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

Deadline for manuscript submissions: closed (15 March 2024) | Viewed by 16140

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Special Issue Editors

Prof. Dr. Yana Topalova

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Guest Editor

Center of Competence “Clean Technologies for Sustainable Environment – Water, Wastes, Energy for Circular Economy”, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Dragan Tzankov Blvd. 8, 1164 Sofia, Bulgaria
Interests: biological control and water management; environmental biotechnologies, biodegradation of xenobiotics; innovation in biotechnologies

Dr. Irina Schneider

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Guest Editor

Center of Competence “Clean Technologies for Sustainable Environment – Water, Wastes, Energy for Circular Economy”, Faculty of Biology, Sofia University “St. Kliment Ohridski”, Dragan Tzankov Blvd. 8, 1164 Sofia, Bulgaria
Interests: environmental biotechnologies; wastewater treatment; bioaugmentation

Special Issue Information

Dear Colleagues,

Wastewater treatment (domestic, industrial, hospital) is one of the most important environmental technologies. Today's water treatment technologies must be considered from the perspective of the big picture, horizontal and vertical comprehensiveness: origin and transport of wastewater, purification, reuse, inclusion in water receivers, distribution of volatile pollutants and odors in the air, and carbon dioxide emissions. The creation of water treatment technologies, their integration into the environment, management, and improvement needs to be considered and work to solve the global environmental challenges of our time, laid down in European legislation, UN goals, corporate environmental policies, and ESG standards. Among the most important environmental challenges that need to be incorporated into the overall management strategy of water treatment technologies are: saving and circular use of resources and energy, obtaining products with added value, renewable energy, and resources in the course of technologies, reduction of carbon emissions and greenhouse gas emissions, and identification of hazards to human health and nature and their targeted elimination, including xenobiotics, antibiotics, microplastics, viruses (SARS-CoV-2), pathogenic bacteria, parasites, etc. Particular attention is paid to the control of those hazards that remain after treatment and pass into the water receivers, or remain in the water for reuse and damage human health and greatly reduce biodiversity. Significant emphasis is placed on deep (solving problems at the micro- and nano-level) and high technologies and biotechnologies (including modern analytical systems, biosensors, microchips, specialized software, and artificial intelligence) for solving the above-mentioned global problems. One of the most powerful tools for meeting the global challenges in water treatment is bio-, technological, and managerial innovation, as well as combinations of them. The journal will accept articles in, but not be limited to, the topics listed below.

Innovative solutions in sewage treatment: biotechnological, technological, and hybrid modules;
Saving and producing energy and resources in water treatment;
Water treatment and reduction of CO₂ emission;
Deep technologies for enhancement of sewage treatment;
Bioaugmentation of activated sludge and biofilm activities;
Biological control of viruses and other pathogens in water treatment (analysis and elimination);
Control and elimination of toxic substances—xenobiotics, hormones, antibiotics, microplastics;
Circular solutions in management of water treatment.

Prof. Dr. Yana Topalova
Dr. Irina Schneider
Guest Editors

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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

sewage treatment
global ecological changes
wastewater treatment technologies
innovations
circular solutions

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Published Papers (12 papers)

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Research

12 pages, 676 KiB

Open AccessEditor’s ChoiceArticle

Microbial Electrolysis Cell Exergy Evaluation

by Valentin Nenov, Lyubka Atanasova, Hyusein Yemendzhiev and Ralitza Koleva

Processes 2024, 12(2), 319; https://doi.org/10.3390/pr12020319 - 2 Feb 2024

Viewed by 1048

Abstract

Bio-electrochemical systems have increasingly become the focus of research due to their potential in environmental biotechnology, particularly in the domains of waste utilization and energy recovery. A prominent method within this domain is the transformation of organic matter into hydrogen via microbial electrolysis cells (MECs). This study offers a thorough analysis of MEC performance, employing exergy analysis and incorporating relevant data from the existing literature. The findings of this research indicate a relationship between process efficiency and effective electron transfer originating from biological oxidation to the cathode reaction, facilitating hydrogen generation. The assessment performed revealed that the exergy efficiency of the process varies by a wide range, depending on conditions such as substrate type and concentration, applied external voltage, and the presence of specific inhibitors. This interplay between substrate concentration, overall efficiency, and energy requirement underlines the complex dynamics of optimizing MEC performance. Our insights provide understanding of the challenges in bio-electrochemical systems, offering implications for their sustainable and efficient use in environmental biotechnology. The theoretical analysis involved assessing the utilization of glucose and glycerol, along with the evaluation of electrical energy consumption and hydrogen yield. Our results demonstrate that a higher applied voltage is associated with greater exergy efficiency. Furthermore, after comparing the use of glucose and glycerol as substrates, our study supports the preferential application of glucose for enhanced efficiency. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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16 pages, 1960 KiB

Open AccessArticle

Modeling of Effect of Pseudomonas aureofaciens AP-9 on Bioremediation of Phenol-Contaminated River Sediments

by Ivaylo Yotinov, Mihaela Kirilova, Ivelina Delcheva, Gavril Tagarev, Yovana Todorova, Irina Schneider and Yana Topalova

Processes 2024, 12(1), 44; https://doi.org/10.3390/pr12010044 - 23 Dec 2023

Viewed by 930

Abstract

One of the most widespread and risky pollutants in the environment is phenol. It is a by-product of many industrial, agricultural, and other anthropogenic activities. Microbial-assisted transformation, known as bioremediation, is an effective and cheap method for treating groundwater, soil, and sediments contaminated with phenol and its derivates. This study aims to assess the effect of the addition of a selected, pre-adapted bacterial strain Pseudomonas aureofaciens AP-9 on key kinetic, microbiological, and enzymological parameters of simulated bioremediation processes for the removal of phenol (250 mg/kg). The early effect of adding this microbial biodegradant in contaminated sediments is insignificant. The effect of added bacteria is manifested at the 48th hour by a restructuring of the microbial sediment communities and an increase in the number of cultivated microorganisms. This preparation of the sediment communities for a prolonged detoxification process is also confirmed by the repeated induction and very high increase in the activity of the enzymes directly involved in the cleavage of the benzene ring. The effectiveness of phenol removal at the 48th hour is increased by 15%, too. Considering this stimulation of a sustainable long-term bioremediation process, we can conclude that microbiological pre-adapted inoculants are an important mechanism for the management of bioremediation detoxification processes and can increase their effectiveness. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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19 pages, 1708 KiB

Open AccessEditor’s ChoiceArticle

Panoramic Semiquantitave Analysis for Multielement Characterization of Liquid and Solid Waste Samples

by Valentina Lyubomirova, Iva Belovezhdova, Rumyana Djingova, Petar Petrov and Ekaterina Todorova

Processes 2023, 11(12), 3379; https://doi.org/10.3390/pr11123379 - 6 Dec 2023

Viewed by 898

Abstract

Wastewater treatment results in large amounts of sewage sludge in the wastewater treatment plant (WWTP) which imposes on its reuse. The most promising application is as a fertilizer in agriculture which is regulated by national and European legislation. Along with the mandatory determination of potentially toxic elements (PTEs), in order to assess not only the risks, but also the beneficial properties, the determination of the total chemical composition is desirable. Inductively coupled plasma mass spectrometry (ICP-MS) is the most promising technique for multielement characterization which can be applied both for quantitative and semiquantitative analysis. A significant difference between the approaches is that the semiquantitative analysis is performed after a calibration with one standard solution containing at least three elements, but, at the same time, the accuracy is worse. In the present work, the accuracy of semiquantitative analysis with a different number of calibration elements using both water standard solutions and certified reference material (CRM) for calibration was investigated for the determination of 69 elements in sewage sludge CRMs and samples. It has been found that the accuracy can vary within a wide range, depending on the concentration of the elements, the number of calibration elements, and/or the presence of neighboring masses. In order to obtain an accuracy of up to 30%, it is recommended to shorten the mass intervals and perform the calibration with at least 18 elements, mainly microelements. The method was applied for fast panoramic analysis of sewage sludge samples from WWTPs and the concentrations were close to the data from quantitative analysis. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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14 pages, 1217 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Biodegradation and Utilization of the Pesticides Glyphosate and Carbofuran by Two Yeast Strains

by Katya Stoyanova, Maria Gerginova, Nadejda Peneva, Ivayla Dincheva and Zlatka Alexieva

Processes 2023, 11(12), 3343; https://doi.org/10.3390/pr11123343 - 30 Nov 2023

Cited by 2 | Viewed by 1519

Abstract

The widespread use of synthetic pesticides in agricultural practice is associated with the risk of environmental pollution, damage to non-target organisms, and harm to the health of consumers due to the presence of pesticides in the resulting products. Metabolically active microbial species play a significant role in eliminating harmful chemicals from the environment. The two yeast strains used in this study are Trichosporon cutaneum R57 and Candida tropicalis V1. Both strains showed growth and development in the presence of the pesticides glyphosate and carbofuran used as the sole carbon sources. The gas-chromatographic analysis performed showed that C. tropicalis V1 reached 76% of 0.3 g/L glyphosate biodegradation in 192 h. At the same time, the amount of glyphosate decreased by about 58% in the culture of T. cutaneum R57. During the glyphosate biodegradation process, the presence of the intermediate metabolites methylglycine and glycine was revealed. Strain T. cutaneum R57 demonstrated nearly total biodegradation of 0.3 g/L carbofuran in 192 h of cultivation. Strain C. tropicalis V1 showed a slow decrease (23.4%) of the same amount of carbofuran during 192 h. Pyruvic acid and carbofuran-7-phenol have been found to be intermediate metabolites in the breakdown of carbofuran. This report provides new information on the potential of yeasts to participate in environmental pesticide cleanup processes. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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20 pages, 5226 KiB

Open AccessArticle

Analyzing and Modeling the Municipal Sewage Sludge Drying Process Using Python

by Erik Mihelič, Dušan Klinar, Klavdija Rižnar and Primož Oprčkal

Processes 2023, 11(12), 3263; https://doi.org/10.3390/pr11123263 - 21 Nov 2023

Viewed by 1604

Abstract

The programming language Python offers the opportunity to analyze and model the municipal sewage sludge (MSS) drying process in an illustrative chemical engineering practice. The drying process is performed on a flat plate while maintaining a uniform, parallel drying air speed. The Python program helps to analyze the digitalized weight measurements from each sample. The program enables the sorting of input data, determination of the drying critical point, and evaluation of the first and second drying periods. Moreover, the model calculates the fundamental drying parameter and forms a drying master curve to support the transfer to different drying conditions. The basic parameters calculated are mass transfer coefficient, heat transfer coefficient, and diffusion coefficient. The results are consistent with published data for those coefficients over the drying temperature range of 19.4–52.4 °C and relative humidity range of 8.2–33.6%. The findings of this study demonstrate the potential of Python as a powerful tool for analyzing experimental data and modeling chemical processes, which can lead to improved process design, optimization, and control. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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16 pages, 4245 KiB

Open AccessArticle

Efficiency of Modified Natural Clinoptilolite Tuff for As(III) and As(V) Uptake from Model Polluted Water

by Tsveta Stanimirova and Irina Karadjova

Processes 2023, 11(11), 3211; https://doi.org/10.3390/pr11113211 - 10 Nov 2023

Viewed by 1118

Abstract

Granular and powdery clinoptilolite tuff samples from Beli Plast, Eastern Rhodopes, Bulgaria, were coated with metal hydroxides (Fe, Al, Fe-Mg) by two-step alkalization. The prepared sorbents were tested for As(III) and As(V) uptake from a modeled water solution with an arsenic concentration of 44 μg/L. The granular sorbent was used in the sorption columns and showed a high efficiency of arsenic purification from slightly polluted waters. The calculated maximum sorption capacity for the optimal conditions is 32.9 μg/g. The adsorption proceeds according to the Langmuir model. The mechanism of adsorption is most likely inner-sphere complexation. The sorbents’ complete regeneration was achieved by NaOH treatment. The results of the experiments show good possibilities for obtaining water with an arsenic concentration ranging from below the limit of detection to 3.8 µg/L, which is a significantly lower value than the permitted value of 10 μg/L and close to the national environmental quality standard for shallow waters. The high efficiency shows Fe- or Mg,Fe-coated clinoptilolite sorbents. The sorbents are highly efficient in purifying 400 liters of water with an initial concentration of 44 mg/L of either arsenate or arsenite per 1 kilogram of sorbent at a rate of 2.4–2.0 L/h/kg. The powdered sorbents used in a batch system under “static” conditions showed a much higher adsorption capacity than the granular one. Such sorbents are more suitable for small quantities of water with a high concentration of arsenic. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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18 pages, 5475 KiB

Open AccessArticle

Management of the Risk of Blue-Green Algae Blooms in the Iskar Dam for Drinking Water Quality of Sofia City

by Margita Aleksova, Irina Schneider, Seniha Velisha and Eya Prodanova

Processes 2023, 11(10), 2972; https://doi.org/10.3390/pr11102972 - 13 Oct 2023

Cited by 1 | Viewed by 1813

Abstract

The introduction of systems for ensuring quality and safe drinking water and risk management is the World Health Organization (WHO) good practice introduced as a legislative requirement for all water supply organizations (Directive EU 2020/2184) on the quality of water intended for human consumption. A specific object of this research is the implemented risk assessment and management system, part of the drinking water safety plan for Sofia city. The water supply system from the water source to the end user, operated by Sofiyska voda JSC and part of Veolia, was analyzed. The hazards and risk events were reviewed for each component of the system—the catchment, water source, supply water pipes, drinking water treatment plants (DWTPs) and distribution water network. The results of the risk evaluation show that the risk of an algal bloom falls from medium risk, with a value of 36 in 2018. This risk was new for the Iskar Dam—the main water source for Sofia city. The purpose of the current study is to analyze the risk of blue-green algae blooming and the potential release of toxins in the Iskar Dam. A data analysis of phytoplankton counts, temperature of the water in the dam, precipitation, algal diversity and quantity of microcystins for a period of three years shows that there is a low probability of algae blooming. The concentration of microcystin LR was below 0.6 µg/L and of microcystin YR was below 0.1 µg/L. The highest phytoplankton count was 70,000 cells/mL in 2018, and it decreased to 30,000 cells/mL in 2020. The impact of the risk of “blue-green algae blooms in the Iskar Dam” is assessed as moderate (3) and that has not changed between 2018 and 2022. The likelihood of occurrence of this risk decreased from possible (3) to unlikely (2) after risk reassessment, and the current control effectiveness changed from weakly controlled (4) in 2018 to well controlled (2) in 2022, because more risk management actions were included in Sofiyska voda JSC. The results of the risk evaluation show that the risk of an algal bloom falls into the low-risk category with a value of 12, after measures were considered and a reassessment. As a preventive measure for better management and risk minimization, it is necessary to continue monitoring the phytoplankton count, species composition, concentration of algae toxins (microcystin LR) and nutrients in raw water from the Iskar Dam. This research has added value to the global database for surface water sources intended for human consumption and is focuses on a potential problem, valid for agricultural as well as for urban territories rich in diffused sources of pollution. The specific risk evaluation and management steps could be used and adapted by other water supply companies. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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18 pages, 3602 KiB

Open AccessArticle

Assessment of Denitrification and Nitrification Processes during Landfill Leachate Treatment

by Irina Schneider, Ivaylo Yotinov, Nora Dinova, Bogidara Geneva, Elmira Daskalova, Stilyana Lincheva and Yana Topalova

Processes 2023, 11(10), 2960; https://doi.org/10.3390/pr11102960 - 12 Oct 2023

Viewed by 1161

Abstract

Landfill leachate is generated from waste degradation in landfill sites, and its treatment includes biological or combined treatment with physico-chemical methods. A frequently applied technology in the biological stage of landfill leachate treatment plants is based on denitrification and nitrification. Nevertheless, with the availability of a huge number of scientific reports, the management of denitrification and nitrification (D/N) processes in the frame of real wastewater treatment plants (WWTPs) is rather difficult and always remains a critical technological problem. This study aims to perform a comparative assessment between denitrification and nitrification processes during landfill leachate treatment in three different situations in the WWTP of the Municipal Enterprise for Waste Treatment in Sofia City, Bulgaria. The comparative assessment is based on the biotransformation effectiveness of ammonium ions in the course of nitrification and of nitrates in the course of denitrification. Mixed samples (wastewater and activated sludge) were taken from the sequencing batch reactors operating in the mode of denitrification and nitrification. All physico-chemical (pH, dissolved oxygen, organics concentration, BOD₅:COD, nitrogen and phosphorous) and biological (sludge volume index, sludge biotic index, quantity of aerobic heterotrophs, denitrifiers and nitrifiers, total dehydrogenase activity) indicators were investigated in the samples from the biobasins in the mode of denitrification and nitrification. The conditions for the implementation of the two processes were compared, along with the state of the activated sludge in the different reactors. The obtained results showed that denitrification was the critical process in the technology on the base of D/N. A major factor that managed the denitrification was the lower concentration of biodegradable organic matter which led to a deformation of the activated sludge structure, a decrease in the count of heterotrophic microorganisms, a decrease in the total activity of the activated sludge and an inhibition of the nitrate reductase activity. The nitrification processes were accomplished with high intensity. The results confirmed that D/N could be optimized and controlled using specific wastewater treatment technology parameters and purposely applied indicators. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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23 pages, 3149 KiB

Open AccessArticle

Antimicrobial Resistance of Heterotrophic Bacteria and Enterobacteriaceae Inhabiting an Anthropogenic-Affected River Stretch in Bulgaria

by Zvezdimira Tsvetanova and Hristo Najdenski

Processes 2023, 11(9), 2792; https://doi.org/10.3390/pr11092792 - 19 Sep 2023

Cited by 1 | Viewed by 1076

Abstract

The increasing antimicrobial resistance (AMR) of pathogens is a significant threat to human and animal health, but it is also an environmental challenge for water resources. The present study aimed to quantify heterotrophic bacteria resistant to five groups of antibiotics (ABs) in a selected Yantra River stretch (including its tributary, the Belitsa River); to assess AMR prevalence among Enterobacteriaceae; and to assess the impact of urban effluents or rural runoff on AMR prevalence along the river course at eight sampling points. Culture-dependent methods were used in a population-based study of total AMR and for AB susceptibility testing of Enterobacteriaceae isolates. The data reveal significant differences in AMR dissemination and a lower (up to 10%) proportion of different types of antibiotic-resistant bacteria (ARB) in the Yantra River water compared to the Belitsa River (up to 20%). The incidence of resistant Enterobacteriaceae isolates was in the range of 1% to gentamicin to 36% to ampicillin, including multidrug resistance of 19%, and different AMR patterns of isolates from each river. The prevalence of AMR among aquatic bacteria highlights the need for adequate waste water treatment and for management, monitoring and control of treatment processes to limit anthropogenic pressure through discharge of untreated or incompletely treated waste water and to ensure the ecological well-being of receiving waters. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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14 pages, 3582 KiB

Open AccessArticle

Investigation of the Adsorption Process of Triclosan from an Aqueous Solution, Using Nanoporous Carbon Adsorbents, Obtained after Treatment of Organic Household and Vegetable Waste

by Ivanka Stoycheva, Bilyana Petrova, Boyko Tsyntsarski, Pavlina Dolashka, Angelina Kosateva and Nartzislav Petrov

Processes 2023, 11(9), 2643; https://doi.org/10.3390/pr11092643 - 4 Sep 2023

Cited by 1 | Viewed by 1029

Abstract

The absorption of triclosan on the surface of four different carbon adsorbents, obtained on the base of plant and household waste (RDF), provided by Sofia Waste Plant, was investigated. The obtained results indicate that the most important parameters, which determine the process of triclosan adsorption by adsorbent surface are pore texture, the size of the accessible surface for the molecules of triclosan, and the chemical nature of the adsorbent surface. It was found that the obtained adsorbents can be successfully applied for the extraction of triclosan from waste and drinking water. The possibilities for solid products, obtained by thermal treatment of household and vegetable waste, to be applied successfully in a water purification technique are discussed. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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16 pages, 1092 KiB

Open AccessEditor’s ChoiceArticle

An Investigation into the Potential of a Penicillium Commune Strain to Eliminate Aromatic Compounds

by Maria Gerginova, Katya Stoyanova, Nadejda Peneva, Ivayla Dincheva and Zlatka Alexieva

Processes 2023, 11(8), 2402; https://doi.org/10.3390/pr11082402 - 9 Aug 2023

Viewed by 1331

Abstract

The quantity of industrially polluted waters is increasing everywhere, of which a significant part is occupied by a number of mono- and poly-aromatic compounds. Toxins enter the soil, sewage, and clean water by mixing with or seeping into them from industrial wastewater. By using 18S RNA and ITS sequences, the Penicillium commune AL5 strain that was isolated from Antarctic soil was identified. This study is dedicated to exploring its capacity to metabolize hazardous aromatic compounds. The strain showed very good potential in the degradation of hydroxylated monophenols and possessed exceptional abilities in terms of resorcinol degradation. The strain’s ability to metabolize 0.3 g/L of p-cresol at 10 °C is notable. The strain is also capable of metabolizing LMW PAHs (naphthalene, anthracene, and phenanthrene) and eliminating all three tested compounds under 23 °C, respectively, 77.5%, 93.8%, and 75.1%. At 10 °C, the process slowed down, but the degradation of naphthalene continued to be over 50%. The quantity of PAH and a few significant intermediary metabolites were determined using GC–MS analysis. Sequencing of the enzymes phenol hydroxylase and catechol 1,2-dioxygenase revealed a close association with the genes and proteins in some fungal strains that can degrade the aromatic compounds examined thus far. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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13 pages, 5125 KiB

Open AccessArticle

Valorization of Peanut and Walnut Shells through Utilisation as Biosorbents for the Removal of Textile Dyes from Water

by Svetlana Lazarova, Radoslav Tonev, Sonya Dimitrova, Galina Dimova and Irena Mihailova

Processes 2023, 11(8), 2291; https://doi.org/10.3390/pr11082291 - 31 Jul 2023

Cited by 5 | Viewed by 1358

Abstract

The present research focuses on the application of peanut and walnut shells, in their natural state, for the removal of methylene blue (MB) from water solutions in batch and dynamic (flow-through) conditions. Under batch conditions, at a 100 mg/L MB concentration of aqueous solution, the optimum dose of the studied biosorbents was determined to be 2.5 g/L, reaching about 95–97% efficiency of MB removal for both materials. Langmuir and Freundlich isotherms were used to model and evaluate the experimental data under different initial concentrations of MB (25 to 100 mg/L). The determined maximum adsorption capacities are 41.50 mg/g for walnut shells and 46.80 mg/g for peanut shells. Under flow-through conditions, breakthrough curves are determined for three sizes of fractions (<0.25 mm, 0.315–0.5 mm, and 0.8–1.6 mm). For peanut shells, the smaller the particle size, the higher the adsorption capacity and the column breakthrough time. For walnut shells, however, the particle size seems to have a more complex influence on the adsorption process parameters, and this phenomenon deserves future investigation. The adsorption capacity for one and the same fraction size of 0.315–0.5 mm and initial MB concentration of 50 mg/L is higher under dynamic flow conditions, i.e., 51 mg/g compared to 20 mg/g for walnut shells and 46 mg/g compared to 17.5 mg/g for peanut shells. Full article

(This article belongs to the Special Issue Innovations in Sewage Treatment Focused on Global Environmental Challenges)

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