Research

12 pages, 1386 KiB

Open AccessArticle

Metabolic Functional Community Diversity of Associated Bacteria during the Degradation of Phytoplankton from a Drinking Water Reservoir

by Sheng-Nan Chen, Pan-Lu Shang, Peng-Liang Kang and Man-Man Du

Int. J. Environ. Res. Public Health 2020, 17(5), 1687; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph17051687 - 05 Mar 2020

Cited by 7 | Viewed by 2218

Abstract

In the drinking water reservoir ecosystem, phytoplankton and bacteria play important roles in shaping freshwater health and function. In this work, the associated bacterial community functional diversity during degradation of phytoplankton was determined using the substrate utilization profiling (BIOLOG) technique, meanwhile, the composition [...] Read more.

In the drinking water reservoir ecosystem, phytoplankton and bacteria play important roles in shaping freshwater health and function. In this work, the associated bacterial community functional diversity during degradation of phytoplankton was determined using the substrate utilization profiling (BIOLOG) technique, meanwhile, the composition and concentration of phytoplankton were examined using a microscope. The results indicated that Euglena decreased 58.33% from 0 to 38 d, while the smallest degradation of Bacillariophyta was 20.19%. Average well color development (AWCD_590nm) increased during the static periods from 0 to 38 d; however, the AWCD_590nm of 18 and 38 d had no significant difference (p < 0.05). The Simpson’s index (D) was in accordance with Shannon’s diversity (H) and species richness(S); it was measured to be18 > 38 > 5 > 0 d. There were significant differences in the pattern and level of carbon sources used by the phytoplankton-associated bacteria. In addition, the principle component analyses (PCA) suggested that the first principle component (PC1) and the second principle component (PC2) explained 46.76% and 21.49% of the total variation for bacterial community, respectively. Redundancy analysis (RDA) revealed that cell abundance of phytoplankton was negatively correlated with the AWCD_590nm, amino acids and other functional indexes. Therefore, the data suggest that there are differences in the phytoplankton-associated bacterial community functional diversity during different static stages of water samples collected from the drinking water reservoir. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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13 pages, 1749 KiB

Open AccessArticle

Effects of Pre-Oxidation on Haloacetonitrile and Trichloronitromethane Formation during Subsequent Chlorination of Nitrogenous Organic Compounds

by Ao Wang, Chenshuo Lin, Zhen Shen, Zhigang Liu, Hang Xu, Jiapei Cheng and Xin Wen

Int. J. Environ. Res. Public Health 2020, 17(3), 1046; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph17031046 - 07 Feb 2020

Cited by 7 | Viewed by 2403

Abstract

The reaction between organic matter and disinfectants leads to the formation of disinfection byproducts (DBPs) in drinking water. With the improvement of detection technology and in-depth research, more than 1000 kinds of DBPs have been detected in drinking water. Nitrogenous DBPs (N-DBPs) are [...] Read more.

The reaction between organic matter and disinfectants leads to the formation of disinfection byproducts (DBPs) in drinking water. With the improvement of detection technology and in-depth research, more than 1000 kinds of DBPs have been detected in drinking water. Nitrogenous DBPs (N-DBPs) are more genotoxic and cytotoxic than the regulated DBPs. The main methods are enhanced coagulation, pretreatment, and depth technologies which based are on conventional technology. Amino acids (AAs) are widely found in surface waters and play an important role by providing precursors from which toxic nitrogenous disinfection by-products (N-DBPs) are generated in chlorinated drinking water. The formation of N-DBPs, including dichloroacetonitrile, trichloroacetonitrile, and trichloronitromethane (TCNM), was investigated by analyzing chlorinated water using ozone (OZ), permanganate (PM), and ferrate (Fe(VI)) pre-oxidation processes. This paper has considered the control of pre-oxidation over N-DBPs formation of AAs, OZ, PM, and Fe(VI) pre-oxidation reduced the haloacetonitrile formation in the downstream chlorination. PM pre-oxidation decreased the TCNM formation during the subsequent chlorination, while Fe(VI) pre-oxidation had no significant influence on the TCNM formation, and OZ pre-oxidation increased the formation. OZ pre-oxidation formed the lowest degree of bromine substitution during subsequent chlorination of aspartic acid in the presence of bromide. Among the three oxidants, PM pre-oxidation was expected to be the best choice for reducing the estimated genotoxicity and cytotoxicity of the sum of the measured haloacetonitriles (HANs) and TCNM without bromide. Fe(VI) pre-oxidation had the best performance in the presence of bromide. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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9 pages, 1541 KiB

Open AccessArticle

Responses of Periphyton Microbial Growth, Activity, and Pollutant Removal Efficiency to Cu Exposure

by Wei Zhong, Weiqun Zhao and Jianhui Song

Int. J. Environ. Res. Public Health 2020, 17(3), 941; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph17030941 - 03 Feb 2020

Cited by 4 | Viewed by 2227

Abstract

Periphyton is an effective matrix for the removal of pollutants in wastewater and has been considered a promising method of bioremediation. However, it still needs to be verified whether periphyton can maintain microbial activity and pollutant removal efficiency when dealing with the influence [...] Read more.

Periphyton is an effective matrix for the removal of pollutants in wastewater and has been considered a promising method of bioremediation. However, it still needs to be verified whether periphyton can maintain microbial activity and pollutant removal efficiency when dealing with the influence with complex components, and the underlying mechanisms of periphyton need to be revealed further. Herein, this study investigated the microbial growth, activity and functional responses of periphyton after removal of Cu from wastewater. Results showed that the cultivated periphyton was dominated by filamentous algae, and high Cu removal efficiencies by periphyton were obtained after 108 h treatments. Although 2 mg/L Cu²⁺ changed the microalgal growth (decreasing the contents of total chlorophyll-a (Chla), the carbon source utilization and microbial metabolic activity in periphyton were not significantly affected and even increased by 2 mg/L Cu²⁺. Moreover, chemical oxygen demand (COD) removal rates were sustained after 0.5 and 2 mg/L Cu²⁺ treatments. Our work showed that periphyton had strong tolerance and resistance on Cu stress and is environmentally friendly in dealing with wastewater containing heavy metals, as the microbial functions in pollutant removal could be maintained. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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13 pages, 4334 KiB

Open AccessArticle

Adsorption of Phenol on Commercial Activated Carbons: Modelling and Interpretation

by Bingxin Xie, Jihong Qin, Shu Wang, Xin Li, Hui Sun and Wenqing Chen

Int. J. Environ. Res. Public Health 2020, 17(3), 789; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph17030789 - 28 Jan 2020

Cited by 61 | Viewed by 5040

Abstract

Adsorption by activated carbons (AC) is an effective option for phenolic wastewater treatment. Three commercial AC, including coal-derived granular activated carbons (GAC₉₅₀), coal-derived powdered activated carbons (PAC₈₀₀), and coconut shell-derived powdered activated carbons (PAC₁₀₀₀), were utilized as [...] Read more.

Adsorption by activated carbons (AC) is an effective option for phenolic wastewater treatment. Three commercial AC, including coal-derived granular activated carbons (GAC₉₅₀), coal-derived powdered activated carbons (PAC₈₀₀), and coconut shell-derived powdered activated carbons (PAC₁₀₀₀), were utilized as adsorbent to study its viability and efficiency for phenol removal from wastewater. Pseudo-first order, pseudo-second order, and the Weber–Morris kinetic models were used to find out the kinetic parameters and mechanism of adsorption process. Further, to describe the equilibrium isotherms, the experimental data were analyzed by the Langmuir and Freundlich isotherm models. According to the experimental results, AC presented a micro/mesoporous structure, and the removal of phenol by AC was affected by initial phenol concentration, contact time, pH, temperature, and humic acid (HA) concentration. The pseudo-second order kinetic and Langmuir models were found to fit the experimental data very well, and the maximum adsorption capacity was 169.91, 176.58, and 212.96 mg/g for GAC₉₅₀, PAC₈₀₀, and PAC₁₀₀₀, respectively, which was attributed to differences in their precursors and physical appearance. Finally, it was hard for phenol to be desorbed in a natural environment, which confirmed that commercial AC are effective adsorbents for phenol removal from effluent wastewater. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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14 pages, 25096 KiB

Open AccessArticle

Designing Electric Field Responsive Ultrafiltration Membranes by Controlled Grafting of Poly (Ionic Liquid) Brush

by Tejas Tripathi, Mohanad Kamaz, S. Ranil Wickramasinghe and Arijit Sengupta

Int. J. Environ. Res. Public Health 2020, 17(1), 271; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph17010271 - 30 Dec 2019

Cited by 16 | Viewed by 4982

Abstract

Electric responsive membranes have been prepared by controlled surface grafting of poly (ionic liquid) (PIL) on the commercially available regenerated cellulose ultrafiltration membrane. The incorporation of imidazolium ring on membrane surface was evidenced by FTIR (Fourier transformed infra-red) and EDX (energy-dispersive X-ray) spectroscopy. [...] Read more.

Electric responsive membranes have been prepared by controlled surface grafting of poly (ionic liquid) (PIL) on the commercially available regenerated cellulose ultrafiltration membrane. The incorporation of imidazolium ring on membrane surface was evidenced by FTIR (Fourier transformed infra-red) and EDX (energy-dispersive X-ray) spectroscopy. The PIL grafting resultedin a rougher surface, reduction in pore size, and enhancement in hydrophilicity. The interaction of the electric field between the charged PIL brush and the oscillating external electric field leads to micromixing, and hence it is proposed to break the concentration polarization. This micromixing improves the antifouling properties of the responsive membranes. The local perturbation was found to decrease the water flux, while it enhanced protein rejection. At a higher frequency (1kHz) of the applied electric field, the localized heating predominates compared to micromixing. In the case of a lower frequency of the applied electric field, more perturbation can lead to less permeability, whereas it will have a better effect in breaking the concentration polarization. However, during localized heating at a higher frequency, though perturbation is less, a heating induced reduction in permeability was observed. The electric field response of the membrane was found to be reversible in nature, and hence has no memory effect. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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16 pages, 8416 KiB

Open AccessArticle

Fabrication of a Novel Antifouling Polysulfone Membrane with in Situ Embedment of Mxene Nanosheets

by Zhen Shen, Wei Chen, Hang Xu, Wen Yang, Qing Kong, Ao Wang, Mingmei Ding and Juan Shang

Int. J. Environ. Res. Public Health 2019, 16(23), 4659; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16234659 - 22 Nov 2019

Cited by 63 | Viewed by 4197

Abstract

Membrane fouling is still a critical issue for the application of ultrafiltration, which has been widely used in water treatment due to its efficiency and simplicity. In order to improve the antifouling property, a new 2D material MXene was used to fabricate composite [...] Read more.

Membrane fouling is still a critical issue for the application of ultrafiltration, which has been widely used in water treatment due to its efficiency and simplicity. In order to improve the antifouling property, a new 2D material MXene was used to fabricate composite ultrafiltration membrane with the approach of in situ embedment during the phase inversion process in this study. Scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), water contact angle, bovine serum albumin rejection and porosity measurements were utilized to characterize the prepared membranes. Due to the hydrophilicity of the MXene, the composite membranes obtained higher hydrophilicity, confirmed by the decreased water contact angle. All the modified membranes had a high bovine serum albumin rejection above 90% while that of the pristine polysulfone membrane was 77.48%. The flux recovery ratio and the reversible fouling ratio of the membranes were also improved along with the increasing content of the MXene. Furthermore, the highest flux recovery ratio could also reach 76.1%. These indicated the good antifouling properties of MXene composite membranes. The enhanced water permeability and protein rejection and excellent antifouling properties make MXene a promising material for antifouling membrane modification. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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15 pages, 3349 KiB

Open AccessArticle

Mechanism Underlying Flow Velocity and Its Corresponding Influence on the Growth of Euglena gracilis, a Dominant Bloom Species in Reservoirs

by Yi Tan, Jia Li, Linglei Zhang, Min Chen, Yaowen Zhang and Ruidong An

Int. J. Environ. Res. Public Health 2019, 16(23), 4641; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16234641 - 22 Nov 2019

Cited by 10 | Viewed by 2985

Abstract

The effects of hydrodynamics on algae growth have received considerable attention, and flow velocity is one of the most frequently discussed factors. For Euglena gracilis, which aggregates resources and is highly resistant to environmental changes, the mechanism underlying the impact of flow [...] Read more.

The effects of hydrodynamics on algae growth have received considerable attention, and flow velocity is one of the most frequently discussed factors. For Euglena gracilis, which aggregates resources and is highly resistant to environmental changes, the mechanism underlying the impact of flow velocity on its growth is poorly understood. Experiments were conducted to examine the response of algae growth to different velocities, and several enzymes were tested to determine their physiological mechanisms. Significant differences in the growth of E. gracilis were found at different flow velocities, and this phenomenon is unique compared to the growth of other algal species. With increasing flow velocity and time, the growth of E. gracilis is gradually inhibited. In particular, we found that the pioneer enzyme is peroxidase (POD) and that the main antioxidant enzyme is catalase (CAT) when E. gracilis experiences flow velocity stress. Hysteresis between total phosphorus (TP) consumption and alkaline phosphatase (AKP) synthesis was observed. Under experimental control conditions, the results indicate that flow velocities above 0.1 m/s may inhibit growth and that E. gracilis prefers a relatively slow or even static flow velocity, and this finding could be beneficial for the control of E. gracilis blooms. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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12 pages, 1319 KiB

Open AccessArticle

Effects of Nanoplastics on Freshwater Biofilm Microbial Metabolic Functions as Determined by BIOLOG ECO Microplates

by Lingzhan Miao, Song Guo, Zhilin Liu, Songqi Liu, Guoxiang You, Hao Qu and Jun Hou

Int. J. Environ. Res. Public Health 2019, 16(23), 4639; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16234639 - 21 Nov 2019

Cited by 35 | Viewed by 4335

Abstract

Nanoplastic (NP) contamination is becoming a pervasive issue as NPs, originating from microplastic particles, pose potentially harmful environmental impacts on aquatic ecosystems. The environmental hazards of NPs on microorganisms have been well documented in recent studies; however, little is known about their ecotoxicity [...] Read more.

Nanoplastic (NP) contamination is becoming a pervasive issue as NPs, originating from microplastic particles, pose potentially harmful environmental impacts on aquatic ecosystems. The environmental hazards of NPs on microorganisms have been well documented in recent studies; however, little is known about their ecotoxicity effects on freshwater biofilms, which serve as important primary producers and decomposers and are highly connected with other ecosystem components. We investigated the effects of NPs on the microbial metabolic functions of freshwater biofilms in terms of carbon source utilization ability. Biofilm samples were collected, cultivated in a hydrodynamic flume for six weeks, and then exposed in polystyrene (PS) beads (100 nm in size) with different NP concentrations (1, 5, and 10 mg/L). BIOLOG ECO microplates were used to quantify carbon source utilization characteristics. The data were analyzed using average well-color development (AWCD), functional diversity indices, and principle component analysis (PCA). Results showed that the total carbon metabolic functions (represented by AWCD) remained constant (p > 0.05) with elevated NP concentrations, but some specific carbon sources (e.g., esters) changed in their utilization ability (p < 0.05). The microbial functional diversity (Shannon–Wiener diversity index, Simpson diversity index, and Shannon evenness index) was significantly reduced under 10 mg/L NPs (p < 0.05), indicating an inhibiting effect of NPs on biofilm metabolic diversity. This study examined NP ecotoxicity effects on microbial metabolic activities at the community level, but further studies are required to fully understand the mechanisms driving this change. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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15 pages, 2894 KiB

Open AccessArticle

Effects of Temperature on the Characteristics of Nitrogen Removal and Microbial Community in Post Solid-Phase Denitrification Biofilter Process

by Qian Zhang, Xue Chen, Wandong Luo, Heng Wu, Xiangyang Liu, Wang Chen, Jianhong Tang and Lijie Zhang

Int. J. Environ. Res. Public Health 2019, 16(22), 4466; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16224466 - 13 Nov 2019

Cited by 15 | Viewed by 2885

Abstract

In order to solve the problems of high energy consumption, complex process and low nitrogen removal efficiency in the currently available low carbon source wastewater treatment processes, a novel coagulation sedimentation/post-solid-phase denitrification biofilter process (CS-BAF-SPDB) was proposed. The effect of temperature on the [...] Read more.

In order to solve the problems of high energy consumption, complex process and low nitrogen removal efficiency in the currently available low carbon source wastewater treatment processes, a novel coagulation sedimentation/post-solid-phase denitrification biofilter process (CS-BAF-SPDB) was proposed. The effect of temperature on the nitrogen removal performance of BAF-SPDB was intensively studied, and the mechanism of the effect of temperature on nitrogen removal performance was analyzed from the perspective of microbial community structure by using the polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that, to realize favorable nitrifying and denitrifying performance simultaneously in the BAF-SPDB unit, the operation temperature should be set above 18 °C. In addition, the influence of the macro operation parameters on the performance of the BAF and SPDB has a direct relationship with the dynamic changes of the micro microbial community. The influence of temperature on nitrification performance in BAF was mainly embodied in the change of composition, amount and activity of ammonia oxidizing bacteria Candidatus Nitrospira defluvii and nitrite oxidizing bacteria Nitrosomonas sp. Nm47, while that on denitrification performance in SPDB is mainly embodied in the change of composition and amount of solid carbon substrate degrading denitrifying bacteria Pseudomonas sp., Myxobacterium AT3-03 and heterotrophic denitrifying bacteria Dechloromonas agitate, Thauera aminoaromatica, Comamonas granuli and Rubrivivax gelatinosus. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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14 pages, 3323 KiB

Open AccessArticle

Comparison of Clay Ceramsite and Biodegradable Polymers as Carriers in Pack-bed Biofilm Reactor for Nitrate Removal

by Qian Zhang, Xue Chen, Heng Wu, Wandong Luo, Xiangyang Liu, Li Feng and Tiantao Zhao

Int. J. Environ. Res. Public Health 2019, 16(21), 4184; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16214184 - 29 Oct 2019

Cited by 14 | Viewed by 2749

Abstract

In recent years, there is a trend of low C/N ratio in municipal domestic wastewater, which results in serious problems for nitrogen removal from wastewater. The addition of an external soluble carbon source has been the usual procedure to achieve denitrification. However, the [...] Read more.

In recent years, there is a trend of low C/N ratio in municipal domestic wastewater, which results in serious problems for nitrogen removal from wastewater. The addition of an external soluble carbon source has been the usual procedure to achieve denitrification. However, the disadvantage of this treatment process is the need of a closed, rather sophisticated and costly process control as well as the risk of overdosing. Solid-phase denitrification using biodegradable polymers as biofilm carrier and carbon source was considered as an attractive alternative for biological denitrification. The start-up time of the novel process using PCL (polycaprolactone) as biofilm carrier and carbon source was comparable with that of conventional process using ceramsite as biofilm carrier and acetate as carbon source. Further, the solid-phase denitrification process showed higher nitrogen removal efficiency under shorter hydraulic retention time (HRT) and low carbon to nitrogen (C/N) ratio since the biofilm was firmly attached to the clear pores on the surface of PCL carriers and in this process bacteria that could degrade PCL carriers to obtain electron donor for denitrification was found. In addition, solid-phase denitrification process had a stronger resistance of shock loading than that in conventional process. This study revealed, for the first time, that the physical properties of the biodegradable polymer played a vital role in denitrification, and the different microbial compositions of the two processes was the main reason for the different denitrification performances under low C/N ratio. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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11 pages, 1951 KiB

Open AccessArticle

The Occurrence and Risks of Selected Emerging Pollutants in Drinking Water Source Areas in Henan, China

by Donghai Wu, Ying Zhou, Guanghua Lu, Kai Hu, Jingjing Yao, Xinghou Shen and Lei Wei

Int. J. Environ. Res. Public Health 2019, 16(21), 4109; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16214109 - 25 Oct 2019

Cited by 18 | Viewed by 3281

Abstract

The occurrence of organic micropollutants (OMPs) in aqueous environments has potential effects on ecological safety and human health. Three kinds of OMPs (namely, pharmaceuticals, ultraviolet (UV) filters and organophosphate esters (OPEs)) in four drinking water source areas in Henan Province of China were [...] Read more.

The occurrence of organic micropollutants (OMPs) in aqueous environments has potential effects on ecological safety and human health. Three kinds of OMPs (namely, pharmaceuticals, ultraviolet (UV) filters and organophosphate esters (OPEs)) in four drinking water source areas in Henan Province of China were analyzed, and their potential risks were evaluated. Among 48 target chemicals, 37 pollutants with total concentrations ranging from 403.0 to 1751.6 ng/L were detected in water, and 13 contaminants with total concentrations from 326.0 to 1465.4 ng/g (dry weight) were observed in sediment. The aqueous pollution levels in Jiangang Reservoir and Shahe Water Source Area were higher than that in Nanwan Reservoir and Baiguishan Reservoir, while the highest total amount of pollutants in sediment was found in Baiguishan Reservoir. Compared with pharmaceuticals and UV filters, OPEs presented higher concentrations in all investigated drinking water source areas. The highest observed concentration was triphenylphosphine oxide (TPPO, 865.2 ng/L) in water and tripentyl phosphate (TPeP, 1289.8 ng/g) in sediment. Moreover, the risk quotient (RQ) analysis implies that the determined aqueous contaminants exhibited high risks to algae and invertebrates, whereas moderate risk to fish was exhibited. The health risk assessment of aqueous OMPs by means of the hazard index (HI) indicates that the risks to adults and children were negligible. These observations are expected to provide useful information for the assessment of water quality in drinking water sources in Henan, China. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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13 pages, 4397 KiB

Open AccessArticle

Changes of Bacterial Communities in Response to Prolonged Hydrodynamic Disturbances in the Eutrophic Water-Sediment Systems

by Haomiao Cheng, Ling Cheng, Liang Wang, Tengyi Zhu, Wei Cai, Zulin Hua, Yulin Wang and Wenfen Wang

Int. J. Environ. Res. Public Health 2019, 16(20), 3868; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16203868 - 12 Oct 2019

Cited by 9 | Viewed by 2428

Abstract

The effects of hydrodynamic disturbances on the bacterial communities in eutrophic aquatic environments remain poorly understood, despite their importance to ecological evaluation and remediation. This study investigated the evolution of bacterial communities in the water–sediment systems under the influence of three typical velocity [...] Read more.

The effects of hydrodynamic disturbances on the bacterial communities in eutrophic aquatic environments remain poorly understood, despite their importance to ecological evaluation and remediation. This study investigated the evolution of bacterial communities in the water–sediment systems under the influence of three typical velocity conditions with the timescale of 5 weeks. The results demonstrated that higher bacterial diversity and notable differences were detected in sediment compared to water using the 16S rRNA gene sequencing. The phyla Firmicutes and γ-Proteobacteria survived better in both water and sediment under stronger water disturbances. Their relative abundance peaked at 36.0%, 33.2% in water and 38.0%, 43.6% in sediment, respectively, while the phylum Actinobacteria in water had the opposite tendency. Its relative abundance grew rapidly in static control (SC) and peaked at 44.8%, and it almost disappeared in disturbance conditions. These phenomena were caused by the proliferation of genus Exiguobacterium (belonging to Firmicutes), Citrobacter, Acinetobacter, Pseudomonas (belonging to γ-Proteobacteria), and hgcI_clade (belonging to Actinobacteria). The nonmetric multidimensional scaling (NMDS) and Venn analysis also revealed significantly different evolutionary trend in the three water-sediment systems. It was most likely caused by the changes of geochemical characteristics (dissolved oxygen (DO) and nutrients). This kind of study can provide helpful information for ecological assessment and remediation strategy in eutrophic aquatic environments. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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17 pages, 4473 KiB

Open AccessArticle

Effects of Freeze-Thaw Cycles on Phosphorus from Sediments in the Middle Reaches of the Yarlung Zangbo River

by Ning Liao, Lai Jiang, Jia Li, Linglei Zhang, Jing Zhang and Zeyu Zhang

Int. J. Environ. Res. Public Health 2019, 16(19), 3783; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16193783 - 08 Oct 2019

Cited by 9 | Viewed by 2958

Abstract

The effect of the freeze-thaw process is an important factor in soil nutrient changes and erosion enhancement. Sediments in the middle reaches of the Yarlung Zangbo River are likely affected by the daily freeze-thaw cycles in winter. Examining the freeze-thaw effects of phosphorus [...] Read more.

The effect of the freeze-thaw process is an important factor in soil nutrient changes and erosion enhancement. Sediments in the middle reaches of the Yarlung Zangbo River are likely affected by the daily freeze-thaw cycles in winter. Examining the freeze-thaw effects of phosphorus from sediments in this area is of great significance for protecting the structure and safety of the ecosystem. The freeze-thaw process of sediments in the middle reaches of the Yarlung Zangbo River was simulated through laboratory experiments, and different phosphorus contents and particle states were synchronously detected and analyzed. The results show that freeze-thaw cycles can accelerate phosphorus migration and release in the sediments, and the total amount of phosphorus release increases by 12%. After being subjected to freeze-thaw cycles, the sediment particles were broken, and the competition between ions for adsorption sites reduced phosphorus adsorption onto the sediments from the middle reaches of the Yarlung Zangbo River. The organic matter on the sediment surface was also broken down, and the energy dispersive spectroscopy (EDS) results showed that the combined ions that were released competed for the adsorption sites on the particle surfaces, thereby promoting phosphorus release. Among the different forms of phosphorus, aluminum-bound phosphorus (Al-P) and iron-bound phosphorus (Fe-P) are the two most released phosphorus forms by the freeze-thaw process. Although the contents of Al-P and Fe-P only account for 2.41% of the total phosphorus content, both phosphorus forms are biologically available, and freeze-thaw cycles may increase the risk of nutrient loss. This research may provide information for the study of phosphorus in river ecosystems in areas subjected to freeze-thaw cycles. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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15 pages, 1970 KiB

Open AccessArticle

Water Environmental Capacity Calculation and Allocation of the Taihu Lake Basin in Jiangsu Province Based on Control Unit

by Juan Huang, Yong Pang, Xiaoqiang Zhang and Yifan Tong

Int. J. Environ. Res. Public Health 2019, 16(19), 3774; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16193774 - 08 Oct 2019

Cited by 19 | Viewed by 3287

Abstract

The water quality target management of the control unit is a convenient and direct technology for water environment management and the development direction of water environment management in China, involving control unit division and water environment capacity calculation. Taking the Taihu Lake Basin [...] Read more.

The water quality target management of the control unit is a convenient and direct technology for water environment management and the development direction of water environment management in China, involving control unit division and water environment capacity calculation. Taking the Taihu Lake Basin in Jiangsu Province as an example, we propose herein the basic principle of the division of a regional control unit in a plain river network and the method of analyzing the rationality of the control unit division. On this basis, the Taihu Lake Basin in Jiangsu Province was divided into 70 control units. To calculate the water environmental capacity in the plain river network area, we established a water environmental capacity calculation framework based on multiple targets of lakes and rivers, and proposed the goal of water quality “double compliance” of the water environmental functional zone and the assessment section. For this study, we calculated the regional water environmental capacity using the mathematical model of the Taihu Lake Basin’s water environmental capacity, and the water environmental capacities of the 70 control units were allocated by the weight coefficient method, which established water area and functional division length. The research results described herein were applied to the pollution permit management of the Taihu Lake Basin in Jiangsu Province. It provides important technical support for the establishment of a pollution permit system based on the total capacity to improve environmental quality. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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9 pages, 2667 KiB

Open AccessArticle

Selective Removal of Malachite Green Dye from Aqueous Solutions by Supported Liquid Membrane Technology

by Mohammad Waqar Ashraf, Nidal Abulibdeh and Abdus Salam

Int. J. Environ. Res. Public Health 2019, 16(18), 3484; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16183484 - 19 Sep 2019

Cited by 12 | Viewed by 2724

Abstract

A lab-scale study on the application of supported liquid membranes (SLM) has been conducted for recovery and selective removal of Malachite Green dye from wastewater. Naturally occurring non-toxic vegetable oils have been used as membrane liquids. Polyvinylidene fluoride (PVDF) films have been used [...] Read more.

A lab-scale study on the application of supported liquid membranes (SLM) has been conducted for recovery and selective removal of Malachite Green dye from wastewater. Naturally occurring non-toxic vegetable oils have been used as membrane liquids. Polyvinylidene fluoride (PVDF) films have been used as supports for the liquid membrane. Various parameters affecting the dye permeation such as initial dye concentration, pH, stripping acid concentration, oil viscosity and membrane stability have been investigated. The highest flux value (1.65 × 10⁻⁵ mg/cm²/sec) was obtained with a sunflower oil supported membrane at pH 11 in the feed and 0.25 M HCl in the stripping solution. The membrane showed good stability under optimum conditions and maximum transport was achieved in 8 h of permeation time. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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18 pages, 4836 KiB

Open AccessArticle

Prospective Application of Palm Oil Mill Boiler Ash as a Biosorbent: Effect of Microwave Irradiation and Palm Oil Mill Effluent Decolorization by Adsorption

by Muhammad Hazwan Hamzah, Muhammad Fitri Ahmad Asri, Hasfalina Che Man and Abdulsalam Mohammed

Int. J. Environ. Res. Public Health 2019, 16(18), 3453; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16183453 - 17 Sep 2019

Cited by 10 | Viewed by 3402

Abstract

Common conventional biological treatment methods fail to decolorize palm oil mill effluent (POME). The present study focused on using the abundant palm oil mill boiler (POMB) ashes for POME decolorization. The POMB ashes were subjected to microwave irradiation and chemical treatment using H [...] Read more.

Common conventional biological treatment methods fail to decolorize palm oil mill effluent (POME). The present study focused on using the abundant palm oil mill boiler (POMB) ashes for POME decolorization. The POMB ashes were subjected to microwave irradiation and chemical treatment using H₂SO₄. The resultant adsorbents were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Brunauer–Emmett–Teller (BET) analyses. The adsorption efficiency was evaluated at various pH levels (2–8.5), adsorption dosages (3–15 g) in 200 mL, and contact times (1–5 h). The microwave-irradiated POMB-retained ash recorded the highest color removal of 92.31%, for which the best conditions were pH 2, 15 g adsorbent dosage in 200 mL, and 5 h of contact time. At these best treatment conditions, the color concentration of the treated effluent was analyzed using the method proposed by the American Dye Manufacturers Institute (ADMI). The color concentration was 19.20 ADMI, which complies with the Malaysia discharge standard class A. The Freundlich isotherm model better fit the experimental data and had a high R² of 0.9740. Based on these results, it can be deduced that microwave-irradiated POMB-retained ash has potential applications for POME decolorization via a biosorption process. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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16 pages, 3227 KiB

Open AccessArticle

The Influence on Contaminant Bioavailability and Microbial Abundance of Lake Hongze by the South-to-North Water Diversion Project

by Yu Yao, Peifang Wang and Chao Wang

Int. J. Environ. Res. Public Health 2019, 16(17), 3068; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16173068 - 23 Aug 2019

Cited by 10 | Viewed by 2091

Abstract

The world famous South-to-North Water Transfer Project was built to alleviate serious water shortages in northern China. Considering that lake Hongze is an important freshwater lake in this region, analyzing the influence of water diversion on typical contaminant bioavailability and microbial abundance could [...] Read more.

The world famous South-to-North Water Transfer Project was built to alleviate serious water shortages in northern China. Considering that lake Hongze is an important freshwater lake in this region, analyzing the influence of water diversion on typical contaminant bioavailability and microbial abundance could aid in achieving a good overall understanding of hydrodynamic variation. Accordingly, in situ high-resolution measurements of diffusive gradients in thin films (DGT) and next-generation high-throughput sequencing were combined in order to survey Lake Hongze and determine the relationship between environmental factors and microbial communities. The DGT method effectively obtained more than the 85% of bioavailable concentrations of the corresponding contaminants; the results showed that labile P, S, Fe, As, and Hg concentrations were higher in areas influenced by water transfer. Moreover, the relative abundance and alpha diversity of the sampling sites distributed in the water transfer area differed significantly from other sites. The pH, conductivity, and labile Mn, As, and P were shown to be the primary environmental factors affecting the abundance and diversity of microbes. With the exception of bioturbation-affected sites controlled by labile Mn and pH, sites distributed in the water diversion area were most affected by As and conductivity, with little spatial discrepancy. Furthermore, site 2, with higher bioturbation abundance, and site 10, with stronger hydrodynamics, had low alpha diversity compared to the other sites. Consequently, the bioavailability of typical contaminants such as P, S, As, Hg, Fe, Mg, Cd, Pb, and Mn, as well as the diversity and abundance of microbial in the sites influenced by the water diversion, were significantly different to the other sites. Thus, the impacts of the South-to-North Water Transfer Project on participant lakes were non-negligible overall in the investigation. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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13 pages, 1455 KiB

Open AccessArticle

Enhanced Simultaneous Nitrogen and Phosphorus Removal in A Denitrifying Biological Filter Using Waterworks Sludge Ceramsite Coupled with Iron-Carbon

by Xiaoying Zheng, Mengqi Jin, Hang Xu, Wei Chen, Yuan Zhang, Mengmeng Yang, Xiaoyao Shao, Zhi Xu and Weihong Wang

Int. J. Environ. Res. Public Health 2019, 16(15), 2646; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16152646 - 24 Jul 2019

Cited by 14 | Viewed by 3139

Abstract

In this study, waterworks sludge ceramsite (WSC) was combined with 3% iron-carbon matrix in a denitrifying biological filter (ICWSC-DNBF) to enhance the simultaneous removal of carbon, nitrogen and phosphorus in secondary effluent of wastewater treatment plant (SE-WTP). The chemical oxygen demand (COD) and [...] Read more.

In this study, waterworks sludge ceramsite (WSC) was combined with 3% iron-carbon matrix in a denitrifying biological filter (ICWSC-DNBF) to enhance the simultaneous removal of carbon, nitrogen and phosphorus in secondary effluent of wastewater treatment plant (SE-WTP). The chemical oxygen demand (COD) and nitrogen removal, as well as phosphorus removal and the adsorbed forms of phosphorus were measured and the removal mechanism of these pollutants by the ICWSC-DNBF system for treating SE-WTP were investigated. The results showed that the ICWSC-DNBF achieved good removals of COD, NH₄⁺-N, NO₃⁻-N, total N and total P; effluent concentrations were 17.23 mg/L, 3.72 mg/L, 14.32 mg/L, 17.38 mg/L and 0.82 mg/L, respectively. WSC enhanced the P removal due to its high specific surface area and the high number of adsorption sites. Fe-P and Al-P were the main forms of P adsorbed by WSC, accounting for 78.53% of the total adsorbed P. WSC coupled with Fe and C improved the biodegradability of SE-WTP and promoted the removal of organic matter. The removal of N was attributed to the abundant denitrifying microorganisms in the system and the electrochemical effect produced by the internal electrolysis of Fe and C. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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13 pages, 2745 KiB

Open AccessArticle

Preparation of Ceramsite Based on Waterworks Sludge and Its Application as Matrix in Constructed Wetlands

by Yaning Wang, Jinhu Yang, Hang Xu, Chenwei Liu, Zhen Shen and Kai Hu

Int. J. Environ. Res. Public Health 2019, 16(15), 2637; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16152637 - 24 Jul 2019

Cited by 29 | Viewed by 3597

Abstract

The recycling of waterworks sludge has become a trending issue because it not only solves the problem of difficult disposal but also saves land resources. This paper aimed to provide a new idea for the utilization of waterworks sludge to form ceramsite and [...] Read more.

The recycling of waterworks sludge has become a trending issue because it not only solves the problem of difficult disposal but also saves land resources. This paper aimed to provide a new idea for the utilization of waterworks sludge to form ceramsite and to purify sewage. The specific surface area, average pore size, and pore volume of the made ceramsite were 8.15 m²/g, 8.53 nm, and 1.88 cm²/g, respectively. The made ceramsite was applied in a vertical-flow constructed wetland, and the removal efficiency of nitrogen, phosphorus and organic matter in sewage were investigated under the conditions of different start-up periods, hydraulic retention times, matrix filling heights and water quality. The removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH₃-N), and total phosphorus (TP) in the constructed wetlands were stable at 70%, 60%, and 79%, respectively. This constructed wetland with a ceramic matrix has certain advantages in the total amount of denitrifying microorganisms, with a proportion of 14.92%. The results prove the feasibility of preparing ceramsite from waterworks sludge and applying it as a matrix in a constructed wetland to purify sewage. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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19 pages, 2096 KiB

Open AccessArticle

The Driving Forces of Point Source Wastewater Emission: Case Study of COD and NH₄-N Discharges in Mainland China

by Zhaofang Zhang, Weijun He, Juqin Shen, Min An, Xin Gao, Dagmawi Mulugeta Degefu, Liang Yuan, Yang Kong, Chengcai Zhang and Jin Huang

Int. J. Environ. Res. Public Health 2019, 16(14), 2556; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16142556 - 17 Jul 2019

Cited by 11 | Viewed by 3185

Abstract

Excess consumption of water resources and environmental pollution have become major challenges restricting sustainable development in China. In order to prevent the pollution of water resources, policymakers should have reliable emission reduction strategies. This paper aims to contribute new knowledge by analyzing the [...] Read more.

Excess consumption of water resources and environmental pollution have become major challenges restricting sustainable development in China. In order to prevent the pollution of water resources, policymakers should have reliable emission reduction strategies. This paper aims to contribute new knowledge by analyzing the spatial-temporal characteristics and driving forces of point source emission. The chemical oxygen demand (COD) and ammonia nitrogen (NH₄-N) emission variations in 31 provinces and municipalities of mainland China during the years 2004–2017 are analyzed. The results obtained using the logarithmic mean Divisia index (LMDI) method indicate that: (1) the COD and NH₄-N emission effects have similar temporal characteristics. Technology improvement and pollutant emission intensity are the main factors inhibiting the incremental COD and NH₄-N emission effects, while economic development is the main driving factor of COD and NH₄-N emission effects. Population increases play a relatively less important role in COD and NH₄-N emission effects. (2) The spatial features of COD and NH₄-N emission effects show differences among provinces and municipalities. The reduction of COD emission effects in each province and municipality is obviously better than that of NH₄-N emissions. (3) In the eastern, central, and the western regions of China, the total COD emission effect shows a downward trend, while apart from the central region, the NH₄-N emission effect appears to be rising in the east and west of China. Therefore, increasing investment into pollution treatment, promoting awareness of water conservation, strengthening technological and financial support from the more developed eastern to the less developed central and western regions, can help to reduce the COD and NH₄-N emissions in China. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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13 pages, 2544 KiB

Open AccessArticle

The Tolerance Characteristics of Resident Fish in the Upper Yangtze River under Varying Gas Supersaturation

by Qianfeng Ji, Shudan Xue, Quan Yuan, Yuan Yuan, Yuanming Wang, Ruifeng Liang, Jingjie Feng, Kefeng Li and Ran Li

Int. J. Environ. Res. Public Health 2019, 16(11), 2021; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16112021 - 06 Jun 2019

Cited by 15 | Viewed by 3042

Abstract

In circumstances where total dissolved gas (TDG) levels are variable, the peak TDG and duration are expected to be the dominant drivers of fish survival. Focusing on the peak TDG and duration in natural rivers, a laboratory experiment and field experiments in the [...] Read more.

In circumstances where total dissolved gas (TDG) levels are variable, the peak TDG and duration are expected to be the dominant drivers of fish survival. Focusing on the peak TDG and duration in natural rivers, a laboratory experiment and field experiments in the upper Yangtze River were conducted with Prenant’s Schizothoracin (Schizothorax prenanti), a rare species inhabiting the upper Yangtze River, to examine the tolerance characteristics of fish under varying gas supersaturation levels. The results of the field experiments showed that TDG supersaturation in natural rivers changed greatly during the flood period due to reservoir regulation. The survival of fish was affected by TDG levels, water depth and TDG fluctuation range. A high TDG level, and shallow compensatory water depth caused fish mortality in the field experiment to be higher in September than in July. The results of the laboratory experiment showed that fish tolerance was lower under fluctuating TDG supersaturation than under constant TDG supersaturation. The tolerance of fish to TDG supersaturation varied depending on peak TDG and duration. Under the fluctuation range of 115–125%, fish survival in the 6 h–6 h cycle was significantly different from that in the 8 h–8 h cycle. The fluctuation cycle did not affect fish survival at the fluctuation range of 110–130%. Intermittent lower TDG supersaturation does not significantly increase the tolerance of fish. This study revealed the tolerance characteristics of resident fish in the upper Yangtze River to TDG supersaturation, which provides a reference to the ecological operation of reservoirs and may contribute to the protection of aquatic organisms. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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18 pages, 3547 KiB

Open AccessArticle

Analyses on the Temporal and Spatial Characteristics of Water Quality in a Seagoing River Using Multivariate Statistical Techniques: A Case Study in the Duliujian River, China

by Xuewei Sun, Huayong Zhang, Meifang Zhong, Zhongyu Wang, Xiaoqian Liang, Tousheng Huang and Hai Huang

Int. J. Environ. Res. Public Health 2019, 16(6), 1020; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16061020 - 20 Mar 2019

Cited by 31 | Viewed by 3517

Abstract

In the Duliujian River, 12 water environmental parameters corresponding to 45 sampling sites were analyzed over four seasons. With a statistics test (Spearman correlation coefficient) and multivariate statistical methods, including cluster analysis (CA) and principal components analysis (PCA), the river water quality temporal [...] Read more.

In the Duliujian River, 12 water environmental parameters corresponding to 45 sampling sites were analyzed over four seasons. With a statistics test (Spearman correlation coefficient) and multivariate statistical methods, including cluster analysis (CA) and principal components analysis (PCA), the river water quality temporal and spatial patterns were analyzed to evaluate the pollution status and identify the potential pollution sources along the river. CA and PCA results on spatial scale revealed that the upstream was slightly polluted by domestic sewage, while the upper-middle reach was highly polluted due to the sewage from feed mills, furniture and pharmaceutical factories. The middle-lower reach, moderately polluted by sewage from textile, pharmaceutical, petroleum and oil refinery factories as well as fisheries and livestock activities, demonstrated the water purification role of wetland reserves. Seawater intrusion caused serious water pollution in the estuary. Through temporal CA, the four seasons were grouped into three clusters consistent with the hydrological mean, high and low flow periods. The temporal PCA results suggested that nutrient control was the primary task in mean flow period and the monitoring of effluents from feed mills, petrochemical and pharmaceutical factories is more important in the high flow period, while the wastewater from domestic and livestock should be monitored carefully in low flow periods. The results may provide some guidance or inspiration for environmental management. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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16 pages, 5704 KiB

Open AccessArticle

Influence of Pyrolysis Temperature on Cadmium Removal Capacity and Mechanism by Maize Straw and Platanus Leaves Biochars

by Haixia Wang, Mingliang Zhang and Qi Lv

Int. J. Environ. Res. Public Health 2019, 16(5), 845; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16050845 - 08 Mar 2019

Cited by 11 | Viewed by 2836

Abstract

The influence of pyrolysis temperature on cadmium (Cd) removal capacity and mechanisms by maize straw biochars (MSB) and Platanus leaves biochars (PLB) pyrolyzed at 300, 400, 500 and 600 °C was investigated. The results showed that the biochars pyrolyzed at 500 °C had [...] Read more.

The influence of pyrolysis temperature on cadmium (Cd) removal capacity and mechanisms by maize straw biochars (MSB) and Platanus leaves biochars (PLB) pyrolyzed at 300, 400, 500 and 600 °C was investigated. The results showed that the biochars pyrolyzed at 500 °C had the highest adsorption capacity for Cd, and the maximum adsorption at pH 5.0 was 35.46 mg/g and 25.45 mg/g for MSB and PLB, respectively. The increase in adsorption efficiency with increasing temperature indicated that the adsorption of Cd onto the biochars was endothermic. Based on the balance analysis between cations (Ca²⁺ and Mg²⁺) released and Cd adsorbed onto biochar in combination with SEM-EDX, FTIR, and XRD analysis, it was concluded that cation exchange, complexation with surface functional groups, precipitation with minerals (CdCO₃), and coordination with π electrons were the dominant mechanisms responsible for Cd adsorption by MSB. With the pyrolysis temperature increasing from 300 to 600 °C, the contribution of cation exchange (Ca²⁺ and Mg²⁺) on Cd removal by MSB decreased from 37.4% to 11.7%, while the contribution of precipitation with Otavite (CdCO₃) and Cd²⁺-π electrons interaction increased. For PLB, the insoluble Cd minerals were not detected by XRD, and the contribution of cation exchange had no significant difference for PLB pyrolyzed at 300, 400, 500 and 600 °C. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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12 pages, 2354 KiB

Open AccessArticle

Environmental, Ecological, and Economic Benefits of Biofuel Production Using a Constructed Wetland: A Case Study in China

by Dong Liu, Changxin Zou and Mengjia Xu

Int. J. Environ. Res. Public Health 2019, 16(5), 827; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16050827 - 07 Mar 2019

Cited by 11 | Viewed by 3300

Abstract

Here we show a constructed wetland (CW), a viable alternative wastewater treatment system, be used to produce biofuels from biomass by using nitrogen contained in domestic wastewater. We summarize the potential biomass yield evaluated as cellulosic ethanol bioenergy production, and combine the life [...] Read more.

Here we show a constructed wetland (CW), a viable alternative wastewater treatment system, be used to produce biofuels from biomass by using nitrogen contained in domestic wastewater. We summarize the potential biomass yield evaluated as cellulosic ethanol bioenergy production, and combine the life cycle analysis with a mass balance approach to estimate the energetic, environmental, and economic performance of a CW biofuel system. The results showed that the annual aboveground biomass yield of a CW in Zhoushan, Zhejiang Province, China, averaged 37,813 kg ha⁻¹ year⁻¹ as the by-product of treating waste N, which is about one order of magnitude larger than traditional biofuel production systems. The biomass yield in the Zhoushan CW system had life cycle environment benefits of 8.8 Mg (1 Mg = 10⁶ g) CO₂ equivalent ha⁻¹ year⁻¹ of greenhouse gas emission reduction. The CW in Zhoushan had a net energy gain of 249.9 GJ (1 GJ = 10⁹ J) ha⁻¹ year⁻¹ while the wastewater treatment plant (WTP) consumes 7442.5 GJ ha⁻¹ year⁻¹. Moreover, the CW reduced greenhouse gas emissions to 2714 times less than that of the WTP. The CW also provided various ecosystem services, such as regional climate regulation and habitat conservation. We suggest that the potential use of a CW as biofuel production and carbon sequestration via nitrogen-negative input can be explored more widely in the future. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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14 pages, 3846 KiB

Open AccessFeature PaperArticle

Impacting Microbial Communities and Absorbing Pollutants by Canna Indica and Cyperus Alternifolius in a Full-Scale Constructed Wetland System

by Yinghai Wu, Tao He, Chen Chen, Xiaohang Fang, Dongyang Wei, Jing Yang, Renduo Zhang and Rui Han

Int. J. Environ. Res. Public Health 2019, 16(5), 802; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16050802 - 05 Mar 2019

Cited by 16 | Viewed by 3433

Abstract

Wetland plants that cover the wetlands play an important role in reducing pollutants. The aim of this study was to investigate the effect of two plant species on microbial communities and nitrogen-removal genes and to evaluate the contributions of absorbing pollutants by Canna [...] Read more.

Wetland plants that cover the wetlands play an important role in reducing pollutants. The aim of this study was to investigate the effect of two plant species on microbial communities and nitrogen-removal genes and to evaluate the contributions of absorbing pollutants by Canna indica (CI) and Cyperus alternifolius (CA) to the removal performance in both a vertical subsurface flow constructed wetland and a horizontal subsurface flow constructed wetland, which were part of a full-scale hybrid constructed wetland system. The microbial assemblages were determined using 16S rRNA high-throughput sequencing. Results showed that the presence of CI and CA positively affected microbial abundance and community in general and which was positive for the total bacteria and ammonia nitrogen removal in the CWs. The higher abundance of Nitrospirae appeared in the non-rhizosphere sediment (NRS) than that in the rhizosphere sediment (RS). More denitrification genes were found in NRS than in RS. The copy numbers of narG, nirS and nosZ genes for CA were higher than those for CI. Wetland plant species can significantly (P < 0.05) affect the distribution of microbial communities in RS. Plant selection is important to promote the development of microbial communities with a more active and diverse catabolic capability and the contribution of plant absorption to the overall removal rate of wetland system can be neglected. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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11 pages, 1691 KiB

Open AccessArticle

Response of Freshwater Biofilms to Antibiotic Florfenicol and Ofloxacin Stress: Role of Extracellular Polymeric Substances

by Chaoqian Wang, Deming Dong, Liwen Zhang, Ziwei Song, Xiuyi Hua and Zhiyong Guo

Int. J. Environ. Res. Public Health 2019, 16(5), 715; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16050715 - 27 Feb 2019

Cited by 27 | Viewed by 3147

Abstract

Antibiotic residues have been detected in aquatic environments worldwide. Biofilms are one of the most successful life forms, and as a result are ubiquitous in natural waters. However, the response mechanism of freshwater biofilms to the stress of various antibiotic residues is still [...] Read more.

Antibiotic residues have been detected in aquatic environments worldwide. Biofilms are one of the most successful life forms, and as a result are ubiquitous in natural waters. However, the response mechanism of freshwater biofilms to the stress of various antibiotic residues is still unclear. Here, the stress of veterinary antibiotic florfenicol (FF) and fluoroquinolone antibiotic ofloxacin (OFL) on freshwater biofilms were investigated by determining the changes in the key physicochemical and biological properties of the biofilms. The results showed that the chlorophyll a content in biofilms firstly decreased to 46–71% and then recovered to original content under the stress of FF and OFL with high, mid, and low concentrations. Meanwhile, the activities of antioxidant enzymes, including superoxide dismutase and catalase, increased between 1.3–6.7 times their initial values. FF was more toxic to the biofilms than OFL. The distribution coefficients of FF and OFL binding in extracellular polymeric substances (EPS)-free biofilms were 3.2 and 6.5 times higher than those in intact biofilms, respectively. It indicated that EPS could inhibit the FF and OFL accumulation in biofilm cells. The present study shows that the EPS matrix, as the house of freshwater biofilms, is the primary barrier that resists the stress from antibiotic residues. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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16 pages, 9817 KiB

Open AccessArticle

Synthesis of Porous Boron-Doped Carbon Nitride: Adsorption Capacity and Photo-Regeneration Properties

by Xiang Guo, Lei Rao, Peifang Wang, Lixin Zhang and Yuxiong Wang

Int. J. Environ. Res. Public Health 2019, 16(4), 581; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16040581 - 17 Feb 2019

Cited by 16 | Viewed by 4231

Abstract

Carbon nitride (CN) with improved adsorption–degradation capacity was synthesized using B₂O₃ and CN via calcination. The pollutant removal capacity of this B₂O₃/CN (B-CN) was studied by a powder suspension experiment and added into concrete to evaluate [...] Read more.

Carbon nitride (CN) with improved adsorption–degradation capacity was synthesized using B₂O₃ and CN via calcination. The pollutant removal capacity of this B₂O₃/CN (B-CN) was studied by a powder suspension experiment and added into concrete to evaluate the adsorption and degradation of methylene blue (MB). The characterizations of all samples indicate that B₂O₃ significantly affects CN, e.g., by increasing the CN specific surface area to 3.6 times the original value, extending visible light adsorption, and narrowing the band gap from 2.56 eV to 2.42 eV. Furthermore, the results show that B-CN composite materials have a higher MB-removal efficiency, with the adsorption capacity reaching 43.11 mg/g, which is about 3.3 times that of pristine CN. The MB adsorption process on B2-CN is mainly via electrostatic attraction and π–π interactions. In addition, B-CN added into concrete also has good performance. After five adsorption–degradation cycles, B-CN and photocatalytic concrete still exhibit a good regenerate ability and excellent stability, which are very important for practical applications. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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14 pages, 3141 KiB

Open AccessArticle

Characterization of Aerobic Denitrifying Bacterium Pseudomonas mendocina Strain GL6 and Its Potential Application in Wastewater Treatment Plant Effluent

by Wen Zhang, Cheng Yan, Jianing Shen, Ruping Wei, Yan Gao, Aijun Miao, Lin Xiao and Liuyan Yang

Int. J. Environ. Res. Public Health 2019, 16(3), 364; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16030364 - 28 Jan 2019

Cited by 35 | Viewed by 4307

Abstract

To remove nitrate in wastewater treatment plant effluent, an aerobic denitrifier was newly isolated from the surface flow constructed wetland and identified as Pseudomonas mendocina strain GL6. It exhibited efficient aerobic denitrification ability, with the nitrate removal rate of 6.61 mg (N)·L⁻¹ [...] Read more.

To remove nitrate in wastewater treatment plant effluent, an aerobic denitrifier was newly isolated from the surface flow constructed wetland and identified as Pseudomonas mendocina strain GL6. It exhibited efficient aerobic denitrification ability, with the nitrate removal rate of 6.61 mg (N)·L⁻¹·h⁻¹. Sequence amplification indicated that the denitrification genes napA, nirK, norB, and nosZ were present in strain GL6. Nitrogen balance analysis revealed that approximately 74.5% of the initial nitrogen was removed as gas products. In addition, the response surface methodology experiments showed that the maximum removal of total nitrogen occurred at pH 7.76, C/N ratio of 11.2, temperature of 27.8 °C, and with shaking at 133 rpm. Furthermore, under the optimized cultivation condition, strain GL6 was added into wastewater treatment plant effluent and the removal rates of nitrate nitrogen and total nitrogen reached 95.6% and 73.6%, respectively. Thus, P. mendocina strain GL6 has high denitrification potential for deep improvement of effluent quality. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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24 pages, 14146 KiB

Open AccessArticle

The Hydraulic Driving Mechanisms of Cyanobacteria Accumulation and the Effects of Flow Pattern on Ecological Restoration in Lake Dianchi Caohai

by Peng Zhang, Rui-Feng Liang, Peng-Xiao Zhao, Qing-Yuan Liu, Yong Li, Kai-Li Wang, Ke-Feng Li, Ying Liu and Peng Wang

Int. J. Environ. Res. Public Health 2019, 16(3), 361; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16030361 - 28 Jan 2019

Cited by 14 | Viewed by 3509

Abstract

Due to rapid increases in socioeconomic development and the human population over the past few decades, the shallow lakes in China have suffered from eutrophication and poor water quality. The conditions in Lake Dianchi Caohai, which is in the northern part of Lake [...] Read more.

Due to rapid increases in socioeconomic development and the human population over the past few decades, the shallow lakes in China have suffered from eutrophication and poor water quality. The conditions in Lake Dianchi Caohai, which is in the northern part of Lake Dianchi, are considered the most serious. The ecological restoration of Lake Dianchi Caohai began in the late 1980s. Lake managers and the public have been puzzled by the lack of a significant response of the water quality to the flow pattern despite the tremendous investment in water quality improvements. Therefore, lake managers desperately need to understand the responses of pollutant behaviors to proposed management measures. In this paper, a depth-averaged two-dimensional hydrodynamic and water quality model based on hydrological data, measured lake bed elevation, and water quality data is developed to simulate the flow field and water quality of Lake Dianchi Caohai. This model was validated using water quality data from the Caohaizhongxin site in 2016, and a close agreement was found between the model results and observations. Wind-driven circulation in Lake Dianchi Caohai was observed in the model results, which revealed that the lake flow pattern was dominated by wind-driven circulation, while the inflow/outflow played only a subsidiary role during this period. The formation of the wind-driven current in Lake Dianchi Caohai could be roughly divided into three stages. The hydrodynamic processes connected with the distribution of chlorophyll a are evaluated and discussed to adequately understand the hydraulic mechanisms driving the accumulation of cyanobacteria. Moreover, we designed three scenarios after comparing all possible operation scenarios to analyze the contributions of each different operation scenario to the water quality improvements. The optimal ecological operation scenario which has the best impacts on the water quality, especially the reduction in Chla and NH₃-N concentration, is proposed based on our comprehensive analysis. The water quality improvement and management suggestions proposed in this paper are based on lake flow patterns and make up for previous studies that did not consider the effects of hydraulic characteristics on water quality improvement in Lake Dianchi Caohai. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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12 pages, 2298 KiB

Open AccessArticle

Distribution and Release Characteristics of Phosphorus in a Reservoir in Southwest China

by Yuanming Wang, Kefeng Li, Ruifeng Liang, Shiqing Han and Yong Li

Int. J. Environ. Res. Public Health 2019, 16(3), 303; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph16030303 - 23 Jan 2019

Cited by 12 | Viewed by 2884

Abstract

Dam construction changes the nutrient transport of a river system. Phosphorus is an important fundamental material in the global biochemical cycle and is always a limiting factor in the primary productivity of reservoirs. Extending the study of phosphorus in reservoirs is necessary given [...] Read more.

Dam construction changes the nutrient transport of a river system. Phosphorus is an important fundamental material in the global biochemical cycle and is always a limiting factor in the primary productivity of reservoirs. Extending the study of phosphorus in reservoirs is necessary given the dam construction in southwest China. Zipingpu Reservoir was chosen as the research site in this study. The form and distribution of phosphorus in the reservoir’s surface sediments and overlying water were analyzed. The results showed that overall, the total phosphorus (TP) content of surface sediments in the Zipingpu Reservoir decreased from the tail to the front of the dam. The TP content ranged from 682.39 to 1609.06 mg/kg, with an average value of 1121.08 mg/kg. The TP content at some sampling points was affected by exogenous input. Inorganic phosphorus (IP) was the main form of phosphorus in surface sediments and had a proportion of 89.38%. Among the forms of IP, the content of Ca-P was larger than that of O-P; Ex-P, Fe-P, and Al-P had the lowest contents. Particulate phosphorus (PP) was the main form of phosphorus in the overlying water of the Zipingpu Reservoir and was strongly affected by hydrodynamic conditions. The content of total dissolved phosphorus (TDP) in the overlying water was relatively low. To further understand the risk of phosphorus release in the surface sediments in the reservoir, the rate and flux of phosphorus exchange at the sediment-overlying water interface were investigated through laboratory experiments. The results showed that both water temperature and pH significantly affected the sediment release rate, but the influence of water temperature was more significant. Acidic and alkaline conditions were conducive to the release of phosphorus from sediment, while a neutral environment was not. The release rate significantly increased with increasing water temperature, and a positive linear relationship was found between these two parameters. The sediment exhibited absorption characteristics when the water temperature was extremely low and exhibited releasing characteristics at a high temperature. These results could provide a theoretical basis for the management and protection of reservoir water environments. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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12 pages, 3045 KiB

Open AccessArticle

Defense Mechanisms of Two Pioneer Submerged Plants during Their Optimal Performance Period in the Bioaccumulation of Lead: A Comparative Study

by Dian Li, Linglei Zhang, Min Chen, Xiaojia He, Jia Li and Ruidong An

Int. J. Environ. Res. Public Health 2018, 15(12), 2844; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15122844 - 13 Dec 2018

Cited by 5 | Viewed by 3028

Abstract

Ceratophyllum demersum L. and Hydrilla verticillata (L.f.) Royle, two pioneer, submerged plants, effectively remove heavy metals from contaminated water. The present work evaluates the bioaccumulation and defense mechanisms of these plants in the accumulation of lead from contaminated water during their optimal performance [...] Read more.

Ceratophyllum demersum L. and Hydrilla verticillata (L.f.) Royle, two pioneer, submerged plants, effectively remove heavy metals from contaminated water. The present work evaluates the bioaccumulation and defense mechanisms of these plants in the accumulation of lead from contaminated water during their optimal performance period. C. demersum and H. verticillata were investigated after 14 days of exposure to various lead concentrations (5–80 μM). The lead accumulation in both C. demersum and H. verticillata increased with an increasing lead concentration, reaching maximum values of 2462.7 and 1792 mg kg⁻¹ dw, respectively, at 80 μM. The biomass and protein content decreased significantly in C. demersum when exposed to lead. The biomass of H. verticillata exposed to lead had no significant difference from that of the controls, and the protein content increased for the 5–10 μM exposure groups. The malondialdehyde (MDA) content and superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO) activities were much higher in C. demersum, suggesting considerable damage from lipid peroxidation and sensitivity to lead stress. Enzyme inhibition and inactivation were also observed in C. demersum at high lead concentrations (40–80 μM). The excellent growth status, low damage from lipid peroxidation, and high activity of catalase (CAT) and phenylalanine ammonia-lyase (PAL) observed in H. verticillata illustrate its better tolerance under the same lead stress. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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12 pages, 1070 KiB

Open AccessArticle

An Optimization Model for a Wetland Restoration Project under Uncertainty

by Baofeng Cai, Yang Zhang, Xianen Wang and Yu Li

Int. J. Environ. Res. Public Health 2018, 15(12), 2795; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15122795 - 10 Dec 2018

Cited by 10 | Viewed by 3027

Abstract

Restoring natural wetlands with conservation projects is an urgent task for human well-being. This paper introduces the Interval linear programming (ILP) method in wetland restoration projects for the first time and builds an optimization model. The purpose of the optimization model is to [...] Read more.

Restoring natural wetlands with conservation projects is an urgent task for human well-being. This paper introduces the Interval linear programming (ILP) method in wetland restoration projects for the first time and builds an optimization model. The purpose of the optimization model is to find an optimal restoration measures allocation pattern that can minimize the total investment in wetland restoration projects and obtain additional ecological environment and socio-economic benefits. The optimization model can also decrease the influence of interval uncertainty in the system by expressing the executed solution as interval numbers with an upper bound and a lower bound. The result of the optimization model for the wetland restoration project indicated a range of 6.84%–15.43% reduction on comparison with the original scheme which verified the effectiveness and validity of this optimization model. Our findings indicate that higher ecological and social benefits of wetland restoration projects can be achieved with lower restoration investment on the application of the reasonable and optimal restoration measures allocation pattern by the optimization model. The results of interval solutions can provide guidance for project managers to select a satisfactory decision-making plan by adjusting the decision variables in the interval solutions according to the practical situation. It can be seen that reeds were suggested to be planted over 46.75 km², with the same lower bound and higher bound. Meanwhile, populus euphratica, and dryland willow were recommended to be planted in a mixed forest pattern within the interval of 30.54 km² to 37.25 km², and so forth. With the optimal solutions obtained from the model, the total project investment would be in the range of 2193.14 (10⁴ CNY) to 2416.01 (10⁴ CNY). Future improvements of our optimization model in wetland restoration projects should consider other kinds of uncertainties in the system such as stochastic uncertainties, fuzzy uncertainties, and integrated uncertainties. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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14 pages, 2323 KiB

Open AccessArticle

Do Wet-Dry Ratio and Fe-Mn System Affect Oxidation-Reduction Potential Nonlinearly in the Subsurface Wastewater Infiltration Systems?

by Xiaorong Zhang, Haibo Li, Yinghua Li, Fei Guo, Zhongxin Yang and Jianing Bai

Int. J. Environ. Res. Public Health 2018, 15(12), 2790; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15122790 - 09 Dec 2018

Cited by 7 | Viewed by 3408

Abstract

To understand characteristics of on-line oxidation-reduction potential (ORP) in a subsurface wastewater infiltration system (SWIS) under different intermittent influent conditions, ORP among five matrix depths at wet-dry ratios (R_wds) of 2:1, 1:1 and 1:2 with a hydraulic load of 0.10 m [...] Read more.

To understand characteristics of on-line oxidation-reduction potential (ORP) in a subsurface wastewater infiltration system (SWIS) under different intermittent influent conditions, ORP among five matrix depths at wet-dry ratios (R_wds) of 2:1, 1:1 and 1:2 with a hydraulic load of 0.10 m³·(m²·d)⁻¹ were monitored. Results showed that the optimal R_wd for the SWIS was 1:1. In that case, ORP at 40 and 65 cm depths changed significantly, by 529 mV and 261 mV, respectively, from the inflow period to the dry period, which was conducive to the recovery of the oxidation environment. It was concluded that ORP varied nonlinearly in strongly aerobic and hypoxic environment. Wastewater was fed into the SWIS at 80 cm and dissolved oxygen diffused at the initial period of one cycle. As a consequence, ORP at 65 cm increased with water content increasing. However, ORP at 40 and 95 cm displayed inverse trends. Moreover, results showed that ORP decreased with Fe²⁺ and Mn²⁺ increasing under aerobic conditions (p < 0.05) because Fe²⁺ and Mn²⁺ moved with wastewater flow. Effluent met reuse requirements and no clogging was found in the SWIS during the operation. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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12 pages, 1191 KiB

Open AccessArticle

Comparing Ozonation and Biofiltration Treatment of Source Water with High Cyanobacteria-Derived Organic Matter: The Case of a Water Treatment Plant Followed by a Small-Scale Water Distribution System

by I-Chieh Chien, Sheng-Pei Wu, Hsien-Chun Ke, Shang-Lien Lo and Hsin-hsin Tung

Int. J. Environ. Res. Public Health 2018, 15(12), 2633; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15122633 - 24 Nov 2018

Cited by 11 | Viewed by 4418

Abstract

High cyanobacteria-derived dissolved organic carbon (DOC) in source water can cause drinking water quality to deteriorate, producing bad taste, odor, toxins, and possibly elevated levels of disinfection byproduct (DBP) precursors. Conventional water treatment processes do not effectively remove algal organic substances. In this [...] Read more.

High cyanobacteria-derived dissolved organic carbon (DOC) in source water can cause drinking water quality to deteriorate, producing bad taste, odor, toxins, and possibly elevated levels of disinfection byproduct (DBP) precursors. Conventional water treatment processes do not effectively remove algal organic substances. In this study, rapid-sand-filtration effluent from a water treatment plant on Kinmen Island, where serious cyanobacterial blooms occurred, was used to evaluate the DOC- and DBP-removal efficiency of ozonation and/or biofiltration. To simulate a small-scale water distribution system following water treatment, 24 h simulated distribution system (SDS) tests were conducted. The following DBPs were analyzed: trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and trichloronitromethane (TCNM). Applying biological activated-carbon filtration (BAC) on its own achieved the greatest reduction in SDS-DBPs. Ozonation alone caused adverse effects by promoting THM, HAA, and TCNM formation. Ozonation and BAC filtration yielded better DOC removal (51%) than BAC filtration alone (41%). Considering the cost of ozonation, we suggest that when treating high cyanobacterial organic matter in water destined for a small-scale water distribution system, BAC biofiltration alone could be an efficient, economical option for reducing DBP precursors. If DOC removal needs to be improved, preceding ozonation could be incorporated. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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17 pages, 4025 KiB

Open AccessArticle

Spatio-Temporal Differences in Nitrogen Reduction Rates under Biotic and Abiotic Processes in River Water of the Taihu Basin, China

by Jiaxun Guo, Lachun Wang, Xiya Guo, Gengmao Zhao, Jiancai Deng and Chunfen Zeng

Int. J. Environ. Res. Public Health 2018, 15(11), 2568; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15112568 - 16 Nov 2018

Cited by 3 | Viewed by 2951

Abstract

Understanding spatio-temporal differences in nitrogen (N) transformation, transport and reduction rates in water bodies is critical to achieve effective mitigation of river eutrophication. We performed culture experiments in six rivers in the Taihu Basin using a custom made in-situ experimental apparatus. We investigated [...] Read more.

Understanding spatio-temporal differences in nitrogen (N) transformation, transport and reduction rates in water bodies is critical to achieve effective mitigation of river eutrophication. We performed culture experiments in six rivers in the Taihu Basin using a custom made in-situ experimental apparatus. We investigated spatio-temporal differences in reduce processes and rates of different N forms and assessed the contribution of biological processes to dissolved inorganic N (DIN) reduce. Results showed that biological processes played a major role in N reduction in summer, while non-microbial processes were dominant in winter. We observed significant spatial and temporal differences in the studied mechanisms, with reduction rates of different N compounds being significantly higher in summer and autumn than spring and winter. Reduction rates ranged from 105.4 ± 25.3 to 1458.8 ± 98.4 mg·(m³·d)⁻¹ for total N, 33.1 ± 12.3 to 440.9 ± 33.1 mg·(m³·d)⁻¹ for ammonium, 56.3 ± 22.7 to 332.1 ± 61.9 mg·(m³·d)⁻¹ for nitrate and 0.4 ± 0.3 to 31.8 ± 9.0 mg·(m³·d)⁻¹ for nitrite across four seasons. Mean DIN reduction rates with and without microbial activity were 96.0 ± 46.4 mg·(m³·d)⁻¹ and 288.1 ± 67.8 mg·(m³·d)⁻¹, respectively, with microbial activity rates accounting for 29.7% of the DIN load and 2.2% of the N load. Results of correlation and principal component analysis showed that the main factors influencing N processing were the concentrations of different N forms and multiple environmental factors in spring, N concentrations, DO and pH in summer, N concentrations and water velocity in autumn and N concentrations in winter. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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19 pages, 4248 KiB

Open AccessArticle

Investigation of the Inhibitory Effects of Mangrove Leaves and Analysis of Their Active Components on Phaeocystis globosa during Different Stages of Leaf Age

by Min Zhao, Han Xiao, Dong Sun and Shunshan Duan

Int. J. Environ. Res. Public Health 2018, 15(11), 2434; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15112434 - 01 Nov 2018

Cited by 9 | Viewed by 3191

Abstract

The presence of harmful algal blooms (HABs) can cause significant problems to the quality of the water, the marine ecosystems, and the human health, and economy worldwide. Biological remediation can inhibit harmful algal growth efficiently in an environmental-friendly manner. Therefore, the research conducted [...] Read more.

The presence of harmful algal blooms (HABs) can cause significant problems to the quality of the water, the marine ecosystems, and the human health, and economy worldwide. Biological remediation can inhibit harmful algal growth efficiently in an environmental-friendly manner. Therefore, the research conducted on biological remediation with regard to the inhibition of HABs is becoming a major focus in marine ecology. To date, no study has been reported with regard to the red tides occurring in mangrove wetlands. Therefore, the present study used two mangrove species, namely Bruguiera gymnorrhiza and Kandelia candel and one harmful algae species Phaeocystis globosa as experimental organisms. The present study determined the inhibitory effects and algae physiology of specific aqueous extracts from mangrove leaves on the viability of harmful algae, and analyzed the main chemical composition of the aqueous extracts by ultra-performance liquid chromatography coupled to high resolution mass spectrometry (UPLC-QTOF-MS). The results indicated that the aqueous extracts from different leaf ages of B. gymnorrhiza and K. candel leaves exhibited apparent inhibitory effects on the growth of P. globosa. The inhibitory effects of B. gymnorrhiza and K. candel leaves aqueous extracts on the growth of P. globosa were in the following order: senescent > mature > young leaves. The levels of the parameters superoxide dismutase (SOD) activity, glutathione (GSH), and malondialdehyde (MDA)content in P. globosa following treatment with B. gymnorrhiza and K. candel leaves aqueous extracts were increased as follows: senescent > mature > young leaves. Simultaneously, the intensity of the ion peaks of the specific secondary metabolites assigned 4 (No.: 4 Rt: 2.83 min), 7 (No.: 7 Rt: 3.14 min), 8 (No.: 8 Rt: 3.24 min), 9 (No.: 9 Rt: 3.82min) and 10 (No.: 10 Rt: 4.10 min) were increased. These metabolites were found in the aqueous extracts from B. gymnorrhiza leaves. The intensities of the ion peaks of the secondary metabolites 7, 8 in the aqueous extracts from the K. candel leaves were also increased. The majority of the substances that inhibited the algae found in the mangrove plants were secondary metabolites. Therefore, we considered that the norsesquiterpenes compounds 4, 8, 9, and 10 and a phenolic glycoside compound 7 were the active constituents in the aqueous extracts of the mangrove leaves responsible for the inhibition of algae growth. This evidence provided theoretical guidance for the development of biological methods to control red tides and for the further use of substances with antiproliferative activity against algae. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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11 pages, 887 KiB

Open AccessArticle

Bioaccumulation and Biomagnification of 2-Ethylhexyl-4-dimethylaminobenzoate in Aquatic Animals

by Guanghua Lu, Ranran Zhou, Sheng Li, Tianjian Dang and Jianchao Liu

Int. J. Environ. Res. Public Health 2018, 15(11), 2395; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15112395 - 29 Oct 2018

Cited by 8 | Viewed by 3262

Abstract

2-Ethylhexyl-4-dimethylaminobenzoate (EHDAB) is a commonly used organic ultraviolet filter. The bioaccumulation and biomagnification of EHDAB were investigated in two aquatic animals, the larvae of midge (Chironomus riparius) and crucian carp (Carassius carassius), and the metabolic enzyme responses in fish [...] Read more.

2-Ethylhexyl-4-dimethylaminobenzoate (EHDAB) is a commonly used organic ultraviolet filter. The bioaccumulation and biomagnification of EHDAB were investigated in two aquatic animals, the larvae of midge (Chironomus riparius) and crucian carp (Carassius carassius), and the metabolic enzyme responses in fish liver were determined. EHDAB in the larvae of midge reached a steady state within 10 days of sediment exposure. The biota-sediment accumulation factors ranged from 0.10 to 0.54, and were inversely proportional to the exposure concentrations. The EHDAB-contaminated larvae were used to feed the crucian carp. Within 28 days of feeding exposure, the EHDAB levels in fish tissues gradually increased with the increase of the exposure concentration, exhibiting an apparent concentration-dependence and time-dependence. The liver and kidneys were the main organs of accumulation, and the biomagnification factors of EHDAB ranged from 8.97 to 11.0 and 6.44 to 10.8, respectively. In addition, EHDAB significantly increased the activities of cytochrome P450 (CYP) 1A, CYP3A and glutathione S-transferase in the fish liver. Our results indicate that EHDAB may pose a risk of biomagnification in an aquatic environment and influence the biological processes of exposed organisms. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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15 pages, 2002 KiB

Open AccessArticle

The Effect of Different Habitat Types and Ontogenetic Stages on the Diet Shift of a Critically Endangered Fish Species, Coreius guichenoti (Sauvage and Dabry de Thiersant, 1874)

by Zhi Yang, Xiaojuan Chen, Na Zhao, Huiyuan Tang, Jiangping Tao, Peng Zhang, Fang Shi and Chengyan Wan

Int. J. Environ. Res. Public Health 2018, 15(10), 2240; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15102240 - 12 Oct 2018

Cited by 7 | Viewed by 3134

Abstract

This study examined the effect of habitat types and ontogenetic stages on the diet shift of Coreius guichenoti (Sauvage and Dabry de Thiersant, 1874), a critically endangered fish species. Based on the stable isotope analysis method, the following was explored: the variations in [...] Read more.

This study examined the effect of habitat types and ontogenetic stages on the diet shift of Coreius guichenoti (Sauvage and Dabry de Thiersant, 1874), a critically endangered fish species. Based on the stable isotope analysis method, the following was explored: the variations in δ¹³C and δ¹⁵N values, isotopic niche width and four basal food sources (Mollusks, Macrocrustaceans, Aquatic insect larvae and particulate organic matters (POMs)) among three essential habitat types (the spawning ground, natural riverine feeding and nursery area, and Three Gorges Reservoir area) and between two ontogenetic stages (immature and fully mature stages). A diet shift associated with habitat type changes was observed, but there were no obvious differences in diet composition between the two ontogenetic stages. Dietary plasticity and a preference for specific foods were the important determinants of feeding behavior through the life history of this species. POM was important for the survival of this species in the resource-limited spawning ground, but this species fed more heavily on higher-order consumers in resource-abundant areas. This study highlights the importance of maintaining free connectivity among different habitats (particularly spawning grounds) to ensure the long-term sustainability of potamodromous fish species as well as the full investigation of all types of critical habitats for understanding the trophic ecology of a single fish species. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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19 pages, 3570 KiB

Open AccessArticle

The Pertinence of Microwave Irradiated Coconut Shell Bio-Sorbent for Wastewater Decolourization: Structural Morphology and Adsorption Optimization Using the Response Surface Method (RSM)

by Mohammed Abdulsalam, Hasfalina Che Man, Aida Isma Idris, Zurina Zainal Abidin and Khairul Faezah Yunos

Int. J. Environ. Res. Public Health 2018, 15(10), 2200; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15102200 - 09 Oct 2018

Cited by 14 | Viewed by 3297

Abstract

Palm oil mill effluent contains carcinogenic coloured compounds that are difficult to separate due to their aromatic structure. Though colour treatment using adsorption processes at lower pH (<4) have been reported effectual, due to its acidity the remediated effluent poses an environmental hazard [...] Read more.

Palm oil mill effluent contains carcinogenic coloured compounds that are difficult to separate due to their aromatic structure. Though colour treatment using adsorption processes at lower pH (<4) have been reported effectual, due to its acidity the remediated effluent poses an environmental hazard as a result. Thus, the current study focused on achieving decolourization at neutral pH by enhancing the morphology of the coconut shell activated carbon (CSAC) using N₂ as activating-agent with microwave irradiation heating. The microwave pretreated and non-pretreated CSAC were characterized using scanned electron microscopy (SEM), energy dispersive X-ray (EDX) and Brunauer-Emmett-Teller (BET) analysis. A significant modification in the porous structure with a 66.62% increase in the specific surface area was achieved after the pretreatment. The adsorption experimental matrix was developed using the central composite design to investigate the colour adsorption performance under varied pH (6–7), dosage (2–6 g) and contact time (10–100 min). At optimum conditions of neutral pH (7), 3.208 g dosage and contact time of 35 min, the percentage of colour removal was 96.29% with negligible differences compared with the predicted value, 95.855%. The adsorption equilibrium capacity of 1430.1 ADMI × mL/g was attained at the initial colour concentration of 2025 ADMI at 27 °C. The experimental data fitted better with the Freundlich isotherm model with R² 0.9851. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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19 pages, 1116 KiB

Open AccessArticle

Assessment of the Multi-Objective Reservoir Operation for Maintaining the Turbidity Maximum Zone in the Yangtze River Estuary

by Yang Yu, Peifang Wang, Chao Wang, Xun Wang and Bin Hu

Int. J. Environ. Res. Public Health 2018, 15(10), 2118; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15102118 - 26 Sep 2018

Cited by 8 | Viewed by 2972

Abstract

The construction of multifunction reservoirs is important for flood control, agriculture irrigation, navigation, and hydropower generation, but dam construction will inevitably affect the downstream flow and sediment regimes, which can cause some environmental and ecological consequences. Therefore, this paper aims to propose a [...] Read more.

The construction of multifunction reservoirs is important for flood control, agriculture irrigation, navigation, and hydropower generation, but dam construction will inevitably affect the downstream flow and sediment regimes, which can cause some environmental and ecological consequences. Therefore, this paper aims to propose a framework for assessing the multiobjective reservoir operation model based on environmental flows for sustaining the suspended sediment concentration (SSC) requirements in the turbidity maximum zone (TMZ). The Yangtze River Estuary was used as a case study. Through using an analytical model, a quantitative correlation between SSC and water flow rate was established. Then, the quantitative correlation and the SSC requirements were applied to determine the environmental flows for the estuarine TMZ. Subsequently, a multiobjective reservoir operation model was developed for the Three Gorges Reservoir (TGR), and an improved nondominated sorting genetic algorithm III based on elimination operator was applied to the model. An uncertainty analysis and a comparative analysis were used to assess the model’s performance. The results showed that the proposed multiobjective reservoir operation model can reduce ecological deficiency under wet, normal, and dry years by 33.65%, 35.95%, and 20.98%, with the corresponding hydropower generation output lost by 3.37%, 3.88%, and 2.95%, respectively. Finally, we discussed ecological satiety rates under optimized and practical operation of the TGR in wet, normal, and dry years. It indicated that the multiobjective-optimized runoff performs better at maintaining the TMZ in the Yangtze River Estuary than practical runoff. More importantly, the results can offer guidance for the management of the TGR to improve the comprehensive development and protection of the estuarine ecological environment. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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15 pages, 2605 KiB

Open AccessArticle

Relationship between Photosynthetic Capacity and Microcystin Production in Toxic Microcystis Aeruginosa under Different Iron Regimes

by Xun Wang, Peifang Wang, Chao Wang, Jin Qian, Tao Feng and Yangyang Yang

Int. J. Environ. Res. Public Health 2018, 15(9), 1954; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15091954 - 07 Sep 2018

Cited by 7 | Viewed by 3443

Abstract

Blooms of harmful cyanobacteria have been observed in various water bodies across the world and some of them can produce intracellular toxins, such as microcystins (MCs), which negatively impact aquatic organisms and human health. Iron participates significantly in cyanobacterial photosynthesis and is proposed [...] Read more.

Blooms of harmful cyanobacteria have been observed in various water bodies across the world and some of them can produce intracellular toxins, such as microcystins (MCs), which negatively impact aquatic organisms and human health. Iron participates significantly in cyanobacterial photosynthesis and is proposed to be linked to MC production. Here, the cyanobacteria Microcystis aeruginosa was cultivated under different iron regimes to investigate the relationship between photosynthetic capacity and MC production. The results showed that iron addition increased cell density, cellular protein concentration and the Chl-a (chlorophyll-a) content. Similarly, it can also up–regulate photosynthetic capacity and promote MC–leucine–arginine (MC–LR) production, but not in a dose–dependent manner. Moreover, a significant positive correlation between photosynthetic capacity and MC production was observed, and electron transport parameters were the most important parameters contributing to the variation of intracellular MC–LR concentration revealed by Generalized Additive Model analysis. As the electron transport chain was affected by iron variation, adenosine triphosphate production was inhibited, leading to the alteration of MC synthetase gene expression. Therefore, it is demonstrated that MC production greatly relies on redox status and energy metabolism of photosynthesis in M. aeruginosa. In consequence, more attention should be paid to the involvement of photosynthesis in the regulation of MC production by iron variation in the future. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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18 pages, 3838 KiB

Open AccessArticle

Ecohydraulogical Characteristic Index System of Schizopygopsis younghusbandi during Spawning Periods in the Yarlung Tsangpo River

by Qing-Yuan Liu, Jia Li, Rui-Dong An and Yong Li

Int. J. Environ. Res. Public Health 2018, 15(9), 1949; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15091949 - 06 Sep 2018

Cited by 8 | Viewed by 3112

Abstract

To address the species decline in aboriginal fish in the Yarlung Tsangpo River Basin and the lack of research on the habitat characteristics of fish spawning grounds, this paper studied the changing trends in runoff in spawning grounds and the habitat conditions characteristics [...] Read more.

To address the species decline in aboriginal fish in the Yarlung Tsangpo River Basin and the lack of research on the habitat characteristics of fish spawning grounds, this paper studied the changing trends in runoff in spawning grounds and the habitat conditions characteristics of Schizopygopsis younghusbandi during the spawning period. In conventional approaches, inaccurate statistical results are obtained when a full river section is taken as the region to be assessed, so a new method for determining the statistical boundaries of characteristic indexes was proposed. By combining hydrological analyses, mathematical statistics, and numerical simulations, the statistical boundary of the index was determined, and a suitable range for the habitat characteristic indexes for the spawning field was finally obtained. The results showed that (1) the maximum percentage of the statistical boundary for the spawning grounds was 39% near the banks on both sides of the river; (2) the flow during the spawning period exhibited small variations, a short duration and a fluctuation cycle and was dominated by water rising events, and the interannual growth trend in the daily flow was obvious; and (3) during the spawning period, the flow velocity of the fish habitat was small, the turbulence level of the fluid was low, and the flow regime was stable. A suitable range for the habitat characteristic index of the target fish provided the basic data for the protection of aboriginal fish and was beneficial to maintain the balance of aquatic ecological system in the Yarlung Tsangpo River. The results of this study contribute to the rational development of water resources in the basin and the protection of species diversity and water environment. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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12 pages, 1610 KiB

Open AccessArticle

Water Quality of Inflows to the Everglades National Park over Three Decades (1985–2014) Analyzed by Multivariate Statistical Methods

by Lei Wan and Xiaohui Fan

Int. J. Environ. Res. Public Health 2018, 15(9), 1882; https://0-doi-org.brum.beds.ac.uk/10.3390/ijerph15091882 - 30 Aug 2018

Cited by 2 | Viewed by 3196

Abstract

The Everglades, a vast subtropical wetland, dominates the landscape of south Florida and is widely recognized as an ecosystem of great ecological importance. Data from seven inflow sites to the Everglades National Park (ENP) were analyzed over three decades (1985–2014) for temporal trends [...] Read more.

The Everglades, a vast subtropical wetland, dominates the landscape of south Florida and is widely recognized as an ecosystem of great ecological importance. Data from seven inflow sites to the Everglades National Park (ENP) were analyzed over three decades (1985–2014) for temporal trends by the STL (integrated seasonal-trend decomposition using LOESS) method. A cluster analysis (CA) and principal component analysis (PCA) were applied for the evaluation of spatial variation. The results indicate that the water quality change trend is closely associated with rainfall. Increasing rainfall results in increasing flow and thus, decreasing concentrations of nitrogen and phosphorus. Based on 10 variables, the seven sampling stations were classified by CA into four distinct clusters: A, B, C, and D. The PCA analysis indicated that total nitrogen (TN) and total phosphorus (TP) are the main pollution factors, especially TN. The results suggest that non-point sources are the main pollution sources and best management practices (BMPs) effectively reduce organic nitrogen. However, TN and TP control is still the focus of future work in this area. Increasing the transfer water quantity can improve the water quality temporarily and planting submersed macrophytes can absorb nitrogen and phosphorus and increase the dissolved oxygen (DO) concentration in water, continuously improving the water quality. Full article

(This article belongs to the Special Issue Water Quality Improvement and Ecological Restoration)

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