Special Issue "Innovative Technology and Integrated Management for Wastewater Treatment and Reuse"

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Wastewater Treatment and Reuse".

Deadline for manuscript submissions: closed (10 January 2022) | Viewed by 4868

Special Issue Editors

Prof. Dr. Yongjun Sun
E-Mail Website
Guest Editor
College of Urban Construction, Nanjing Tech University, Nanjing 211816, China
Interests: flocculation and flocculants; coagulation and coagulants; industrial wastewater treatment; domestic sewage treatment; advanced oxidation technology
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Kinjal J. Shah
E-Mail Website
Guest Editor
College of Urban Construction, Nanjing Tech University, Nanjing 211816, China
Interests: green chemistry; water-energy-nexus; water treatment
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Recent developments threaten to compromise the safety and security of water for over two billion people due to dwindling clean water resources and limited water supplies. Meanwhile, the huge demand for clean water is rapidly rising due to population growth. The improper management of water resources, rapid growth of industrialization, and contamination of waterways are also increasing the difficulties. This situation is being exacerbated by climate change via changing rain patterns. Therefore, the United Nations has prioritized clean water in the Sustainable Development Goals (SDG-6). Globally, more than 80% of wastewater is discharged without any additional treatment; thus, there is a need to develop technology for untreated wastewater and subsequently increasing the recycling and reuse of water. The drivers of water/wastewater treatment require innovative technology, performance optimization, reduced environmental footprints, integration management and meeting regulatory requirements. All these factors should eventually lead the treatment of wastewater towards realizing the SDG developed by the United Nations.

Prof. Dr. Yongjun Sun
Prof. Dr. Kinjal J. Shah
Prof. Dr. Shu-Yuan Pan
Guest Editors

Manuscript Submission Information

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Keywords

  • water–energy nexus
  • hybrid treatment
  • clean water
  • municipal wastewater
  • low-cost technology
  • green technology
  • reclaimed water

Published Papers (6 papers)

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Research

Article
Catalytic Ozonation for Effective Degradation of Coal Chemical Biochemical Tail Water by Mn/[email protected] Catalyst
Water 2022, 14(2), 206; https://doi.org/10.3390/w14020206 - 11 Jan 2022
Viewed by 291
Abstract
An Mn/[email protected] mud (RM) catalyst was prepared from RM via a doping–calcination method. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterize the surface morphology, crystal morphology, and elemental composition of the Mn/[email protected] catalyst, respectively. In addition, preparation and [...] Read more.
An Mn/[email protected] mud (RM) catalyst was prepared from RM via a doping–calcination method. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were used to characterize the surface morphology, crystal morphology, and elemental composition of the Mn/[email protected] catalyst, respectively. In addition, preparation and catalytic ozonation conditions were optimized, and the mechanism of catalytic ozonation was discussed. Lastly, a fuzzy analytic hierarchy process (FAHP) was adopted to evaluate the degradation of coal chemical biochemical tail water. The best preparation conditions for the Mn/[email protected] catalyst were found to be as follows: (1) active component loading of 3%, (2) Mn/Ce doping ratio of 2:1, (3) calcination temperature of 550 °C, (4) calcination time of 240 min, and (5) fly ash floating bead doping of 10%. The chemical oxygen demand (COD) removal rate was 76.58% under this preparation condition. The characterization results suggested that the pore structure of the optimized Mn/[email protected] catalyst was significantly improved. Mn and Ce were successfully loaded on the catalyst in the form of MnO2 and CeO2. The best operating conditions in the study were as follows: (1) reaction time of 80 min, (2) initial pH of 9, (3) ozone dosage of 2.0 g/h, (4) catalyst dosage of 62.5 g/L, and (5) COD removal rate of 84.96%. Mechanism analysis results showed that hydroxyl radicals (•OH) played a leading role in degrading organics in the biochemical tail water, and adsorption of RM and direct oxidation of ozone played a secondary role. FAHP was established on the basis of environmental impact, economic benefit, and energy consumption. Comprehensive evaluation by FAHP demonstrated that D3 (with an ozone dosage of 2.0 g/H, a catalyst dosage of 62.5 g/L, initial pH of 9, reaction time of 80 min, and a COD removal rate of 84.96%) was the best operating condition. Full article
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Article
Removal of Cd (II) Ions from Bioretention System by Clay and Soil Wettability
Water 2021, 13(22), 3164; https://doi.org/10.3390/w13223164 - 10 Nov 2021
Cited by 2 | Viewed by 461
Abstract
In this work, a silane modifier with benzyl substitutes (OFS-B) and linear substitutes (OFS-L) was used to modify bentonite clay and soil, and the results were characterized by Fourier transform-infrared absorption spectroscopy (FT-IR) and powder-X-ray diffraction (XRD) analysis. A contact angle analysis was [...] Read more.
In this work, a silane modifier with benzyl substitutes (OFS-B) and linear substitutes (OFS-L) was used to modify bentonite clay and soil, and the results were characterized by Fourier transform-infrared absorption spectroscopy (FT-IR) and powder-X-ray diffraction (XRD) analysis. A contact angle analysis was performed to determine the wettability of modified clay and soil. The findings revealed that silane-modified OFS-L clay and soil produced wettable surfaces, while OFS-B exhibited hydrophobic properties. These clays and soils were used in a bioretention system for Cd (II) removal. In the study, seven different types of bioretention systems, including natural, OFS-L, and OFS-B modified clay and soil, as well as natural, OFS-L, and OFS-B modified soil, were applied to Cyperus alternifolius plants without an additional layer. The removal capacity of Cd (II) was measured in the following order: modified clay > modified soil > original clay/soil > no layer, i.e., 99.48%, 92.22%, 88.10/78.5%, and 30.0%, respectively. OFS-L removed more Cd (II) than OFS-B during the modification. OFS-L now improves the bioavailability and accumulation of Cd (II) in the plant (18.5 µg/g) and has a higher chlorophyll-b concentration (1.92 mg/g fresh weight) than other systems. The wettable clay exhibited clay leaching into the various levels of the bioretention system. In the bioretention system, benzyl substituted clay prevented the penetration of water and formed a Cd (II) agglomeration. When compared to non-wettable modifiers, these results indicated that wettable clay material could be a capable material for removing Cd (II). Full article
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Article
Quantitative Analysis of Malachite Green in Environmental Samples Using Liquid Chromatography-Mass Spectrometry
Water 2021, 13(20), 2864; https://doi.org/10.3390/w13202864 - 14 Oct 2021
Viewed by 675
Abstract
Water is an essential part of life, however, with continued modernization, it has become a dumping place for many pollutants including dyes. The polluted water can severely affect human health. Polluted water can enter into the human body through different channels, including the [...] Read more.
Water is an essential part of life, however, with continued modernization, it has become a dumping place for many pollutants including dyes. The polluted water can severely affect human health. Polluted water can enter into the human body through different channels, including the food web. Thus, it is very important for human beings and animals to have access to pollution free water. To get the knowledge of the pollutants, in this case, a dye, we need sensitive analytical procedure which could tell the amount of dye in water and also steps to get the pollutant removed from water. In this work, a liquid chromatography–mass spectrometry (LC-MS/MS) based analytical method was developed to determine malachite green. The method was developed after proper optimization of the experimental conditions, where finally, ethanol, a green solvent and formic acid, a food additive was selected to constitute the mobile phase in ratio 1.5:1.0. Different validation parameters were used to authenticate the reliability of the method. Based on the experiment results, the method was found to be linear in the range of 0.1 to 10 mg/L with an excellent correlation coefficient of 0.9995. The corresponding linear regression equation was found to be A = −6863.2 + 105,520 C; where A is the area of the peak and C is the concentration of malachite green. The precision study proves the reproducibility of LC-MS/MS procedure, throughout the precision experiment percent relative standard deviation (% RSD) was found to be between 0.709–1.893%. Similarly, the experiments on the recovery suggest a recovery of 97.28–98.75%. The new method was applied to check the amount of malachite green in environmental samples including the industrial wastewater. The wastewater sample was extracted using the solid phase extraction (SPE) technique, where a new adsorbent—wood apple hydrochar—was synthesized and used as the solid phase for the preparation of a solid phase extraction column to extract the malachite green. The synthesized adsorbent was characterized using different techniques. To conclude, the developed method can be used for determination of malachite green in environmental samples, and the SPE technique using wood apple hydrochar can successfully extract the dye from the water samples. Full article
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Article
Dairy Wastewater Treatment with Organic Coagulants: A Comparison of Factorial Designs
Water 2021, 13(16), 2240; https://doi.org/10.3390/w13162240 - 17 Aug 2021
Cited by 1 | Viewed by 864
Abstract
Optimization of coagulant dosage and pH to reduce the turbidity and chemical oxygen demand (COD) of synthetic dairy wastewater (SDW) was investigated using a full factorial design (FFD) and full factorial design with center point (FFDCP). Two organic coagulants, polyacrylamide (PAM) and Tanfloc [...] Read more.
Optimization of coagulant dosage and pH to reduce the turbidity and chemical oxygen demand (COD) of synthetic dairy wastewater (SDW) was investigated using a full factorial design (FFD) and full factorial design with center point (FFDCP). Two organic coagulants, polyacrylamide (PAM) and Tanfloc were used. The optimal values of coagulant dosage and pH were determined using a multiple response optimization tool and desirability function. The results obtained revealed that the optimum condition for removing turbidity and COD were at pH 5.0 using 50 mg L−1 of coagulant. The same optimum point was obtained in both experimental designs, indicating a good agreement between them. In optimum conditions, the expected removal of turbidity was above 98% with PAM and above 95% with Tanfloc. The estimated COD removal was above 72% with PAM and above 65% with Tanfloc. The addition of center points with replicates in the factorial design allowed to obtain the estimate of the experimental error with a smaller number of runs, allowing to save time and cost of the experimental tests. Moreover, the addition of center points did not affect the estimates of the factorial effects and it was possible to verify the effect of curvature, allowing obtaining information about the factors at intermediate levels. Full article
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Article
Treatment of Purified Terephthalic Acid Wastewater by Ozone Catalytic Oxidation Method
Water 2021, 13(14), 1906; https://doi.org/10.3390/w13141906 - 09 Jul 2021
Viewed by 933
Abstract
In this study, a Cu–[email protected] ozone catalyst with multiple active components was prepared through the impregnation method to treat purified terephthalic acid (PTA) wastewater, and characterized by X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy, specific surface area analysis, X-ray energy spectroscopy, X-ray [...] Read more.
In this study, a Cu–[email protected] ozone catalyst with multiple active components was prepared through the impregnation method to treat purified terephthalic acid (PTA) wastewater, and characterized by X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy, specific surface area analysis, X-ray energy spectroscopy, X-ray photoelectron spectroscopy, and other methods. The Cu–[email protected] ozone catalyst had a developed pore structure with a large specific surface area and crystal structure. After calcination, the metallic elements Cu and Ce existed in the state of oxides CuO and CeO2. The effects of reaction time, solution pH, catalyst dosage, and ozone dosage on the catalytic oxidation performance of the Cu–[email protected] ozone catalyst were studied. Adding tert-butanol reduced the removal rate of COD from the PTA wastewater through the catalytic oxidation system, which proves that a Cu–[email protected] ozone catalyst treatment process of PTA wastewater follows the free-radical reaction mechanism. The results of 3D fluorescence spectroscopy analysis show that the organic matter in the PTA wastewater was converted into tryptophan organic matter and aromatic organic matter after the reaction of the catalytic oxidation system. Ultraviolet absorption spectroscopy analysis indicated that in unsaturated chemical bonds, some conjugated structures and benzene ring structures of organic matter in the PTA wastewater were destroyed. Full article
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Article
Preparation and Characterization of High-Efficiency Magnetic Heavy Metal Capture Flocculants
Water 2021, 13(13), 1732; https://doi.org/10.3390/w13131732 - 23 Jun 2021
Cited by 1 | Viewed by 1007
Abstract
In this study, a high-efficiency magnetic heavy metal flocculant [email protected] was prepared based on carboxymethyl chitosan and magnetic Fe3O4. It was characterized by SEM, FTIR, XPS, XRD and VSM, and the Cu(II) removal rate was used as the evaluation [...] Read more.
In this study, a high-efficiency magnetic heavy metal flocculant [email protected] was prepared based on carboxymethyl chitosan and magnetic Fe3O4. It was characterized by SEM, FTIR, XPS, XRD and VSM, and the Cu(II) removal rate was used as the evaluation basis for the preparation process. The effects of AMPS content, total monomer concentration, photoinitiator concentration and reaction time on the performance of [email protected] flocculation to remove Cu(II) were studied. The characterization results show that [email protected] has been successfully prepared and exhibits good magnetic induction characteristics. The synthesis results show that under the conditions of 10% AMPS content, 35% total monomer concentration, 0.04% photoinitiator concentration, and 1.5 h reaction time, the best yield of [email protected] is 77.69%. The best removal rate is 87.65%. In addition, the response surface optimization of the synthesis process of [email protected] was performed. The optimal synthesis ratio was finally determined as iron content 6.5%, CMFS: 29.5%, AM: 53.9%, AMPS: 10.1%. High-efficiency magnetic heavy metal flocculant [email protected] shows excellent flocculation performance in removing Cu(II). This research provides guidance and ideas for the development of efficient and low-cost flocculation technology to remove Cu(II) in wastewater. Full article
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