Special Issue "10th Anniversary of Processes: Recent Advances in Environmental and Green Processes"

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: 10 October 2023 | Viewed by 14815

Special Issue Editor

Department of Chemical, Biological and Environmental Engineering, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
Interests: design and use of biological systems for the treatment of organic waste (composting and anaerobic digestion); nanotechnology for environmental remediation; solid-state fermentation to convert wastes into bioproducts
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

To celebrate this momentous occasion, a Special Issue “10th Anniversary of Processes: Recent Advances in Environmental and Green Processes” is being prepared, inviting both members of the Editorial Board and outstanding renowned authors, including past editors and authors, to submit a paper on the subject of environmental processes.

Topics of interest include, but are not limited to:

  • Waste treatment;
  • Composting;
  • Anaerobic digestion;
  • Polluted gas treatment;
  • Odors and their treatment;
  • Wastewater treatment: nitrogen and phosphorous;
  • Wastewater treatment: heavy metals and organic pollutants;
  • Electrochemical fuel cells;
  • Soil bioremediation;
  • CO2 abatement and valorization

Prof. Dr. Antoni Sánchez
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • waste
  • wastewater
  • gas treatment
  • odors
  • composting
  • anaerobic digestion
  • soil bioremediation

Published Papers (18 papers)

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Research

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Article
French Fries’ Color and Frying Process in Relation to Used Plant Oils
Processes 2023, 11(10), 2839; https://doi.org/10.3390/pr11102839 - 27 Sep 2023
Viewed by 253
Abstract
Fast-food establishments today often sell fried food without proper control over the frying oil, and french fries are a prime example. Neglecting the maintenance of frying oil can lead to decreased taste, health concerns, and operational inefficiencies. The following plant oils were used [...] Read more.
Fast-food establishments today often sell fried food without proper control over the frying oil, and french fries are a prime example. Neglecting the maintenance of frying oil can lead to decreased taste, health concerns, and operational inefficiencies. The following plant oils were used in the frying process: rapeseed, sunflower, and palm oil. The degree of frying was measured by the total polar meter (TPM), until the achievement of 24%. To accurately assess the color characteristics of the french fry samples, Minolta CM 2600d color measurement instrument was used. Statistically significant differences were observed between some color parameters (L, a, b, C, and h) and TPM values. The following correlations were observed: 0.530 was obtained for TPM and h (hue angle) in french fries fried in palm oil; negative correlation (−0.214) between TPM and L (lightness) was obtained in french fries fried in rapeseed oil. While we have observed certain correlations from our experimental data, it is important to note that the color of french fries may not be the sole determinant of fried oil quality. Other external factors, such as temperature, chemical composition, and potato cultivar, can also significantly influence the color of french fries. Full article
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Article
A Comparative Study on the Bioavailability and Soil-to-Plant Transfer Factors of Potentially Toxic Element Contamination in Agricultural Soils and Their Impacts: A Case Study of Dense Farmland in the Western Region of Saudi Arabia
Processes 2023, 11(9), 2515; https://doi.org/10.3390/pr11092515 - 22 Aug 2023
Viewed by 549
Abstract
Soil and aquatic pollution by heavy metal (Pb, Cr, Cu, Fe, Zn, and Ni) ions has become one of the prime problems worldwide. Thus, the purpose of the current study is to conduct hydrogeological research and quantify the main trace metals in the [...] Read more.
Soil and aquatic pollution by heavy metal (Pb, Cr, Cu, Fe, Zn, and Ni) ions has become one of the prime problems worldwide. Thus, the purpose of the current study is to conduct hydrogeological research and quantify the main trace metals in the edible vegetables, soil, irrigation water, pesticides, and fertilizers in the farmland near Jeddah city, Saudi Arabia. Samples of soil, water, and plants such as coriander (Coriandrum sativum), dill (Anethum graveolens), parsley (Petroselinum crispum), and arugula (Eruca sativa) were collected, acid-digested, and analyzed using an inductively coupled plasma–optical emission spectrometer (ICP–OES). The levels of the elements in soil were determined in the order of Fe > Zn > Cu > Cr > Ni > Pb, whereas the sequence in plants was Fe > Cr > Zn > Pb> Ni > Cu, and in water, the order was Pb > Fe > Cu > Zn> Ni = Cr. In soil, the levels of Fe, Cr, and Pb were higher than the recommended values set by the World Health Organization (WHO) and the Food Administration Organization (FAO). In soil, Pb and Zn uptake increased with an increase in the availability of both elements, whereas in plants, Zn and Pb uptake occurs primarily through the plant roots, and some specific proteins facilitate metal transport and movement across the membrane. In soil, the root cell walls first bind to metal ions, which are taken up across the plasma membrane. The levels of the investigated elements in water and vegetables samples were below the permissible limits set by the FAO and within the allowable limits in the available pesticides and fertilizers. The transfer factor (TF) of metal absorption from soil to plant (TFsoil-plant) and from irrigated water to plant (TFwater-plant) in the study area was determined, followed by correlation and statistical treatment according to the date. The TF values were used to assess the metal levels in collected plant, soil, and water samples. The computed values of TF implied that plant leaves and soil were safe from the risk of heavy metals. Water irrigation causes heavy metal accumulation in soil and vegetables, with varying concentrations. The results of this study revealed no abnormal metal accumulation due to irrigation and no health risks to consumers. Full article
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Article
Modelling the Effect of Water Removal by Reverse Osmosis on the Distillation of Mixtures of Short-Chain Organic Acids from Anaerobic Fermentation
Processes 2023, 11(8), 2362; https://doi.org/10.3390/pr11082362 - 05 Aug 2023
Viewed by 792
Abstract
Anaerobic fermentation (AF) to produce sustainable short-chain organic acids (SCOAs) has found no commercial application so far. This is due to several limitations, including the high energy consumption of the SCOAs’ separation from water by distillation. This study used AspenPlus simulations to investigate [...] Read more.
Anaerobic fermentation (AF) to produce sustainable short-chain organic acids (SCOAs) has found no commercial application so far. This is due to several limitations, including the high energy consumption of the SCOAs’ separation from water by distillation. This study used AspenPlus simulations to investigate the benefits of reverse osmosis (RO) to remove water and concentrate the SCOAs from AF before their separation by distillation. The effect of RO on distillation reflux ratio, heat energy requirements, column diameter and equipment costs was simulated for the processing of model SCOA-containing streams, representing AF effluents. A total of 90 simulations were carried out, investigating three different SCOA compositions, corresponding to different ratios of lactic, acetic and propionic acids, three different concentrations of the total SCOAs (10, 50, 100 g/kg in the stream entering RO) and different extents of water removal by RO. RO brought a reduction in the distillation reboilers’ duty of up to more than 90%, with a reduction of column diameter of up to more than 70%. The total energy consumption, equipment cost and NPV (net present value) of the RO plus distillation process were in all cases more favourable than for the process without membranes. Full article
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Article
Harnessing Digestate Potential: Impact of Biochar and Reagent Addition on Biomethane Production in Anaerobic Digestion Systems
Processes 2023, 11(8), 2284; https://doi.org/10.3390/pr11082284 - 29 Jul 2023
Viewed by 367
Abstract
This article reports on an experiment that aimed to investigate the effects of digestate and cosubstrate input with varying biochar concentrations on methane production in anaerobic digestion processes. The findings revealed distinct trends in methane production among the substrates. Further investigations were conducted [...] Read more.
This article reports on an experiment that aimed to investigate the effects of digestate and cosubstrate input with varying biochar concentrations on methane production in anaerobic digestion processes. The findings revealed distinct trends in methane production among the substrates. Further investigations were conducted to evaluate the effects of different types of biochars on biomethane production from raw cattle manure digestate. Four conditions were tested: one raw digestate condition and three digestate conditions containing 1% of a different biochar type to one another. BC1 (PEFC-certified spruce BC) and BC2 (oak wood BC) showed promising results in enhancing biomethane production. About 884.23 NmL of methane was produced, with a yield and productivity of 22.80 NmL.g−1 and 1.62 NmL.g−1.day−1 with BC1. However, BC3 (cow and chicken manure digestate BC) demonstrated lower biomethane production compared to raw digestate. Additionally, the study explored the effects of adding reagents to digestate. Hematite and iron chloride salt did not show any positive effects on biomethane production when biochar was introduced, while activated carbon powder significantly improved biomethane production rates by approximately 11.18%. Full article
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Article
Complex Agent for Phosphate Sequestration from Digested Sludge Liquor: Performances and Economic Cost Analysis
Processes 2023, 11(7), 2050; https://doi.org/10.3390/pr11072050 - 09 Jul 2023
Viewed by 549
Abstract
Phosphorus (P) management in the “water-energy-resource-nexus” in wastewater treatment plants (WWTPs) remains a longstanding challenge. P adsorption from the P-enriched digested sludge liquor (DSL) is a comparatively more practical and economically viable approach for P recovery in WWTPs. However, high concentrations of impurities [...] Read more.
Phosphorus (P) management in the “water-energy-resource-nexus” in wastewater treatment plants (WWTPs) remains a longstanding challenge. P adsorption from the P-enriched digested sludge liquor (DSL) is a comparatively more practical and economically viable approach for P recovery in WWTPs. However, high concentrations of impurities in DSL might pose a negative and interferential effect on P adsorption, hindering the application of sorbents or precipitation methods. Given such a situation, highly efficient and cost-effective sorbent towards P reclamation from DSL is highly needed. Therefore, this study aims to develop a novel complex agent containing aluminum coagulant and superparamagnetic nano-sorbent (SNS) that can be used in magnetic seeding coagulation for P recovery. The complex agents with different PACl: SNS ratios showed varied turbidity removal rates and P recovery efficiencies and the optimal ratio was 15 mg PACl: 15 g SNS. PAC and SNS showed significant interaction because PAC could enhance P adsorption by shielding the interferential effect of colloidal impurities. In addition, the complex is highly regenerative, with turbidity and P removal rate stably maintained at 70–80% after 10 adsorption/regeneration cycles. The cost–benefit analysis of the dosing complex agent showed a dosing cost of 0.154 EUR/m3, admittedly much higher than the conventional magnetic seeding coagulation, which could probably be covered by the profit if the expensive and rare P product is reclaimed. This work indicated that the complex agent was superior due to its high adsorption capacity, easy separation, and repeated dosing, and therefore had the potential for P recovery from DSL. Full article
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Article
Determination of Soil Agricultural Aptitude for Sugar Cane Production in Vertisols with Machine Learning
Processes 2023, 11(7), 1985; https://doi.org/10.3390/pr11071985 - 30 Jun 2023
Viewed by 543
Abstract
Sugarcane is one of the main agro-industrial products consumed worldwide, and, therefore, the use of suitable soils is a key factor to maximize its production. As a result, the need to evaluate soil matrices, including many physical, chemical, and biological parameters, to determine [...] Read more.
Sugarcane is one of the main agro-industrial products consumed worldwide, and, therefore, the use of suitable soils is a key factor to maximize its production. As a result, the need to evaluate soil matrices, including many physical, chemical, and biological parameters, to determine the soil’s aptitude for growing food crops increases. Machine learning techniques were used to perform an in-depth analysis of the physicochemical indicators of vertisol-type soils used in sugarcane production. The importance of the relationship between each of the indicators was studied. Furthermore, and the main objective of the present work, was the determination of the minimum number of the most important physicochemical indicators necessary to evaluate the agricultural suitability of the soils, with a view to reducing the number of analyses in terms of physicochemical indicators required for the evaluation. The results obtained relating to the estimation of agricultural capability using different numbers of parameters showed accuracy results of up to 91% when implementing three parameters: Potassium (K), Calcium (Ca) and Cation Exchange Capacity (CEC). The reported results, relating to the estimation of the physicochemical parameters, indicated that it was possible to estimate eleven physicochemical parameters with an average accuracy of 73% using only the data of K, Ca and CEC as input parameters in the Machine Learning models. Knowledge of these three parameters enables determination of the values of soil potential in regard to Hydrogen (pH), organic matter (OM), Phosphorus (P), Magnesium (Mg), Sulfur (S), Boron (B), Copper (Cu), Manganese (Mn), and Zinc (Zn), the Calcium/Magnesium ratio (Ca/Mg), and also the texture of the soil. Full article
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Article
Removal of Organic Contaminants in Gas-to-Liquid (GTL) Process Water Using Adsorption on Activated Carbon Fibers (ACFs)
Processes 2023, 11(7), 1932; https://doi.org/10.3390/pr11071932 - 27 Jun 2023
Viewed by 479
Abstract
Gas-To-Liquid (GTL) processing involves the conversion of natural gas to liquid hydrocarbons that are widely used in the chemical industry. In this process, the Fischer–Tropsch (F-T) approach is utilized and, as a result, wastewater is produced as a by-product. This wastewater commonly contains [...] Read more.
Gas-To-Liquid (GTL) processing involves the conversion of natural gas to liquid hydrocarbons that are widely used in the chemical industry. In this process, the Fischer–Tropsch (F-T) approach is utilized and, as a result, wastewater is produced as a by-product. This wastewater commonly contains alcohols and acids as contaminants. Prior to discharge, the treatment of this wastewater is essential, and biological treatment is the common approach. However, this approach is not cost effective and poses various waste-related issues. Due to this, there is a need for a cost-effective treatment method. This study evaluated the adsorption performance of activated carbon fibers (ACFs) for the treatment of GTL wastewater. The ACF in this study exhibited a surface area of 1232.2 m2/g, which provided a significant area for the adsorption to take place. Response surface methodology (RSM) under central composite design was used to assess the effect of GTL wastewater’s pH, initial concentration and dosage on the ACF adsorption performance and optimize its uptake capacity. It was observed that ACF was vitally affected by the three studied factors (pH, initial concentration and dosage), where optimum conditions were found to be at a pH of 3, 1673 mg/L initial concentration and 0.03 g of dosage, with an optimum uptake of 250 mg/L. Kinetics and isotherm models were utilized to fit the adsorption data. From this analysis, it was found that adsorption was best described using the pseudo-second order and Freundlich models, respectively. The resilience of ACF was shown in this study through conducting a regeneration analysis, as the results showed high regeneration efficiency (~86%) under acidic conditions. The results obtained from this study show the potential of using ACF under acidic conditions for the treatment of industrial GTL wastewater. Full article
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Article
Development of Geopolymer Mortars Using Air-Cooled Blast Furnace Slag and Biomass Bottom Ashes as Fine Aggregates
Processes 2023, 11(6), 1597; https://doi.org/10.3390/pr11061597 - 23 May 2023
Cited by 2 | Viewed by 784
Abstract
The aim of this study is to compare the mechanical and physical properties of different geopolymer mortars made with granulated blast furnace slag as a geopolymer source material, NaOH (8 M) as the activating solution, and three different types of fine aggregates (air-cooled [...] Read more.
The aim of this study is to compare the mechanical and physical properties of different geopolymer mortars made with granulated blast furnace slag as a geopolymer source material, NaOH (8 M) as the activating solution, and three different types of fine aggregates (air-cooled blast furnace slag, biomass bottom ashes, and silica sand). The samples were made with an aggregate/geopolymer ratio of 3/1, and physical (density and mercury intrusion porosimetry), mechanical (compressive and flexural strength), and acid attack resistance were determined. When air-cooled blast furnace slag is used, the mechanical and acid attack properties are improved compared with silica sand and biomass bottom ashes because of the existence of amorphous phases in this slag, which increase the geopolymer reaction rate despite the particle size being higher than other aggregates. It can be highlighted that the use of ACBFS as a fine aggregate in geopolymer mortars produces better properties than in cement Portland mortar. Full article
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Article
Enhanced Treatment of Basic Red 46 by Ozonation in a Rotating Packed Bed with Liquid Detention
Processes 2023, 11(5), 1345; https://doi.org/10.3390/pr11051345 - 26 Apr 2023
Viewed by 562
Abstract
This study investigated the use of ozone in a rotating packed bed (RPB) with liquid detention for the treatment of Basic Red 46 (BR-46). Liquid detention means that liquid accumulates at the lower section to a certain level in the RPB, which leads [...] Read more.
This study investigated the use of ozone in a rotating packed bed (RPB) with liquid detention for the treatment of Basic Red 46 (BR-46). Liquid detention means that liquid accumulates at the lower section to a certain level in the RPB, which leads to longer liquid residence time and greater liquid holdup in the packing and cavity in the RPB. The experimental results showed that the presence of liquid detention in the RPB significantly enhanced the BR-46 treatment effect and ozone absorption rate. With 200 mL of liquid detention in the RPB, the decolorization rate, COD degradation rate, and ozone absorption rate were 34.7%, 62.8%, and 80.0% higher than those without liquid detention. The effects of the rotational speed of the RPB, ozone concentration, initial BR-46 concentration, liquid and gas flow rates on BR-46 degradation were also investigated, and it was found that the high-gravity environment is beneficial to the degradation of BR-46. These results suggest that with the utilization of the liquid detention phenomena in the high-gravity devices, the applications of the high-gravity technology can be extended to the processes where a long liquid residence time is required. Full article
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Article
Comparative Analysis of Three WEEE Management Scenarios Based on LCA Methodology: Case Study in the Municipality of Iasi, Romania
Processes 2023, 11(5), 1305; https://doi.org/10.3390/pr11051305 - 23 Apr 2023
Cited by 2 | Viewed by 1022
Abstract
The increasing consumption of electrical and electronic equipment (EEE), correlated with the fast innovation pace in this field, generates a large amount of annual waste. The current established management practices cannot keep up with it, and the results are of increased significance given [...] Read more.
The increasing consumption of electrical and electronic equipment (EEE), correlated with the fast innovation pace in this field, generates a large amount of annual waste. The current established management practices cannot keep up with it, and the results are of increased significance given the negative effects on the environment and human health. Thus, the current study aimed to analyze the environmental impact of three different scenarios of waste electrical and electronic equipment (WEEE) management, following population awareness campaigns regarding its collection in the Municipality of Iasi, Romania. Data processing was carried out considering Life Cycle Assessment (LCA) methodology with the established functional unit for each scenario according to the collected amount. The results were quantified using the CML2001 and ReCiPe methods and showed that the highest environmental impact was obtained for scenario II (S2) (1.59 × 10−7 pers. equiv. using the CML2001 method and 32.7 pers. equiv. using the ReCiPe method), while the lowest for scenario I (S1) (6.42 × 10−8 pers. equiv. using the CML2001 method and 13.8 pers. equiv. using the ReCiPe method). The process with the highest contribution to the total environmental impact was the collection stage for all scenarios, with the exception of scenario S2, in which case the highest value was generated for the landfill process following the application of the ReCiPe method (39.93%). The current study provides value to a critical issue in the environmental area and supports the development of sustainable WEEE management processes. Full article
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Article
Prediction of Oxygen Content in Boiler Flue Gas Based on a Convolutional Neural Network
Processes 2023, 11(4), 990; https://doi.org/10.3390/pr11040990 - 24 Mar 2023
Viewed by 670
Abstract
As one of the core pieces of equipment of the thermal power generation system, the economic and environmental performance of a boiler determines the energy efficiency of the thermal power generation unit. The oxygen content in boiler flue gas is an important parameter [...] Read more.
As one of the core pieces of equipment of the thermal power generation system, the economic and environmental performance of a boiler determines the energy efficiency of the thermal power generation unit. The oxygen content in boiler flue gas is an important parameter reflecting the combustion status of the furnace, and accurate prediction of flue gas oxygen content is of great significance for online boiler optimization. In order to solve the online prediction problem of the oxygen content in boiler flue gas, a CNN is applied to build a time series prediction model, which takes the time series samples within a fixed time window as the input of the model and uses several feature extraction modules containing convolutional, activation, and pooling layers for feature extraction and compression, and the model output is the oxygen content in boiler flue gas. Since the oxygen content in boiler flue gas is not only correlated with other variables but also influenced by its own historical trend, the input of the CNN model is improved, and an oxygen content in boiler flue gas time series prediction model (TS-CNN) is established, which takes the historical values of the boiler flue gas oxygen content as the input of the model. The comparison test results show that the R2 and RMSE of the TS-CNN model are 0.8929 and 0.1684, respectively. The prediction accuracy is higher than the CNN model, LSSVM model, and BPNN model by 18.6%, 31.2%, and 54.6%, respectively. Full article
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Article
Management of Agricultural Water Containing Acetimidothioic Acid Pesticide through Catalytic Oxidation to Facilitate Reclaimed Water Recycling for Sustainable Food Production
Processes 2023, 11(3), 792; https://doi.org/10.3390/pr11030792 - 07 Mar 2023
Viewed by 758
Abstract
Agro-industrial discharge contains acetimidothioic acid, which is commercially named “Lanox 90” and is a widely applied insecticide in greenhouses, and the result is wastewater loaded with this insecticide. Treating such wastewater is a must to reduce the environmental impact as well as to [...] Read more.
Agro-industrial discharge contains acetimidothioic acid, which is commercially named “Lanox 90” and is a widely applied insecticide in greenhouses, and the result is wastewater loaded with this insecticide. Treating such wastewater is a must to reduce the environmental impact as well as to facilitate the opportunity for water recycling. Thus, the present work introduced Montmorillonite (MMT) clay as a novel Fenton reaction source to treat wastewater loaded with Lanox 90 insecticide as a benign sustainable strategy. Scanning electron microscopy (SEM) supported with energy-dispersive X-ray spectroscopy (EDX) and Fourier-transform infrared spectroscopy (FTIR) were used to characterize the MMT sample. Response surface methodology based on Box–Behnken analysis was selected to optimize the parametric circumstances. The optimized parameters of the proposed technique were obtained at a pH of 2.6 with the addition of 0.8 and 854 mg/L of MMT and H2O2, respectively, to attain the highest predicted Lanox 90 removal rate of 97%. Analysis of variance (ANOVA) was used to examine the statistical data and displayed a significant quadratic model. Ultimately, the results reveal that the oxidation system is exothermic and has a non-spontaneous nature, and the reaction kinetics are categorized according to the second-order reaction kinetic rate. The results of the current study indicate the importance of MMT for treating wastewater. These results confirm the possibility of using oxidation technique as a suitable candidate for greenhouse effluent management to enhance the efficiency of water recycling for smart irrigation. Full article
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Article
Estimation of 137Cs Distribution and Recovery Using Various Types of Sorbents in the Black Sea Surface Layer
Processes 2023, 11(2), 603; https://doi.org/10.3390/pr11020603 - 16 Feb 2023
Cited by 2 | Viewed by 848
Abstract
Monitoring 137Cs in seawater is necessary for the timely detection of radioactive contamination. The possibility of sorption and the sorption efficiency of 137Cs from seawater were studied for the first time during several cruises of the R/V (research vessel) Professor Vodyanitsky [...] Read more.
Monitoring 137Cs in seawater is necessary for the timely detection of radioactive contamination. The possibility of sorption and the sorption efficiency of 137Cs from seawater were studied for the first time during several cruises of the R/V (research vessel) Professor Vodyanitsky using various types of sorbents based on transition metal ferrocyanides (Anfezh, Niket, Uniket, FSS, FD-M, FIC, Termoxid 35, NKF-C) and zirconium phosphate (Termoxid 3A). The influence of the seawater flow rate and volume of the sorbent used for the recovery of 137Cs was estimated. The ferrocyanide sorbents Niket, Uniket, Termoxid 35, and FIC showed the best sorption efficiency (60–100%) at a seawater flow rate of 2–4 column volumes per minute. The data obtained during three cruises on the R/V Professor Vodyanitsky were analyzed. A detailed (28 sampling points) spatial distribution of 137Cs in the Black Sea along the southern coast of Crimea was studied using the sorbents that showed the best characteristics. An increase in 137Cs activity in the study area was not found, and the average activity was 9.01 ± 0.87 Bq/m3. Full article
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Article
Thermal Stability for the Continuous Production of γ-Valerolactone from the Hydrogenation of N-Butyl Levulinate in a CSTR
Processes 2023, 11(1), 237; https://doi.org/10.3390/pr11010237 - 11 Jan 2023
Cited by 1 | Viewed by 1004
Abstract
γ-valerolactone can be a game-changer in the chemical industry because it could substitute fossil feedstocks in different fields. Its production is from the hydrogenation of levulinic acid or alkyl levulinates and can present some risk of thermal runaway. To the best of our [...] Read more.
γ-valerolactone can be a game-changer in the chemical industry because it could substitute fossil feedstocks in different fields. Its production is from the hydrogenation of levulinic acid or alkyl levulinates and can present some risk of thermal runaway. To the best of our knowledge, no studies evaluate the thermal stability of this production in a continuous reactor. We simulated the thermal behavior of the hydrogenation of butyl levulinate over Ru/C in a continuous stirred-tank reactor and performed a sensitivity analysis. The kinetic and thermodynamic constants from Wang et al.’s articles were used. We found that the risk of thermal stability is low for this chemical system. Full article
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Article
Experimental Investigation on Pyrolysis of Domestic Plastic Wastes for Fuel Grade Hydrocarbons
Processes 2023, 11(1), 71; https://doi.org/10.3390/pr11010071 - 28 Dec 2022
Cited by 3 | Viewed by 2040
Abstract
Plastics usage is rising daily because of increased population, modernization, and industrialization, which produces a lot of plastic garbage. Due to their various chemical structures, long chain polymeric compositions, and thermal/decomposition behavior, it is challenging to recycle these plastic wastes into hydrocarbon fuels. [...] Read more.
Plastics usage is rising daily because of increased population, modernization, and industrialization, which produces a lot of plastic garbage. Due to their various chemical structures, long chain polymeric compositions, and thermal/decomposition behavior, it is challenging to recycle these plastic wastes into hydrocarbon fuels. In the current work, domestic plastic waste was pyrolyzed at 473 to 973 K in a fixed bed reactor and compared with the three virgin plastics LDPE (low-density polyethylene), HDPE (high-density polyethylene), and PP (polypropylene), as well as a mixture of the three (virgin mixed plastics). The pyrolysis results showed that maximum liquid hydrocarbons obtained from HDPE, LDPE, PP, mixed plastic, and domestic waste were 64.6 wt.%, 62.2 wt.%, 63.1 wt.%, 68.6 wt.%, and 64.6 wt.% at 773 K, respectively. The composition of liquid fuels was characterized using FTIR and GC-MS, which showed a wide spectrum of hydrocarbons in the C8–C20 range. Furthermore, liquid fuel characteristics such as density, viscosity, fire and flash point, pour point, and calorific value were examined using ASTM standards, and the results were found to be satisfactory. This study provides an innovative method for recycling waste plastics into economical hydrocarbon fuel for use in transportation. Full article
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Article
Research on the Application of Coal Gasification Slag in Soil Improvement
Processes 2022, 10(12), 2690; https://doi.org/10.3390/pr10122690 - 13 Dec 2022
Cited by 1 | Viewed by 844
Abstract
SEM, particle size analysis, and contaminant content of coarse coal gasification slag (CCGS) produced by Shenhua Xinjiang Chemical Co., Ltd. were measured, respectively, and the physicochemical properties of the soil after improvement using gasification slag were investigated in this paper. The results showed [...] Read more.
SEM, particle size analysis, and contaminant content of coarse coal gasification slag (CCGS) produced by Shenhua Xinjiang Chemical Co., Ltd. were measured, respectively, and the physicochemical properties of the soil after improvement using gasification slag were investigated in this paper. The results showed that the slag was porous, the particle size was small and the pollutant content was extremely low. Its pollutants were closely related to the pollutants in the raw coal. The coarse slag had a limited effect on soil particle size and texture improvement; the soil water retention performance increased with the increase of proportion of the slag, while pH and conductivity decreased; the improvement effect on soil SOM and available potassium was remarkable; the larger the proportion of the slag, the stronger the effect on maintaining soil alkali-hydrolyzed nitrogen, ammonium nitrogen, and available phosphorus. However, the effect was small, and increased the ion content, especially the cation in soil, and the sum of the eight soil ions before and after evaporation decreased. The results demonstrated that the CCGS generated by the corporation is feasible for soil improvement, and the study has important reference value for the comprehensive utilization of coal gasification slag. Full article
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Review

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Review
Bibliometric Analysis of Constructed Wetlands with Ornamental Flowering Plants: The Importance of Green Technology
Processes 2023, 11(4), 1253; https://doi.org/10.3390/pr11041253 - 19 Apr 2023
Cited by 1 | Viewed by 993
Abstract
The use of constructed wetlands (CWs) for wastewater treatment has earned high interest around the world. However, innovations to improve its removal efficiency and adoption have been suggested in the last decades. For instance, the use of ornamental flowering plants (OFP), which make [...] Read more.
The use of constructed wetlands (CWs) for wastewater treatment has earned high interest around the world. However, innovations to improve its removal efficiency and adoption have been suggested in the last decades. For instance, the use of ornamental flowering plants (OFP), which make wetland treatment systems more aesthetic and is an option for the production of commercial flowers while the water is cleansed. The objectives of this study were to identify through a bibliometric analysis (2000–2022) the main OFP that have been used in CWs and their functionality as phytoremediators (removal effects), as well as the authors, collaborations, main investigations, and the countries where such investigations have been carried out. To this respect, 10,254 studies on CWs were identified. The United States and China were the leading countries in the use of this eco-technology. Subsequently, regarding the use of OFP, the analysis revealed 92 studies on this matter in which Mexico has three researchers who lead the use of OFP in CWs (almost 40% of publications of CWs with OFP), where the main species studied include Canna hybrids, Zantedeschia aethiopica, Strelitzia reginae, Iris species, Spathiphyllum sp., and Anturium sp. These species may remove between 30–90% of pollutants of organic compounds, 30–70% of heavy metals and drugs, and about 99.9% of pathogens. Thus, this study may help researchers to identify OFP for new CWs design, and to know new future research directionsand collaboration approaches in this area using multipurpose alternatives like those of CWs with OFP. More research can still be carried out on the use of CWs with OFP in temperate climates, as well as evaluating the influence of different substrates and water flow on the growth of these plants. Full article
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Perspective
Mini-Review of Best Practices for Greenhouse Gas Reduction in Singapore’s Semiconductor Industry
Processes 2023, 11(7), 2120; https://doi.org/10.3390/pr11072120 - 16 Jul 2023
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Abstract
Climate change is an urgent global concern driven by human activities and the subsequent rise in greenhouse gas (GHG) emissions. The semiconductor industry has emerged as a significant contributor to GHG emissions, yet there is a lack of clear guidelines for effective reduction [...] Read more.
Climate change is an urgent global concern driven by human activities and the subsequent rise in greenhouse gas (GHG) emissions. The semiconductor industry has emerged as a significant contributor to GHG emissions, yet there is a lack of clear guidelines for effective reduction methods specifically tailored to domestic and international semiconductor manufacturing. This mini-review addresses this gap by proposing implementation principles for optimal control technology aimed at mitigating GHG emissions in the semiconductor industry. Drawing upon guidance from the Intergovernmental Panel on Climate Change (IPCC) and established reduction methods, our focus is on the deployment of efficient exhaust gas destruction equipment for removing GHGs from critical processes such as Etching, ThinFilm (including chemical/physical vapor deposition), and Diffusion. By examining and consolidating current best practices, this review provides a foundation for developing comprehensive guidelines and standards that support the semiconductor industry’s transition to more sustainable operations. Considering the vast body of literature in this field, we highlight the significance of this study as it contributes to the ongoing research efforts in reducing GHG emissions. The objective of this study is to identify research gaps and motivate further investigations, while also providing practical recommendations for reducing GHG emissions in the semiconductor industry. Full article
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