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Yang X, Huang G, Chen Z, Feng Q, An C, Lyu L, Bi H, Zhou S. Spotlight on the vertical migration of aged microplastics in coastal waters. J Hazard Mater 2024; 469:134040. [PMID: 38503206 DOI: 10.1016/j.jhazmat.2024.134040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 03/09/2024] [Accepted: 03/13/2024] [Indexed: 03/21/2024]
Abstract
Coastal waters are complex and dynamic areas with unique environmental attributes that complicate the vertical migration of microplastics (MPs). The MPs that enter coastal waters from diverse sources, including terrestrial, riverine, oceanic, and shoreline inputs undergo various aging pathways. In this study, the variations in the physiochemical characteristics of MPs undergoing various aging pathways and their vertical migration under dynamic conditions subjected to the effects of different MP characteristics and coastal environmental features were comprehensively explored. Opposite effects of aging on the vertical migration of hydrophobic and hydrophilic MPs were observed, with aging appearing to promote the dispersion of hydrophobic MPs but enhance the vertical migration of hydrophilic ones. The positive role of salinity and the negative role of humic acid (HA) concentrations on MP vertical migration were identified, and the mechanisms driving these effects were analyzed. Notably, intense turbulence not only promoted the floating of positively buoyant MPs but also reversed the migration direction of negatively buoyant MPs from downward to upward. Aging-induced changes in MP characteristics had a limited effect on MP vertical migration. The inherent characteristics of MPs and the surrounding environmental features, however, played major roles in their vertical migration dynamics. ENVIRONMENTAL IMPLICATION: Microplastics (MPs) have emerged as a significant global environmental concern and the coastal zones are the hotspots for MP pollution due to their high population density. This study comprehensively investigated the variations in the physiochemical characteristics of MPs undergoing various aging pathways. Their vertical migration patterns under dynamic conditions subjected to the effects of different MP characteristics and coastal environmental features were revealed. The roles of turbulence and MP density in their migration were identified. The findings of this study have important implications for understanding the transport and determining the ecological risks of MPs in coastal waters.
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Affiliation(s)
- Xiaohan Yang
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC H3G 1M8, Canada
| | - Guohe Huang
- Environmental Systems Engineering, Faculty of Engineering and Applied Science, University of Regina, Regina, SK S4S 0A2, Canada
| | - Zhikun Chen
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC H3G 1M8, Canada
| | - Qi Feng
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC H3G 1M8, Canada
| | - Chunjiang An
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC H3G 1M8, Canada.
| | - Linxiang Lyu
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC H3G 1M8, Canada
| | - Huifang Bi
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC H3G 1M8, Canada
| | - Siyuan Zhou
- Department of Building, Civil and Environmental Engineering, Concordia University, Montreal, QC H3G 1M8, Canada
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Blancho F, Lapointe M, Quevedo AC, Kannan K, Tufenkji N. Demonstrating scale-up of a novel water treatment process using super-bridging agents. Water Res 2024; 254:121301. [PMID: 38417265 DOI: 10.1016/j.watres.2024.121301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Revised: 01/22/2024] [Accepted: 02/09/2024] [Indexed: 03/01/2024]
Abstract
Fiber-based materials have emerged as a promising option to increase the efficiency of water treatment plants while reducing their environmental impacts, notably by reducing the use of unsustainable chemicals and the size of the settling tank. Cellulose fiber-based super-bridging agents are sustainable, reusable, and versatile materials that considerably improve floc separation in conventional settling tanks or via alternative screening separation methods. In this study, the effectiveness of fiber-based materials for wastewater treatment was evaluated at lab-scale (0.25 L) and at pilot-scale (20 L) for two separation methods, namely settling and screening. For the fiber-based method, the performance of floc separation during settling was slightly affected by an 80x upscaling factor. A small decrease in turbidity removal from 93 and 86 % was observed for the jar and pilot tests, respectively. By contrast, the turbidity removal of the conventional treatment, i.e., no fibers with a settling separation, was largely affected by the upscaling with turbidity removals of 84 and 49 % for jar and pilot tests, respectively. Therefore, results are suggesting that fiber-based super-bridging agents could be implemented in full-scale water treatment plants. Moreover, the tested fibers increase the robustness of treatment by providing better floc removal than conventional treatment under several challenging conditions such as low settling time and screening with coarse screen mesh size. Furthermore, at both lab-scale and pilot-scale, the use of fiber-based materials reduced the demand for coagulant and flocculant, potentially lowering the operational costs of water treatment plants and reducing the accumulation of metal-based coagulants and synthetic polymers in sludge. Acute toxicity tests using the model organism Daphnia magna show that the cellulose fibers introduce insignificant toxicity at the optimized fiber concentration. Although dedicated mechanistic studies are required at various scales to understand in detail the influence of fibers on water treatment (coagulation/flocculation time, floc formation, floc size distribution velocity gradient, etc.), the efficacy and scalability of the fiber-based approach, along with its minimal environmental impact, position it as a viable and sustainable option for existing and future wastewater treatment plants.
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Affiliation(s)
- Florent Blancho
- Department of Chemical Engineering, McGill University, Quebec H3A 0C5, Canada
| | - Mathieu Lapointe
- Department of Construction Engineering, École de technologie supérieure - University of Québec, Québec H3C 1K3, Canada.
| | - Ana C Quevedo
- Department of Chemical Engineering, McGill University, Quebec H3A 0C5, Canada
| | - Krishnaveni Kannan
- Department of Chemical Engineering, McGill University, Quebec H3A 0C5, Canada
| | - Nathalie Tufenkji
- Department of Chemical Engineering, McGill University, Quebec H3A 0C5, Canada.
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3
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Deng R, Chen B, Wang F, Tian L, Lin Z, Zhang K, Mao J, Yang M, Jiang J. Settling characteristics of scleral lenses in Chinese adults with refractive error. Cont Lens Anterior Eye 2024; 47:102108. [PMID: 38171997 DOI: 10.1016/j.clae.2023.102108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/05/2024]
Abstract
PURPOSE To investigate the settling characteristics of a scleral lens in Chinese adults with refractive error and to provide guidance for its clinical application. METHODS A total of 21 healthy Chinese adults (27.2 ± 4.1 years) with refractive error were enrolled in this study. The average spherical equivalent was -5.50 ± 2.92 D. Subjects were fitted with 15.6 mm diameter scleral lenses. The central post-lens tear thickness (PoLTT) was measured immediately after lens placement, 30, 60, 120, and 240 min after lens insertion at the dispensing visit and immediately after lens placement and 240 min after three months through optical coherence tomography. Statistical analyses were conducted using repeated measures analysis of variance and paired-t test. RESULTS At the dispensing visit, the amount of settling after 240 min of lens wear was 126 ± 33 μm. After three months, the amount of settling was 98 ± 55 μm after 240 min. No significant difference was detected in the PoLTT immediately after lens placement between the dispensing visit and after three months (t = -0.246, p = 0.807), while a significant difference was noted at 240 min after lens insertion (t = -6.575, p < 0.001). The amount of settling was higher at the dispensing visit than that after three months (average difference = 28 ± 63 μm, t = 2.733, p = 0.01). The prediction model of PoLTT over time was y = 26.263-0.690 × t + 0.001 × t2 + 0.926 × y30 (R2 = 0.939), where y denotes the predicted PoLTT at t min after lens insertion, y30 denotes the PoLTT at 30 min after lens insertion. CONCLUSION For the investigated small-diameter scleral lens (material: Boston XO, diameter: 15.6 mm, four-zone and periphery toric design), the PoLTT decreased over time after lens insertion in Chinese adults with refractive error, and the amount of settling varied among individuals (range: 71-204 μm). The amount of settling did not increase further after three months, indicating the long-term fitting stability of the scleral lens. Practitioners could estimate the PoLTT using the prediction model based on the PoLTT at 30 min after wearing lenses.
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Affiliation(s)
- Ruzhi Deng
- Eye Hospital, Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang 325027, China
| | - Bichi Chen
- Vision X Medical Technology Co., Ltd., Shanghai 201114, China
| | - Feifu Wang
- Eye Hospital, Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang 325027, China
| | - Li Tian
- Eye Hospital, Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang 325027, China
| | - Zhiyang Lin
- Eye Hospital, Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang 325027, China
| | - Kou Zhang
- Eye Hospital, Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang 325027, China
| | - Jieli Mao
- Eye Hospital, Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang 325027, China
| | - Maoyuan Yang
- Eye Hospital, Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang 325027, China
| | - Jun Jiang
- Eye Hospital, Wenzhou Medical University, National Clinical Research Center for Ocular Diseases, Wenzhou, Zhejiang 325027, China.
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Huang YP, Wang X, Wang RL, He JT, Huang Y, Hang ZY, Chen X, Li ZH. Managing stability of aerobic granules by coordinating diameter and denitrification. Sci Total Environ 2024; 906:167795. [PMID: 37838046 DOI: 10.1016/j.scitotenv.2023.167795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/10/2023] [Accepted: 10/11/2023] [Indexed: 10/16/2023]
Abstract
Aerobic Granular Sludge (AGS) technology is a promising solution for wastewater treatment due to its structure and high biomass retention capacity. However, the stability of AGS is still a challenge for widespread use. This study investigated the relationships among granule stability, granule diameter, biomass retention capacity, and denitrification efficiency. The results showed that granule diameter did not necessarily indicate granule stability, nor was it associated with biomass retention capacity. For mature granules, promoting simultaneous nitrification and denitrification rather than anoxic denitrification was found to improve granule stability. The deterioration of clarification capacity caused by increased anoxic denitrification at high nitrate concentration was not indicated by diameters or the commonly used SVI5/SVI30. Therefore, ensuring coordination between diameter and denitrification control is crucial for the stability of AGS. These results provide a basis for further research and development of efficient and user-friendly methods for monitoring granular stability.
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Affiliation(s)
- Yong-Peng Huang
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Xin Wang
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Ruo-Lan Wang
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Jin-Tao He
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yuan Huang
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Zhen-Yu Hang
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Xi Chen
- School of Urban Planning and Municipal Engineering, Xi'an Polytechnic University, Xi'an 710048, China
| | - Zhi-Hua Li
- Key Laboratory of Northwest Water Resource, Environment, and Ecology, MOE, School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China; Xi'an Key Laboratory of Intelligent Equipment Technology for Environmental Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China.
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Kyriakoudes G, Turner A. Suspended and deposited microplastics in the coastal atmosphere of southwest England. Chemosphere 2023; 343:140258. [PMID: 37751808 DOI: 10.1016/j.chemosphere.2023.140258] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 09/28/2023]
Abstract
Atmospheric microplastics (MPs) have been sampled from coastal southwest England during twelve periods over a 42-day timeframe in late autumn. MPs were dominated by fibres, with foams, fragments and pellets also observed. The majority of fibres were identified as the semisynthetic polymer, rayon, while other shapes were dominated by various petroleum-based thermoplastics (including polyvinyl acetate, polyvinyl alcohol, polyamide and polyester) and paints. MP concentrations suspended in air ranged from 0.016 to 0.238 items per m3 but displayed no clear dependence on wind speed or direction. Total depositional fluxes ranged from 0.47 to 3.30 m-2 h-1 and showed no clear dependence on wind conditions or electrical conductivity of precipitation (as a measure of maritime influence). However, the concentration of deposited MPs in rainwater was inversely related to rainfall volume, suggesting that incipient precipitation acts to efficiently washout microplastics. A comparison of deposited and suspended MPs by size, shape and polymer type suggests that larger fibres constructed of rayon, polyamide and acrylic are preferentially removed from the atmosphere relative to smaller, non-fibrous MPs and particles constructed of polyester. A quantitative comparison of deposited and suspended MPs provided estimates of location- and environment-specific net settling velocities of between about 7 and 180 m h-1 and corresponding residence times for an air column of 5000 m of between about 30 and 700 h. The findings of the study contribute to an improved understanding of the occurrence, transport and deposition of MPs in the atmosphere more generally.
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Affiliation(s)
- Giannis Kyriakoudes
- School of Geography, Earth and Environmental Sciences, University of Plymouth University Plymouth, PL4 8AA, UK
| | - Andrew Turner
- School of Geography, Earth and Environmental Sciences, University of Plymouth University Plymouth, PL4 8AA, UK.
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Wang Y, Chen X, Wang F, Cheng N. Influence of typical clay minerals on aggregation and settling of pristine and aged polyethylene microplastics. Environ Pollut 2023; 316:120649. [PMID: 36375574 DOI: 10.1016/j.envpol.2022.120649] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 11/06/2022] [Accepted: 11/10/2022] [Indexed: 06/16/2023]
Abstract
Microplastics (MPs) are emerging as a class of pollutants that are a potential threat to biological and human health. Aggregation and settling are crucial to controlling MPs transport and environmental fate. However, the influence of clay minerals in the aqueous environment on the aggregation-settling processes of larger size MPs and its mechanisms remain unclear. In this study, homoaggregation of pristine and aged polyethylene microplastics (PEs) and heteroaggregation-settling of PEs with typical clay minerals (chlorite, illite, kaolinite, montmorillonite) under different hydrochemical conditions (NaCl, CaCl2, MgCl2) were systematically investigated. The results showed that the cation type has a greater influence on the homoaggregation system. In detail, the aged PEs is more stable than pristine PEs in monovalent electrolyte solutions, but not in divalent electrolytes. In heteroaggregation systems, electrostatic repulsion dominates the interaction of PEs (pristine, aged) with clay minerals. However, the settling ratio of PEs (pristine, aged) contributed by clay minerals is not very dependent on the clay mineral type. Conversely, high NaCl concentrations are more conducive to the heteroaggregation-settling of PEs, which can be explained by the DLVO theory. The findings of this study provide new insights into the environmental fate and distribution of MPs in natural waters.
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Affiliation(s)
- Yi Wang
- Fujian Provincial Engineering Research Center for Monitoring and Assessing Terrestrial Disasters, Fujian Normal University, Fuzhou, 350007, China; School of Geographical Sciences, Fujian Normal University, Fuzhou, China, Fuzhou, 350007, China; State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou, 350007, China
| | - Xingwei Chen
- Fujian Provincial Engineering Research Center for Monitoring and Assessing Terrestrial Disasters, Fujian Normal University, Fuzhou, 350007, China; School of Geographical Sciences, Fujian Normal University, Fuzhou, China, Fuzhou, 350007, China; State Key Laboratory for Subtropical Mountain Ecology of the Ministry of Science and Technology and Fujian Province, Fujian Normal University, Fuzhou, 350007, China.
| | - Feifeng Wang
- Fujian Province Key Laboratory of Pollution Control and Resource Recycling, Fuj Ian Normal University, Fuzhou, 350007, China
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Van Winckel T, Ngo N, Sturm B, Al-Omari A, Wett B, Bott C, Vlaeminck SE, De Clippeleir H. Enhancing bioflocculation in high-rate activated sludge improves effluent quality yet increases sensitivity to surface overflow rate. Chemosphere 2022; 308:136294. [PMID: 36084824 DOI: 10.1016/j.chemosphere.2022.136294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 08/02/2022] [Accepted: 08/29/2022] [Indexed: 06/15/2023]
Abstract
High-rate activated sludge (HRAS) relies on good bioflocculation and subsequent solid-liquid separation to maximize the capture of organics. However, full-scale applications often suffer from poor and unpredictable effluent suspended solids (ESS). While the biological aspects of bioflocculation are thoroughly investigated, the effects of fines (settling velocity < 0.6 m3/m2/h), shear and surface overflow rate (SOR) are unclear. This work tackled the impact of fines, shear, and SOR on the ESS in absence of settleable influent solids. This was assessed on a full-scale HRAS step-feed (SF) and pilot-scale HRAS contact-stabilization (CS) configuration using batch settling tests, controlled clarifier experiments, and continuous operation of reactors. Fines contributed up to 25% of the ESS in the full-scale SF configuration. ESS decreased up to 30 mg TSS/L when bioflocculation was enhanced with the CS configuration. The feast-famine regime applied in CS promoted the production of high-quality extracellular polymeric substances (EPS). However, this resulted in a narrow and unfavorable settling velocity distribution, with 50% ± 5% of the sludge mass settling between 0.6 and 1.5 m3/m2/h, thus increasing sensitivity towards SOR changes. A low shear environment (20 s-1) before the clarifier for at least one min was enough to ensure the best possible settling velocity distribution, regardless of prior shear conditions. Overall, this paper provides a more complete view on the drivers of ESS in HRAS systems, creating the foundation for the design of effective HRAS clarifiers. Tangible recommendations are given on how to manage fines and establish the optimal settling velocity of the sludge.
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Affiliation(s)
- Tim Van Winckel
- Center of Microbial Ecology and Technology (CMET), Faculty of Bioscience Engineering, Ghent University, 9000, Gent, Belgium; District of Columbia Water and Sewer Authority, Blue Plains Advanced Wastewater Treatment Plant, 5000 Overlook Ave, SW, Washington DC, 20032, USA; Department of Civil, Environmental and Architectural Engineering, The University of Kansas, KS, USA
| | - Nam Ngo
- District of Columbia Water and Sewer Authority, Blue Plains Advanced Wastewater Treatment Plant, 5000 Overlook Ave, SW, Washington DC, 20032, USA; Department of Civil and Environmental Engineering, The Catholic University of America, Washington DC, USA
| | - Belinda Sturm
- Department of Civil, Environmental and Architectural Engineering, The University of Kansas, KS, USA
| | - Ahmed Al-Omari
- District of Columbia Water and Sewer Authority, Blue Plains Advanced Wastewater Treatment Plant, 5000 Overlook Ave, SW, Washington DC, 20032, USA
| | | | | | - Siegfried E Vlaeminck
- Research Group of Sustainable Energy, Air and Water Technology, Department of Bioscience Engineering, University of Antwerp, 2020, Antwerpen, Belgium.
| | - Haydée De Clippeleir
- District of Columbia Water and Sewer Authority, Blue Plains Advanced Wastewater Treatment Plant, 5000 Overlook Ave, SW, Washington DC, 20032, USA
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Chen Z, Qiu S, Li M, Xu S, Ge S. Effect of free ammonia shock on Chlorella sp. in wastewater: Concentration-dependent activity response and enhanced settleability. Water Res 2022; 226:119305. [PMID: 36332297 DOI: 10.1016/j.watres.2022.119305] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 09/12/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
The unstable microbial activity and unsatisfactory settling performance impede the development and implementation of microalgal wastewater treatment, especially in high-ammonium wastewater in the presence of free ammonia (FA). The shock of FA due to the nutrient fluctuation in wastewater was demonstrated as the primary stress factor suppressing microalgal activities. Recent study has clearly revealed the inhibition mechanism of FA at a specific high level (110.97 mg/L) by inhibiting the genetic information processing, photosynthesis, and nutrient metabolism. However, the effects of various FA shock concentrations on microalgal activities and settling performance remain unknown, limiting the wastewater bioremediation efficiencies improvement and the process development. Herein, a concentration-dependent shock FA (that was employed on microalgae during their exponential growth stages) effect on microalgal growth and photosynthesis was observed. Results showed that the studied five FA shock concentrations ranging from 25 to 125 mg/L significantly inhibited biomass production by 14.7-57.0%, but sharp reductions in photosynthesis with the 36.0-49.0% decreased Fv/Fm values were only observed when FA concentration was above 75.0 mg/L. On the other hand, FA shock enhanced microalgal settling efficiency by 12.8-fold, which was believed to be due to the stimulated intra- and extracellular protein contents and thereby the enhanced extracellular polymer substances (EPS) secretion. Specifically, FA shock induced 40.2 ± 2.3% higher cellular protein content at the cost of the decreased carbohydrates (22.6 ± 1.3%) and fatty acid (39.0 ± 0.8%) contents, further improving the protein secretion by 1.21-fold and the EPS production by 40.2 ± 2.3%. These FA shock-induced variations in intra- and extracellular biomolecules were supported by the up-regulated protein processing and export at the assistance of excessive energy generated from fatty acid degradation and carbohydrates consumption. In addition, FA shock significantly decreased the biomass nutritional value as indicated by the 1.86-fold lower essential amino acid score and nearly 50% reduced essential to non-essential amino acids ratio, while slightly decreased the biodiesel quality. This study is expected to enrich the knowledge of microalgal activities and settling performance in response to fluctuant ammonium concentrations in wastewater and to promote the development of microalgal wastewater treatment.
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Affiliation(s)
- Zhipeng Chen
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing, Jiangsu 210094, China
| | - Shuang Qiu
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing, Jiangsu 210094, China
| | - Mengting Li
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing, Jiangsu 210094, China
| | - Shiling Xu
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing, Jiangsu 210094, China
| | - Shijian Ge
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Xiao Ling Wei 200, Nanjing, Jiangsu 210094, China.
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Manzi HP, Zhang M, Salama ES. Extensive investigation and beyond the removal of micro-polyvinyl chloride by microalgae to promote environmental health. Chemosphere 2022; 300:134530. [PMID: 35405188 DOI: 10.1016/j.chemosphere.2022.134530] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Revised: 03/23/2022] [Accepted: 04/04/2022] [Indexed: 06/14/2023]
Abstract
Microplastics (MPs) remediation via algae could be a prospective strategy to address MPs pollution concerns. In this study, Chlorella sp. GEEL-08 was exposed to different gradient concentrations ranging from 0 to 200 mg L-1 of polyvinyl chloride (PVC0.2μm). Microalgal growth, total nitrogen (TN), total phosphorus (TP), and cations (Cu, Zn, Na, and K) removal were investigated. The oxidative stress enzymes such as superoxide dismutase (SOD) and malonaldehyde (MDA) were also assessed. The addition of 50 mg L-1 mPVC resulted in the highest growth along with >99% removal of nutrients (TN and TP) and >80% removal of cations. However, the addition of 100-200 mg L-1 mPVC inhibited microalgal growth by 8.8-12.3%. The stress-induced by mPVC was highly observed at 200 mg L-1 mPVC on the 4th d with 70.8 U mgprot-1 and 62.3 nmol mgprot-1 of SOD and MDA, respectively. Fourier-transform infrared spectroscopy (FTIR) spectra confirmed that microalgal biomass retained mPVC. Thermogravimetric analysis/derivative thermogravimetric analysis (TGA/DTG) spectra showed that the organic matter of microalgal biomass attached with mPVC was decomposed faster than control, indicating the possibilities of using this biomass for pyrolysis and the formation of bio-products.
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Affiliation(s)
- Habasi Patrick Manzi
- Department of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou City, 730000, Gansu Province, PR China
| | - Min Zhang
- Department of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou City, 730000, Gansu Province, PR China
| | - El-Sayed Salama
- Department of Occupational and Environmental Health, School of Public Health, Lanzhou University, Lanzhou City, 730000, Gansu Province, PR China.
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Cohen-Lévy J, Boulos C, Rompré P, Montpetit A, Kerstein RB. Is the quality of occlusal contacts comparable after aligner and fixed orthodontic therapy? A non-randomized cohort comparison using computerized occlusal analysis during 6 months of retention. Cranio 2022:1-13. [PMID: 35362367 DOI: 10.1080/08869634.2022.2056688] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Less than ideal contacts have been reported following aligner therapy, but it is considered a transitory problem, spontaneously resolving with the phenomenon of settling. Methods: Thirty-nine orthodontic patients (14 treated with aligners; 25 with fixed appliances) were evaluated with a digital occlusal analysis system (T-scan™10), assessing Maximum Intercuspation contact simultaneity, symmetry, and relative force distribution at treatment completion and after 3 and 6 months. RESULTS No significant differences in occlusal contact quality were found between groups at treatment completion or follow-up. The center of force moved posteriorly and remained stable after 3 months but was located more anteriorly in females (p = 0.01). One-third of patients (both groups combined) had marked contact force asymmetry even after 6 months' retention. Conclusion: Occlusal contacts were comparable at completion of treatment with aligners or brackets and after 3-6 months of retention. Settling did not improve marked asymmetry in all patients.
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Affiliation(s)
- Julia Cohen-Lévy
- Orthodontic Clinic, Faculty of Dental Medicine and Oral Health Sciences, McGill University, MTL, Quebec, Canada
| | - Colette Boulos
- Orthodontic Clinic, Faculty of Dental Medicine and Oral Health Sciences, McGill University, MTL, Quebec, Canada
| | - Pierre Rompré
- Orthodontic Clinic, Faculty of Dental Medicine and Oral Health Sciences, McGill University, MTL, Quebec, Canada
| | - Andrée Montpetit
- Orthodontic Clinic, Faculty of Dental Medicine and Oral Health Sciences, McGill University, MTL, Quebec, Canada
| | - Robert Barry Kerstein
- Former Asst. Professor, Department of Restorative Dentistry, Tufts University School of Dental Medicine, Boston, MA USA
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Usanase G, Azema N, Bitouri YE, Souche JC, Gonzalez C. Contribution of settling measurements to the study of polycyclic aromatic hydrocarbons' (PAHs) mobilisation during resuspension of PAHs-associated sediment. Environ Sci Pollut Res Int 2021; 28:68349-68363. [PMID: 34272663 DOI: 10.1007/s11356-021-15236-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/27/2021] [Indexed: 06/13/2023]
Abstract
This paper aims to investigate the effect of the settling behaviour of sediment particles during resuspension on the mobilisation of pollutants such as polycyclic aromatic hydrocarbons (PAHs). Sediments were collected in different areas (basin, channel, beach) of a Mediterranean harbour, located in the south of France (the Grau du Roi harbour), and then separated into different size fractions: large (80-1000 μm), intermediate (40-80 μm), and fine (< 40 μm). Total PAHs concentrations in the initial sediment ranged from 320 to 1043 μg kg-1. Study of the settling behaviour of the PAH-contaminated sediment revealed two sedimentation regimes: sedimentation by mass, which exhibits a sharp interface between the supernatant and the deposit, and sedimentation by clarification with no interface. It appears that sediment particles settle either by the clarification regime or by a combination of the two sedimentation regimes, depending on the size fraction. Particle size distribution monitoring during the settling process allowed the identification of sediment particles less than 20 μm which remain in the water column up to 20 min after resuspension and appear to be the ones that can potentially mobilise PAHs.
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Affiliation(s)
- Gisèle Usanase
- LMGC, IMT Mines Alès, Univ Montpellier, CNRS, Alès, France
| | - Nathalie Azema
- LMGC, IMT Mines Alès, Univ Montpellier, CNRS, Alès, France
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12
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Zhao J, Li Y, Wang X, Xia X, Shang E, Ali J. Ionic-strength-dependent effect of suspended sediment on the aggregation, dissolution and settling of silver nanoparticles. Environ Pollut 2021; 279:116926. [PMID: 33751945 DOI: 10.1016/j.envpol.2021.116926] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/25/2021] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
Suspended sediment (SS) is ubiquitous in natural waters and plays a key role in the fate of engineered nanomaterials. In this study, the effect of SS on the aggregation, settling, and dissolution of polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) was investigated under environmentally relevant conditions. The heteroaggregation of AgNPs with SS was not observed at low ionic strength (≤0.01 M) due to high electrostatic repulsion and steric forces. At higher NaCl concentrations (0.1 and 0.3 M), PVP-AgNPs were found to attach onto the SS surface, and the formation of AgNP-SS heteroaggregates strongly promoted settling of PVP-AgNPs due to the overwhelming gravity force. PVP-AgNP dissolution was reduced after the addition of sediment to ultrapure water because the presence of sediment-associated dissolved organic matter (SS-DOM). The formation of an AgCl layer on PVP-AgNP surface in 0.01 M NaCl solution resulted in the minor effect of SS on AgNP dissolution. After addition of SS, the dissolved silver concentrations of PVP-AgNP increased in 0.1 and 0.3 M NaCl solution. The interactions of SS-DOM with AgNPs under different NaCl concentrations interfered the dissolution of AgNPs in sediment-laden water. This study provides new insight into the fate of AgNPs in sediment-laden water under various environmental conditions.
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Affiliation(s)
- Jian Zhao
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China
| | - Yang Li
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China.
| | - Xinjie Wang
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China
| | - Xinghui Xia
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China
| | - Enxiang Shang
- College of Science and Technology, Hebei Agricultural University, Huanghua, Hebei, 061100, China
| | - Jawad Ali
- Key Laboratory of Water and Sediment Sciences of Ministry of Education, State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, China
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13
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Walker M, Hammel JU, Wilde F, Hoehfurtner T, Humphries S, Schuech R. Estimation of sinking velocity using free-falling dynamically scaled models: Foraminifera as a test case. ACTA ACUST UNITED AC 2021; 224:jeb.230961. [PMID: 33443040 PMCID: PMC7927657 DOI: 10.1242/jeb.230961] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 12/10/2020] [Indexed: 11/20/2022]
Abstract
The velocity of settling particles is an important determinant of distribution in extinct and extant species with passive dispersal mechanisms, such as plants, corals and phytoplankton. Here, we adapted dynamic scaling, borrowed from engineering, to determine settling velocity. Dynamic scaling leverages physical models with relevant dimensionless numbers matched to achieve similar dynamics to the original object. Previous studies have used flumes, wind tunnels or towed models to examine fluid flow around objects with known velocities. Our novel application uses free-falling models to determine the unknown sinking velocity of planktonic Foraminifera – organisms important to our understanding of the Earth's current and historic climate. Using enlarged 3D printed models of microscopic Foraminifera tests, sunk in viscous mineral oil to match their Reynolds numbers and drag coefficients, we predicted sinking velocity of real tests in seawater. This method can be applied to study other settling particles such as plankton, spores or seeds. Summary: A novel method to determine the sinking velocity of biologically important micro-scale particles using 3D printed scale models.
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Affiliation(s)
- Matthew Walker
- School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Green Lane, Lincoln LN6 7DL, UK
| | - Jörg U Hammel
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Outstation at DESY, Building 66, Notkestr. 85, D-22607 Hamburg, Germany
| | - Fabian Wilde
- Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Outstation at DESY, Building 66, Notkestr. 85, D-22607 Hamburg, Germany
| | - Tatjana Hoehfurtner
- School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Green Lane, Lincoln LN6 7DL, UK
| | - Stuart Humphries
- School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Green Lane, Lincoln LN6 7DL, UK
| | - Rudi Schuech
- School of Life Sciences, Joseph Banks Laboratories, University of Lincoln, Green Lane, Lincoln LN6 7DL, UK
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14
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Liu J, Liu A, Guo J, Zhou T, Zhang WX. Enhanced aggregation and sedimentation of nanoscale zero-valent iron (nZVI) with polyacrylamide modification. Chemosphere 2021; 263:127875. [PMID: 32835968 DOI: 10.1016/j.chemosphere.2020.127875] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/24/2020] [Accepted: 07/27/2020] [Indexed: 06/11/2023]
Abstract
Nanoscale zero-valent iron (nZVI) settled slowly and incompletely in a nano-iron reactor (NIR) in wastewater treatment, and the effluent quality and processing capacity of nZVI were degenerated. Herein, three types of polyacrylamide (PAM), anionic-APAM (nZVIAPAM), cationic-CPAM (nZVICPAM), and nonionic-NPAM (nZVINPAM)) were applied to modify the nZVI (nZVIPAM), which were proved to enhance aggregation and sedimentation in the gravity settling clarifier of NIR. PAM modification lead to aggregate by forming large agglomerates. The median sizes of aggregates were 32, 194, 168 and 133 μm respectively for nZVI, nZVICPAM, nZVINPAM, and nZVIAPAM. Under quiescent conditions, bare nZVI needed 5 min to reach sedimentation equilibrium, while nZVIPAM just within 1 min nZVICPAM settled more quickly and completely than nZVINPAM and nZVIAPAM. The Fe concentration in the dynamic flow NIR effluent could keep a low level for 8 h for nZVIPAM, while bare nZVI for 6 h. Iron concentration was 3.11, 0.037, 0.93, and 1.20 mg·L-1 for nZVI, nZVICPAM, nZVINPAM, and nZVIAPAM after 8-h-reaction. Meanwhile, the reactivity of nZVIPAM was kept much longer for lead removal in the NIR. Results demonstrated PAM modifications (especially CPAM) provided a reliable solution for nZVI aggregation and sedimentation in wastewater treatment.
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Affiliation(s)
- Jing Liu
- State Key Laboratory for Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Airong Liu
- State Key Laboratory for Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China.
| | - Jie Guo
- State Key Laboratory for Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Tao Zhou
- State Key Laboratory for Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
| | - Wei-Xian Zhang
- State Key Laboratory for Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai, 200092, China; Shanghai Institute of Pollution Control and Ecological Security, Shanghai, 200092, China
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15
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Ma J, Jing Y, Gao L, Chen J, Wang Z, Weng L, Li H, Chen Y, Li Y. Hetero-aggregation of goethite and ferrihydrite nanoparticles controlled by goethite nanoparticles with elongated morphology. Sci Total Environ 2020; 748:141536. [PMID: 32798881 DOI: 10.1016/j.scitotenv.2020.141536] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 07/28/2020] [Accepted: 08/04/2020] [Indexed: 05/20/2023]
Abstract
The dispersities of goethite nanoparticles (GTNPs) and ferrihydrite nanoparticles (FHNPs) affect the transport and retention of nanoparticle-associated contaminants. However, the effects of interaction on nanoparticle stability under varying environmental conditions have not been previously investigated. This study utilized settling experiments, a semi-empirical model, and the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to study the homo-aggregation and hetero-aggregation of GTNPs and FHNPs. The pure system of GTNPs tended to aggregate more easily than that of FHNPs, especially under the conditions of high pH (7.0-9.0), high ionic strength (IS, 10 mM), and low concentrations of humic acid (HA) (2 mg L-1). This aggregation was attributed to the elongated morphology of GTNPs, which contributed to surface heterogeneity. The GTNPs and FHNPs mixtures rapidly coagulated, particularly under the surface-charge disequilibrium caused by an increase in negative charges or IS. Hetero-aggregation increased with increase in the GTNPs ratio, indicating that the elongated GTNPs dominated the coagulation of the Fe mineral nanoparticle mixture, which was attributed to the surface heterogeneity and high probability collisions between the GTNPs. Although DLVO neglects the influence of heterogeneity on the nanoparticle surfaces, SEM revealed that hetero-aggregation of GTNPs and FHNPs occurred. The results obtained in this study provide novel and valuable insights into the behaviors of GTNPs and FHNPs mixtures and suggest that during the gradual transformation of FHNPs to GTNPs in soil or aquatic environments, the hetero-aggregation of GTNPs and FHNPs may be enhanced, thus promoting contaminant immobilization.
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Affiliation(s)
- Jie Ma
- Key Laboratory for Environmental Factors Control of Agro-Product Quality Safety, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China; Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China
| | - Yilun Jing
- College of Marine and Environmental Science, Tianjin University of Science and Technology, Tianjin 300457, China; School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China
| | - Lijun Gao
- College of Marine and Environmental Science, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Jingping Chen
- College of Marine and Environmental Science, Tianjin University of Science and Technology, Tianjin 300457, China; College of Resources and Environment, Huazhong Agricultural University, Wuhan 430070, China
| | - Zhiqiao Wang
- Key Laboratory for Environmental Factors Control of Agro-Product Quality Safety, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China; Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China
| | - Liping Weng
- Key Laboratory for Environmental Factors Control of Agro-Product Quality Safety, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China; Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China.
| | - Haiming Li
- College of Marine and Environmental Science, Tianjin University of Science and Technology, Tianjin 300457, China.
| | - Yali Chen
- Key Laboratory for Environmental Factors Control of Agro-Product Quality Safety, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China; Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China
| | - Yongtao Li
- Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin 300191, China; College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China
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16
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van Dijk EJH, Pronk M, van Loosdrecht MCM. A settling model for full-scale aerobic granular sludge. Water Res 2020; 186:116135. [PMID: 32891906 DOI: 10.1016/j.watres.2020.116135] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 05/22/2020] [Accepted: 06/30/2020] [Indexed: 06/11/2023]
Abstract
The settling behavior of aerobic granular sludge (AGS) in full-scale reactors is different from the settling of normal activated sludge. Current activated sludge models lack the features to describe the segregation of granules based on size during the settling process. This segregation plays an important role in the granulation process and therefore a better understanding of the settling is essential. The goal of this study was to model and evaluate the segregation of different granule sizes during settling and feeding in full-scale aerobic granular sludge reactors. Hereto the Patwardhan and Tien model was used. This model is an implementation of the Richardson and Zaki model, allowing for multiple classes of particles. To create the granular settling model, the most relevant parameters were identified using aerobic granular sludge from different full-scale Nereda® reactors. The settling properties of individual granules were measured as was the bulk behavior of granular sludge beds with uniform granular sludge particles. The obtained parameters were combined in a model containing multiple granule classes, which then was validated for granular sludge settling in a full-scale Nereda® reactor. In practice a hydraulic selection pressure is used to select for granular sludge. Under the same hydraulic selection pressure the model predicted that different stable granular size distributions can occur. This indicates that granular size distribution control would need a different mechanism then the hydraulic selection pressure alone. This model can be used to better understand and optimize operational parameters of AGS reactors that depend on granular sludge size, like biological nutrient removal. Furthermore insights from this model can also be used in the development of continuously fed AGS systems.
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Affiliation(s)
- Edward J H van Dijk
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, Delft, 2629, HZ, the Netherlands; Royal HaskoningDHV, Laan1914 35, Amersfoort, 3800, AL, the Netherlands.
| | - Mario Pronk
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, Delft, 2629, HZ, the Netherlands; Royal HaskoningDHV, Laan1914 35, Amersfoort, 3800, AL, the Netherlands
| | - Mark C M van Loosdrecht
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, Delft, 2629, HZ, the Netherlands
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17
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Ramírez-López J, Otero-Colina G, Estrada-Venegas EG, Ballesteros-Barrera C, Quero-Rico HJ. Dispersal and resistance to starvation in Raoiella indica (Acari: Tenuipalpidae). Exp Appl Acarol 2020; 82:229-241. [PMID: 32997221 DOI: 10.1007/s10493-020-00545-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 09/11/2020] [Indexed: 06/11/2023]
Abstract
Raoiella indica Hirst (Tenuipalpidae) is an obligate phytophagous mite that has rapidly colonized wide areas of tropical America and causes severe injuries, mainly to plants in the families Arecaceae, Heliconiaceae, Zingiberaceae and Musaceae. This study evaluates biological attributes of the species that could explain its potential as invasive pest, its capacity to survive when deprived of food and its dispersal mechanisms, including passive displacement by wind and possible phoretic association with insects. This mite has a higher resistance to starvation than other phytophagous mites, with a maximum 12 days for adult females. Its main dispersal is by wind, even at low velocities. Phoresy on insects was not observed.
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Affiliation(s)
- José Ramírez-López
- Colegio de Postgraduados, Postgrado en Fitosanidad, Orientación en Entomología y Acarología, Km 36.5 Carr, México-Texcoco, C.P. 56230, Montecillo, Estado de México, Mexico
| | - Gabriel Otero-Colina
- Colegio de Postgraduados, Postgrado en Fitosanidad, Orientación en Entomología y Acarología, Km 36.5 Carr, México-Texcoco, C.P. 56230, Montecillo, Estado de México, Mexico.
| | | | | | - Hermilo Jorge Quero-Rico
- Universidad Nacional Autónoma de México, Instituto de Biología, Cto. Zona Deportiva S/N, C.U., Coyoacán, C.P. 04510, Ciudad de México, Mexico
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18
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Bondelind M, Sokolova E, Nguyen A, Karlsson D, Karlsson A, Björklund K. Hydrodynamic modelling of traffic-related microplastics discharged with stormwater into the Göta River in Sweden. Environ Sci Pollut Res Int 2020; 27:24218-24230. [PMID: 32306266 PMCID: PMC7326794 DOI: 10.1007/s11356-020-08637-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 03/27/2020] [Indexed: 05/06/2023]
Abstract
Microplastics (MP) are transported from land-based sources from rivers to marine waters. However, there is currently little knowledge about MP fate from land sources to marine waters. Traffic is estimated to be one of the largest sources of MP; hence, stormwater is expected to be an important transportation route of MP to marine waters. The aim of this study was to investigate the effect of the size and density of tyre wear particles in road run-off on their fate in the Göta River in Sweden using hydrodynamic modelling. The model of the stretch of Göta River, Sweden's largest river, passing through Gothenburg (Sweden's second largest city) and out to the sea, was set up using MIKE 3 FM software. Literature data were used to define the MP characteristics: concentrations in stormwater, prevalent particle sizes, density of MP commonly occurring in road run-off and settling velocities. Results show that higher concentrations of MP are found on the south side of the river, compared with the north side, due to higher annual average daily traffic loads along the south side of the river. The mixing processes in the river and the MP concentrations were generally influenced by the vertical water density gradient caused by saline water from the Kattegat strait. While most MP with higher density and larger size settle in the river, smaller MP with density close to 1.0 g/cm3 do not settle in the river and therefore reach the Kattegat strait and the marine environments. Further research is needed to describe the fate and transport of microplastics in the stormwater system, including treatment facilities, i.e. biofouling, aggregation, degradation and/or further fragmentation and settling.
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Affiliation(s)
- Mia Bondelind
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Sven Hultins gata 6, SE-412 96, Gothenburg, Sweden
| | - Ekaterina Sokolova
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Sven Hultins gata 6, SE-412 96, Gothenburg, Sweden.
| | - Ailinh Nguyen
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Sven Hultins gata 6, SE-412 96, Gothenburg, Sweden
| | - Dick Karlsson
- Sustainable Waste and Water, City of Gothenburg, Box 123, SE-424 23, Angered, Sweden
| | - Anna Karlsson
- Tyréns AB, Lilla Badhusgatan 2, SE-411 21, Gothenburg, Sweden
| | - Karin Björklund
- Department of Architecture and Civil Engineering, Chalmers University of Technology, Sven Hultins gata 6, SE-412 96, Gothenburg, Sweden
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19
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Theurillat X, Redeuil K, Nicolas M, Nagy K. Mitigating the formation of monochloropropanediol diesters in vegetable oils by removing their residual sediments. Food Chem 2020; 313:125926. [PMID: 31945703 DOI: 10.1016/j.foodchem.2019.125926] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/15/2019] [Accepted: 11/18/2019] [Indexed: 11/28/2022]
Abstract
This study investigates whether the formation of monochloropropane diol fatty acid esters (MCPDE) can be mitigated by removing the residual sediments from vegetable oils. Settling and centrifugation were conducted in crude sunflower and palm oil and the purified oils and their sediment-rich fractions were heated and analyzed for their MCPDE content. Increased MCPDE levels by factors of x2 to x6 were found in the sediment-rich fractions of settled sunflower oils compared to the sediment-free oil. The sediment-containing fraction could be however purified by ultracentrifugation resulting in the mitigation of MCPDE levels by a factor of 10. The effect of residual sediment on the MCPDE formation was also confirmed in the case of palm oil showing x2 to x10 more MCPDE formation in the sediment containing fractions compared to the purified oil. These results confirm that the mechanical removal of the trace sediments from crude vegetable oils results in reduced MCPDE levels.
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Affiliation(s)
- Xanthippe Theurillat
- Société des Produits Nestlé SA. - Nestlé Research Lausanne, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland.
| | - Karine Redeuil
- Société des Produits Nestlé SA. - Nestlé Research Lausanne, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland.
| | - Marine Nicolas
- Société des Produits Nestlé SA. - Nestlé Research Lausanne, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland.
| | - Kornél Nagy
- Société des Produits Nestlé SA. - Nestlé Research Lausanne, Vers-chez-les-Blanc, 1000 Lausanne 26, Switzerland.
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20
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Al-Dawery SK, Ahmed A, Reddy SS, Al-Hadhrami O, Al-Lamki K. Cost-effective treatment of sludge conditioning using supernatant fluid polyelectrolyte. Environ Sci Pollut Res Int 2020; 27:10790-10801. [PMID: 31950420 DOI: 10.1007/s11356-020-07694-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 01/09/2020] [Indexed: 06/10/2023]
Abstract
Treatment of activated sludge using pure polyelectrolyte and its supernatant fluids for sludge dewatering was examined. The supernatant was used for treatment of fresh sludge for reducing the total cost of sludge conditioning by almost 50% and had great impact on wastewater treatment especially on that with large flow rate. The utilization of supernatant can be considered as a sustainable and economical method for pollution reduction especially in the developing countries. This would overcome the problem of imperfect mixing, difficulties in operated sludge conditioning, and utilized wasted polyelectrolyte. A slightly high positively charged polyelectrolyte was selected during this study. The results showed this polymer and the supernatant had significant influence on the sludge volume index (SVI) and sludge settling. The SVI and settling were improved by 50% and 60%, respectively. We found the sludge treated with supernatant showed a highest sludge settling properties compared with using pure polyelectrolyte especially for sludge samples with low total suspended solid (TSS) and SVI. Using mixed supernatant with pure polyelectrolyte showed higher settling compared to second treatment. Zeta potentials were measured, and increases in zeta potentials were observed for use of both pure polymer and supernatant fluids. The experiments of using supernatants for sludge treatment were found to reflect the use of waste for waste and principle of circulation cleaning; thus it can be a valuable reference for the researchers working in the field of sludge treatment.
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Affiliation(s)
- Salam K Al-Dawery
- Department of Chemical Engineering, College of Engineering and Architecture, University of Nizwa, Nizwa, Sultanate of Oman.
| | - Anwar Ahmed
- Department of Civil and Environmental Engineering, College of Engineering and Architecture, University of Nizwa, Nizwa, Sultanate of Oman
| | - Sajjala S Reddy
- Department of Civil and Environmental Engineering, College of Engineering and Architecture, University of Nizwa, Nizwa, Sultanate of Oman
| | - Omaima Al-Hadhrami
- Department of Chemical Engineering, College of Engineering and Architecture, University of Nizwa, Nizwa, Sultanate of Oman
| | - Kareema Al-Lamki
- Department of Chemical Engineering, College of Engineering and Architecture, University of Nizwa, Nizwa, Sultanate of Oman
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Battaglia P, Consoli P, Ammendolia G, D'Alessandro M, Bo M, Vicchio TM, Pedà C, Cavallaro M, Andaloro F, Romeo T. Colonization of floats from submerged derelict fishing gears by four protected species of deep-sea corals and barnacles in the Strait of Messina (central Mediterranean Sea). Mar Pollut Bull 2019; 148:61-65. [PMID: 31422304 DOI: 10.1016/j.marpolbul.2019.07.073] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 07/29/2019] [Accepted: 07/29/2019] [Indexed: 06/10/2023]
Abstract
The distribution of floating litter in marine waters, influenced by currents and wind drag, often determines the dispersal of its encrusting fauna. In the present paper, we observed for the first time the colonization of rafting floats from abandoned, lost or derelict fishing gears (ALDFG) by the four protected deep-sea species: Errina aspera, Desmophyllum pertusum, Madrepora oculata Pachylasma giganteum. Overall, 41 floats, colonized by deep benthic species, were found stranded on the shore of the Sicilian coast of the Strait of Messina, between 2016 and 2019. Species composition, number and occurrence of colonizing organisms were analyzed. On the basis of the species composition (the association between E. aspera, P. giganteum and Megabalanus tulipiformis), the knowledge on their ecology, biogeography, path of local currents, it was possible to define that the area of origin of the most part of these fishing net floats was the Strait of Messina.
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Affiliation(s)
- Pietro Battaglia
- SZN, Stazione Zoologica Anton Dohrn, Villa Pace, via Consolare Pompea (93,51 km), 98167 Messina, Italy.
| | - Pierpaolo Consoli
- SZN, Stazione Zoologica Anton Dohrn, Villa Pace, via Consolare Pompea (93,51 km), 98167 Messina, Italy
| | | | - Michela D'Alessandro
- ISPRA, Institute for Environmental Protection and Research, BIO-CIT, Via dei Mille, 46, 98057, Milazzo, ME, Italy
| | - Marzia Bo
- DISTAV, Department of Earth, Environment and Life Sciences, University of Genoa, Corso Europa 16, 16132 Genova, Italy
| | | | - Cristina Pedà
- ISPRA, Institute for Environmental Protection and Research, BIO-CIT, Via dei Mille, 46, 98057, Milazzo, ME, Italy
| | - Mauro Cavallaro
- Department of Veterinary Sciences, University of Messina, Polo Universitario dell'Annunziata, 98168, Messina, Italy
| | - Franco Andaloro
- SZN, Stazione Zoologica Anton Dohrn, Villa Pace, via Consolare Pompea (93,51 km), 98167 Messina, Italy
| | - Teresa Romeo
- SZN, Stazione Zoologica Anton Dohrn, Villa Pace, via Consolare Pompea (93,51 km), 98167 Messina, Italy; ISPRA, Institute for Environmental Protection and Research, BIO-CIT, Via dei Mille, 46, 98057, Milazzo, ME, Italy
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Li Y, Wang X, Fu W, Xia X, Liu C, Min J, Zhang W, Crittenden JC. Interactions between nano/micro plastics and suspended sediment in water: Implications on aggregation and settling. Water Res 2019; 161:486-495. [PMID: 31229729 DOI: 10.1016/j.watres.2019.06.018] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/04/2019] [Accepted: 06/07/2019] [Indexed: 06/09/2023]
Abstract
Interactions between nano/microplastics and suspended sediment (SS) in natural waters are important for the environmental fate of plastic particles. This study investigated the effect of heteroaggregation between nano/microplastics and SS on the settling of aggregates. In NaCl solutions (0.05-0.5 M), large SS (100-500 μm in diameter) significantly increased the settling ratio of polystyrene nanoplastics (PSNPs) with an average diameter of 100 nm due to the formation of PSNPs-SS aggregates. The settling ratio of the heteroaggregates increased significantly when the NaCl concentration increased from 50 to 200 mM. This was primarily because higher ionic strength reduced the electrostatic repulsion between large SS and PSNPs, and subsequently increased the heteroaggregation rate. No obvious differences in settling ratios were observed in 200 or 500 mM NaCl solutions because the heteroaggregation entered the diffusion-controlled regime. However, in HA solutions (10-50 mg L-1), the surface adsorption of HA on PSNPs and large SS reduced the heteroaggregation of PSNPs-SS and thus led to the low co-settling ratio due to the steric hindrance according to the DLVO theory. In contrast, polyethylene microplastics (PEMPs) with diameters of 1.0-1.2 mm were found to always float on water surface (up to 8 months), even after addition of 500 mg L-1 small SS (<10 μm in diameter). Clearly, the heteroaggregation of PEMPs and small SS had minor effect on the settling of PEMPs due to the overwhelming boyanccy. These results provided new insight into the fate and distribution of nano/microplastics in aquatic environment, which affect the bioavailability of plastic particles in natural waters.
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Affiliation(s)
- Yang Li
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, PR China; John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA.
| | - Xinjie Wang
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, PR China
| | - Wanyi Fu
- John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Xinghui Xia
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, PR China
| | - Changqing Liu
- School of Environmental and Municipal Engineering, Qingdao University of Technology, Qingdao, 266033, PR China
| | - Jiacheng Min
- John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Wen Zhang
- John A. Reif, Jr. Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA.
| | - John Charles Crittenden
- State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing, 100875, PR China; School of Civil and Environmental Engineering and the Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta, GA, 30332, USA
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Murray L, Tran T, Van Thang V, McDonald N, Beggs S, Fisher J. Assistance for parents with unsettled infants in Central Vietnam: a qualitative investigation of health professionals' perspectives. BMC Pediatr 2019; 19:160. [PMID: 31109311 PMCID: PMC6526599 DOI: 10.1186/s12887-019-1532-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 05/09/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Unsettled infant behaviours are a common concern for parents internationally, and have been associated with maternal stress, reduced parenting confidence, and postnatal mental health problems among parents. Little information currently exists regarding available support for the parents of unsettled infants in low-and-middle income countries such as Vietnam. We aimed to describe how unsettled infant behaviour was understood and investigated by Vietnamese health professionals, and what health education was provided to parents regarding infant sleep and settling. METHODS This qualitative study elicited the perspectives of Vietnamese health professionals working in Thua Thien Hue Province, Vietnam. A semi-structured interview guide included participant demographics, and questions about providing assistance to the parents of unsettled infants, understandings of unsettled infant behaviour, management of unsettled infant behaviour and health education. Individual interviews or small-group discussions were undertaken in Vietnamese, data were translated and analysed in English. The authors used a thematic approach to analysis, supported by Nvivo software. RESULTS Nine health professionals (four primary care doctors, one paediatrician and four nurses/midwives) working in urban and rural areas of Thua Thien Hue were interviewed. Four themes were created that reflected the responses to the literature-based interview questions. Health professionals described having received little formal training about infant sleep and settling, thus based their advice on personal experience. Information on infant sleep and settling was not included in health education for new mothers, which focused on breastfeeding and preventing malnutrition. Where advice was given, it was generally based on settling strategies involving high levels of caregiver intervention (holding, rocking, breastfeeding on demand and tolerating frequent overnight wakings) rather than behaviour management style strategies. Participants emphasised the importance of recognising and responding to infant behavioural cues (e.g infants cry when hungry). CONCLUSIONS There is an unmet need for information on infant sleep and settling for new parents and health professionals in Vietnam. Our findings suggest information for caregivers on how to respond sensitively to infant tired signs should be formally included in the training of health professionals in LALMI settings. Sleep and settling information should also be part of culturally appropriate multi-component maternal and child health interventions aimed at promoting early childhood development.
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Affiliation(s)
- Linda Murray
- School of Medicine, University of Tasmania, Hobart, Tasmania, Australia. .,Institute of Community Health Research, Faculty of Public Health, College of Medicine and Pharmacy, Hue University, Hue, Vietnam. .,College of Health Sciences, Massey University, Wellington, New Zealand.
| | - Thach Tran
- School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
| | - Vo Van Thang
- Institute of Community Health Research, Faculty of Public Health, College of Medicine and Pharmacy, Hue University, Hue, Vietnam
| | - Nicole McDonald
- School of Public Health and Social Work, Queensland University of Technology, Brisbane, QLD, Australia
| | - Sean Beggs
- School of Medicine, University of Tasmania, Hobart, Tasmania, Australia
| | - Jane Fisher
- School of Public Health and Preventive Medicine, Monash University, Melbourne, VIC, Australia
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Watkins L, McGrattan S, Sullivan PJ, Walter MT. The effect of dams on river transport of microplastic pollution. Sci Total Environ 2019; 664:834-840. [PMID: 30769307 DOI: 10.1016/j.scitotenv.2019.02.028] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 01/31/2019] [Accepted: 02/02/2019] [Indexed: 05/06/2023]
Abstract
Dams are known to trap pollutants such as metals and PCBs in the sediment that accumulates within their reservoirs. As more attention is paid to microplastics, an emerging contaminant in waterways worldwide, and how they move along rivers, whether microplastic particles also accumulate behind dams is an important question for informing estimates of global river inputs to oceans. In this study, we measured microplastic concentrations above, below, and within the reservoirs of six dams near Ithaca, NY USA. Samples were processed following the wet peroxide oxidation method and visual counting, followed by Raman Spectroscopy validation. We found that microplastic concentrations in sediment within reservoirs was significantly higher than in sediment above the dams (p = 0.005), and in water samples, concentrations within reservoirs was significantly lower (p = 0.02). Plastic fibers were the dominant plastic type, but in within-reservoir sediment samples, less abundant plastic types such as plastic fragments were found in higher proportions. These results show that the sediment collecting behind dams is one sink for microplastics in river systems at long timescales, indicating that accounting for dams may be important when modeling global riverine microplastic transport.
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Affiliation(s)
- Lisa Watkins
- Soil & Water Lab, Biological and Environmental Engineering, Cornell University, Ithaca, NY 14850, USA.
| | - Susan McGrattan
- Soil & Water Lab, Biological and Environmental Engineering, Cornell University, Ithaca, NY 14850, USA
| | | | - M Todd Walter
- Soil & Water Lab, Biological and Environmental Engineering, Cornell University, Ithaca, NY 14850, USA
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25
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Li Y, Wolanski E, Dai Z, Lambrechts J, Tang C, Zhang H. Trapping of plastics in semi-enclosed seas: Insights from the Bohai Sea, China. Mar Pollut Bull 2018; 137:509-517. [PMID: 30503462 DOI: 10.1016/j.marpolbul.2018.10.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 10/14/2018] [Accepted: 10/15/2018] [Indexed: 06/09/2023]
Abstract
Microplastics are abundant in semi-enclosed seas, presumably because of local trapping. To investigate this trapping effect, we confronted the SLIM plastic oceanography model with field data of the distribution of microplastics in the Bohai Sea, China. Seven source locations were selected to reveal the fate of plastic debris from industrial and domestic usages. The model predictions compared well with the observed distribution of microplastics, highlighting that most plastics were trapped in the Bohai Sea. The model suggests that microplastics distribution within the Bohai Sea both in the water and on the bottom varies seasonally with wind and currents and depends on a complex interaction between source locations, prevailing hydrodynamic conditions, degradation, settling and resuspension rates. Further field studies are warranted to enable the models to better parameterize the fate of microplastics, and particularly the accumulation zones, in other poorly flushed semi-enclosed seas worldwide, where microplastics should be classified as a persistent pollutant.
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Affiliation(s)
- Yanfang Li
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Shandong, China.
| | - Eric Wolanski
- TropWATER and College of Science and Engineering, James Cook University, Townsville, Qld 4810, Australia
| | - Zhenfei Dai
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Shandong, China
| | - Jonathan Lambrechts
- Catholic University of Louvain, Institute of Mechanics, Materials and Civil Engineering (IMMC), B-1348 Louvain-la-Neuve, Belgium
| | - Cheng Tang
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Shandong, China
| | - Hua Zhang
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Shandong, China
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26
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Chae M, Xia L, Zhu C, Bressler DC. Accelerating settling rates of biosolids lagoons through thermal hydrolysis. J Environ Manage 2018; 220:227-232. [PMID: 29778959 DOI: 10.1016/j.jenvman.2018.05.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 05/09/2018] [Accepted: 05/14/2018] [Indexed: 06/08/2023]
Abstract
Although the improved dewaterability and digestibility of primary biosolids subjected to thermal hydrolysis has been studied for decades, there are a surprisingly small number of studies exploring the use of this thermal treatment for digested biosolids that are typically left to settle in large settling lagoons. This is likely because of the high capital and operating costs associated with thermal hydrolysis, coupled with the limited applications and value of the resulting products. However, due to the anticipated increases in the amount of generated biosolids combined with issues surrounding potential environmental release and the limited availability of land for additional lagoons, other biosolids management strategies are being explored. Here, we show that thermal hydrolysis at 280 °C for 1 h resulted in 78.2 ± 0.8% settling after 2 h. Furthermore, addition of phosphoric acid to lower the pH of the hydrolysate to pH 3 resulted in increased settling rates, but the final volume of unsettled material after 2 h was statistically similar to the thermally hydrolyzed material without pH adjustment (75.7 ± 2.3%). Remarkably, when the pH of the digested biosolids was adjusted to 3 prior to thermal hydrolysis, a settling rate of 87.3 ± 1.1% was observed after just 15 min. Significantly, the dewaterability of thermally hydrolyzed biosolids was measured in our experiments through natural settling, without the use of external mechanics. Taken together, the data presented in this paper demonstrate that high temperature thermal hydrolysis is a promising method for accelerating the settling rates of digested biosolids and may represent a viable alternative to building and maintaining biosolids lagoons.
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Affiliation(s)
- Michael Chae
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, T6G 2P5, Canada.
| | - Lin Xia
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, T6G 2P5, Canada.
| | - Chengyong Zhu
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, T6G 2P5, Canada.
| | - David C Bressler
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, T6G 2P5, Canada.
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27
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Holness MB. Melt segregation from silicic crystal mushes: a critical appraisal of possible mechanisms and their microstructural record. Contrib Mineral Petrol 2018; 173:48. [PMID: 30996392 PMCID: PMC6438595 DOI: 10.1007/s00410-018-1465-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 04/03/2018] [Indexed: 06/01/2023]
Abstract
One of the outstanding problems in understanding the behavior of intermediate-to-silicic magmatic systems is the mechanism(s) by which large volumes of crystal-poor rhyolite can be extracted from crystal-rich mushy storage zones in the mid-deep crust. The mechanisms commonly invoked are hindered settling, micro-settling, and compaction. The concept of micro-settling involves extraction of grains from a crystal framework during Ostwald ripening and has been shown to be non-viable in the metallic systems for which it was originally proposed. Micro-settling is also likely to be insignificant in silicic mushes, because ripening rates are slow for quartz and plagioclase, contact areas between grains in a crystal mush are likely to be large, and abundant low-angle grain boundaries promote grain coalescence rather than ripening. Published calculations of melt segregation rates by hindered settling (Stokes settling in a crystal-rich system) neglect all but fluid dynamical interactions between particles. Because tabular silicate minerals are likely to form open, mechanically coherent, frameworks at porosities as high as ~ 75%, settling of single crystals is only likely in very melt-rich systems. Gravitationally-driven viscous compaction requires deformation of crystals by either dissolution-reprecipitation or dislocation creep. There is, as yet, no reported microstructural evidence of extensive, syn-magmatic, internally-generated, viscous deformation in fully solidified silicic plutonic rocks. If subsequent directed searches do not reveal clear evidence for internally-generated buoyancy-driven melt segregation processes, it is likely that other factors, such as rejuvenation by magma replenishment, gas filter-pressing, or externally-imposed stress during regional deformation, are required to segregate large volumes of crystal-poor rhyolitic liquids from crustal mushy zones.
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Affiliation(s)
- Marian B. Holness
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ UK
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28
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Caluwé M, Dobbeleers T, Daens D, Blust R, Geuens L, Dries J. The effect of the feeding pattern of complex industrial wastewater on activated sludge characteristics and the chemical and ecotoxicological effluent quality. Environ Sci Pollut Res Int 2017; 24:10796-10807. [PMID: 28290086 DOI: 10.1007/s11356-017-8712-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 02/28/2017] [Indexed: 06/06/2023]
Abstract
Research has demonstrated that the feeding pattern of synthetic wastewater plays an important role in sludge characteristics during biological wastewater treatment. Although considerable research has been devoted to synthetic wastewater, less attention has been paid to industrial wastewater. In this research, three different feeding strategies were applied during the treatment of tank truck cleaning (TTC) water. This industry produces highly variable wastewaters that are often loaded with hazardous chemicals, which makes them challenging to treat with activated sludge (AS). In this study, it is shown that the feeding pattern has a significant influence on the settling characteristics. Pulse feeding resulted in AS with a sludge volume index (SVI) of 68 ± 15 mL gMLSS-1. Slowly and continuously fed AS had to contend with unstable SVI values that fluctuated between 100 and 600 mL gMLSS-1. These fluctuations were clearly caused by the feeding solution. The obtained settling characteristics are being supported by the microscopic analysis, which revealed a clear floc structure for the pulse fed AS. Ecotoxicological effluent assessment with bacteria, Crustacea and algae identified algae as the most sensitive organism for all effluents from all different reactors. Variable algae growth inhibitions were measured between the different reactors. The chemical and ecotoxicological effluent quality was comparable between the reactors.
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Affiliation(s)
- Michel Caluwé
- Research group BioGEM, Bio-Chemical Green Engineering & Materials, Faculty of Applied Engineering, University of Antwerp, Salesianenlaan 90, 2660, Antwerp, Belgium
- SPHERE, Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
| | - Thomas Dobbeleers
- Research group BioGEM, Bio-Chemical Green Engineering & Materials, Faculty of Applied Engineering, University of Antwerp, Salesianenlaan 90, 2660, Antwerp, Belgium
| | - Dominique Daens
- Research group BioGEM, Bio-Chemical Green Engineering & Materials, Faculty of Applied Engineering, University of Antwerp, Salesianenlaan 90, 2660, Antwerp, Belgium
| | - Ronny Blust
- SPHERE, Systemic Physiological and Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020, Antwerp, Belgium
| | - Luc Geuens
- Research group BioGEM, Bio-Chemical Green Engineering & Materials, Faculty of Applied Engineering, University of Antwerp, Salesianenlaan 90, 2660, Antwerp, Belgium
| | - Jan Dries
- Research group BioGEM, Bio-Chemical Green Engineering & Materials, Faculty of Applied Engineering, University of Antwerp, Salesianenlaan 90, 2660, Antwerp, Belgium.
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29
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Kim KY, Ahn HW, Kim SH, Nelson G. Effects of a new type of clear overlay retainer on occlusal contacts. Korean J Orthod 2017; 47:207-212. [PMID: 28523247 PMCID: PMC5432442 DOI: 10.4041/kjod.2017.47.3.207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/26/2016] [Accepted: 12/27/2016] [Indexed: 11/10/2022] Open
Abstract
The popularity of clear overlay retainers (CORs) has increased recently because of their advantages such as better esthetics, cost effectiveness, easy fabrication, and good compliance. However, a deficiency in posterior occlusal settling is a reported limitation of CORs. The aim of this study was to evaluate the posterior occlusal contact changes in a new type of clear orthodontic retainer called Oral-treaper (OTP), which consists of three layers and has stronger mechanical characteristics than do conventional retainers. Three patients who completed fixed orthodontic treatment received OTP as a removable retainer. Cast models were fabricated after the removal of fixed appliances (T1) and after 4 to 11 months of using the retainers (T2). We evaluated all the cast models to compare the post-orthodontic settling pattern during the use of the OTPs. The depth of occlusal contacts was evaluated using color maps. The OTP did not prevent vertical settling in all patients but resulted in an improvement in posterior occlusal contact points.
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Affiliation(s)
- Kyoung Yeon Kim
- Department of Orthodontics, Graduate School, Kyung Hee University, Seoul, Korea
| | - Hyo-Won Ahn
- Department of Orthodontics, Graduate School, Kyung Hee University, Seoul, Korea
| | - Seong-Hun Kim
- Department of Orthodontics, Graduate School, Kyung Hee University, Seoul, Korea
| | - Gerald Nelson
- Division of Orthodontics, Department of Orofacial Science, University of California San Francisco, CA, USA
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30
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Lama S, Muylaert K, Karki TB, Foubert I, Henderson RK, Vandamme D. Flocculation properties of several microalgae and a cyanobacterium species during ferric chloride, chitosan and alkaline flocculation. Bioresour Technol 2016; 220:464-470. [PMID: 27611030 DOI: 10.1016/j.biortech.2016.08.080] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 08/13/2016] [Accepted: 08/18/2016] [Indexed: 06/06/2023]
Abstract
Flocculation holds great potential as a low-cost harvesting method for microalgae biomass production. Three flocculation methods (ferric chloride, chitosan, and alkaline flocculation) were compared in this study for the harvesting of 9 different freshwater and marine microalgae and one cyanobacterium species. Ferric chloride resulted in a separation efficiency greater than 90% with a concentration factor (CF) higher than 10 for all species. Chitosan flocculation worked generally very well for freshwater microalgae, but not for marine species. Alkaline flocculation was most efficient for harvesting of Nannochloropsis, Chlamydomonas and Chlorella sp. The concentration factor was highly variable between microalgae species. Generally, minimum flocculant dosages were highly variable across species, which shows that flocculation may be a good harvesting method for some species but not for others. This study shows that microalgae and cyanobacteria species should not be selected solely based on their productivity but also on their potential for low-cost separation.
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Affiliation(s)
- Sanjaya Lama
- Laboratory for Aquatic Biology, KU Leuven Campus Kulak, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium; Department of Biotechnology, School of Science, Kathmandu University, Dhulikhel, Nepal
| | - Koenraad Muylaert
- Laboratory for Aquatic Biology, KU Leuven Campus Kulak, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium
| | - Tika Bahadur Karki
- Department of Biotechnology, School of Science, Kathmandu University, Dhulikhel, Nepal
| | - Imogen Foubert
- KU Leuven Kulak, Research Unit Food & Lipids, Department of Molecular and Microbial Systems Kulak, Etienne Sabbelaan 53, B-8500 Kortrijk, Belgium; Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium
| | - Rita K Henderson
- bioMASS lab, School of Chemical Engineering, The University of New South Wales, Sydney 2052, Australia
| | - Dries Vandamme
- Laboratory for Aquatic Biology, KU Leuven Campus Kulak, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium.
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Korkakaki E, van Loosdrecht MCM, Kleerebezem R. Survival of the fastest: Selective removal of the side population for enhanced PHA production in a mixed substrate enrichment. Bioresour Technol 2016; 216:1022-1029. [PMID: 27343455 DOI: 10.1016/j.biortech.2016.05.125] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/09/2016] [Accepted: 05/28/2016] [Indexed: 06/06/2023]
Abstract
The success of enriching PHA-producers in a feast/famine regime strongly depends on the substrate utilized. A distinction can be made between substrates that select for PHA-producers (e.g. volatile fatty acids) and substrates that select for growing organisms (e.g. methanol). In this study the feasibility of using such a mixed substrate was evaluated. A sedimentation step was introduced in the cycle after acetate depletion and the supernatant containing methanol was discharged. This process configuration resulted in an increased maximum PHA storage capacity of the biomass from 48wt% to 70wt%. A model based on the experimental results indicated that the length of the pre-settling period and the supernatant volume that is discharged play a significant role for the elimination of the side population. However, the kinetic properties of the two different populations determine the success of the proposed strategy.
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Affiliation(s)
- Emmanouela Korkakaki
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Mark C M van Loosdrecht
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Robbert Kleerebezem
- Department of Biotechnology, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands.
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Kiventerä J, Leiviskä T, Keski-Ruismäki K, Tanskanen J. Characteristics and settling behaviour of particles from blast furnace flue gas washing. J Environ Manage 2016; 172:162-170. [PMID: 26945188 DOI: 10.1016/j.jenvman.2016.02.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 02/21/2016] [Indexed: 06/05/2023]
Abstract
A lot of particles from iron-making are removed with blast furnace off-gas and routed to the gas cleaning system. As water is used for cleaning the gas, the produced wash water contains a large amount of particles such as valuable Fe and C. However, the presence of zinc prevents recycling. In addition, the high amount of calcium results in uncontrolled scaling. Therefore, the properties of the wash water from scrubber and sludge, from the Finnish metal industry (SSAB Raahe), were evaluated in this study. Size fractionation of wash water revealed that Fe, Zn, Al, Mn, V, Cr and Cd appeared mainly in the larger fractions (>1.2 μm) and Na, Mg, Si, Ni, K, Cu and As appeared mainly in the smaller fractions (<1.2 μm) or in dissolved form. Calcium was found both in the larger fractions and dissolved (∼60 mg/L). Most of the particles in wash water were included in the 1.2-10 μm particle size and were settled effectively. However, a clear benefit was observed when using a chemical to enhance particle settling. In comparison to 2.5 h of settling without chemical, the turbidity was further decreased by about 94%, iron 85% and zinc 50%. Coagulation-flocculation experiments indicated that both low and high molecular weight cationic polymers could provide excellent purification results in terms of turbidity. Calcium should be removed by other methods. The particles in sludge were mostly in the 2-4 μm or 10-20 μm fractions. Further sludge settling resulted in high solids removal.
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Affiliation(s)
- Jenni Kiventerä
- University of Oulu, Chemical Process Engineering, P.O. Box 4300, FIN-90014 University of Oulu, Oulu, Finland.
| | - Tiina Leiviskä
- University of Oulu, Chemical Process Engineering, P.O. Box 4300, FIN-90014 University of Oulu, Oulu, Finland.
| | | | - Juha Tanskanen
- University of Oulu, Chemical Process Engineering, P.O. Box 4300, FIN-90014 University of Oulu, Oulu, Finland.
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Tijani HI, Abdullah N, Yuzir A, Ujang Z. Rheological and fractal hydrodynamics of aerobic granules. Bioresour Technol 2015; 186:276-285. [PMID: 25836036 DOI: 10.1016/j.biortech.2015.02.107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 02/26/2015] [Accepted: 02/27/2015] [Indexed: 06/04/2023]
Abstract
The structural and hydrodynamic features for granules were characterized using settling experiments, predefined mathematical simulations and ImageJ-particle analyses. This study describes the rheological characterization of these biologically immobilized aggregates under non-Newtonian flows. The second order dimensional analysis defined as D2=1.795 for native clusters and D2=1.099 for dewatered clusters and a characteristic three-dimensional fractal dimension of 2.46 depicts that these relatively porous and differentially permeable fractals had a structural configuration in close proximity with that described for a compact sphere formed via cluster-cluster aggregation. The three-dimensional fractal dimension calculated via settling-fractal correlation, U∝l(D) to characterize immobilized granules validates the quantitative measurements used for describing its structural integrity and aggregate complexity. These results suggest that scaling relationships based on fractal geometry are vital for quantifying the effects of different laminar conditions on the aggregates' morphology and characteristics such as density, porosity, and projected surface area.
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Affiliation(s)
- H I Tijani
- Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia.
| | - N Abdullah
- Palm Oil Research Center, Faculty of Biosciences and Medical Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia.
| | - A Yuzir
- Centre for Environmental Sustainability and Water Security (IPASA), Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 Johor Bahru, Malaysia.
| | - Zaini Ujang
- Ministry of Education Malaysia, Blok E8, Kompleks E, Pusat Pentadbiran Kerajaan Persekutuan, 62604 Putrajaya, Malaysia.
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Prigiobbe V, Ko S, Huh C, Bryant SL. Measuring and modeling the magnetic settling of superparamagnetic nanoparticle dispersions. J Colloid Interface Sci 2015; 447:58-67. [PMID: 25700211 DOI: 10.1016/j.jcis.2015.01.056] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 01/08/2015] [Accepted: 01/20/2015] [Indexed: 02/05/2023]
Abstract
In this paper, we present settling experiments and mathematical modeling to study the magnetic separation of superparamagnetic iron-oxide nanoparticles (SPIONs) from a brine. The experiments were performed using SPIONs suspensions of concentration between 3 and 202g/L dispersed in water and separated from the liquid under the effect of a permanent magnet. A 1D model was developed in the framework of the sedimentation theory with a conservation law for SPIONs and a mass flux function based on the Newton's law for motion in a magnetic field. The model describes both the hindering effect of suspension concentration (n) during settling due to particle collisions and the increase in settling rate due to the attraction of the SPIONs towards the magnet. The flux function was derived from the settling experiments and the numerical model validated against the analytical solution and the experimental data. Suspensions of SPIONs were of 2.8cm initial height, placed on a magnet, and monitored continuously with a digital camera. Applying a magnetic field of 0.5T of polarization, the SPION's velocity was of approximately 3·10(-5)m/s close to the magnet and decreases of two orders of magnitude across the domain. The process was characterized initially by a classical sedimentation behavior, i.e., an upper interface between the clear water and the suspension slowly moving towards the magnet and a lower interface between the sediment layer and the suspension moving away from the magnet. Subsequently, a rapid separation of nanoparticle occured suggesting a non-classical settling phenomenon induced by magnetic forces which favor particle aggregation and therefore faster settling. The rate of settling decreased with n and an optimal condition for fast separation was found for an initial n of 120g/L. The model agrees well with the measurements in the early stage of the settling, but it fails to describe the upper interface movement during the later stage, probably because of particle aggregation induced by magnetization which is not accounted for in the model.
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Affiliation(s)
- Valentina Prigiobbe
- Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, 200 E. Dean Keeton St., C0300, Austin, 78712 TX, USA.
| | - Saebom Ko
- Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, 200 E. Dean Keeton St., C0300, Austin, 78712 TX, USA
| | - Chun Huh
- Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, 200 E. Dean Keeton St., C0300, Austin, 78712 TX, USA
| | - Steven L Bryant
- Department of Chemical and Petroleum Engineering, University of Calgary, 2500 University Dr. NW, Calgary T2N 1N4, Canada(1)
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Mukherjee D, Leo BF, Royce SG, Porter AE, Ryan MP, Schwander S, Chung KF, Tetley TD, Zhang J, Georgopoulos PG. Modeling physicochemical interactions affecting in vitro cellular dosimetry of engineered nanomaterials: application to nanosilver. J Nanopart Res 2014; 16:2616. [PMID: 25598696 PMCID: PMC4295810 DOI: 10.1007/s11051-014-2616-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Engineered nanomaterials (ENMs) possess unique characteristics affecting their interactions in biological media and biological tissues. Systematic investigation of the effects of particle properties on biological toxicity requires a comprehensive modeling framework which can be used to predict ENM particokinetics in a variety of media. The Agglomeration-diffusion-sedimentation-reaction model (ADSRM) described here is stochastic, using a direct simulation Monte Carlo method to study the evolution of nanoparticles in biological media, as they interact with each other and with the media over time. Nanoparticle diffusion, gravitational settling, agglomeration, and dissolution are treated in a mechanistic manner with focus on silver ENMs (AgNPs). The ADSRM model utilizes particle properties such as size, density, zeta potential, and coating material, along with medium properties like density, viscosity, ionic strength, and pH, to model evolving patterns in a population of ENMs along with their interaction with associated ions and molecules. The model predictions for agglomeration and dissolution are compared with in vitro measurements for various types of ENMs, coating materials, and incubation media, and are found to be overall consistent with measurements. The model has been implemented for an in vitro case in cell culture systems to inform in vitro dosimetry for toxicology studies, and can be directly extended to other biological systems, including in vivo tissue subsystems by suitably modifying system geometry.
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Affiliation(s)
- Dwaipayan Mukherjee
- Environmental and Occupational Health Sciences Institute (EOHSI), Rutgers University, Piscataway, NJ, USA
| | - Bey Fen Leo
- Department of Materials and London Centre of Nanotechnology, Imperial College London, London, UK
| | - Steven G Royce
- Environmental and Occupational Health Sciences Institute (EOHSI), Rutgers University, Piscataway, NJ, USA
| | - Alexandra E Porter
- Department of Materials and London Centre of Nanotechnology, Imperial College London, London, UK
| | - Mary P Ryan
- Department of Materials and London Centre of Nanotechnology, Imperial College London, London, UK
| | - Stephan Schwander
- Environmental and Occupational Health Sciences Institute (EOHSI), Rutgers University, Piscataway, NJ, USA
| | - Kian Fan Chung
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Teresa D Tetley
- National Heart and Lung Institute, Imperial College London, London, UK
| | - Junfeng Zhang
- Nicholas School of the Environment and Duke Global Health Institute, Duke University, Durham, NC, USA
| | - Panos G Georgopoulos
- Environmental and Occupational Health Sciences Institute (EOHSI), Rutgers University, Piscataway, NJ, USA
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Jassby D, Xiao Y, Schuler AJ. Biomass density and filament length synergistically affect activated sludge settling: systematic quantification and modeling. Water Res 2014; 48:457-465. [PMID: 24144433 DOI: 10.1016/j.watres.2013.10.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 09/21/2013] [Accepted: 10/01/2013] [Indexed: 06/02/2023]
Abstract
Settling of the biomass produced during biological treatment of wastewater is a critical and often problematic process. Filamentous bacteria content is the best-known factor affecting biomass settleability in activated sludge wastewater treatment systems, and varying biomass density has recently been shown to play an important role as well. The objective of this study was to systematically determine how filament content and biomass density combine to affect microbial biomass settling, with a focus on density variations over the range found in full-scale systems. A laboratory-scale bioreactor system was operated to produce biomass with a range of filamentous bacterium contents. Biomass density was systematically varied in samples from this system by addition of synthetic microspheres to allow separation of filament content and density effects on settleability. Fluorescent in-situ hybridization indicated that the culture was dominated by Sphaerotilus natans, a common contributor to poor settling in full-scale systems. A simple, image-based metric of filament content (filament length per floc area) was linearly correlated with the more commonly used filament length per dry biomass measurement. A non-linear, semi-empirical model of settleability as a function of filament content and density was developed and evaluated, providing a better understanding of how these two parameters combine to affect settleability. Filament content (length per dry biomass weight) was nearly linearly related to sludge volume index (SVI) values, with a slightly decreasing differential, and biomass density exhibited an asymptotic relationship with SVI. The filament content associated with bulking was shown to be a function of biomass density. The marginal effect of filament content on settleability increased with decreasing biomass density (low density biomass was more sensitive to changes in filament content than was high density biomass), indicating a synergistic relationship between these factors. Consideration of both biomass density and filament content, as by the methods and model described herein, should improve operation and troubleshooting of settling processes for biological solids.
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Affiliation(s)
- D Jassby
- Department of Chemical and Environmental Engineering, University of California Riverside, Riverside, CA 92521, USA
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