Submit to Separations Review for Separations Propose a Special Issue

Journal Menu

Journal Browser

Separation Technologies in Water and Wastewater Treatment and Resources Recovery

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Published Papers

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

Deadline for manuscript submissions: closed (20 January 2024) | Viewed by 14993

Share This Special Issue

Special Issue Editors

Dr. Małgorzata Szlachta

E-Mail Website
Guest Editor

1. Circular Economy Solutions Unit, Geological Survey of Finland, P.O. Box 96, FI-02151 Espoo, Finland
2. Faculty of Environmental Engineering, Wrocław University of Science and Technology, Wybrzeże S. Wyspiańkiego 27, 50-370 Wrocław, Poland
Interests: water quality; environmental chemistry; physicochemical treatment technologies; adsorption; ion exchange; electrochemical methods; industrial wastewater treatment; recovery of valuable elements

Dr. Izabela Kowalska

E-Mail Website
Guest Editor

Faculty of Environmental Engineering, Wrocław University of Science and Technology, Wybrzeże S. Wyspiańkiego 27, 50-370 Wrocław, Poland
Interests: pressure-driven membrane processes; membrane hybrid processes; membrane technology in environmental engineering; industrial wastewater treatment; recovery of valuable components from waste streams; environmental chemistry

Special Issue Information

Dear Colleagues,

An increasing world population results in a growing demand for water, food, energy, and minerals. This increase, coupled with aspirations to a higher material standard of living, is likely to substantially increase pressures on the environment and demand for resources. The application of state-of-the-art separation technologies and sustainable methods for recovery for strategically important elements from water and industrial wastewater supports the circular green economy concept. Furthermore, the circular economy approach drives the emergence of new innovative techniques and technological solutions in water and wastewater engineering. Hence, we are introducing this Special Issue to discuss the latest developments and trends in separation processes in this field and achievements in separation technologies to recover valuable elements from water and wastewater, emphasizing the water-intensive industrial sectors.

Original research and review papers are welcome, and topics of interest include but are not limited to:

Advanced separation methods for water and industrial wastewater treatment;
Modified or improved separation techniques;
Processes simulation and modeling;
Recovery of metals, minerals, and nutrients;
Novel and highly efficient separation materials.

Dr. Małgorzata Szlachta
Dr. Izabela Kowalska
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

Separation techniques
Water treatment
Wastewater treatment
Resource recovery
Critical raw materials
Inorganic contaminants
Organic contaminants

Published Papers (6 papers)

Download All Papers

Research

Jump to: Review

20 pages, 4458 KiB

Open AccessArticle

A Fixed-Bed Column with an Agro-Waste Biomass Composite for Controlled Separation of Sulfate from Aqueous Media

by Mostafa Solgi, Bernd G. K. Steiger and Lee D. Wilson

Separations 2023, 10(4), 262; https://doi.org/10.3390/separations10040262 - 17 Apr 2023

Cited by 6 | Viewed by 1737

Abstract

An agro-waste composite with a pelletized form was prepared and characterized via IR and ¹³C solids NMR spectroscopy. Thermal gravimetry analysis (TGA) was used to study the weight loss profiles, while SEM images provided insight on the biocomposite morphology, along with characterization of the sulfate adsorption properties under equilibrium and dynamic conditions. The sulfate monolayer adsorption capacity (q_e = 23 mg/g) of the prepared agro-waste pellets was estimated from the adsorption isotherm results by employing the Langmuir model, and comparable fitting results were obtained by the Freundlich model. The dynamic adsorption properties were investigated via adsorption studies with a fixed bed column at pH 5.2. The effects of various parameters, including flow rate, bed height and initial concentrations of sulfate, were evaluated to estimate the optimal conditions for the separation of sulfate. The experimental data of the breakthrough curves were analyzed using the Thomas and Yoon–Nelson models, which provided satisfactory best-fits for the fixed bed kinetic adsorption results. The predicted adsorption capacities for all samples according to the Thomas model concur with the experimental values. The optimum conditions reported herein afford the highest dynamic adsorption capacity (30 mg/g) as follows: 1100 mg/L initial sulfate concentration, 30 cm bed height and 5 mL/min flow rate. The breakthrough time was measured to be 550 min. This study contributes to a strategy for controlled separation of sulfate using a sustainable biocomposite material that is suitable for fixed-bed column point-of-use water treatment systems. Full article

(This article belongs to the Special Issue Separation Technologies in Water and Wastewater Treatment and Resources Recovery)

► Show Figures

Graphical abstract

15 pages, 2820 KiB

Open AccessEditor’s ChoiceArticle

Effect of Surfactants on Reverse Osmosis Membrane Performance

by Aymen Halleb, Mitsutoshi Nakajima, Fumio Yokoyama and Marcos Antonio Neves

Separations 2023, 10(3), 168; https://doi.org/10.3390/separations10030168 - 02 Mar 2023

Cited by 3 | Viewed by 2407

Abstract

The aim of this study was to evaluate the performance of a reverse osmosis (RO) membrane in surfactant removal using various surfactant model aqueous solutions. The separation tests were performed with laboratory scale units in a dead-end configuration. Cellulose Acetate (CA) and Polyamide (PA) RO membranes were used with nonionic, anionic, or cationic surfactants at a wide range of concentrations. Membrane performance was evaluated using permeate flux and total organic carbon (TOC) rejection. The effects of surfactant type and concentration on RO membranes were assessed. Permeate flux of the PA membrane depended on the surfactant type and concentration. The separation of cationic surfactant aqueous solutions yielded the lowest permeate flux, followed by nonionic and anionic surfactant aqueous solutions, respectively. Surfactant adsorption on the membrane surface occurred at very low concentration of cationic and nonionic surfactants due to electrostatic and hydrophobic interactions, respectively, which affected permeate flux, and micelles did not affect the permeate flux of PA membrane. However, for CA membrane the permeate flux was not affected by the feed solution. Both membranes exhibited satisfactory TOC rejection (92–99%). This study highlights the importance of assessing interactions between membrane material and surfactant molecules to mitigate membrane fouling and guarantee a better performance of the RO membrane. Full article

(This article belongs to the Special Issue Separation Technologies in Water and Wastewater Treatment and Resources Recovery)

► Show Figures

Figure 1

23 pages, 5474 KiB

Open AccessArticle

Polymer-Based Nano-Adsorbent for the Removal of Lead Ions: Kinetics Studies and Optimization by Response Surface Methodology

by Abdullahi Haruna Birniwa, Sana Kehili, Mujahid Ali, Haruna Musa, Umar Ali, Shamsul Rahman Mohamed Kutty, Ahmad Hussaini Jagaba, Shehu Sa’ad Abdullahi, Elsayed Mohamed Tag-Eldin and Habibun Nabi Muhammad Ekramul Mahmud

Separations 2022, 9(11), 356; https://doi.org/10.3390/separations9110356 - 08 Nov 2022

Cited by 26 | Viewed by 2806

Abstract

This work successfully created a polypyrrole-polyethyleneimine (PPy-PEI) nano adsorbent for the elimination of the lead ion Pb²⁺ from an aqueous solution. An efficient conducting polymer-based adsorbent called as was created using ammonium persulfate (NH4)₂S₂O₈ as an oxidant (PPy-PEI). The PEI hyper-branched polymer with terminal amino groups was added to the PPy adsorbent to offer heavy metals more effective chelating sites. Pb²⁺ removal from aqueous solution using polyethyleneimine micro adsorbent was successfully accomplished using a batch equilibrium technique (PPy-PEI). The generated water-insoluble polymer nanoadsorbent had enough nitrogen atoms; therefore, an effort was made to link PEI, a water-soluble PPy, with PPy, a conjugated polymer, for lead ion adsorption from an aqueous solution. The generated PPy-PEI nanoadsorbents were discovered to have average particle sizes of 18–34 nm and a Brunauer-Emmet-Teller surface area of 17 m²/g, respectively. The thermal behavior of the composites was investigated using thermo gravimetric and differential scanning calorimetric methods. The lead ion adsorption efficacy of pure polypyrrole was found to be 38%; however, a batch equilibrium technique employing nanoadsorbent revealed with the maximum adsorption capacity of 75.60 mg g⁻¹. At pH 10 and 30 min of contact time at 50 °C, 0.2 g of adsorption was shown to be the ideal dosage. X-ray diffraction analysis, energy-dispersive ray spectroscopy, and Fourier transform infrared ray spectrum support the lead ion adsorption by PPy-PEI nanoadsorbents. The cauli-like structure was visible using field emission scanning electron microscopy. Studying the thermodynamic showed that the adsorption was endothermic as illustrated from the positive value of value of ΔH° is 1.439 kJ/mol which indicates that the uptake of Pb²⁺ onto nanoadsorbent PPy-PEI could be attributed to a physical adsorption process. According to the values of ΔG°, the adsorption process was spontaneous at all selected temperatures. The positive value of ΔS° value (43.52 j/mol) suggested an increase in the randomness at the solid/solution interface during the adsorption process. The adsorption data meet the pseudo-second-order kinetic model and suited the Langumuir isothermal model effectively. Full article

(This article belongs to the Special Issue Separation Technologies in Water and Wastewater Treatment and Resources Recovery)

► Show Figures

Figure 1

24 pages, 2578 KiB

Open AccessArticle

Techno-Economic Analysis of Brine Treatment by Multi-Crystallization Separation Process for Zero Liquid Discharge

by Kristofer Poirier, Najah Al Mhanna and Kumar Patchigolla

Separations 2022, 9(10), 295; https://doi.org/10.3390/separations9100295 - 08 Oct 2022

Cited by 4 | Viewed by 3409

Abstract

This study analyses the concept of a novel multi-crystallization system to achieve zero liquid discharge (ZLD) for desalination plants using an innovative heat recovery system consisting of a heat transfer fluid and a compressor to reduce energy consumption. The main focus is to recover water and separately extract salts from seawater brines with high purity, including calcite, anhydrite, sodium chloride, and epsomite, which can be sold to the cement industry. The system is compared with a conventional brine treatment system. The energy demand and economic feasibility of both systems are assessed to evaluate profitability at a scale of 1000 kg/h. The results estimate that the utilization of a heat recovery fluid reduces energy consumption from 690 kWh_th/ton of feed brine to 125.90 kWh_th/ton equaling a total electric consumption of 60.72 kWh_e/ton. The system can recover 99.2% of water and reduce brine discharge mass by 98.9%. The system can recover 53.8% of calcite at near 100% purity, 96.4% of anhydrite at 97.7% purity, 91.6% of NaCl at near 100% purity, and 71.1% of epsomite at 40.7% purity. Resource recovery accounts for additional revenues, with halite and water accounting respectively for 69.85% and 29.52% of the income. The contribution of calcite and anhydrite to revenue is very low due to their low production. The levelized cost of water (LCOW) of the multi-crystallization system is 13.79 USD/m³ as opposed to 7.85 USD/m³ for the conventional ZLD system. The economic analyses estimate that the conventional ZLD system can achieve payback after 7.69 years. The high electricity cost, which accounts for 68.7% of the annual expenses, can be produced from renewable sources. Full article

(This article belongs to the Special Issue Separation Technologies in Water and Wastewater Treatment and Resources Recovery)

► Show Figures

Figure 1

19 pages, 4600 KiB

Open AccessArticle

Recovery of Palladium and Gold from PGM Ore and Concentrates Using ZnAl-Layered Double Hydroxide@zeolitic Imidazolate Framework-8 Nanocomposite

by Nkositetile Raphael Biata, Silindokuhle Jakavula, Anele Mpupa, Richard M. Moutloali and Philiswa Nosizo Nomngongo

Separations 2022, 9(10), 274; https://doi.org/10.3390/separations9100274 - 30 Sep 2022

Cited by 2 | Viewed by 1677

Abstract

Gold (Au) and palladium (Pd) are platinum group metals (PGMs) that are considered critical in society because they are required in several industrial applications. Their shortage has caused the urgent need for their recovery from secondary resources. Therefore, there is a need to develop functional materials with high adsorption capacity and selectivity for recovery of PGMs from various secondary sources. In this study, a Zn-Al-layered double hydroxide@zeolitic imidazolate framework-8 (Zn–Al–LDH@ZIF–8) nanocomposite was used as an adsorbent for the recovery of Au and Pd from ore concentrates. The Zn–Al–LDH@ZIF–8 nanocomposite was characterised using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, zeta potential, and X-ray diffraction (XRD) spectroscopy. The recovery of Au(III) and Pd(II) was achieved using ultrasound-assisted dispersive µ-solid-phase extraction (UA-D-µ-SPE) and their quantification was attained using an inductively coupled plasma mass spectrometer (ICP-MS). The results showed that the surface of the adsorbent remained positively charged in a wide pH range, which endowed the nanocomposite with high adsorption affinity towards Au(III) and Pd(II). Under optimised conditions, the equilibrium studies revealed that the adsorption of Au(III) and Pd(II) ions followed the Langmuir isotherm model with maximum sorption capacities of 163 mg g⁻¹ and 177 mg g⁻¹ for Au(III) and Pd(II), respectively. The nanocomposite possessed relatively good regeneration, reusability, and stability characteristics, with its performance decreasing by only 10% after five adsorption–desorption cycles. Full article

(This article belongs to the Special Issue Separation Technologies in Water and Wastewater Treatment and Resources Recovery)

► Show Figures

Figure 1

Review

Jump to: Research

25 pages, 1608 KiB

Open AccessReview

Research Progress on Process-Intensified Water Treatment Applications

by Turkan Kopac

Separations 2022, 9(11), 353; https://doi.org/10.3390/separations9110353 - 07 Nov 2022

Cited by 2 | Viewed by 1581

Abstract

Process intensification (PI) is aimed towards essentially smaller, cleaner, safer, energy-efficient sustainable technologies involving the application of a number of strategies, including reducing the number of devices, miniaturization, process integration, improving mass and heat transfer, novel energy and separation techniques and combined optimization and control methodologies. Over the recent years, PI has attracted attention in the domain of aqueous medium adsorptive separations and wastewater treatment as well. Thus far, a limited number of investigations have appeared in the literature; in addition, there is yet a lack of published methods to follow the intensified solutions for processes in wastewater treatment. In this connection, this article aims to present an overview of the recent applications and advances in process-intensified decolorization of dyes; removal of aromatic hydrocarbons from wastewaters; and recovery of proteins, heavy metals and rare earth elements from aqueous media. Selected applications have been identified in terms of the PI techniques, and the corresponding process improvements have been discussed for a variety of examples with the aim of contributing to the future progress of applications. It has been confirmed that considerable process improvements could be possible, such as intensified process efficiency, improved adsorption and separation performance, and minimized sorbent requirement and processing time. Even though there have been considerable developments in the field, there is still a need for further developments for the enhancement of the technologies in adsorption wastewater treatment using a systems approach. Full article

(This article belongs to the Special Issue Separation Technologies in Water and Wastewater Treatment and Resources Recovery)

► Show Figures