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Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater

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A special issue of Separations (ISSN 2297-8739). This special issue belongs to the section "Environmental Separations".

Deadline for manuscript submissions: closed (31 August 2023) | Viewed by 43855

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Special Issue Editors

Dr. Amin Mojiri

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Guest Editor

School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
Interests: waste management; wastewater treatment; water quality engineering; water treatment; anammox
Special Issues, Collections and Topics in MDPI journals

Dr. Mohammed J.K. Bashir

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Guest Editor

School of Engineering and Technology, Central Queensland University, 120 Spencer St., Melbourne, VIC 3000, Australia
Interests: emerging contaminants; membrane separation; bioenergy production; water-energy nexus; resource recovery; wastewater treatment; advanced oxidation processes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Water is the main natural resource that is necessary for sustainable development. With industrialization and urbanization, water pollution has become increasingly severe. Among contaminants, emerging contaminants (ECs) are of particular concern worldwide as they are widely applied, relatively stable and non-biodegradable, bioaccumulative, and toxic for human health and the environment. Unfortunately, conventional treatment plants are not effective in removing these pollutants. As a result, new separation techniques and materials for the removal of ECs have attracted significant research attention.

This Special Issue of the Separations journal invites original and review articles on advanced removal and separation techniques developed for emerging contaminants in water and wastewater. The scope may cover developing new materials or processes, adsorption, membrane filtration, reverse osmosis, ion exchange, oxidation, floatation and coagulation, and biological-based systems.

We are happy to invite you to submit a manuscript for this Special Issue of Separations. Full research, reviews, and communication articles are all welcomed.

Dr. Amin Mojiri
Dr. Mohammed J.K. Bashir
Guest Editors

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. Separations 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 2600 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

emerging contaminants
separation processes
water treatment
membrane technology
adsorption
oxidation
filtration
biological-based systems

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Published Papers (9 papers)

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Research

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13 pages, 2391 KiB

Open AccessArticle

Sewage Water Treatment Using Chlorella Vulgaris Microalgae for Simultaneous Nutrient Separation and Biomass Production

by Motasem Y. D. Alazaiza, Shan He, Dongxiao Su, Salem S. Abu Amr, Pey Yi Toh and Mohammed J. K. Bashir

Separations 2023, 10(4), 229; https://doi.org/10.3390/separations10040229 - 26 Mar 2023

Cited by 24 | Viewed by 10608

Abstract

Recovery of wastewater is essential for better management of water resources and can aid in reducing regional or seasonal water shortages. When algae were used to clean wastewater, amazing benefits were guaranteed, such as a decrease in the formation of dangerous solid sludge and the creation of valuable algal biomass through recycling of the nutrients in the wastewater. The trace elements nitrogen, phosphorus, and others that microalgae need for cell development are frequently present in contaminated wastewater. Hence, microalgal bioremediation is used in this study as an effective technique for the simultaneous treatment of COD, NH₃-N, and orthophosphate from domestic wastewater and biomass production. Different concentrations of wastewaters were used. The maximum removals attained were: 84% of COD on the fifth day using the lowest mixing ratio of 50%, 95% of ammoniacal nitrogen, and 97% of phosphorus. The highest biomass production was achieved at day 12, except for the mixing ratio of 80% where the growth rate increased until day 14 at 400 mg/L. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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17 pages, 2798 KiB

Open AccessArticle

Combined Effects of Polyamide Microplastics and Hydrochemical Factors on the Transport of Bisphenol A in Groundwater

by Zhou Cheng, Xuanhao Lin, Ming Wu, Guoping Lu, Yanru Hao, Cehui Mo, Qusheng Li, Jianfeng Wu, Jichun Wu and Bill X. Hu

Separations 2023, 10(2), 123; https://doi.org/10.3390/separations10020123 - 9 Feb 2023

Cited by 9 | Viewed by 3237

Abstract

Polyamide (PA) and bisphenol A (BPA) are selected as typical microplastic and endocrine-disrupting chemicals in this study. The adsorption of BPA on the surface of PA and the effect of PA on the transport behavior of BPA in groundwater are systematically investigated using a combination of batch experiments, column experiments and numerical models. The results of scanning electron microscope (SEM) and Fourier transform infrared spectra (FTIR) show that the surface of PA particles is changed significantly after adsorption of BPA. The isothermal adsorption process of BPA can be simulated by the Langmuir model and the Freundlich model. Kinetic adsorption, on the other hand, can be fitted by a quasi-first-order adsorption model, and the adsorption results indicate that the maximum adsorption of BPA on PA reaches 13 mg·g⁻¹. The results of the column experiments suggest that the mass recovery rate of BPA decreases with PA content, and increases with flow velocity, while initial concentration has no apparent influence on BPA transport. In addition, due to the hydrolysis of BPA, the mass recovery rate of BPA does not change with pH under conditions of pH < 10.2 and increases substantially to 94% when pH > 10.2. Moreover, Ca²⁺ has a significant inhibitory effect on the transport of BPA, while Na⁺ has no apparent influence on the transport of BPA. The transport process of BPA in porous media is simulated using a single-point kinetic model, and the fitted mathematical relationships for the variation of kinetic parameters with environmental factors are obtained by regression analysis. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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24 pages, 6080 KiB

Open AccessArticle

Synthesis of Gum Arabic Magnetic Nanoparticles for Adsorptive Removal of Ciprofloxacin: Equilibrium, Kinetic, Thermodynamics Studies, and Optimization by Response Surface Methodology

by Abdullahi Haruna Birniwa, Rania Edrees Adam Mohammad, Mujahid Ali, Muhammad Faisal Rehman, Shehu Sa’ad Abdullahi, Sayed M. Eldin, Suwaiba Mamman, Abubakar Chadi Sadiq and Ahmad Hussaini Jagaba

Separations 2022, 9(10), 322; https://doi.org/10.3390/separations9100322 - 21 Oct 2022

Cited by 47 | Viewed by 3564

Abstract

Given the increasing risks that antibiotic abuse poses to microecology and human health, it is imperative to develop incredibly powerful adsorbents. This study investigated the use of environmentally sustainable polymeric nanocomposite based on gum arabic (GA) and magnetic nanoparticles (MNPs) synthesized via co-precipitation method to form gum arabic magnetitic nanoparticles (GA-MNPs) as an efficient adsorbent for ciprofloxacin (CIP) removal from aqueous solution. The physicochemical properties and morphology of the synthesized GA-MNPs were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Energy Dispersive X-Ray Analysis (EDX). The experiment was designed by response surface methodology (RSM) and the Central Composite Design (CCD) was utilized to optimize the operating variables: contact time (0–120 min), pH (3–10), adsorbent dosage (0.10–0.40 g/L), and concentration of adsorbate (5–100 mg/L). Results showed that 96.30% was the maximum percentage of CIP removed. The adsorption effect of the CIP molecule on the surface of the GA-MNPs was investigated using regression analysis and analysis of variance. Furthermore, Freundlich Isotherm and Pseudo Second order kinetic equations have the highest consistency with experimental investigations suggesting double-layer adsorption. This implies that chemisorption was the mechanism involved. In addition, the calculated thermodynamic parameters were postulating an exothermic and spontaneous method in nature. Owing to its adsorption selectivity and recyclability, GA-MNPs could be classified as an environmentally friendly, less expensive, and highly efficient promising adsorbent for remediation of CIP from aqueous solution. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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15 pages, 3276 KiB

Open AccessArticle

Integrated Electro-Ozonation and Fixed-Bed Column for the Simultaneous Removal of Emerging Contaminants and Heavy Metals from Aqueous Solutions

by Amin Mojiri, Noriatsu Ozaki, John L. Zhou, Reza Andasht Kazeroon, Mohammad Ali Zahed, Shahabaldin Rezania, Mohammadtaghi Vakili, Shahin Gavanji and Hossein Farraji

Separations 2022, 9(10), 276; https://doi.org/10.3390/separations9100276 - 1 Oct 2022

Cited by 3 | Viewed by 2600

Abstract

In the current study, an integrated physiochemical method was utilized to remove tonalide (TND) and dimethyl phthalate (DMP) (as emerging contaminants, ECs), and nickel (Ni) and lead (Pb) (as heavy metals), from synthetic wastewater. In the first step of the study, pH, current (mA/cm²), and voltage (V) were set to 7.0, 30, and 9, respectively; then the removal of TND, DMP, Ni, and Pb with an electro-ozonation reactor was optimized using response surface methodology (RSM). At the optimum reaction time (58.1 min), ozone dosage (9.4 mg L⁻¹), initial concentration of ECs (0.98 mg L⁻¹), and initial concentration of heavy metals (28.9 mg L⁻¹), the percentages of TND, DMP, Ni, and Pb removal were 77.0%, 84.5%, 59.2%, and 58.2%, respectively. For the electro-ozonation reactor, the ozone consumption (OC) ranged from 1.1 kg to 3.9 kg (kg O₃/kg Ecs), and the specific energy consumption (SEC) was 6.95 (kWh kg⁻¹). After treatment with the optimum electro-ozonation parameters, the synthetic wastewater was transferred to a fixed-bed column, which was filled with a new composite adsorbent (named BBCEC), as the second step of the study. BBCEC improved the efficacy of the removal of TND, DMP, Ni, and Pb to more than 92%. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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17 pages, 1246 KiB

Open AccessArticle

The Efficiency of Green Technology Innovation and Its Influencing Factors in Wastewater Treatment Companies

by Xiaofeng Xu, Qiang Zhou, Xiangyu Chen, Yiqi Li and Yiqiu Jiang

Separations 2022, 9(10), 263; https://doi.org/10.3390/separations9100263 - 21 Sep 2022

Cited by 6 | Viewed by 2994

Abstract

To achieve the harmonious development of economic growth and the environment, nations must pay more attention to wastewater treatment and boost efficiency using green technology. This study applies the Malmquist-DEA model to assess the efficiency of green technology innovation in 19 Chinese wastewater treatment companies between 2017 and 2020. In addition, focus is placed on the core wastewater treatment technology of the companies with excellent performance, indicating how wastewater treatment companies may improve their green technology. The results of the study indicate that, first, the overall effectiveness of green technology innovation in companies follows a rising and then decreasing trend. In 2020, wastewater treatment companies’ green technology innovation efficiency was around 17.4 percent lower than in 2017. Improving technical progress is the key to boosting the total factor productivity of wastewater treatment companies. Second, based on the Tobit regression, the shareholding ratio of companies has a positive influence on the technical efficiency of companies. Therefore, China should increase innovation capacity and productivity, adopt current sewage treatment technology from overseas, and thus gradually achieve clean sewage utilization and ecological environment management. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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21 pages, 6589 KiB

Open AccessArticle

Synthesis, Characterization, and Performance Evaluation of Hybrid Waste Sludge Biochar for COD and Color Removal from Agro-Industrial Effluent

by Ahmad Hussaini Jagaba, Shamsul Rahman Mohamed Kutty, Sule Abubakar, Abdullahi Haruna Birniwa, Ibrahim Mohammed Lawal, Ibrahim Umaru, Abdullahi Kilaco Usman, Nura Shehu Aliyu Yaro, Nabil Al-Zaqri, Basheer M. Al-Maswari, Mohamad Nasir Mohamad Ibrahim and Fida Hussain

Separations 2022, 9(9), 258; https://doi.org/10.3390/separations9090258 - 13 Sep 2022

Cited by 30 | Viewed by 3244

Abstract

Agro-waste management processes are evolving through the development of novel experimental approaches to understand the mechanisms in reducing their pollution levels efficiently and economically from industrial effluents. Agro-industrial effluent (AIE) from biorefineries that contain high concentrations of COD and color are discharged into the ecosystem. Thus, the AIE from these biorefineries requires treatment prior to discharge. Therefore, the effectiveness of a continuous flow bioreactor system (CFBS) in the treatment of AIE using hybrid waste sludge biochar (HWSB) was investigated. The use of a bioreactor with hydraulic retention time (HRT) of 1–3 days and AIE concentrations of 10–50% was used in experiments based on a statistical design. AIE concentration and HRT were optimized using response surface methodology (RSM) as the process variables. The performance of CFBS was analyzed in terms of COD and color removal. Findings indicated 76.52% and 66.97% reduction in COD and color, respectively. During biokinetic studies, the modified Stover models were found to be perfectly suited for the observed measurements with R² values 0.9741 attained for COD. Maximum contaminants elimination was attained at 30% AIE and 2-day HRT. Thus, this study proves that the HWSB made from biomass waste can potentially help preserve nonrenewable resources and promote zero-waste attainment and principles of circular economy. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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18 pages, 3938 KiB

Open AccessArticle

Microplastics and Heavy Metals Removal from Fresh Water and Wastewater Systems Using a Membrane

by Simphiwe Dineo Nkosi, Soraya Phumzile Malinga and Nonhlangabezo Mabuba

Separations 2022, 9(7), 166; https://doi.org/10.3390/separations9070166 - 30 Jun 2022

Cited by 8 | Viewed by 5305

Abstract

Water pollution, resulting from the degradation of plastics into microplastics, exposes humans and other living organisms to contaminated drinking water. Microplastics are capable of adsorbing toxic heavy metals which are carcinogenic and may affect the reproductive functions of living organisms. Hence, this study focuses on the characterization and quantification of microplastics in water to raise the awareness and propose a method of dealing with this emerging pollutant in various aqueous environments. The microplastics were separated from water using polyvinylidene difluoride (PVDF) and PVDF modified with carbon nano-onions (CNOs). The PVDF exhibited the highest concentration of microplastics in the wastewater influent (140 ± 1.85 MP/L) compared to the effluent (8.8 ± 2.10 MP/L), tap water (6.5 ± 5.77 MP/L), and lake water (10 ± 2.65 MP/L). The stereo microscope displayed red, blue, and black colored plastics. The morphological properties were determined using SEM. ATR-FTIR, equipped with Spectrum 10 Spectroscopy Software was used to establish the presence of high-density polyethylene (50%), poly(1,4-butylene terephthalate) (16.6%), nylon 12 (16.6%), and cellulose (16.6%) in the influent. The quantification of heavy metals extracted from the microplastics indicated that the concentrations of As (1.759 to 8.699 mg/L), Cu (83.176 mg/L) and Zn (0.610 mg/L) were above the acceptable limits. Our work is beneficial for the development of a microplastics monitoring protocol for various municipalities. Water treatment plants may also include the treatment of microplastics in the influent and monitor the effluent before the water is released back into the environment. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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Review

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36 pages, 4971 KiB

Open AccessReview

A Comprehensive Review of the Developments in Electrocoagulation for the Removal of Contaminants from Wastewater

by Mohamed Ammar, Ezz Yousef, Muhammed A. Mahmoud, Sherif Ashraf and Jonas Baltrusaitis

Separations 2023, 10(6), 337; https://doi.org/10.3390/separations10060337 - 30 May 2023

Cited by 18 | Viewed by 6449

Abstract

Water organic pollution has become a major issue. A large number of people suffer from the decline in water quality. In addition, polluted water can lead to health problems or excessive deaths. In this regard, an increasingly important method for efficient water treatment is electrocoagulation (EC), the technology that encompasses a small equipment size combined with a simple operation compared to other water treatment methods. The importance of EC is especially accentuated by the recent decarbonization efforts due to the increasing availability of renewable electricity systems. This review provides an overview of the most recent developments in EC technology as it pertains to wastewater treatment. The EC is preferred for organic wastewater treatment over other traditional treatment methods due to its easy setup and low material costs. Moreover, the EC is very powerful in destabilizing organic impurities by charge neutralization and then coagulating to form flocs. In addition, EC has shown high efficiency not only in removing various organic pollutants but also in emerging persistent contaminants, such as microplastics. For these reasons, the EC mechanisms and related functional modalities are reviewed, as well as extensive details are provided on the diversity of the removed contaminants. Overall, this review provides significant new knowledge of interest for environmental chemical researchers in particular and engineers in general on the details of the EC technology for wastewater treatment and water purification. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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17 pages, 1385 KiB

Open AccessReview

Application of O₃/PMS Advanced Oxidation Technology in the Treatment of Organic Pollutants in Highly Concentrated Organic Wastewater: A Review

by Bojiao Yan, Qingpo Li, Xinglin Chen, Huan Deng, Weihao Feng and Hai Lu

Separations 2022, 9(12), 444; https://doi.org/10.3390/separations9120444 - 15 Dec 2022

Cited by 2 | Viewed by 2656

Abstract

The ozone/peroxymonosulfate (O₃/PMS) system has attracted widespread attention from researchers owing to its ability to produce hydroxyl radicals (•OH) and sulfate radicals (SO₄^•−) simultaneously. The existing research has shown that the O₃/PMS system significantly degrades refinery trace organic compounds (TrOCs) in highly concentrated organic wastewater. However, there is still a lack of systematic understanding of the O₃/PMS system, which has created a significant loophole in its application in the treatment of highly concentrated organic wastewater. Hence, this paper reviewed the specific degradation effect, toxicity change, reaction mechanism, various influencing factors and the cause of oxidation byproducts (OBPs) of various TrOCs when the O₃/PMS system is applied to the degradation of highly concentrated organic wastewater. In addition, the effects of different reaction conditions on the O₃/PMS system were comprehensively evaluated. Furthermore, given the limited understanding of the O₃/PMS system in the degradation of TrOCs and the formation of OBPs, an outlook on potential future research was presented. Finally, this paper comprehensively evaluated the degradation of TrOCs in highly concentrated organic wastewater by the O₃/PMS system, filling the gaps in scale research, operation cost, sustainability and overall feasibility. Full article

(This article belongs to the Special Issue Separation Processes for Effective Removal of Emerging Contaminants from Water and Wastewater)

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