Photocatalytic Applications in Wastewater Treatment

A special issue of Environments (ISSN 2076-3298).

Deadline for manuscript submissions: 30 July 2024 | Viewed by 6051

Special Issue Editors


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Guest Editor
Faculty of Environment and Life, Beijing University of Technology, Beijing, China
Interests: photocatalysis; advanced oxidation processes; ultrafast spectroscopy

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Guest Editor
College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
Interests: advanced oxidation processes; water treatment; environmental catalysis; green catalysts
Special Issues, Collections and Topics in MDPI journals

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Guest Editor
Department of Chemistry, Tsinghua University, Beijing, China
Interests: photocatalysis; organic semiconductor; reactive oxygen species

Special Issue Information

Dear Colleagues,

Wastewater treatment is a critical aspect of sustainable development and environmental protection, as it helps to maximize water conservation, achieve water circulation, and promote the harmonious coexistence between humans and nature. However, traditional wastewater treatment methods have some limitations, such as a high energy consumption, the generation of secondary pollutants, and limited efficiency regarding the degradation of complex organic compounds. Photocatalysis has emerged as a promising technology for the treatment of wastewater, owing to its sustainable and cost-effective approach to removing organic pollutants from wastewater.

The Special Issue entitled "Photocatalytic Applications in Wastewater Treatment" aims to gather the latest research, innovations, and advances in photocatalytic processes for the treatment of wastewater contaminated with various types of pollutants. We welcome the submission of papers that attend to various topics of interest, including the methods employed to synthesize novel photocatalysts, the advanced techniques used to characterize photocatalysts, the mechanisms involved in the photocatalytic degradation of organic pollutants, and the optimization of photocatalytic systems for wastewater treatment. Additionally, submissions that consider the integration of photocatalysis with other treatment processes, as well as the environmental and economic impacts of photocatalytic wastewater treatment, are welcome. While these topics are not exhaustive, they provide a comprehensive overview of this Special Issue’s areas of interest.

This Special Issue will provide valuable insights into the current state-of-the-art in photocatalytic wastewater treatment, which is a critical environmental challenge faced by many countries worldwide. The use of photocatalysis in wastewater treatment has the potential to significantly reduce the environmental impact of wastewater discharge and alleviate the burden on conventional treatment processes. We invite authors to submit contributions that will enhance our understanding of this emerging technology and its potential application in solutions that aim to mitigate the growing problem of wastewater pollution.

Prof. Dr. Zhen Wei
Dr. Yueping Bao
Dr. Wenlu Li
Guest Editors

Manuscript Submission Information

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Published Papers (4 papers)

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Research

17 pages, 6919 KiB  
Article
Life Cycle Assessment of Immobilised and Slurry Photocatalytic Systems for Removal of Natural Organic Matter in Water
by Dan C. A. Gowland, Neil Robertson and Efthalia Chatzisymeon
Environments 2024, 11(6), 114; https://doi.org/10.3390/environments11060114 - 28 May 2024
Viewed by 414
Abstract
This study investigates the environmental impacts caused by the scaling up of the photocatalytic purification of drinking water using ultraviolet light-emitting diode technology. The life cycle assessment methodology was utilised to estimate the environmental impacts of two different reactor setups commonly used in [...] Read more.
This study investigates the environmental impacts caused by the scaling up of the photocatalytic purification of drinking water using ultraviolet light-emitting diode technology. The life cycle assessment methodology was utilised to estimate the environmental impacts of two different reactor setups commonly used in lab-scale studies: an immobilised and a suspended TiO2 catalytic system. The functional unit adopted was the treatment of 1 L of water with an initial 7.8 mg/L concentration of natural organic matter, achieving a final 1 mg/L concentration. The use of a suspended photocatalyst was found to have an environmental footprint that was 87% lower than that of the immobilised one. From the sensitivity analysis, the environmental hotspots of the treatment process were the electricity usage and immobilised catalyst production. Therefore, alternative scenarios investigating the use of a renewable electricity mix and recyclable materials were explored to enhance the environmental performance of the photocatalytic treatment process. Using a renewable electricity mix, a decrease of 55% and 15% for the suspended and immobilised catalyst, respectively, was observed. Additionally, the process of recycling the glass used to support the immobilised catalyst achieved a maximum reduction of 22% in the environmental impact from the original scenario, with 100 glass reuses appearing to provide diminishing returns on the environmental impact savings. Full article
(This article belongs to the Special Issue Photocatalytic Applications in Wastewater Treatment)
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12 pages, 1462 KiB  
Article
Coupled Photocatalysis and Microalgal–Bacterial Synergy System for Continuously Treating Aquaculture Wastewater Containing Real Phthalate Esters
by Ying-Chien Chung and Chih-Yu Chen
Environments 2023, 10(12), 215; https://doi.org/10.3390/environments10120215 - 5 Dec 2023
Viewed by 1540
Abstract
We developed a system combining visible-light photocatalysis with biological treatment for the continuous removal of phthalate esters (PAEs) from both synthetic and real aquaculture wastewater. We investigated the effects of different operating factors, including the coexistence of glucose or PAEs, on individual PAE [...] Read more.
We developed a system combining visible-light photocatalysis with biological treatment for the continuous removal of phthalate esters (PAEs) from both synthetic and real aquaculture wastewater. We investigated the effects of different operating factors, including the coexistence of glucose or PAEs, on individual PAE removal by using a photobiological system (PBS). In wastewater containing a mixture of PAEs, that is, containing di-(2-ethylhexyl)phthalate (DEHP), dibutyl phthalate (DBP), and dimethyl phthalate (DMP), a coimmobilized bioreactor system comprising the bacterium Pseudomonas putida and the microalga Chlorella vulgaris demonstrated a higher removal efficiency than immobilized P. putida alone or a coculture of immobilized P. putida and suspended C. vulgaris did. The PBS employed for the continuous treatment of real aquaculture wastewater containing DEHP (0.62 ± 0.05 mg/L), DBP (8.7 ± 0.9 mg/L), and DMP (17.4 ± 1.5 mg/L) achieved at least 99.5% PAE removal and 99.2% mineralization efficiency under optimal operating conditions. After 42 days of treatment, inoculated Pseudomonas (98.12%) remained the predominant genus in the bioreactor. The results reveal that the symbiotic microalgal–bacterial system is a feasible alternative to a pure P. putida immobilized bioreactor for reducing CO2 emissions from mineralized PAEs through microalgal activity. Full article
(This article belongs to the Special Issue Photocatalytic Applications in Wastewater Treatment)
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20 pages, 3848 KiB  
Article
Effect of Pharmaceutical Compounds (Diclofenac, Ibuprofen, and Erythromycin) on the Heterotrophic Behaviors of Biomass of a Membrane Bioreactor to Treat Urban Wastewater
by Laura Antiñolo Bermúdez, Verónica Díaz Mendoza, José Manuel Poyatos Capilla, María del Mar Muñío Martínez and Jaime Martín Pascual
Environments 2023, 10(12), 198; https://doi.org/10.3390/environments10120198 - 22 Nov 2023
Viewed by 1676
Abstract
The increasing prevalence of pharmaceutical substances in wastewater is emerging as a pressing ecological issue on a global scale. The purpose of this study was to evaluate the biological influence of pharmaceutical compounds on the heterotrophic biomass residing in a membrane bioreactor. The [...] Read more.
The increasing prevalence of pharmaceutical substances in wastewater is emerging as a pressing ecological issue on a global scale. The purpose of this study was to evaluate the biological influence of pharmaceutical compounds on the heterotrophic biomass residing in a membrane bioreactor. The study examined the way microorganisms react to antibiotic and anti-inflammatory compounds, with the goal of proactively tackling potential issues and developing solutions that may emerge withing wastewater treatment plant bioreactors. Respirometric tests were carried out to determine the kinetic response of the heterotrophic biomass. The same study was carried out in the steady state of the plant under different conditions of hydraulic retention times (6 and 12 h) and biomass concentration (2888 ± 371 mg/L to 7477 ± 869 mg/L). A response surface statistical analysis was applied to determine the effect of the variables on the rate of substrate degradation for organic matter removal and the growth rate of net heterotrophic biomass. The results show that the biological response of the biomass is concerned when exposed to a combination of pharmaceutical substances such as ibuprofen, diclofenac, and erythromycin, in four cycles of operation at 16 varying concentrations of pharmaceuticals in each cycle. This suggests the presence of a synergistic effect among these pharmaceuticals, leading to a noticeable slower kinetic response in the biomass. Full article
(This article belongs to the Special Issue Photocatalytic Applications in Wastewater Treatment)
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10 pages, 6407 KiB  
Article
Effects of Substituting Activated Carbon with Titanium-Dioxide-Coated Cenospheres in Conventional Aquarium Filters
by Monika R. Snowdon, Robert F. L. Liang, Avneet Kaur, Erika A. Burton, Shasvat Rathod, Wenkai Fang, Hadi A. Dhiyebi, Leslie M. Bragg, Norman Y. Zhou, Mark R. Servos and Marina Freire-Gormaly
Environments 2023, 10(11), 188; https://doi.org/10.3390/environments10110188 - 31 Oct 2023
Viewed by 1539
Abstract
We investigated the effectiveness of TiO2 cenospheres in reducing the concentrations of three common harmful compounds, ammonium, nitrate, and nitrite, in fish aquariums. These cenospheres can contribute to more sustainable and eco-friendly aquarium filtration systems while also improving the health of fish. [...] Read more.
We investigated the effectiveness of TiO2 cenospheres in reducing the concentrations of three common harmful compounds, ammonium, nitrate, and nitrite, in fish aquariums. These cenospheres can contribute to more sustainable and eco-friendly aquarium filtration systems while also improving the health of fish. We designed a 30-day experiment with three treatment groups based on the filter type: (1) a control group with a conventional aquarium filter, (2) a group with a TiO2 cenosphere filter, and (3) a group with a dark TiO2 cenosphere filter. The water quality was the same baseline in all groups, and each tank was monitored daily for changes in temperature, pH, ammonia, nitrate, and nitrite concentrations. We found that the TiO2 cenosphere filter was effective in reducing the concentrations of all three pollutants. By the end of the experimental period, the average concentration of nitrite in the control group was 10.7 µM, while the average concentration in the TiO2 cenosphere filter group dropped 55% to 4.7 µM from the baseline. The average concentration of nitrate was reduced by 17% and ammonia by 28% in the cenosphere-treated group. Hence, the cenospheres were effective in reducing the concentrations of all three pollutants, with the greatest reduction seen for nitrite. These findings support further investigation for incorporating TiO2 cenospheres into aquarium filtration to help reduce the environmental burden of the aquarium industry. Full article
(This article belongs to the Special Issue Photocatalytic Applications in Wastewater Treatment)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Recent Strategies to Improve the Photocatalytic Activity of 2D SnS2 under Visible Light Irradiation

Ardiansyah Taufik 1 and Gimyeong Seong 2,*

Abstract: Tin (II) sulfide (SnS2) has emerged as one of the good candidates for visible light photocatalytic materials. As a member of the transition metal dichalcogenides (TMDs) family, SnS2 has a band gap of approximately 2.20 eV and a layered structure, making it a viable material for visible light activation with a high specific surface area. However, the application of SnS2 as a visible light photocatalyst still faces limitations such as high recombination of electrons and holes, as well as poor selectivity in its perfect crystal structure. Therefore, ongoing research focuses on strategies to improve the photocatalytic performance of SnS2. In this comprehensive review, we analyze recent advances and promising strategies for enhancing the photocatalytic performance of SnS2. Various approaches have been successfully reported, including controlling the reactive facets of SnS2, inducing defects in the crystal structure, manipulating morphologies, depositing noble metals, and forming heterostructures. We provide a detailed understanding of these phenomena as well as the preparation techniques involved. This review article aims to guide readers in considering the future potential applications of SnS2 as a promising visible light photocatalyst.

Keywords: SnS2; Photocatalytic; Visible Light; defect; heterostructure

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