Journal Description
Clean Technologies
Clean Technologies
is an international, peer-reviewed, open access journal of scientific research on technology development aiming to reduce the environmental impact of human activities, and is published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, ESCI (Web of Science), Inspec, AGRIS, RePEc, and other databases.
- Journal Rank: CiteScore - Q2 (Environmental Science (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 26.6 days after submission; acceptance to publication is undertaken in 3.8 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review, and reviewer names published annually in the journal.
Impact Factor:
3.8 (2022);
5-Year Impact Factor:
3.7 (2022)
Latest Articles
Exploration of In Vitro Voltage Production by a Consortium of Chemolithotrophic Microorganisms Using Galena (PbS) as a Sulphur Source
Clean Technol. 2024, 6(1), 62-76; https://doi.org/10.3390/cleantechnol6010005 - 03 Jan 2024
Abstract
Sulphur plays a fundamental role in the biological processes of chemolithotrophic microorganisms. Due to the redox characteristics of sulphur, microorganisms use it for metabolic processes. Such is the case of the dissimilatory processes in the anaerobic respiration of reducing microorganisms. The production of
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Sulphur plays a fundamental role in the biological processes of chemolithotrophic microorganisms. Due to the redox characteristics of sulphur, microorganisms use it for metabolic processes. Such is the case of the dissimilatory processes in the anaerobic respiration of reducing microorganisms. The production of electrical energy from the metabolism of native microorganisms using sulphur as substrate from inorganic mineral sources in the form of Galena (PbS) was achieved using MR mineral medium with 15% (w/v) of PbS mineral concentrate. At 400 h of growth, the highest voltage produced in an experimental unit under anaerobic conditions was 644 mV. The inoculum was composed of microorganisms with spiral morphology, and at the final stages of energy production, the only microorganism identified was Bacillus clausii. This microorganism has not been reported in bioelectrochemical systems, but it has been reported to be present in corrosive environments and reducing anoxic environments.
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(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)
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Comprehensive Study of Energy Characteristics and Biohazard Assessment of Municipal Solid Waste from the Landfill of the City of Atyrau
Clean Technol. 2024, 6(1), 49-61; https://doi.org/10.3390/cleantechnol6010004 - 02 Jan 2024
Abstract
This article presents the results of the study of the morphological composition of municipal solid waste (MSW) from the landfill of Atyrau city, and the waste’s energy characteristics and presence of microorganisms, including bacteria, fungi and viruses. This study was carried out under
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This article presents the results of the study of the morphological composition of municipal solid waste (MSW) from the landfill of Atyrau city, and the waste’s energy characteristics and presence of microorganisms, including bacteria, fungi and viruses. This study was carried out under a government order to determine the feasibility of recycling accumulated and incoming waste into electricity and its hazard to the environment and the workers involved in handling it. At the moment, there is no MSW recycling in Kazakhstan, which has led to the accumulation of more than 125 million tons of waste with an annual increase of 5 million tons. The research included four major cities (Almaty, Shymkent, Atyrau and Astana), which were selected not only on the basis of population, but also because the cities were located in different climatic zones. Samples were collected at the city landfills: 10 samples with an average distance of 100 m from each other were collected to provide a maximum coverage of both recently received waste and long-time stored waste. The research showed that neither climatic conditions nor the population size had a significant impact on MSW density, the values of which ranged from 120.1 kg/m3 to 145.4 kg/m3, as this indicator directly depends on the quality of life. The mass of the combustible fraction ranged from 39.41% to 54.62% and was mainly represented by plastic, textile and paper waste. The average value for the four cities was 50.30%. The higher calorific value fell in the range of 24.22–30.49 MJ/kg, with an average value of 26.71 MJ/kg. Microbiological studies showed little difference in average composition regardless of climatic conditions. Thus, no sharp differences in MSW composition, its energy characteristics and microbiological composition were found. The results of this study may be useful for optimising MSW recycling and disposal processes, as well as for developing measures to reduce their negative impact on the environment and human health.
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(This article belongs to the Special Issue Environmental Engineering Perspectives on Waste Management, Nature-Based Solutions (NbS) and Green/Blue Infrastructure)
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Open AccessArticle
CO2 Capture Using Deep Eutectic Solvents Integrated with Microalgal Fixation
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Clean Technol. 2024, 6(1), 32-48; https://doi.org/10.3390/cleantechnol6010003 - 30 Dec 2023
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In this study, we investigated the use of functionalized deep eutectic solvents (DESs) as a medium for CO2 capture integrated with CO2 desorption and biofixation in microalgal culture, as an approach for carbon capture, utilization, and storage (CCUS). The newly devised
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In this study, we investigated the use of functionalized deep eutectic solvents (DESs) as a medium for CO2 capture integrated with CO2 desorption and biofixation in microalgal culture, as an approach for carbon capture, utilization, and storage (CCUS). The newly devised DES formulation—comprising choline chloride, ethylene glycol, and monoethanolamine—demonstrated a significant advancement in CO2 absorption capacity compared with conventional solvents. Effective CO2 desorption from the solvent was also achieved, recovering nearly 90% of the captured CO2. We then examined the application of the functionalized DESs to promote microalgal cultivation using a Chlorella sp. strain. The experimental results indicated that microalgae exposed to DES-desorbed CO2 exhibited heightened growth rates and enhanced biomass production, signifying the potential of DES-driven CO2 capture for sustainable microalgal biomass cultivation. This research contributes to the growing field of CCUS strategies, offering an avenue for efficient CO2 capture and conversion into valuable biomasses, thereby contributing to both environmental sustainability and bioresource use.
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Open AccessArticle
Individual Characteristics as Motivators of Sustainable Behavior in Electronic Vehicle Rental
Clean Technol. 2024, 6(1), 18-31; https://doi.org/10.3390/cleantechnol6010002 - 30 Dec 2023
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This study investigates the understudied area of motivational factors influencing the rental intention of electric vehicles (EVs) within the context of their integration into urban transportation to combat air pollution and reduce carbon footprints and explores the critical factors influencing consumer behavior towards
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This study investigates the understudied area of motivational factors influencing the rental intention of electric vehicles (EVs) within the context of their integration into urban transportation to combat air pollution and reduce carbon footprints and explores the critical factors influencing consumer behavior towards EV rental, focusing on hedonic motivation, service level, consumer habits, and willingness to pay. Utilizing multiple linear regression analysis on 302 valid samples from Texas, USA, the research identifies the significant impact of these factors on rental intention. Notably, the service level emerges as the most influential predictor while emphasizing the unique and less studied role of hedonic and personal characteristics as essential antecedents of rental intention. The findings, supplemented by a Monte Carlo simulation, reveal that these personal and motivational characteristics are pivotal in shaping rental intentions, accounting for approximately 47.2% of the variance in rental intention. The study contributes valuable insights into the EV rental market, offering theoretical implications for the EV literature and practical strategies for car rental enterprises to tap into consumer patterns effectively.
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Open AccessArticle
From Fruit Waste to Hydrogels for Agricultural Applications
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Clean Technol. 2024, 6(1), 1-17; https://doi.org/10.3390/cleantechnol6010001 - 27 Dec 2023
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Here, we describe and assess a method for reusing specific food waste to make hydrogels, which can be employed to improve the efficacy of agrochemicals and water. It represents an approach for tackling current challenges, such as food waste, water management, and pesticide
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Here, we describe and assess a method for reusing specific food waste to make hydrogels, which can be employed to improve the efficacy of agrochemicals and water. It represents an approach for tackling current challenges, such as food waste, water management, and pesticide optimization. Depending on the formulation, the hydrogels were created by crosslinking pectin and starch with CaCl2 or sodium trimetaphosphate. FTIR and SEM were employed to investigate the methylation degree of the extracted pectin, as well as the surface morphology and interior structure of the hydrogels. The swelling behavior and water retention in sandy soil have been investigated. In addition to the hydrogels’ potential to control and reduce pesticide loss, the herbicide Picloram is a model compound. The results show that the hydrogels have important swelling, up to 300%, and a capacity to retain water, preserve, and increase the water content in sandy soil up to 12 days. Picloram experiments show that hydrogels can limit herbicide mobility for up to 30 days under controlled conditions. The conversion of food wastes to highly valuable materials is a promising approach to optimize the water consumption and the loss of agrochemicals regarding sustainable agriculture.
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Open AccessArticle
Eco-Friendly Depolymerization of Alginates by H2O2 and High-Frequency Ultrasonication
Clean Technol. 2023, 5(4), 1402-1414; https://doi.org/10.3390/cleantechnol5040069 - 06 Dec 2023
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Marine biomass has attracted attention as an environmentally sustainable energy source that can replace petroleum-based resources. Alginates, the main natural polysaccharides extracted from seaweeds, are used in various fields, such as food, pharmaceuticals, and chemical raw materials. Because the versatile applications of alginates
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Marine biomass has attracted attention as an environmentally sustainable energy source that can replace petroleum-based resources. Alginates, the main natural polysaccharides extracted from seaweeds, are used in various fields, such as food, pharmaceuticals, and chemical raw materials. Because the versatile applications of alginates depend on their physicochemical properties, which are controlled by their molecular weights, proper alginate depolymerization should be established. Previous approaches have limitations such as long reaction times and environmental issues. In this study, we report eco-friendly alginate depolymerization using hydrogen peroxide (H2O2)-induced oxidative decomposition and high-frequency ultrasonication. In oxidative decomposition, the depolymerization tendency depends on both the temperature and the use of iron oxide catalysts that can promote the Fenton reaction. Ultrasonication is effective in promoting selective depolymerization and ring-opening reactions. Oligo-alginates obtained through the precise molecular weight regulation of alginate offer potential applications in medical devices and platform chemicals.
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Open AccessArticle
Phyto-Synthesis and Characterization of Silver Nanoparticles Using Box-Behnken Design and Its Anti-Alternaria Activity
Clean Technol. 2023, 5(4), 1381-1401; https://doi.org/10.3390/cleantechnol5040068 - 30 Nov 2023
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Alternaria alternata is a global fungal pathogen that causes symptoms such as leaf blight and seed rot resulting in economically significant yield losses in different varieties of crops. Green synthesis of nanoparticles is preferred over other methods of synthesis due to their safety,
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Alternaria alternata is a global fungal pathogen that causes symptoms such as leaf blight and seed rot resulting in economically significant yield losses in different varieties of crops. Green synthesis of nanoparticles is preferred over other methods of synthesis due to their safety, eco-friendly approach, and cost-effectiveness. Phyto-synthesis of silver nanoparticles (Ag-NPs) using seed extract of Abrus precatorious was optimized and characterized using the Box-Behnken design (BBD). Ag-NPs with a UVmax of 409.01 nm and a crystallite and particle size of 23.75 and 34.36 nm, respectively, were synthesized. In vitro anti-alternaria activity of Ag-NPs showed a concentration-dependent inhibition of the mycelia with a maximum inhibition of 54.61% at 200 ppm which was significantly different (p < 0.05) from propiconazole (1 ppm) with 100% inhibition. A scanning electron micrograph (SEM) of mycelia treated with 200 ppm of Ag-NPs showed a shrunken and shriveled mycelia while the ultrastructure of the mycelia under a transmission electron microscope (TEM) showed the alteration of the fungus cell wall and disappearance of cellular organelles compared to the control sample, while energy dispersive x-ray spectroscopy (EDX) analysis of the mycelia showed the localization of elemental Ag (0.95%) within the cell of the fungus compared to the control. The results of this study highlighted the antifungal potential of Ag-NPs against fungicide-resistant Alternaria alternata to reduce the environmental impact of synthetic fungicides.
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A Comparative Analysis of Different Hydrogen Production Methods and Their Environmental Impact
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Clean Technol. 2023, 5(4), 1344-1380; https://doi.org/10.3390/cleantechnol5040067 - 29 Nov 2023
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This study emphasises the growing relevance of hydrogen as a green energy source in meeting the growing need for sustainable energy solutions. It foregrounds the importance of assessing the environmental consequences of hydrogen-generating processes for their long-term viability. The article compares several hydrogen
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This study emphasises the growing relevance of hydrogen as a green energy source in meeting the growing need for sustainable energy solutions. It foregrounds the importance of assessing the environmental consequences of hydrogen-generating processes for their long-term viability. The article compares several hydrogen production processes in terms of scalability, cost-effectiveness, and technical improvements. It also investigates the environmental effects of each approach, considering crucial elements such as greenhouse gas emissions, water use, land needs, and waste creation. Different industrial techniques have distinct environmental consequences. While steam methane reforming is cost-effective and has a high production capacity, it is coupled with large carbon emissions. Electrolysis, a technology that uses renewable resources, is appealing but requires a lot of energy. Thermochemical and biomass gasification processes show promise for long-term hydrogen generation, but further technological advancement is required. The research investigates techniques for improving the environmental friendliness of hydrogen generation through the use of renewable energy sources. Its ultimate purpose is to offer readers a thorough awareness of the environmental effects of various hydrogen generation strategies, allowing them to make educated judgements about ecologically friendly ways. It can ease the transition to a cleaner hydrogen-powered economy by considering both technological feasibility and environmental issues, enabling a more ecologically conscious and climate-friendly energy landscape.
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Open AccessReview
Poly(lactic acid) and Its Blends for Packaging Application: A Review
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Clean Technol. 2023, 5(4), 1304-1343; https://doi.org/10.3390/cleantechnol5040066 - 10 Nov 2023
Abstract
Biopolymers obtained from renewable resources are an interesting alternative to conventional polymers obtained from fossil resources, as they are sustainable and environmentally friendly. Poly(lactic acid) (PLA) is a biodegradable aliphatic polyester produced from 100% renewable plant resources and plays a key role in
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Biopolymers obtained from renewable resources are an interesting alternative to conventional polymers obtained from fossil resources, as they are sustainable and environmentally friendly. Poly(lactic acid) (PLA) is a biodegradable aliphatic polyester produced from 100% renewable plant resources and plays a key role in the biopolymer market, and is experiencing ever-increasing use worldwide. Unfortunately, this biopolymer has some usage limitations when compared with traditional polymers; therefore, blending it with other biopolymers, such as poly(butylene succinate) (PBS), poly(butylene succinate-co-butylene adipate) (PBSA), poly(butylene adipate-co-butylene terephthalate) (PBAT) and different poly(hydroxyalkanoates) (PHA), is considered an interesting method to improve it significantly, customize its properties and extend the range of its applications. The following review highlights, in its first part, the physico-chemical and mechanical properties of PLA in comparison to the other biopolymers listed above, highlighting the various drawbacks of PLA. The second part of the review deals with recent developments, results, and perspectives in the field of PLA-based blends.
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(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)
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Transient Behavior Analysis of Microgrids in Grid-Connected and Islanded Modes: A Comparative Study of LVRT and HVRT Capabilities
Clean Technol. 2023, 5(4), 1287-1303; https://doi.org/10.3390/cleantechnol5040065 - 10 Nov 2023
Cited by 1
Abstract
Microgrids, with integrated PV systems and nonlinear loads, have grown significantly in popularity in recent years, making the evaluation of their transient behaviors in grid-connected and islanded operations paramount. This study examines a microgrid’s low-voltage ride-through (LVRT) and high-voltage ride-through (HVRT) capabilities in
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Microgrids, with integrated PV systems and nonlinear loads, have grown significantly in popularity in recent years, making the evaluation of their transient behaviors in grid-connected and islanded operations paramount. This study examines a microgrid’s low-voltage ride-through (LVRT) and high-voltage ride-through (HVRT) capabilities in these operational scenarios. The microgrid’s behavior was analyzed using both electromagnetic transient (EMT) and RMS simulation methods. Two operational modes, grid-connected and islanded, were considered. A three-phase diesel generator acted as a reference machine in islanded mode. Findings highlighted distinct behaviors in the two operational modes. The EMT simulation revealed in-depth characteristics of electrical parameters, showing high-frequency oscillations more precisely than the RMS simulation. Additionally, the transient recovery times were longer in islanded mode compared to grid-connected mode. The EMT simulation offers a more detailed portrayal of transient behaviors than the RMS simulation, especially in capturing high-frequency disturbances. However, its completion time becomes significantly extended with longer simulation durations. Microgrids showcase distinct transient behaviors in grid-connected versus islanded modes, especially in LVRT and HVRT scenarios. These findings are critical for the design and operation of modern microgrids.
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(This article belongs to the Topic Smart Solar Energy Systems)
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Open AccessFeature PaperArticle
A Green Approach to Valorizing Abundant Aquatic Weeds for Nutrient-Rich Edible Paper Sheets Production in Bangladesh
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Clean Technol. 2023, 5(4), 1269-1286; https://doi.org/10.3390/cleantechnol5040064 - 23 Oct 2023
Abstract
The rapid and unprecedented expansion of the global population highlights concerns about the sufficiency of food resources to sustain this growth. This study investigates and substantiates the feasibility of renewable food resources in order to meet the nutritional requirements of consumers. Three edible
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The rapid and unprecedented expansion of the global population highlights concerns about the sufficiency of food resources to sustain this growth. This study investigates and substantiates the feasibility of renewable food resources in order to meet the nutritional requirements of consumers. Three edible aquatic weeds, helencha (Enhydra fluctuans), malancha (Alternanthera philoxeroides), and kalmi (Ipomoea aquatica), were used to produce edible paper sheets. The composition of the raw aquatic weeds and paper sheet samples was analyzed, including the proximate composition, amino acid content, minerals and heavy metal contents, and bioactive compounds. The dried raw aquatic weeds and paper sheets showed similar proximate compositions, with carbohydrates being the highest component (50.38–64.63%), followed by crude protein (15.25–19.13%), ash (9.30–15.88%), and lipid (1.55–3.43%). The raw weeds and paper sheets were rich in essential minerals like Na, Ca, and Zn with contents ranging from 27.7 mg/100 g to 30.4 mg/100 g, 126.8 mg/100 g to 489.65 mg/100 g, and 4.5 mg/100 g to 16.3 mg/100 g, respectively. Acceptable levels of heavy metals, including Ni, Pb, and Cu, were found. The paper sheets contained seven essential and eight non-essential amino acids. Among the essential amino acids, the phenylalanine content was the highest at 2735.9 mg/100 g in E. fluctuans paper sheets, followed by methionine at 2377.29 mg/100 g in the raw E. fluctuans and histidine at 1972.6 mg/100 g in E. fluctuans paper sheets. A. philoxeroides sheets showed the highest total amino acid content (16,146.81 mg/100 g), while I. aquatica showed the lowest (13,118.67 mg/100 g). The aquatic weed paper sheets were rich in bioactive compounds, and the numbers in E. fluctuans, A. philoxeroides, and I. aquatica paper sheets were 31, 33, and 40, respectively. There were no significant changes in the nutritional content of the aquatic weeds in paper sheet form compared with the raw weeds, which suggests promising prospects for their production and consumption as a source of nutrition and bioactive compounds.
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(This article belongs to the Special Issue Biomass-Based Green Technologies for Modern Bioeconomy)
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Open AccessReview
ZnO for Photoelectrochemical Hydrogen Generation
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and
Clean Technol. 2023, 5(4), 1248-1268; https://doi.org/10.3390/cleantechnol5040063 - 20 Oct 2023
Abstract
The rise in the Earth’s surface temperature on an annual basis has stimulated scientific and engineering interest in developing and implementing alternative energy sources. Besides cost, the main requirements for alternative energy sources are renewability and environmental friendliness. A prominent representative that allows
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The rise in the Earth’s surface temperature on an annual basis has stimulated scientific and engineering interest in developing and implementing alternative energy sources. Besides cost, the main requirements for alternative energy sources are renewability and environmental friendliness. A prominent representative that allows the production of “green” energy is the conversion of solar photons into a practical energy source. Among the existing approaches in solar energy conversion, the process of photoelectrochemical (PEC) hydrogen extraction from water, which mimics natural photosynthesis, is promising. However, direct decomposition of water by sunlight is practically impossible since water is transparent to light waves longer than 190 nm. Therefore, applying a photoelectrochemical process using semiconductor materials and organic compounds is necessary. Semiconductor materials possessing appropriately positioned valence and conduction bands are vital constituents of photoelectrodes. Certain materials exhibit semiconductor characteristics that facilitate the reduction-oxidation (RedOx) reaction of water (H2O) under specific circumstances. ZnO holds a unique position in the field of photocatalysis due to its outstanding characteristics, including remarkable electron mobility, high thermal conductivity, transparency, and more. This article offers an overview of studies exploring ZnO’s role as a photocatalyst in the generation of hydrogen from water.
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(This article belongs to the Special Issue Solar-Driven Hydrogen Production)
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Delipidation of Chicken Feathers by Lipolytic Bacillus Species Isolated from River-Borne Sediments
Clean Technol. 2023, 5(4), 1235-1247; https://doi.org/10.3390/cleantechnol5040062 - 18 Oct 2023
Abstract
Though the keratin content of chicken feathers is being explored for many potential uses, the crude lipid content of the biomass significantly hinders the valorization processes. Therefore, this study explored the potential of bacteria isolated from sediment for lipolytic properties. Sediment-associated strains were
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Though the keratin content of chicken feathers is being explored for many potential uses, the crude lipid content of the biomass significantly hinders the valorization processes. Therefore, this study explored the potential of bacteria isolated from sediment for lipolytic properties. Sediment-associated strains were evaluated for lipolytic activity on tween 80–peptone agar. The best lipolytic bacterium was used to break down the lipid content of chicken feathers. The results showed that out of six bacterial strains with variable lipolytic activity, strain TTs1 showed the largest zone of precipitate around the colony, which is why it was selected and identified as Bacillus sp. TTs1. The maximum lipase production of 1530.5 U/mL by strain TTs1 was achieved at 96 h post-fermentation, with optimal process conditions of initial pH (10), incubation temperature (45 °C), agitation speed (140 rpm), inoculum size (2% v/v) and tween 80 (10% v/v). The total free fatty acid (0.58%) was liberated from chicken feathers at a concentration of 6% (w/v). Crude fat extraction from both untreated and TTs1-pretreated chicken feathers showed fat contents of 2.1 ± 0.42% and 0.92 ± 0.13%, respectively. The findings of this study highlight the biotechnological relevance of strain TTs1 in lipase production and the sustainable delipidation of lipid-rich bioresources.
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(This article belongs to the Special Issue Valorization of Industrial and Agro Waste)
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Assessing the Sustainable Potential of Corrugated Board-Based Bundle Packaging of PET Bottles: A Life Cycle Perspective—A Case Study
Clean Technol. 2023, 5(4), 1214-1234; https://doi.org/10.3390/cleantechnol5040061 - 13 Oct 2023
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Large amounts of PET bottles are used worldwide as primary packaging for numerous liquids, including water and soft drinks. In many cases, between two and eight of such bottles are bundled for transport and sales using plastic collation shrink film. This study evaluates
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Large amounts of PET bottles are used worldwide as primary packaging for numerous liquids, including water and soft drinks. In many cases, between two and eight of such bottles are bundled for transport and sales using plastic collation shrink film. This study evaluates paper-based alternatives for plastic bundling material using a life cycle assessment (LCA) of four different types of bundle packaging: LDPE shrink film, recycled Low-Density Polyethylene (rLDPE) shrink film, Ecogrip (existing paper-based bundle packaging) and Ecobundle (new paper-based bundle packaging). The study focuses on the case of bundling six bottles of 1.5 L of sparkling water. The most environmentally friendly option is identified, taking into consideration the material usage, effects on human health and effects on the biosphere. It is concluded that the new corrugated board-based bundling method (Ecobundle) is very promising. Further optimization of the design, minimization of material, improved choice of materials and improved design of the production machinery may result in a corrugated board performing even better than rLDPE shrink film in terms of the global warming potential.
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Open AccessCommunication
Evaluation of the Effectiveness of Treatments to Remove Per- and Polyfluoroalkyl Substances from Water—Are We Using the Right Approach? Proposal of a Paradigm Shift from “Chemical Only” towards an Integrated Bio-Chemical Assessment
Clean Technol. 2023, 5(4), 1203-1213; https://doi.org/10.3390/cleantechnol5040060 - 28 Sep 2023
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Per- and polyfluoroalkyl substances (PFASs) have been under intense investigation by the scientific community due to their persistence in the environment and potentially hazardous effects on living organisms. In order to tackle the presence of these compounds in water, to date, the research
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Per- and polyfluoroalkyl substances (PFASs) have been under intense investigation by the scientific community due to their persistence in the environment and potentially hazardous effects on living organisms. In order to tackle the presence of these compounds in water, to date, the research has been strongly focused on the evaluation of the effectiveness of different types of technologies. Considering the extreme complexity of the matter of PFASs and our relatively low knowledge in this topic, the following question arises: is the “chemical only” approach that is followed for evaluating the effectiveness of technologies for PFAS removal from water reliable enough? In this work, some limitations of the present approach are discussed, highlighting the reasons why it cannot be considered a reliable tool to correctly estimate the effectiveness of technology when referring to emerging compounds such as PFASs. Bioassays can play a key role in moving towards an integrated bio-chemical evaluation (chemical analysis and ecotoxicological evaluation), which is strongly encouraged. This represents the only way to completely characterize a water matrix and fully evaluate the impact of technologies when dealing with micropollutants in water, such as PFASs. Future research should focus on defining an optimal battery of bioassays that specifically fit to best represent changes in water quality in terms of short- and long-term impacts on living organisms.
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Open AccessArticle
Quantitating Wastewater Characteristic Parameters Using Neural Network Regression Modeling on Spectral Reflectance
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Clean Technol. 2023, 5(4), 1186-1202; https://doi.org/10.3390/cleantechnol5040059 - 27 Sep 2023
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Wastewater (WW) analysis is a critical step in various operations, such as the control of a WW treatment facility, and speeding up the analysis of WW quality can significantly improve such operations. This work demonstrates the capability of neural network (NN) regression models
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Wastewater (WW) analysis is a critical step in various operations, such as the control of a WW treatment facility, and speeding up the analysis of WW quality can significantly improve such operations. This work demonstrates the capability of neural network (NN) regression models to estimate WW characteristic properties such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia (NH3-N), total dissolved substances (TDS), total alkalinity (TA), and total hardness (TH) by training on WW spectral reflectance in the visible to near-infrared spectrum (400–2000 nm). The dataset contains samples of spectral reflectance intensity, which were the inputs, and the WW parameter levels (BOD, COD, NH3-N, TDS, TA, and TH), which were the outputs. Various NN model configurations were evaluated in terms of regression model fitness. The mean-absolute-error (MAE) was used as the metric for training and testing the NN models, and the coefficient of determination (R2) between the model predictions and true values was also computed to measure how well the NN models predict the true values. The highest R2 (0.994 for training set and 0.973 for testing set) and lowest MAE (0.573 mg/L BOD, 6.258 mg/L COD, 0.369 mg/L NH3-N, 6.98 mg/L TDS, 2.586 m/L TA, and 0.014 mmol/L TH) were achieved when NN models were configured for single-variable output compared to multiple-variables output. Hyperparameter grid-search and k-fold cross-validation improved the NN model prediction performance. With online spectral measurements, the trained neural network model can provide non-contact and real-time estimation of WW quality at minimum estimation error.
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Open AccessArticle
Heat Recovery Potential in a Semi-Closed Greenhouse for Tomato Cultivation
Clean Technol. 2023, 5(4), 1159-1185; https://doi.org/10.3390/cleantechnol5040058 - 22 Sep 2023
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This study first presents the development and the experimental validation of a numerical model of a semi-closed greenhouse using a dynamic thermal simulation. The second objective was to identify the influential parameters on the indoor climate and to calculate the heating demand of
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This study first presents the development and the experimental validation of a numerical model of a semi-closed greenhouse using a dynamic thermal simulation. The second objective was to identify the influential parameters on the indoor climate and to calculate the heating demand of the greenhouse. The model reproduced the behavior of a full-scale experimental greenhouse in Carquefou (France). The comparison with experimental measurements recorded over an entire season of tomato cultivation validated the numerical model. The result of the simulated energy consumption was 310 kWh/m2/year with a relative error of 3.5%. The parametric study identified that the evapotranspiration power and ventilation rate were the most influential input variables, accounting for 50% and 32%, respectively, of the heating demand. The most sensitive output variable was indoor humidity. The presence of a thermal buffer zone all around the greenhouse reduced the energy consumption by 48%, and thermal/shading screens reduced it by 30%. The final objective was to assess the amount of heat recovery potential over the year and each week, depending on the energy storage strategy. Around 43 kWh/m2/year can be recovered over the year, leading to a potential energy savings of 24%.
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Open AccessArticle
Performance Analysis of Conventional IPMSM and NCPM Based IPMSM
Clean Technol. 2023, 5(3), 1140-1158; https://doi.org/10.3390/cleantechnol5030057 - 21 Sep 2023
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This paper proposes a NCPM (Nano-composite coated permanent magnets)-based IPMSM (Interior Permanent Magnet Synchronous Motor) electric drive system, especially applicable for electric vehicles (EV). For an EV, an increase in the “T/A (torque per ampere)” condition is highly recommended, as it directly affects
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This paper proposes a NCPM (Nano-composite coated permanent magnets)-based IPMSM (Interior Permanent Magnet Synchronous Motor) electric drive system, especially applicable for electric vehicles (EV). For an EV, an increase in the “T/A (torque per ampere)” condition is highly recommended, as it directly affects the maximum distance run by EV on a single charge. Due to NCPM, a substantial increase in magnetic flux intensity, resistance to corrosion and Curie temperature are observed. As a result, the proposed drive clearly exhibits a higher power to weight ratio. Also, it is capable of delivering higher T/A to the drive system without any considerable change in two important factors of EV: (1) mass and volume of the drive system (2) battery capacity of the drive system. Moreover, NCPM performance is less susceptible to temperature variation, which makes it an appropriate candidate for vehicular applications, where temperature inconsistency could be a common issue during working conditions. Also, NCPM-based IPMSM offers a quicker speed response than conventional IPMSM, thus providing higher acceleration, which is one of the important performance factors for vehicular applications. A vector controlled mathematical model of IPMSM and NCPM-based IPMSM is tested for various speed commands. Also, the NCPM-based IPMSM, in the proposed configuration, is fed from a three-level DCMLI (diode clamped multi-level inverter), as the drive system is considered for medium to high power applications. A comparative performance analysis is carried out between the proposed drive system and a conventional IPMSM-based drive system using MATLAB/SIMULINK to indicate the efficacy of the proposed configuration.
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Open AccessArticle
Coupling a Gas Turbine Bottoming Cycle Using CO2 as the Working Fluid with a Gas Cycle: Exergy Analysis Considering Combustion Chamber Steam Injection
Clean Technol. 2023, 5(3), 1115-1139; https://doi.org/10.3390/cleantechnol5030056 - 21 Sep 2023
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Gas turbine power plants have important roles in the global power generation market. This paper, for the first time, thermodynamically examines the impact of steam injection for a combined cycle, including a gas turbine cycle with a two-stage turbine and carbon dioxide recompression.
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Gas turbine power plants have important roles in the global power generation market. This paper, for the first time, thermodynamically examines the impact of steam injection for a combined cycle, including a gas turbine cycle with a two-stage turbine and carbon dioxide recompression. The combined cycle is compared with the simple case without steam injection. Steam injection’s impact was observed on important parameters such as energy efficiency, exergy efficiency, and output power. It is revealed that the steam injection reduced exergy destruction in components compared to the simple case. The efficiencies for both cases were obtained. The energy and exergy efficiencies, respectively, were found to be 30.4% and 29.4% for the simple case, and 35.3% and 34.1% for the case with steam injection. Also, incorporating steam injection reduced the emissions of carbon dioxide.
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Open AccessArticle
The Application of UAVs in the Evaluation of Thermal Comfort Levels in Buildings Equipped with Internal Greenhouses
Clean Technol. 2023, 5(3), 1080-1114; https://doi.org/10.3390/cleantechnol5030055 - 20 Sep 2023
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A greenhouse is used to improve thermal comfort (TC) levels for its occupants in winter conditions using solar radiation, which involves low energy consumption. The aim of this research is the application of unmanned aerial vehicles (UAVs) in the evaluation of thermal comfort
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A greenhouse is used to improve thermal comfort (TC) levels for its occupants in winter conditions using solar radiation, which involves low energy consumption. The aim of this research is the application of unmanned aerial vehicles (UAVs) in the evaluation of thermal comfort levels in buildings equipped with internal greenhouses. The new building design is developed numerically, and a building thermal simulator (BTS) numerical model calculates the indoor environmental variables. A new alternative and expeditious method to measure occupants’ comfort levels using UAV technology is applied using a UAV dynamic simulator (UAV DS). The evolution of the measured variables used for evaluating the predicted mean vote (PMV) is compared using the two numerical methodologies: BTS and UAV DS. In the second one, the mean radiant temperature (MRT) measuring methodology, the floor temperature, the lateral walls’ temperatures, the ceiling temperatures, and the air temperature are applied. In the method presented in this paper, a new building design is developed numerically, which includes a central greenhouse equipped with a semispherical dome, four auditoriums distributed around the central greenhouse, occupant distribution, and a ventilation methodology. The building geometry, the solar radiation on transparent surfaces, the TC, and the UAV mission methods are presented. The results show that, in general, the central greenhouse and the ventilation methodologies provide acceptable TC levels. The UAV monitoring mission, which includes two vehicles, provides good environmental variable replication, particularly when the environmental variables present greater variations. In the auditorium and greenhouse, the ceiling and lateral surface temperatures, respectively, can be used as an MRT approximation. The BTS numerical model is also important for developing buildings using renewable energy sources to improve the TC levels.
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