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23421. 题目: Dissolved inorganic nitrogen in a tropical estuary at Malaysia: transport and transformation
文章编号: N19020810
期刊: Biogeosciences
作者: Shan Jiang, Moritz Müller, Jie Jin, Ying Wu, Kun Zhu, Guosen Zhang, Aazani Mujahid, Tim Rixen, Mohd Fakharuddin Muhamad, Edwin Sien Aun Sia, Faddrine Holt Ajon Jang, and Jing Zhang
更新时间: 2019-02-08
摘要: Dissolved inorganic nitrogen (DIN), including nitrate, nitrite and ammonium, frequently acts as the limitation for primary productivity. Our study focused on the transport and transformation of dissolved inorganic nitrogen in a tropical estuary, i.e. Rajang river estuary, in Borneo, Malaysia. Three cruises were conducted in August 2016, February–March and September 2017, covering both dry and wet seasons. Before entering the coastal delta, decomposition of the terrestrial organic matter and the subsequent soil leaching was assumed to be the main source of DIN in the river water. In the estuary, decomposition of dissolved organic nitrogen was an additional DIN source, which markedly increased DIN concentrations in August 2016 (dry season). In the wet season (February 2017), ammonium concentration showed a relatively conservative distribution during the mixing and nitrate addition was weak. In September 2017 (dry season), La Niña induced high precipitation and discharge rates, decreased reaction intensities of ammonification and nitrification and hence the distribution of DIN species in the estuary water was similar with the trend found in the wet season. The magnitude of riverine DIN flux varied between 77.2 and 101.5 ton N d-1, which might be an important support for the coastal primary productivity.
23422. 题目: Modification of corn stover for improving biodegradability and anaerobic digestion performance by Ceriporiopsis subvermispora
文章编号: N19020809
期刊: Bioresource Technology
作者: WenBo Huang, Akiber Chufo Wachemo, HaiRong Yuan, XiuJin Li
更新时间: 2019-02-08
摘要: Ceriporiopsis subvermispora was used to modify corn stover for improving the biodegradability and biomethane yield. Corn stover was incubated with C. subvermispora for 5-90 days then anaerobically digested. It was found that the corn stover modified for 15 days achieved the highest biomethane yield of 235 mL·g-1VS, which was an increase of 15.2% over that of the non-modified one. The mechanism analyses indicated that the improvement resulted from the combined roles of degradation selectivity, destruction of lignocellulosic structures, and linkages. The analyses showed that C. subvermispora has a high relative selectivity of lignin degradation. The structure of the lignin and the linkages among lignin and hemicellulose and cellulose were broken obviously by acetyl group removal, and the enzymatic hydrolysis of cellulose was increased by 35.61%. The finding indicated that C. subvermispora modification is one of the effective methods for enhancing biomethane yield of corn stover.
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23423. 题目: Highly synergistic effects on ammonium removal by the co-system of Pseudomonas stutzeri XL-2 and modified walnut shell biochar
文章编号: N19020808
期刊: Bioresource Technology
作者: Yang Yu, Qiang An, Ying Zhou, Shuman Deng, Yue Miao, Bin Zhao, Li Yang
更新时间: 2019-02-08
摘要: Pseudomonas stutzeri strain XL-2 presented efficient ammonium removal due to heterotrophic nitrification-aerobic denitrification. The modified walnut shell biochar also showed ammonium adsorption due to chemical interaction. The complex of modified biochar and strain XL-2 exhibited excellent synergistic effects on ammonium removal, especially in unfavorable environment. The maximum average ammonium removal rate of the complex was 4.40 mg·L-1·h-1, which was 3.01 times higher than that of pure bacteria and 5.57 times higher than that of biochar. A large number of irregular pores and hydrophilic functional groups promoted the immobilization of strain XL-2 on biochar. Adsorption of ammonium, high specific surface area and release of Mg2+ by biochar enhanced biodegradation of strain XL-2. Approximately 96.34% - 98.73% of ammonium was removed in a sequencing batch reactor (SBR) inoculating with the complex of strain XL-2 and biochar, which was much higher than the treatment efficiency of free bacteria in SBR.
23424. 题目: Biochar effect associated with compost and iron to promote Pb and As soil stabilization and Salix viminalis L. growth
文章编号: N19020807
期刊: Chemosphere
作者: Manhattan Lebrun, Florie Miard, Romain Nandillon, Gabriella S. Scippa, Sylvain Bourgerie, Domenico Morabito
更新时间: 2019-02-08
摘要: Soil pollution by metal(loid)s is one of the most significant problems in Europe. To remediate and potentially rehabilitate these contaminated sites, phytoremediation procedures are being put into place, often using amendments to help offset the extreme conditions of such soils. The aim of this study was to define the best amendment to use on the field. This was done by studying how the addition of three different amendments (biochar, compost and iron grit), alone or in combination, could affect: (i) soil physico-chemical properties, (ii) Salix viminalis growth, and (iii) metal(loid) stabilization. A 69 day-mesocosm study was thus set up using a former mine technosol, the three amendments applied alone or combined, and S. viminalis cuttings. The results showed that biochar and/or compost improved the soil fertility and the soil pore water characteristics, with reductions of acidity, metal(loid) mobility and toxicity, while iron grit amendment presented negative effects on such parameters. Such ameliorations allowed better plant growth and higher biomass production. In addition, stress indicators (leaf pigment content and root guaiacol peroxidase activity) showed a reduction in plant stress following biochar and/or compost application. Finally, among the different treatments, the use of compost or a biochar-compost combination showed better results in terms of improvement of soil conditions, increase in plant growth and reduced translocation of metal(loid)s towards upper parts, making these two treatments a valuable option for a field trial.
23425. 题目: Hydrophobicity-dependent electron transfer capacities of dissolved organic matter derived from chicken manure compost
文章编号: N19020806
期刊: Chemosphere
作者: Xiao Xiao, Bei-Dou Xi, Xiao-Song He, Hui Zhang, Dan Li, Xin-Yu Zhao, Xiao-Hui Zhang
更新时间: 2019-02-08
摘要: The electron transfer capacities (ETC) of dissolved organic matter (DOM) are related to their hydrophobicity. However, the underlying mechanism is poorly understood. The DOM was extracted from chicken manure compost, and fractionated into four fractions based on hydrophobicity, i.e., hydrophobic acid (HOA), hydrophobic base (HOB), hydrophilic matter (HIM) and acid insoluble matter (AIM) fractions. The composition, structure and ETC of the four fractions were measured using spectral technology and electrochemical methods. The results showed that the HOA and AIM fractions consisted mainly of fulvic- and humic-like substances, the HOB fraction comprised mainly organic nitrogen compounds, and the HIM was mainly composed of carbohydrates and protein-like matter. The electron donating capacities (EDC) and electron accepting capacities (EAC) of the four fractions were in the range of 616.90–5224.66 and 7.30–191.20 μmoL/g(C), respectively, The HOB fraction exhibited the highest EDC among the four fractions, followed by the HOA, AIM and HIM fractions. The EAC of the four fractions was characterized by the order of AIM, HOB, HOA and HIM. The tryptophan- and humic-like substances and organic nitrogen compounds accounted for the EDC, whereas the carboxyl group on aromatic substance responsible for the EAC.
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23426. 题目: High-concentration nitrogen removal coupling with bioelectric power generation by a self-sustaining algal-bacterial biocathode photo-bioelectrochemical system under daily light/dark cycle
文章编号: N19020805
期刊: Chemosphere
作者: Jian Sun, Wenjing Xu, Bihai Cai, Guofu Huang, Hongguo Zhang, Yaping Zhang, Yong Yuan, Kenlin Chang, Kangxing Chen, Yenping Peng, Kufan Chen
更新时间: 2019-02-08
摘要: High-concentration nitrogen removal coupled with bioelectric power generation in an algal-bacterial biocathode photo-bioelectrochemical system (PBES) was investigated. The PBES can self-sustaining operation with continuous power output under day/night cycle by alternately using photosynthetic dissolved oxygen and nitrate/nitrite as cathodic electron acceptors. The PBES generated a high maximum power of 110mw/m2 under illumination and relatively lower power of 40mw/m2 under dark. The bioelectricity generation was accompanied by high-concentration nitrogen removal in the algal-bacterial biocathode. The NH4N was removed completely within 120 h while maximum NO3N removal efficiency of 86% and maximum total nitrogen removal efficiency of 83% can be reached after 192 h at initial NH4N concentration of 314 mg/L and NO3N concentration of 330 mg/L. Combined processes of bioelectrochemical reduction and algal-bacterial interactions provided multiple approaches for nitrogen removal in the biocathode, including nitrifying using photosynthetic oxygen, bioelectrochemical denitrification using the cathode as electron donor, heterotrophic denitrification using photosynthetically produced dissolved organic matters as carbon source and algal-bacterial uptake. Accelerated nitrogen removal with simultaneously improved cathode performance was observed at high concentration of nitrogen and phosphate buffer due to enhanced algal activities for photosynthetic oxygen release and enhanced algal-bacterial interactions for nitrogen transformation. Addition of external organic carbon negatively affected nitrification and decreased cathode potential due to oxygen consumption by aerobic carbon oxidation but enhanced denitrification due to continuous release of high concentration of photosynthetically produced dissolved organic matters by alga. The PBEC was demonstrated as an energy-saving approach for high-strengthen nitrogenous wastewater treatment.
23427. 题目: Solubilization of organic matter by electrochemical treatment of sludge: Influence of operating conditions
文章编号: N19020804
期刊: Journal of Environmental Management
作者: M. Pérez-Rodríguez, A. Cano, U. Durán, J.A. Barrios
更新时间: 2019-02-08
摘要: Sludge generated after wastewater treatment represents an important challenge due to the large amounts produced and the need to adequately treat it. Anaerobic digestion is the preferred treatment process to obtain renewable energy as well as a biosolid with the potential to be reused in land application. This process generates biogas (methane and carbon dioxide) that may be used for energy co-generation. However, anaerobic digestion is limited by the hydrolysis step since bacteria need to break down organic matter and large molecules to allow conversion into biogas. In this study, electrochemical treatment of sludge is proposed to solubilize organic matter. Boron-doped diamond electrodes were used to treat waste activated sludge under different experimental conditions (current density, flow rate, time) to evaluate their influence on the solubilization of organic matter (in terms of chemical oxygen demand). The degree of solubilization ranged between 0.31 and 1.78%. Based on the results, optimal operating conditions were current density of 19.3 mA cm−2, flow rate of 4 L min−1, and treatment time of 30 min. Furthermore, treatment flow rate was found to play a key role in solubilization, as the process is controlled by mass transfer.
23428. 题目: Emulating natural wetlands oxygen conditions for the removal of N and P in agricultural wastewaters
文章编号: N19020803
期刊: Journal of Environmental Management
作者: Adriana Roé-Sosa, Jesus Gabriel Rangel-Peraza, Abraham E. Rodríguez-Mata, Aurora Pat-Espadas, Yaneth Bustos-Terrones, Ismael Diaz-Peña, Cuong Manh Vu, Leonel Ernesto Amabilis-Sosa
更新时间: 2019-02-08
摘要: The aim of this research was to evaluate a constructed wetland system (CW) operated under aerobic-anoxic-aerobic conditions to remove C, N and P from water with high concentrations of the last two nutrients. A series of three CW were operated continuously for 190 days. An aerobic vertical CW was used in the first and third stages and an anoxic horizontal CW was used in the second stage. The total nitrogen (TN) removal efficiency was 70 ± 1.5%. Similar removal efficiency behavior was observed in others nitrogen compounds, where a removal of 85 ± 1.5% for NO3−-N and 97 ± 2.2% for NH3+N were achieved. The combination of different oxygen conditions enhanced oxidation of nitrates and the assimilation of ammonium by vegetation. On the other hand, 54 ± 6.5% total phosphorus (TP) was removed in the entire system, which is higher than the reported in several investigations, including mechanized and controlled systems such as activated sludge. The phosphorous removal efficiency was attributed to the adequate design and configuration of CW, which facilitated dissolved oxygen (DO) conditions required for phosphorus capture. Despite in this investigation the CW was not designed for an optimal removal of organic matter the removal efficiency of this parameter was 64 ± 7.5%. The successful results suggest that the combination of aerobic-anoxic-aerobic stages is a technically suitable option for the treatment of agricultural wastewater with high content of N and P.
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23429. 题目: Mid to late Holocene hydrological and sea-level change reconstructions from La Mancha coastal lagoon, Veracruz, Mexico
文章编号: N19020802
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Elsa Arellano-Torres, Alexander Correa-Metrio, Diego López-Dávila, Jaime Escobar, Jason H. Curtis, María Cecilia Cordero-Oviedo
更新时间: 2019-02-08
摘要: We studied a 13-meter sediment core collected from La Mancha coastal lagoon, Veracruz, Mexico, to determine paleoenvironmental variations linked to the mid- to late Holocene sea-level rise. We examined modern and fossil benthic foraminiferal assemblages, isotopic values in tests of Ammonia tepida (δ18O-foram and δ13C-foram), δ13C in organic matter (δ13C-org), and sediment elemental ratios (Fe/Ca, Ca/Ti, and K/Rb) to reconstruct salinity variations, coastal processes, and the morphologic evolution of a partially closed coastal lagoon. We identified four main periods of environmental change: (1) From ~7800 to 6500 cal. yr. BP, the core site was an open lagoon with higher oceanic influence than today, through the presence of a southern mouth, as evidenced by the euryhaline assemblage Ammonia-Quinqueloculina-Bolivina-Nonionella. Low δ18O-foram and high δ13C values on foraminifera shells indicate greater inputs of seawater, and δ13C-org values reflect a lagoon environment. Elemental ratios of lower Fe/Ca, moderate Ca/Ti, and higher K/Rb suggest increased coastal weathering and reduced detrital deposits than today. (2) From ~6500 to 4600 cal. yr. BP., the lagoon experienced the progressive closure of the southern mouth, to the point that sedimentation restricted seawater entrance, as evidenced by variable δ13C-org values, a lowering trend in δ18O-foram and δ13C-foram values, low Fe/Ca, higher Ca/Ti but moderate K/Rb values. At this time, benthic foraminifera were dominated by the opportunistic Ammonia-Elphidium polyhaline assemblage. (3) From ~4600 to 1400 cal. yr. BP, the northern mouth was the only source of seawater to the lagoon, establishing the optimal environment for calcareous foraminifera of the polyhaline assemblage Ammonia-Elphidium. Lowest δ13C-org values indicate greater organic input by terrestrial plants. (4) At 1400 cal. yr. BP, modern conditions of a partially closed lagoon were established, while increased terrigenous inputs and freshwater runoff favored the growth of agglutinated foraminifera species. At millennial time scales, in addition to the sea level rise effects, the lagoon evolution fits in the paleoclimatic context that links insolation, the latitudinal change of ITCZ, ocean currents, longshore drift and moisture transport, as driving factors of morphological change in the western coast of the Gulf of Mexico.
23430. 题目: Ultraviolet/persulfate pre-treatment for organic fouling mitigation of forward osmosis membrane: possible application in nutrient mining from dairy wastewater
文章编号: N19020801
期刊: Separation and Purification Technology
作者: Biplob Kumar Pramanik, Faisal I Hai, Felicity A. Roddick
更新时间: 2019-02-08
摘要: The forward osmosis (FO) membrane process has recently established its potential as an alternative option to traditional membrane processes for producing clean water and recovering nutrients from anaerobically treated wastewater streams. However, organic fouling of membrane leads to reduced flux, and, thus, reduced amount of the extractable resources. In this study, the impact of ultraviolet/persulfate (UV/PS) oxidation pre-treatment for the mitigation of organic fouling in the FO process during processing of anaerobically treated dairy effluent (ATDE) was determined using a multi-cycle filtration method. The UV/PS performance was compared with control pre-treatments such as stand-alone ultraviolet (UV) irradiation and potassium persulfate (PS) oxidation. Size exclusion chromatography confirmed that flux reduction over successive filtration cycles was due mainly to the humic substances and building blocks i.e., sub-units of humic substances in the feedwater. Although all investigated pre-treatment options mitigated membrane fouling, UV/PS achieved a greater enhancement in flux and decrease in both reversible and irreversible foulant deposition than stand-alone UV and PS pre-treatments. This was because UV/PS could generate sulfate and hydroxyl radicals, which were effective for decreasing the bulk organic content and fluorescent organic content, and particularly for breaking down the large molecular weight (MW) hydrophobic compounds to small MW hydrophilic components, resulting in less organics adhesion to the membrane. This research shows the applicability of UV/PS pre-treatment for the organic fouling mitigation of FO membrane during processing of ATDE for applications such as nutrient mining from ATDE.
23431. 题目: Novel Crayfish Shell Biochar Nanocomposites Loaded with Ag-TiO 2 Nanoparticles Exhibit Robust Antibacterial Activity
文章编号: N19020714
期刊: Water, Air, & Soil Pollution
作者: Yifan Zeng, Yingwen Xue, Li Long, Jinpeng Yan
更新时间: 2019-02-07
摘要: A fast sol-dipping-gel method was applied to load Ag and TiO2 nanoparticles on the surface of crayfish shell biochar to make an inexpensive and novel nanocomposite. Tetra-n-butyl titanate (Ti(OC4H9)4) and silver nitrate (AgNO3) were used as the nanoparticle precursors. Crayfish shell was pyrolyzed to produce the biochar host. Paper-disk diffusion method was applied to measure antibacterial activities of the nanocomposites to E. coli. The maximum loading rate of TiO2 and Ag nanoparticles on the biochar reached 7.54% and 3.20%, respectively. Results of long-term antibacterial effect experiment showed that the Ag-TiO2-biochar had robust antibacterial activity and could be reused for multiple times. The inactivation of E. coli of initial concentration of 105 CFU/mL by Ag-TiO2-biochar under solar light reached around 99% of sterilization ratio in 5 min. In addition, the antibacterial ability of the nanocomposite was better in light than that in dark due to the presence of TiO2. Findings of this study suggest that the novel nanocomposite is a promising material for water treatment units and household water purifiers.
23432. 题目: Environmental impact of industrial and agricultural activities to the trace element content in soil of Srem (Serbia)
文章编号: N19020713
期刊: Environmental Monitoring and Assessment
作者: Maja Poznanović Spahić, Dragan Manojlović, Pavle Tančić, Željko Cvetković, Zoran Nikić, Renata Kovačević, Sanja Sakan
更新时间: 2019-02-07
摘要: This study reports the contents and sources of Cu, Hg, Cr, Ni, Co, Zn, Pb, Cd, As, and B pollution in soil samples from Srem in the province of Vojvodina (Republic of Serbia). They are collected in the vicinity of local industrial facilities. The main objective of this study is evaluating the impact of the industrial facilities on the eventual contamination of soils used mostly for agricultural manufacturing. This paper describes the implementation of the combination of methods to estimate the ecological status and determine potential ecological risk. This study applies sequential extraction, pollution indices, comparison with the guidelines, and statistical analysis. Other soil parameters, such as organic matter content, pH, and clay content were measured to evaluate their influence on the trace element content. The investigated soil samples exhibited the raised contents of Ni, Hg, and Cu. Elevated contents of toxic elements observed in localities accommodated within an impact zone affected by industrial complexes, indicating a correlation between the contamination of surrounding soil and potential impact on plants. The most mobile elements are Hg, Cd, and B, while Cr is the least mobile and potential least bioavailable. The results indicate Cr and Ni content increase marking the presence of bedrock, notably in the area of underlying ultramafic rocks and the surface zones influenced by diluvial-proluvial and alluvial processes. The second source of Cr and Ni in the soils of Srem is industrial activities such as leather, cement industry, as well as the metal processing factory.
23433. 题目: Reduced daytime net growth rate of Synechococcus spp. in the East China sea in summer estimated using a dilution approach
文章编号: N19020712
期刊: Estuarine, Coastal and Shelf Science
作者: Gwo-Ching Gong, An-Yi Tsai
更新时间: 2019-02-07
摘要: Viruses are thought to play a critical role in aquatic nutrient cycling, yet few field experiments have quantified their significance. We conducted fifteen modified dilution experiments in the East China Sea in summer to determine the growth rate and effect of mortality on growth rates of Synechococcus spp. They were measured in a 0.2 μm dilution series in which the abundance of Synechococcus spp. and nanoflagellates were diluted but the viruses were retained. They were also measured in a 30 kDa filtered natural samples in which the abundance of Synechococcus spp., nanoflagellates and viruses were diluted. We found positive relationships between dilution factor and Synechococcus spp. net growth rates. Instantaneous growth rate of Synechococcus spp in 100% whole water generally exceeded rates in other dilution fraction treatments, a result of net growth rates of Synechococcus spp. in undiluted incubations. Throughout the entire study area, growth rate of Synechococcus app. was highly variable and ranged from 0.01 h−1 to 0.17 h−1, with a maximum value appearing in waters with a salinity of around 31 psμ. Most importantly, net growth rates of Synechococcus spp. were suppressed in the 30 kDa dilution series compared to the 0.2 μm dilution series dilution experiments, suggesting that dissolved organic matter available to heterotrophic bacteria and viral lysis contributed to nutrient cycling and made a difference in the growth rates found in the two dilution series.
23434. 题目: Positive impact of biochar alone and combined with bacterial consortium amendment on improvement of bacterial community during cow manure composting
文章编号: N19020711
期刊: Bioresource Technology
作者: Yumin Duan, Sanjeev Kumar Awasthi, Tao Liu, Shivpal Verma, Quan Wang, Hongyu Chen, Xiuna Ren, Zengqiang Zhang, Mukesh Kumar Awasthi
更新时间: 2019-02-07
摘要: The present work studied to evaluate the effectiveness under the interaction of bacterial consortium and biochar applied to give impetus to bacterial community activities among cow manure composting. High-throughput sequencing technique and six treatments were carried out: T2, T3 and T6 were single apply of bacteria culture (C), 12%wood biochar (12%WB) and 12%wheat straw biochar (12%WSB), respectively, while T4 and T5 were bacterial consortium combined with 12%WB and 12%WSB respectively, and T1 was used as control. The conclusion shows that the richness of bacterial community were most prosperity in T5 and T4 that in line with the statistical analysis angle of curves and cluster. The dominate phyla of Firmicutes, Proteobacteria and Bacteroidetes were accounted to 31.36%, 34.79% and 33.85%, the superior genera were Dysgonomonas (16.55%), Empedobater (9.39%), Atopostipes (13.42%), Tissierella (8.25%), Marinimicrobium (14.45%) and Pseudomonas (9%). Overall, bacterial consortium combined with biochar could stimulate microbe activity to accelerate degradation, enhance richness and alter specific selection of bacterial community.
23435. 题目: Effect of phosphate concentration, anions, heavy metals, and organic matter on phosphate adsorption from wastewater using anodized iron oxide nanoflakes
文章编号: N19020710
期刊: Environmental Research
作者: Muhammad Naveed Afridi, Won-Hee Lee, Jong-Oh Kim
更新时间: 2019-02-07
摘要: Phosphorus is a necessary nutrient for the growth and survival of living beings. Nevertheless, an oversupply of phosphorus in wastewater results in eutrophication. Therefore, its removal from wastewater is important. However, coexisting components, such as anions, heavy metals, and organic matter, might inhibit the phosphate-adsorption mechanism by competing for the active surface sites of the adsorbent. In this study, iron oxide nanoflakes (INFs) were fabricated on iron foil via anodization. The rate of phosphate adsorption from wastewater onto INFs in the presence of three different coexisting components—anions, heavy metals, and organic matter—was evaluated. The morphology of the INFs was analyzed by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. The phosphate adsorption equilibrium time using INFs was found to be 1 h. The Elovich model (R2 > 0.99) and the Langmuir model (R2 >0.95) respectively provided the best description of the adsorption kinetics and isotherm, suggesting the chemisorption nature of adsorption. The estimated adsorption capacity of the INFs was 21.5 mg-P g–1. The effect of anions (chloride, sulfate, nitrate, and carbonate) and heavy metals (Cd, As, Cr, and Pb) was studied at three different molar ratios (0.5:1, 1:1, and 1.5:1). The effect of different types of organic matter, such as citric acid, humic acid, and oxalic acid at concentrations of 100 and 200 mg L–1, was also examined. In five regeneration cycles, the total amount of phosphate adsorbed and desorbed, and the recovery percentage were 6.51 mg-P g–1, 5.16 mg-P g–1, and 79.24%, respectively.
23436. 题目: Iron isotope fractionation in iron-organic matter associations: Experimental evidence using filtration and ultrafiltration
文章编号: N19020709
期刊: Geochimica et Cosmochimica Acta
作者: Elaheh Lotfi-Kalahroodi, Anne-Catherine Pierson-Wickmann, Hélène Guénet, Olivier Rouxel, Emmanuel Ponzevera, Martine Bouhnik-LeCoz, Delphine Vantelon, Aline Dia, Mélanie Davranche
更新时间: 2019-02-07
摘要: Colloids have been recognized as key vectors of pollutants in aqueous environment. Amongst them, those formed by iron (Fe) and organic matter (OM) are of major importance due to their ubiquity in the surface environment and strong affinity for metals. In the recent years, Fe stable isotopes have been increasingly used to elucidate the sources and biogeochemical cycling of Fe in Earth's surface environments. In this study, we aim to elucidate (i) the possible Fe isotopic signature resulting from the Fe/OM colloid formation and (ii) the mechanisms involved in the development of such isotopic signature. For this purpose, Fe-OM associations were synthesized through binding and titration experiments. Various pH levels were used in order to study the isotope behavior of Fe occurring as free species at pH 1, as Fe-OM complexes at pH 2 and as mixed Fe-oxyhydroxide/OM nanoaggregates or particles at pH 6.5. Organic matter-free, Fe-free and OM membrane-deposition experiments were also performed. These suspensions were (ultra)filtered at 0.2 µm, 30 kDa and 5 kDa to evidence the possible Fe isotope fractionation between fractions. This protocol allowed also testing the potential of (ultra)filtration techniques to generate isotope fractionation. The results provided evidence that abiotic Fe precipitation, (ultra)filtration techniques and OM deposition were not able to produce significant Fe isotope fractionation under the experimental conditions. However, at circum-neutral pH, the Fe-OM binding and titration experiments displayed a significant enrichment of heavy Fe isotopes in the < 30 kDa fractions relative to the total Fe pool δ56Fe = 0.35 ± 0.05‰ and 0.26 ± 0.05‰ (95% confidence interval, 2σ and relative to international standard IRMM-14), respectively. Mass balance and error propagation calculation showed Fe isotope fractionation in binding and titration experiments between the > 30 kDa and < 30 kDa fractions for -0.35 ± 0.05‰ and -0.27 ± 0.05‰, respectively. This Fe isotope fractionation could be due to the complexation of Fe by OM in the < 30 kDa fractions. At pH 2, the OM-free experiment, the < 30 kDa fraction showed Fe isotope ratio δ56Fe = 0.75 ± 0.03‰ with an enrichment in heavy Fe isotopes of δ56Fe’ = 0.14 ± 0.04‰ relative the total Fe pool (δ56Fe’ is δ56Fe value which was corrected by δ56Fe of total fraction). This enrichment in heavy Fe isotopes induced an isotopic fractionation factor of -0.87 ± 0.26‰ between the > 30 kDa and < 30 kDa fractions produced by the complexation between the heavy Fe isotopes and OH- ligands in the < 30 kDa fraction. Natural Fe-OM associations were further investigated through oxidation experiments of a reduced wetland soil solution. The oxidized soil solution was (ultra)filtered at 5 µm, 3 µm, 0.2 µm, 30 kDa and 5 kDa. The highest δ56Fe was obtained in the smallest size fraction, i.e. < 5 kDa fraction, yielding a negative isotopic fractionation Δ56Fe >5kDa - <5kDa = -0.23 ± 0.08‰ suggesting that Fe heavy isotopes are preferentially bound to small humic OM molecules in the form of Fe monomers or small clusters. This study highlights the importance of organic matter for metals’ isotopic systems.
23437. 题目: Microwave steam activation, an innovative pyrolysis approach to convert waste palm shell into highly microporous activated carbon
文章编号: N19020708
期刊: Journal of Environmental Management
作者: Peter Nai Yuh Yek, Rock Keey Liew, Mohammad Shahril Osman, Chern Leing Lee, Joon Huang Chuah, Young-Kwon Park, Su Shiung Lam
更新时间: 2019-02-07
摘要: Microwave-steam activation (MSA), an innovative pyrolysis approach combining the use of microwave heating and steam activation, was investigated for its potential production of high grade activated carbon (AC) from waste palm shell (WPS) for methylene blue removal. MSA was performed via pyrolytic carbonization of WPS to produce biochar as the first step followed by steam activation of the biochar using microwave heating to form AC. Optimum yield and adsorption efficiency of methylene blue were obtained using response surface methodology involving several key process parameters. The resulting AC was characterized for its porous characteristics, surface morphology, proximate analysis and elemental compositions. MSA provided a high activation temperature above 500 °C with short process time of 15 min and rapid heating rate (≤150 °C/min). The results from optimization showed that one gram of AC produced from steam activation under 10 min of microwave heating at 550 °C can remove up to 38.5 mg of methylene blue. The AC showed a high and uniform surface porosity consisting high fixed carbon (73 wt%), micropore and BET surface area of 763.1 and 570.8 m2/g respectively, hence suggesting the great potential of MSA as a promising approach to produce high grade adsorbent for dye removal.
23438. 题目: The stimulatory effect of humic acid on the co-metabolic biodegradation of tetrabromobisphenol A in bioelectrochemical system
文章编号: N19020707
期刊: Journal of Environmental Management
作者: Xiujuan Chen, Yuan Xu, Mengjie Fan, Yingwen Chen, Shubao Shen
更新时间: 2019-02-07
摘要: In this paper, the typical organic component of humic acid (HA) was studied to explore its effect on the co-metabolic biodegradation of Tetrabromobisphenol A (TBBPA) in bioelectrochemical systems (BES). The degradation efficiency, intermediate metabolites and microbial diversity were investigated to demonstrate the impact of HA on the biodegradation of TBBPA in BES-HA-T (Bioelectrochemical system with TBBPA as substrate and HA as a stimulating factor). The highest biodegradation rate (93.2%) for TBBPA were obtained, which illustrated that HA played a positive role in the biodegradation of TBBPA. According to the analysis of the intermediate metabolites, it can be concluded that HA has changed the biodegradation pathway of TBBPA. The analysis of microbial diversity showed that the interaction of microorganisms had great effects on the anaerobic biodegradation of TBBPA, especially Trichococcus and Anaerolineaceae. Meanwhile, the abundance of Desulfobulbus in the BES-HA (Bioelectrochemical system with HA as a stimulating factor) had a positive effect on the improvement of electrochemical system performance.
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23439. 题目: Synergistic effects and kinetics of rGO-modified TiO2 nanocomposite on adsorption and photocatalytic degradation of humic acid
文章编号: N19020706
期刊: Journal of Environmental Management
作者: Xiao Zhou, Shaoqi Zhou, Fuzhen Ma, Yanbin Xu
更新时间: 2019-02-07
摘要: Graphene oxide was prepared using the modified Hummers method and reduced graphene oxide (rGO) - titanium dioxide (TiO2) nanocomposite was synthesised using the one-step hydrothermal treatment. The synergistic effects on adsorption and photocatalytic properties of the rGO-TiO2 nanocomposite for the humic acid removal were systematically investigated. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and Raman and infrared (IR) spectroscopy indicate that GO was partially reduced to reduced graphene oxide (rGO) in the hydrothermal synthesis process and anatase TiO2 nanoparticles uniformly grew on the surface of rGO. The photoelectron and photohole generated under visible light irradiation were effectively separated on the surface of rGO-TiO2. The rGO-TiO2 nanocomposite exhibited higher photocatalytic activity as a result of the synergistic effects of surface functional groups for adsorption and the excellent conductivity for photocatalytic reaction. The effect of rGO-TiO2 nanocomposite dosage, light intensity and system temperature on the removal of humic acid solution was investigated. The results show that the removal efficiency of humic acid increased with system temperature and light intensity. When the dosage of rGO-TiO2 nanocomposite was 1.2 g/L, the temperature, the light intensity and the pH of this system was 303 K, 4.37 Wm−2 and 7, respectively, the removal efficiency of humic acid reached 88.7% under visible light irradiation.
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23440. 题目: Natural organic matter removal from algal-rich water and disinfection by-products formation potential reduction by powdered activated carbon adsorption
文章编号: N19020705
期刊: Journal of Environmental Management
作者: Keun-Young Park, Young-Jae Yu, Soon-Jin Yun, Ji-Hyang Kweon
更新时间: 2019-02-07
摘要: Algal blooms intensified operational problems in water treatment due to the increases of taste- and odor-causing compounds and natural organic matter (NOM). Effects of powdered activated carbon (PAC) addition during algal blooms on NOM removal was investigated in this study using an algal-rich water. Water quality analyses including dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV254) and specific UV absorbance (SUVA) were performed to elucidate characteristics of NOM removal by PAC adsorption. Variations of MW distributions and emission/excitation matrix (EEM) spectra with increasing PAC dosages were also measured. In addition, formation potential (FP) of trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs) was evaluated with increasing PAC dosage. The correlations between disinfection by-products formation potential (DBPFP) and water qualities such as DOC, UV254, SUVA, and EEM spectra were also investigated to identify factors associated with DBPFP. The PAC addition was effective to remove NOM, especially low molecular weights NOM and proteinaceous substances with weak aromatics. The PAC addition showed the consistent reduction of THMFPs, HAAFPs, and HANFPs with increasing PAC dosage while the greater reduction of HAN precursors was eminent compared to the other two FPs. The close correlations between UV254 and the three DBPFPs were obtained. The low molecular weight (i.e., 1–700 Da) NOM and three fluorescence spectra peaks, i.e., T1, A and C peaks, also showed high correlation factors with the three DBPFPs. Those analyses with high correlations with DBPFPs would provide useful information to reduce DBPs during algal blooms.
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