USD. The fluidized bed low-temperature gasification technology not only has a good economic and environmental value for the use of alternative fuels in the cement production process, but also is important for the design and operation of industrial-scale gasifiers and for numerical modeling.

Matrimid®/LaNi5 mixed matrix membranes for selective hydrogen separation from industrial waste gas streams

This study reports the synthesis, characterization, and evaluation of Matrimid®/LaNi5 mixed matrix membranes for selective hydrogen separation from industrial waste gas streams. Through a combination of experimental investigation and modelling, hydrogen absorption in LaNi5 intermetallic compounds and its impact on separation performance were explored. It was observed that the composite membranes exhibit significant enhancement in hydrogen permeation compared to pristine Matrimid® membranes. The results showed that Matrimid®/LaNi5 membranes deliver 5 times higher H2 permeability (107 Barrer) and higher selectivity (H2/CO2: 14.5, H2/N2: 83.5, H2/CH4: 78.5 and H2/CO: 84.5). Furthermore, hydrogen permeation flux modelling in Matrimid®/LaNi5 elucidated the contribution of each transport mechanism with high regression coefficients (> 0.92) and within ± 15% error. Moreover, the results demonstrate the capability of Matrimid®/LaNi5 membranes to surpass Robeson upper bound for H2/CO2 while it is almost reached for H2/N2 and H2/CH4 separations, highlighting the potential of these new membranes for industrial-scale applications.

Regulating the composition, structure, and nanoscale dimensions of Yb 2Si 2O 7 environmental barrier coating to achieve a biomimetic teakwood-like functional structure by waste gas recycling

Regulating the composition, structure, and nanoscale dimensions of Yb ₂Si ₂O ₇ environmental barrier coating to achieve a biomimetic teakwood-like functional structure by waste gas recycling

Clustering Analysis of Food Security, Waste and Loss: Malaysia Agricultural Insights

As the world population grows rapidly nowadays, the demand for food has come to rise. The escalating demand for food has caused substantial wastage and loss, which not only hampers food security efforts but also aggravates greenhouse gas (GHG) emissions, intensifying the environmental crisis. Among numerous countries, Malaysia, with its diverse agricultural profile, emerges as a good fit for our case study. This study chooses the clustering technique to examine food sector data in Malaysia and investigate the link between the clustering results on food data and the data on GHG emissions. This case study aims to find crops depending on their production efficiency, underline those that match major waste, and estimate their contribution to greenhouse gas emissions. Three clustering techniques, Gaussian Mixture Modelling (GMM), Birch, and Density Peak clustering, are applied in the Production and Supply Utilisation Accounts (SUA) datasets, help to identify and cluster crops based on their similar traits to acquire uncovered patterns between the food sector and environmental issues. Using cutting-edge clustering algorithms and visualization tools, this study investigated in-depth the complex interactions among food production, waste, and greenhouse gas emissions in Malaysia. By addressing food production efficiency and waste reduction, the outcome will be a cascade of benefits that not only improve food security but also help to lessen negative environmental effects. This study illuminates the multifaceted dynamics of food production, waste, and environmental impact, offering valuable insights and pathways toward a more sustainable future for Malaysia and potentially other nations.

Investigation of the competitive adsorption mechanism between typical volatile organic compounds (VOCs) and water vapor in waste gas emissions from the fermentation industry

ABSTRACT The fermentation waste gas, characterized by high humidity and diverse volatile organic compounds (VOCs), poses challenges for adsorption in activated carbon devices. In this study, starch-based activated carbon was used as an adsorbent, targeting typical VOCs from fermentation industries-methyl mercaptan, toluene, and n-hexane. The adsorption behavior of water vapor and VOCs on the carbon interface was analyzed through adsorption experiments, structure characterization, and molecular simulations. Results showed that at 70% RH, the adsorption capacities of toluene and n-hexane experienced a reduction of 42.15% and 59.24% respectively compared to their respective capacities without water vapor at the breakthrough moment, while methyl mercaptan’s capacity increased by 32.29% due to dissolution in condensed water within micropores. Water displaced all three VOCs during multicomponent adsorption. Reducing surface carboxyl groups, pyrrolic-N, and pyridinic-N enhances selective adsorption of VOCs. Among the VOCs, toluene shows the strongest interaction with activated carbon, followed by n-hexane and then methyl mercaptan. However, a water film under high humidity hinders the adsorption of n-hexane and toluene, reducing selectivity. These research findings will contribute to a comprehensive understanding of the mechanisms underlying the absorption of VOCs in high humidity environments by activated carbon.

Engineering Acetobacterium wieringae for acetone production from syngas

Gas fermentation using acetogenic bacteria offers a sustainable alternative to fossil-based chemical production by converting waste gas streams, such as syngas (CO, H2, CO2), into valuable biocommodities. In this study, strain JM, a novel isolate of the acetogen Acetobacterium wieringae was engineered for autotrophic acetone production. Novel constitutive promoters native to A. wieringae JM were identified and characterized, expanding the genetic toolbox for this organism. These promoters, along with previously described promoters from Clostridium autoethanogenum, were used to control the expression of acetone production operon from C. acetobutylicum, leading to significant improvements in acetone titers. The use of multiple transcriptional units (TUs) for pathway gene expression further enhanced acetone production compared to a single operon. Additionally, the acetoacetyl-CoA acetate/butyrate CoA-transferase enzyme from C. beijerinckii was found to improve acetone production compared to its homolog from C. acetobutylicum. The plasmid-based expression system using the pMTL83151 vector (pCB102 replicon) demonstrated segregational stability and a consistent single-copy number under both selective and non-selective conditions. Fermentation conditions were optimized, with buffer capacity and gas availability identified as critical factors in batch fermentations. The physiology of autotrophic acetone production was further assessed utilizing different gas compositions which significantly impacted carbon flux to acetone. Under optimized conditions with a 20 % CO syngas blend, the engineered A. wieringae JM [pAW_PFTL-APO] strain achieved an acetone titer of 41.3 mM. This study establishes A. wieringae JM as a promising platform for sustainable acetone production from waste gases and provides a foundation for further development of gas-based biorefineries.

UV-promoted carrier transfer regulation of PbS quantum dots modified ZnO for ultra-high response detection of ppb-level triethylamine

Triethylamine (TEA) is internationally recognized as a common industrial waste gas, necessitating the urgent development of gas sensors with high selectivity and sensitivity. Here, the gas sensor derived from ZIF-L modified with PbS quantum dots (QDs) was designed and prepared. The photo-generated charge under UV light interacts with the adsorbed oxygen on the ZnO/PbS surface, resulting in the formation of alternating cycles. The p-n nano heterojunction created at the ZnO/PbS interface facilitates rapid carrier transfer. Therefore, the ZnO/PbS-0.2 sensor exhibits a response to TEA under UV light is as high as 13,600 (Ra/Rg), which is 5 times greater than that of ZnO, and 16 times higher than that of ZnO/PbS-0.2 sensor in darkness. Moreover, the response of ZnO/PbS-0.2 to TEA under UV light is at least 8 times that of the other 7 types of volatile organic compounds (VOCs). In addition, the detection limits of ZnO/PbS-0.2 under UV light are as low as 198 ppb, far below the internationally emission limit value (1 ppm). The ppb-level detection, super-high responsiveness, and outstanding selectivity of ZnO/PbS-0.2 sensor are result from the synergistic effect of the p-n nano heterojunction at the PbS-ZnO interface and abundant photo-generated charge carriers generated under UV light.

Synergistic mechanisms of magnesium slag coupled with dust removal ash for CO2 sequestration via direct aqueous carbonation: High mineralization efficiency and optimization of reaction parameters

Utilizing natural industrial solid waste for CO2 capture and utilization can reduce both the environmental problems caused by industrial solid waste and greenhouse gases. Based on this idea, magnesium slag-based solid waste has great economic and environmental value as CO2 storage and backfill material. In this study, the CO2 mineralization capacity and efficiency of two magnesium slag-based industrial solid wastes including magnesium slag (MS) and dust removal ash (DRA) and their mixtures were studied by gas-liquid two-phase mineralization method. The as-prepared samples were characterized by a series of techniques such as XRF, XRD, SEM, FT-IR and TG tests. The results exhibited that compared with single MS and DRA sample, the mineralization efficiency of composites increased 7.63 % and 14.1 %, respectively, which performed a synergistic effect. In addition, the main operation parameters including reaction temperature, solid-to-liquid ratio and CO2 concentration were investigated, and the temperature of 35 ℃, solid-to-liquid ratio of 0.1 g/mL and CO2 concentration of 30 vol% were chosen as optimum operating parameters. Furthermore, the reaction mechanism of CaCO3 formation and the mineralization efficiency improvement after cooperation were expounded.

Highly stable Co/CeO2 catalyst for high-temperature water–gas shift reaction using a CeO2 support with an optimized precipitant ratio

We report hydrogen production from waste through waste gasification and the water–gas shift reaction using highly stable Co/CeO2 catalysts. Here, careful control of the KOH:K2CO3 precipitant ratio during CeO2 support synthesis yielded highly active and stable Co/CeO2 catalysts. Crucially, the precipitant ratio affects the Co dispersion, oxygen vacancies, crystallinity, and Co-CeO2 interactions, and the Co dispersion increases with increase in KOH content. Further, the oxygen storage capacity improves at the optimal KOH:K2CO3 ratio. In addition, the Co-CeO2 interaction is enhanced when catalysts are synthesized using CeO2 with a large amount of K2CO3. All prepared Co/CeO2 catalysts show high CO conversion, even at extremely high gas hourly space velocities: the Co/CeO2 (λ = 2:1 and 1:1.5) catalysts exhibit stable performance because of robust Co-CeO2 interactions, high oxygen storage capacities, and effective Co dispersions. These findings aid hydrogen production from waste and CeO2 support design for various catalytic reactions.

SAFETY OF BLACK SOLDIER FLY LARVAE: MICROBIAL AND HEAVY METAL RISKS

Black soldier fly larvae (BSFL) are considered a sustainable protein source and an effective means of recycling organic waste. They are rich in nutrients, including proteins and lipids, making them suitable for animal feed and potentially for human consumption. In addition to their nutritional benefits, BSFL also have environmental benefits, i.e., reducing waste and greenhouse gas emissions. However, concerns about their safety persist, particularly regarding contamination by pathogenic microorganisms, toxins, and heavy metals. The aim of our study was to investigate the effect of different feedstuffs on heavy metal accumulation and on the microcenosis (Enterobacteriaceae, aerobic bacterial endospores, microscopic filamentous fungi) of BSFL. BSFL were fed four feed treatments (I: egg pasta cooked in whole milk; II: cooked rice with peas; III: poultry feed; and IV: cooked couscous, boiled eggs, and raw carrot peels). The results of our study showed that feed variants significantly affect the microbial safety of BSFL. Using MALDI-TOF, we identified 13 species of family Enterobacteriaceae in BSFL, including facultative pathogenic species Enterobacter cloacae, Klebsiella aerogenes, Klebsiella pneumoniae, Morganella morganii, and Proteus mirabilis. Our research confirmed that BSFL fed different feed variants under experimental laboratory conditions contained heavy metals, including cadmium, copper, manganese, molybdenum, nickel, lead, and zinc. Cadmium concentrations in BSFL ranged from 0.12 to 0.18 mg.kg-1, with the highest values measured in BSFL in variant IV.

Food Waste to Food Security: Transition from Bioresources to Sustainability

The transition from food waste to food security is a critical component of sustainability efforts. This approach focuses on repurposing organic waste products generated throughout the food supply chain into valuable resources. Food waste, encompassing everything from agricultural residues to post-consumer waste, represents a significant untapped potential that can be harnessed to enhance food security. By implementing strategies such as composting, bioconversion, and innovative recycling technologies, biowastes can be transformed into fertilizers, animal feed, and even new food products, thus closing the loop in the food system and aiding sustainable solutions for waste valorization. This transition not only addresses environmental concerns by reducing landfill waste and greenhouse gas emissions but also contributes to economic sustainability by creating new opportunities within the food production and waste management sectors. Ultimately, transforming food waste into a resource aligns with the broader goals of a circular economy, ensuring a sustainable, resilient, and food-secure future.

ANALYSIS OF POLLUTANTS EMISSIONS IN THE CONDITIONS OF COMBUSTION OF ALTERNATIVE AND TRADITIONAL SOLID FUELS

The problem of pollutant emissions and the correlation of emission values with climate change is an extremely urgent task today. Climate change is causing glaciers to melt, which is causing water levels in reservoirs to rise. The issues of environmental pollution by the products of combustion of solid fuels are becoming more and more relevant. Among the pollutants that enter the air after the combustion of fuel in the furnaces of boiler units, there are also greenhouse gases that stimulate the greenhouse effect, causing climate change. The work determines emission indicators and emissions of pollutants into the atmospheric air. The task of the work is to identify and recommend the use of modern and effective methods for reducing emissions of pollutants into the atmosphere. The work uses analytical articles and sites that raise the problem of climate change. The work also shows the results of calculating pollutant emissions from combined heat and power boilers, carried out according to the recommendations of national guidelines. A high value of dust emission is typical for straw and flax fescue. In terms of nitrogen oxide emissions, wood waste has the highest values. Slightly lower values for the emission of carbon dioxide, methane, NMVOC are determined for wood waste. It is important to note that when gaseous fuels are burned, there will be no emissions of suspended particulate matter. It should also be noted that natural gas and wood waste do not contain sulfur-containing compounds, which ensures the absence of sulfur dioxide in flue gases when fuels are burned. However, when gases are burned, mercury compounds can be released in trace amounts. One of the options for solving the problem is the transition to alternative energy sources. The development of such sources is already underway, but their implementation in practice, unfortunately, is slow.

Numerical simulation and experimental study of hydrogen production from chili straw waste gasification using Aspen Plus

Biomass gasification is a promising method for hydrogen production. This study systematically models the gasification of chili straw waste (CSW) using the Aspen Plus simulator, focusing on the effects of gasification agents—steam, air, and oxygen—and sensitivity analyses of key parameters. Results show that under optimal steam gasification conditions, with a temperature of 700 °C and atmospheric pressure, hydrogen concentration reached 59.61%, while the lower heating value (LHV) decreased to 6.65 MJ/m3 due to CO reduction. In air gasification, increasing air input reduced hydrogen and CO concentrations by 18.5% and 26.6%, respectively, while LHV dropped by 52.5%. Oxygen-enriched gasification significantly improved hydrogen and CO concentrations, increasing LHV by 129.4% as the oxygen fraction rose. Sensitivity analysis revealed that optimal hydrogen production in air-steam gasification occurred with a low equivalence ratio of 0.18, moderate temperature around 700 °C, and atmospheric pressure. These findings highlight the critical role of temperature, pressure, and gasifying agents in optimizing hydrogen production, providing a basis for improving the efficiency of biomass gasification systems.