International Journal of Environmental Research and Public Health

Research

13 pages, 1905 KiB

Open AccessArticle

Advanced Treatment of Coking Wastewater by Polyaluminum Silicate Sulfate for Organic Compounds Removal

by Jiangnan Wang, Fang Chang and Maosheng Zheng

Int. J. Environ. Res. Public Health 2023, 20(14), 6342; https://doi.org/10.3390/ijerph20146342 - 11 Jul 2023

Viewed by 1216

Coking wastewater is a typical high-strength organic wastewater, for which it is difficult to meet discharging standards with a single biological treatment. In this study, effective advanced treatment of coking wastewater was achieved by coagulation with freshly prepared polyaluminum silicate sulfate (PASS). The [...] Read more.

Coking wastewater is a typical high-strength organic wastewater, for which it is difficult to meet discharging standards with a single biological treatment. In this study, effective advanced treatment of coking wastewater was achieved by coagulation with freshly prepared polyaluminum silicate sulfate (PASS). The performance advantage was determined through comparison with commercial coagulants including ferric chloride, polyferric sulfate, aluminum sulfate and polyaluminum chloride. Both single-factor and Taguchi experiments were conducted to determine the optimal conditions for coagulation with COD_Cr and UV₂₅₄ as indicators. A dosage of 7 mmol/L PASS, flocculation velocity of 75 r/min, flocculation time of 30 min, pH of 7, and temperature of 20 °C could decrease the COD_Cr concentration from 196.67 mg/L to 59.94 mg/L. Enhanced coagulation could further help to remove the organic compounds, including pre-oxidation with ozonation, adsorption with activated carbon, assistant coagulation with polyacrylamide and secondary coagulation. UV spectrum scanning and gas chromatography-mass spectrometry revealed that the coagulation process effectively removed the majority of organic compounds, especially the high molecular weight alkanes and heterocyclic compounds. Coagulation with PASS provides an effective alternative for the advanced treatment of coking wastewater. Full article

(This article belongs to the Special Issue Wastewater Treatment Technologies and Analysis)

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15 pages, 3631 KiB

Open AccessArticle

Preparation and Coagulation Performance of Polyaluminum Lanthanum Silicate Coagulant

by Jie He, Qixuan Song and Jian He

Int. J. Environ. Res. Public Health 2023, 20(4), 2793; https://doi.org/10.3390/ijerph20042793 - 4 Feb 2023

Cited by 2 | Viewed by 1201

Abstract

In order to address the growing problem of water pollution caused by the excessive discharge of contaminants and provide a better aquatic ecosystem for the public, increasing attention has been paid to the harmlessness and efficiency of coagulation. In this study, polyaluminum lanthanum [...] Read more.

In order to address the growing problem of water pollution caused by the excessive discharge of contaminants and provide a better aquatic ecosystem for the public, increasing attention has been paid to the harmlessness and efficiency of coagulation. In this study, polyaluminum lanthanum silicate (PALS) was synthesized through co-polymerization as a novel coagulant to treat wastewater. FTIR, XRD, and SEM were used to analyze the morphology and structure of the material, which further confirmed that the PALS was successfully synthesized. The results indicated that PALS had a great performance in the treatment of a kaolin–humic acid suspension under the optimal synthesis conditions with Al/Si = 3, La/Si = 0.1, and basicity = 0.7. Compared with conventional coagulants, PALS exhibited a better performance at a low coagulant dose and could achieve a good removal effect for an ultraviolet wavelength less than 254 nm (UV₂₅₄) (83.87%), residual turbidity (0.49 NTU), and dissolved organic carbon (DOC) (69.57%) at the optimal conditions. Additionally, the PALS showed a better effect on phosphate removal than other coagulants did, where the removal efficiency could reach 99.60%. Charge neutralization and adsorption bridging were the potential wastewater treatment mechanisms employed by the PALS, which showed varied contributions under different pH levels. The results indicated that PALS can be a promising coagulant in water treatment. Full article

(This article belongs to the Special Issue Wastewater Treatment Technologies and Analysis)

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13 pages, 2210 KiB

Open AccessArticle

Biotransformation of 17β-Estradiol through a Denitrifying Sludge

by César Camacho-López, Claudia Romo-Gómez, Elena María Otazo-Sánchez, Otilio Arturo Acevedo-Sandoval, Edelmira García-Nieto and Libertad Juárez-Santacruz

Int. J. Environ. Res. Public Health 2022, 19(20), 13326; https://doi.org/10.3390/ijerph192013326 - 15 Oct 2022

Cited by 2 | Viewed by 1118

Abstract

17β-estradiol (E2) is the natural estrogen with the most significant potential for endocrine disruption in the biota of aquatic ecosystems at trace concentrations. It is, therefore, essential to study treatments for water polluted with E2 that would guarantee its complete elimination and mineralization. [...] Read more.

17β-estradiol (E2) is the natural estrogen with the most significant potential for endocrine disruption in the biota of aquatic ecosystems at trace concentrations. It is, therefore, essential to study treatments for water polluted with E2 that would guarantee its complete elimination and mineralization. Denitrification is a biological process shown to have the capacity to completely biodegrade drugs, such as ampicillin. This work is aimed to evaluate the biotransformation of 17β-estradiol by employing a denitrifying sludge. The assays performed were: (I) abiotic with 3.5 mg E2-C L⁻¹ and (II) denitrifying with 10 mg CH₃COO⁻-C L⁻¹ as the reference, 10 mg E2-C L⁻¹ as the sole electron donor, and a mixture of (mg L⁻¹) 10 E2-C with 10 CH₃COO⁻-C at C N⁻¹ of 1.1. The E2-C and NO₃⁻-N consumption efficiencies were greater than 99%, and HCO₃⁻-C and N₂ production yields were close to 1 in all assays. The denitrifying sludge could biodegrade up to 10 mg E2-C L⁻¹ as the sole electron donor and when mixed with 10 mg CH₃COO⁻-C L⁻¹. No intermediate metabolites were generated from the process. Full article

(This article belongs to the Special Issue Wastewater Treatment Technologies and Analysis)

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9 pages, 1123 KiB

Open AccessArticle

Removal of Polytungstate from Mine Wastewater Using a Flat Renewal Membrane Reactor with N1633 as a Carrier

by Liang Pei, Jia Duo and Linlin Chu

Int. J. Environ. Res. Public Health 2022, 19(17), 11092; https://doi.org/10.3390/ijerph191711092 - 5 Sep 2022

Viewed by 1058

Abstract

A novel flat renewal membrane reactor (FRMR) with mixed amine extractant N1633 dissolved in kerosene and NaOH solvent was studied for the removal of polytungstate [expressed as W₇O₂₄⁶⁻ or W (VI)] from simulated mine wastewater. FRMR contains three parts: [...] Read more.

A novel flat renewal membrane reactor (FRMR) with mixed amine extractant N1633 dissolved in kerosene and NaOH solvent was studied for the removal of polytungstate [expressed as W₇O₂₄⁶⁻ or W (VI)] from simulated mine wastewater. FRMR contains three parts: the feeding cell, reacting cell and renewal cell. A flat membrane of polyacrylonitrile (PAN) was used in the reacting cell, which used mixed solutions of kerosene and NaOH. The amine extractant (N1633) was used as the carrier, and simulated mine wastewater containing polytungstate was used as the feeding solution. The influencing factors of the pH and the other ion strengths in the feeding solutions, the volume ratio of kerosene to NaOH solution, and the N1633 concentration in the renewal solutions were investigated in order to obtain the optimum technique parameters. It was found that the removal percentage of polytungstate could reach 92.5% in 205 min, when the concentration of the carrier (N1633) was 0.18 mol/L, the volume ratio of kerosene and NaOH in the renewal cell was 3:2, the pH in the feeding cell was 4.00, and the initial concentration of polytungstate was 3.50 × 10⁻⁴ mol/L. The stability and feasibility of FRMR were tested by the investigation of polytungstate retention and the reuse of the membrane. Full article

(This article belongs to the Special Issue Wastewater Treatment Technologies and Analysis)

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12 pages, 2748 KiB

Open AccessArticle

Synthesis of CoFe₂O₄/Peanut Shell Powder Composites and the Associated Magnetic Solid Phase Extraction of Phenoxy Carboxylic Acid Herbicides in Water

by Dongliang Ji, Zhaoqin Huang and Buyun Du

Int. J. Environ. Res. Public Health 2022, 19(14), 8450; https://doi.org/10.3390/ijerph19148450 - 11 Jul 2022

Cited by 3 | Viewed by 1243

Abstract

The magnetic biochar material CoFe₂O₄/PCPS (peanut shell powder) was prepared based on the hybrid calcination method. The properties of prepared composites and the extraction effect of magnetic solid phase extraction on phenoxy carboxylic acid herbicides were assessed. The morphology, [...] Read more.

The magnetic biochar material CoFe₂O₄/PCPS (peanut shell powder) was prepared based on the hybrid calcination method. The properties of prepared composites and the extraction effect of magnetic solid phase extraction on phenoxy carboxylic acid herbicides were assessed. The morphology, crystal structure, specific surface area, and pore size distribution of the material were analysed using a transmission electron microscope (TEM), infrared Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and N₂ absorption surface analysis (BET). The results of the magnetic solid phase extraction of a variety of phenoxy carboxylic acid herbicides in water using CoFe₂O₄/PCPS composites showed that, when the mass ratio of CoFe₂O₄ and PCPS was 1:1, 40 mg of the composite was used, and the adsorption time was 10 min at pH 8.50. Methanol was used as the eluent, and the recovery rates of the three phenoxy carboxylic acid herbicides were maintained at 81.95–99.07%. Furthermore, the actual water sample analysis results showed that the established method had good accuracy, stability, and reliability. Full article

(This article belongs to the Special Issue Wastewater Treatment Technologies and Analysis)

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14 pages, 1342 KiB

Open AccessArticle

Dynamics of a Bacterial Community in the Anode and Cathode of Microbial Fuel Cells under Sulfadiazine Pressure

by Zhenzhen Yang, Hongna Li, Na Li, Muhammad Fahad Sardar, Tingting Song, Hong Zhu, Xuan Xing and Changxiong Zhu

Int. J. Environ. Res. Public Health 2022, 19(10), 6253; https://doi.org/10.3390/ijerph19106253 - 20 May 2022

Cited by 5 | Viewed by 1923

Abstract

Microbial fuel cells (MFCs) could achieve the removal of antibiotics and generate power in the meantime, a process in which the bacterial community structure played a key role. Previous work has mainly focused on microbes in the anode, while their role in the [...] Read more.

Microbial fuel cells (MFCs) could achieve the removal of antibiotics and generate power in the meantime, a process in which the bacterial community structure played a key role. Previous work has mainly focused on microbes in the anode, while their role in the cathode was seldomly mentioned. Thus, this study explored the bacterial community of both electrodes in MFCs under sulfadiazine (SDZ) pressure. The results showed that the addition of SDZ had a limited effect on the electrochemical performance, and the maximum output voltage was kept at 0.55 V. As the most abundant phylum, Proteobacteria played an important role in both the anode and cathode. Among them, Geobacter (40.30%) worked for power generation, while Xanthobacter (11.11%), Bradyrhizobium (9.04%), and Achromobacter (7.30%) functioned in SDZ removal. Actinobacteria mainly clustered in the cathode, in which Microbacterium (9.85%) was responsible for SDZ removal. Bacteroidetes, associated with the degradation of SDZ, showed no significant difference between the anode and cathode. Cathodic and part of anodic bacteria could remove SDZ efficiently in MFCs through synergistic interactions and produce metabolites for exoelectrogenic bacteria. The potential hosts of antibiotic resistance genes (ARGs) presented mainly at the anode, while cathodic bacteria might be responsible for ARGs reduction. This work elucidated the role of microorganisms and their synergistic interaction in MFCs and provided a reference to generate power and remove antibiotics using MFCs. Full article

(This article belongs to the Special Issue Wastewater Treatment Technologies and Analysis)

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16 pages, 1324 KiB

Open AccessArticle

The Role of Extracellular Polymeric Substances in the Toxicity Response of Anaerobic Granule Sludge to Different Metal Oxide Nanoparticles

by Huiting Li, Fang Chang, Zhendong Li and Fuyi Cui

Int. J. Environ. Res. Public Health 2022, 19(9), 5371; https://doi.org/10.3390/ijerph19095371 - 28 Apr 2022

Cited by 4 | Viewed by 1599

Abstract

Wastewater treatment plants (WWTP) are regarded as the last barriers for the release of incompletely separated and recycled nanoparticles (NPs) into the environment. Despite the importance and ubiquity of microbial extracellular polymeric substances (EPSs) in the complex wastewater matrix, the interaction between NPs [...] Read more.

Wastewater treatment plants (WWTP) are regarded as the last barriers for the release of incompletely separated and recycled nanoparticles (NPs) into the environment. Despite the importance and ubiquity of microbial extracellular polymeric substances (EPSs) in the complex wastewater matrix, the interaction between NPs and EPSs of anaerobic microflora involved in wastewater treatment and the resultant impact on the biomass metabolomics are unclear. Thus, the impacts of different metal oxide (TiO₂, ZnO, and CuO) NPs on functional bacteria in anaerobic granular sludge (AGS) and the possible toxicity mechanisms were investigated. In particular, the binding quality, enhanced resistance mechanism, and chemical fractional contribution of EPSs from AGS against the nanotoxicity of different NPs was assessed. The results showed that CuO NPs caused the most severe inhibition towards acetoclastic and hydrogenotrophic methanogens, followed by ZnO NPs, whereas TiO₂ NPs caused no inhibition to methanogenesis. Excessive EPS production, especially the protein-like substances, was an effective strategy for reducing certain NPs’ toxicity by immobilizing NPs away from AGS cells, whereas the metabolism restriction on inner microorganisms of AGS induced by CuO NPs can deteriorate the protective role of EPS, indicating that the roles of EPS may not be amenable to generalizations. Further investigations with lactate dehydrogenase (LDH) and reactive oxygen species (ROS) assays indicated that there are greatly essential differences between the toxicity mechanisms of metal NPs to AGS, which varied depending on the NPs’ type and dosage. In addition, dynamic changes in the responses of EPS content to different NPs can result in a significant shift in methanogenic and acidogenic microbial communities. Thus, the production and composition of EPSs will be a key factor in determining the fate and potential effect of NPs in the complex biological matrix. In conclusion, this study broadens the understanding of the inhibition mechanisms of metal oxide NPs on the AGS process, and the influence of EPSs on the fate, behavior, and toxicity of NPs. Full article

(This article belongs to the Special Issue Wastewater Treatment Technologies and Analysis)

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17 pages, 7301 KiB

Open AccessArticle

High Photocatalytic Activity of g-C₃N₄/La-N-TiO₂ Composite with Nanoscale Heterojunctions for Degradation of Ciprofloxacin

by Yanmin Yu, Ke Liu, Yangyang Zhang, Xuan Xing and Hua Li

Int. J. Environ. Res. Public Health 2022, 19(8), 4793; https://doi.org/10.3390/ijerph19084793 - 15 Apr 2022

Cited by 7 | Viewed by 2144

Abstract

Ciprofloxacin (CIP) in natural waters has been taken as a serious pollutant because of its hazardous biological and ecotoxicological effects. Here, a 3D nanocomposite photocatalyst g-C₃N₄/La-N-TiO₂ (CN/La-N-TiO₂) was successfully synthesized by a simple and reproducible in-situ [...] Read more.

Ciprofloxacin (CIP) in natural waters has been taken as a serious pollutant because of its hazardous biological and ecotoxicological effects. Here, a 3D nanocomposite photocatalyst g-C₃N₄/La-N-TiO₂ (CN/La-N-TiO₂) was successfully synthesized by a simple and reproducible in-situ synthetic method. The obtained composite was characterized by XRD, SEM, BET, TEM, mapping, IR, and UV-vis spectra. The photocatalytic degradation of ciprofloxacin was investigated by using CN/La-N-TiO₂ nanocomposite. The main influential factors such as pH of the solution, initial CIP concentration, catalyst dosage, and coexisting ions were investigated in detail. The fastest degradation of CIP occurred at a pH of about 6.5, and CIP (5 mg/L starting concentration) was completely degraded in about 60 min after exposure to the simulated solar light. The removal rates were rarely affected by Na⁺ (10 mg·L⁻¹), Ca²⁺ (10 mg·L⁻¹), Mg²⁺ (10 mg·L⁻¹), and urea (5 mg·L⁻¹), but decreased in the presence of NO₃⁻ (10 mg·L⁻¹). The findings indicate that CN/La-N-TiO₂ nanocomposite is a green and promising photocatalyst for large-scale applications and would be a candidate for the removal of the emerging antibiotics present in the water environment. Full article

(This article belongs to the Special Issue Wastewater Treatment Technologies and Analysis)

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