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32101. 题目: Effects of chemical oxidation on surface oxygen-containing functional groups and adsorption behavior of biochar
文章编号: N18052920
期刊: Chemosphere
作者: Qinya Fan, Jianxiong Sun, Lei Chu, Liqiang Cui, Guixiang Quan, Jinlong Yan, Qaiser Hussain, Muhammad Iqbal
更新时间: 2018-05-29
摘要: Biochar is a beneficial soil amendment but the changes in its surface properties during the aging process, especially the oxygen-containing functional groups and the associated adsorption behaviors, are not well documented. In this paper, the aged wheat straw biochar was simulated by chemical oxidation with HNO3-H2SO4 and NaOH-H2O2 systems. Characterization results showed that carbon loss and oxygen incorporation ran throughout the aging process. Surface oxygen-containing functional groups were found to be increased in all treated biochars, especially for carboxyl. Much more developed mesopores were observed in aging biochar, specific surface area was increased by 126% for biochar treated with NaOH-H2O2, and 226% for biochar treated with 40% of HNO3-H2SO4. Thermogravimetric analysis showed that the increasing oxygen-containing functional groups led to 14% and 30% mass loss by treating biochar with alkali and acid, respectively. The improved biochar surface through the increase of oxygen-containing functional groups enhanced the cadmium sorption capacity, and the sorption capacity increased by 21.2% in maximum. Roughed surface from oxidation was another reason for increasing cadmium adsorption. Results indicated that the adsorption performance of biochar on pollutant would be changed during aging process along with the changing surface properties.
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32102. 题目: Equilibrium sampling reveals increasing thermodynamic potential of polycyclic aromatic hydrocarbons during sewage sludge digestion
文章编号: N18052919
期刊: Chemosphere
作者: Karina K. Sjoeholm, Stine N. Schmidt, Annika Jahnke, Bo Svensmark, Philipp Mayer
更新时间: 2018-05-29
摘要: The reuse of digested sludge from wastewater treatment plants (WWTPs) as soil fertilizer poses a risk for contamination of soil and water environments. The present study provides a new approach for investigating the exposure of hydrophobic organic chemicals in sewage sludge. The methodology of equilibrium sampling with multiple thicknesses of silicone was successfully validated and applied to complex sludge matrices. Polycyclic aromatic hydrocarbon (PAH) concentrations in silicone (C silicone ) were determined and compared across four WWTPs. Activity ratios (ARs), defined as C silicone at equilibrium with digested sludge (final product) over C silicone at equilibrium with secondary sludge (intermediate product), were in the range 0.85–20 with all except one AR>1. These ARs thus revealed increased thermodynamic potential of both parent and alkylated PAHs in digested sludge compared with secondary sludge, and thereby higher exposure of PAHs in sludge after digestion than before digestion. This observation can be explained by the concept of “solvent depletion” as organic matter decreased by a factor of 1.3 during digestion, resulting in reduced sorptive capacity and increased freely dissolved concentrations (C free ). The PAHs with logK ow > 6 had ARs close to 1.3, whereas PAHs with logK ow < 6 showed higher ARs than the organic matter decrease factor of 1.3. C free in digested sludge were higher than reported in rural soil and generally consistent with levels reported for Baltic Sea sediment.
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32103. 题目: Influence of suspended sediment characteristics on the bioaccumulation and biological effects of citalopram in Daphnia magna
文章编号: N18052918
期刊: Chemosphere
作者: Haohan Yang, Guanghua Lu, Zhenhua Yan, Jianchao Liu, Huike Dong
更新时间: 2018-05-29
摘要: The influence of suspended sediment (SPS) characteristics on the bioavailability of the antidepressant citalopram (CIT) was investigated in the cladoceran Daphnia magna. The bioaccumulation, swimming behaviours, psychological indices, and oxidative stress were examined. The CIT bioaccumulation were altered in the presence of SPS, such that the body burden of CIT decreased as the concentration of SPS increased and as the organic carbon content of SPS (f oc ) increased; moreover, the body burden of CIT increased as SPS particle size increased. All the biomarker activities of D. magna were markedly induced at a CIT exposure concentration of 10 μg/L. However, the biological effects of CIT did not depend on the body burden of CIT as SPS concentration increased, while the swimming activities and oxidative stress were significantly enhanced by SPS concentration at 1 g/L. The influences of SPS particle size and f oc on the activities of swimming and physiological indicators were mainly associated with the CIT bioaccumulation, while f oc in SPS was more substantial than particle size. In addition, the antioxidant activities decreased as f oc increased and were significantly strengthened at particle sizes of 30–60 μm. The impacts of different SPS characteristics on the adsorption and desorption capacity of CIT and the ingestion habits of D. magna were the main reasons for the variations in CIT body burden and biological effects. According to the results obtained in this study, the SPS characteristics should be considered in the risk assessment of contaminants in natural aquatic environments.
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32104. 题目: Mechanisms of rice straw biochar effects on phosphorus sorption characteristics of acid upland red soils
文章编号: N18052917
期刊: Chemosphere
作者: Yong Liu, Zhi-Qiang Zhu, Xiao-Song He, Chao Yang, Ying-Qiong Du, Yong-Dong Huang, Peng Su, Shan Wang, Xiao-Xiao Zheng, Ya-Juan Xue
更新时间: 2018-05-29
摘要: An important pathway for biochar to alter the availability of soil phosphorus (P) is to change P sorption characteristics of the soil. The aim of this study was to understand the mechanisms of biochar effects on P sorption in acid upland red soils in the presence of different concentrations of exogenous P. Rice straw biochar (RSB) was prepared and applied at rates of 0, 1%, 3%, and 5% (w/w) to three red soils (MZ1, MZ2, and QY1) differing in initial pH (pH = 4.31, 4.82, and 5.68, respectively). The P sorption characteristics of these red soils were described using the Langmuir and Temkin equations and their relationships with soil basic physicochemical properties were analyzed. Furthermore, a representative red soil (MZ2) was selected to analyze the zeta potential of soil colloids and the chemical properties of sorption equilibrium solution, in order to understand their relationships with P sorption characteristics. Results showed that within a certain range of P concentration in the equilibrium solution, the amount of P sorbed by the three red soils decreased and the corresponding amount of P desorbed increased with increasing amendment rate of RSB. RSB showed the greatest effect on P desorption characteristics of MZ2 soil in the presence of higher exogenous P concentration. With increasing RSB amendment rate, the maximum P sorption of MZ1 soil decreased, while those of MZ2 and QY1 soils increased after an initial decrease. Phosphate sorption equilibrium constant and maximum P buffer capacity of each soil first increased and then decreased. However, a single physicochemical property could not interpret complex changes in multi-factors that jointly determine the P sorption characteristics of red soils. In the case of MZ2 soil, RSB amendment shifted the zeta potential of soil colloids to the negative direction; this decreased the positive charge and increased the negative charge on the soil surface, thus reducing P sorption in the MZ2 soil. In the presence of the same concentration of exogenous P, RSB amendment altered the pH, dissolved organic C (DOC), humification index (HIX), and maximum fluorescence intensity (Fmax) in the sorption equilibrium solution. In most cases, the amount of P sorbed by the MZ2 soil was negatively correlated with the pH value, DOC concentration, HIX value, and Fmax value of humic-like dissolved organic matter (DOM), and positively correlated with the Fmax value of protein-like DOM (P < 0.05 or P < 0.01). The relative fractional distribution of the contents for humic-like and protein-like DOM might determine the difference in the P sorption characteristics of MZ2 soil. In conclusion, different amendment rates of RSB affected the release of phosphate from soil surfaces into the solution by altering basic physicochemical and electrochemical properties of red soils and chemical properties of sorption equilibrium solution.
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32105. 题目: Organic matter decomposition before arsenic speciation analysis of water sample – “Soft decomposition” using nano-photocatalysts
文章编号: N18052916
期刊: Chemosphere
作者: Ewa Biaduń, Natalia Nowak, Joanna Kowalska, Krzysztof Miecznikowski, Beata Krasnod?bska-Ostr?ga
更新时间: 2018-05-29
摘要: The applicability of photolysis in the speciation analysis of arsenic is investigated. The use of nano scale semiconductors (Fe2O3/WO3/Fe2O3 at pH 6) as an active film during solar light irradiation of a water sample, containing some surfactants (SDS), results in the simplification of the organic matter and gives no speciation change in the arsenic. The reproducibility of active layer is shown to be high and the surface roughness of each photoactive sample and photocurrent do not differ by more than 6 and less than 8%, respectively. The procedure of sample pretreatment caused a minimum (8–10%) amount of speciation change, whilst the irradiation is no longer that 2 h. The study indicates that “soft decomposition” can be performed for as long as 4 h, and still give photostable arsenates (III) and methylarsenate species. However, the saturation of the water sample with Ar is required (to reduce the oxygen content) for the longer the decomposition time being applied.
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32106. 题目: Properties of magnetic carbon nanomaterials and application in removal organic dyes
文章编号: N18052915
期刊: Chemosphere
作者: Junhong Wang, Qiang Zhang, Xianzhao Shao, Jianqi Ma, Guanghui Tian
更新时间: 2018-05-29
摘要: Magnetic carbon nanomaterials were prepared facilely by one step hydrothermal synthesis method using biologically regenerated glucose as carbon sources and ferric ammonium citrate as iron sources. As-synthesized nanomaterials were characterized by means of SEM, TEM, XRD, N2 adsorption-desorption, VSM and XPS etc. techniques. Results show as-prepared magnetic nanomaterials are sphere particles with aggregation state and magnetic α-Fe particles are enclosed by carbon matrixes. With increase of calcination temperature, the degrees of the sample aggregation decrease, whereas the average particle sizes, BET specific surface areas and saturation magnetizations increase. The carbon with graphite structure has higher adsorption efficiency than that of amorphous carbon for organic dye rhodamine B in water. Whereas the iron with amorphous structure shows higher photocatalytic activity than that of the iron with crystalline structure for the degradation of rhodamine B. And rhodamine B in water can almost be degraded completely through the combination of adsorption and photocatalysis.

32107. 题目: Redistribution of Cs 137 introduced into montmorillonite in association with organic matter coming from biomass composting
文章编号: N18052914
期刊: Chemosphere
作者: J. Mihalik, M.J. Madruga, M.H. Casimiro, L.M. Ferreira, M.I. Prudêncio
更新时间: 2018-05-29
摘要: The adsorption and later bioavailability of 137Cs from the system humic acid (HA)/humic acid like compounds (HALC) and montmorillonite was investigated. The setup of the experiments should approach as much as possible natural conditions when 137Cs is introduced into soil with HALC from decomposed biomass. The significant differences were found in the trials containing various HA/HALC and also pure montmorillonite. The 137Cs was more available when it reached soil in association with HALC originated from compost than when it was adsorbed on stable humic acids. Moreover, the long term interaction of 137Cs with HALC led to decrease of 137Cs adsorbed on montmorillonite and increase of its bioavailable fraction. UV–Vis spectrometry and infrared spectroscopy showed the clear difference between HA, fresh HALC and old HALC which could partially explain the different results.
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32108. 题目: Removal of PCDD/Fs, PCP and mercury from sediments: Thermal oxidation versus pyrolysis
文章编号: N18052913
期刊: Chemosphere
作者: Moo-Been Chang, Yen-Chen Hsu, Shu-Hao Chang
更新时间: 2018-05-29
摘要: A continuous pilot-scale system (CPS) equipped with effective air pollution control devices (APCDs) is used for remediating the sediments contaminated with PCDD/Fs, PCP and Hg simultaneously. The removal efficiencies of these three pollutants in sediments collected from seawater pond and river, respectively, are evaluated via thermal treatment processes. PAHs and CBz formed during thermal oxidation and pyrolysis are also analyzed for better understanding the behaviors of chlorinated organic compounds. Experimental results indicate that low-molecular-weight PAHs are closely related to the formation of CBz, PCDD/Fs, and CPs, while low chlorinated PCDD/Fs and CBz are predominant in flue gas with thermal oxidation. However, the PM concentration is higher in thermal oxidation than pyrolysis due to the higher air flow rate of thermal oxidation. It may bring more particles out of the furnace and have a greater potential to form PCDD/Fs within APCDs. Besides, the high air flow also dilutes the Hg vapor in flue gas and would require more energy to condense and collect Hg with the quench tower. Furthermore, for removal of total amount of PCDD/Fs, pyrolysis is better than thermal oxidation. Thus, pyrolysis is more suitable for remediating the contaminated sediment. The removal efficiencies of PCDD/Fs, PCP and Hg in sediments achieved with pyrolysis increase with increasing operating temperature and retention time in CPS. Overall, the residual concentrations of PCDD/Fs and PCP in river sediment are higher than that in seawater-pond sediment since significant formation of tar is observed due to higher organic matter content in river sediment.

32109. 题目: Sorption of perfluoroalkyl substances (PFASs) to an organic soil horizon – Effect of cation composition and pH
文章编号: N18052912
期刊: Chemosphere
作者: Hugo Campos Pereira, Malin Ullberg, Dan Berggren Kleja, Jon Petter Gustafsson, Lutz Ahrens
更新时间: 2018-05-29
摘要: Accurate prediction of the sorption of perfluoroalkyl substances (PFASs) in soils is essential for environmental risk assessment. We investigated the effect of solution pH and calculated soil organic matter (SOM) net charge on the sorption of 14 PFASs onto an organic soil as a function of pH and added concentrations of Al3+, Ca2+ and Na+. Often, the organic C-normalized partitioning coefficients (K OC ) showed a negative relationship to both pH (Δlog K OC /ΔpH = -0.32 ± 0.11 log units) and the SOM bulk net negative charge (Δlog K OC = -1.41 ± 0.40 per log unit molc g-1). Moreover, perfluorosulfonic acids (PFSAs) sorbed more strongly than perfluorocarboxylic acids (PFCAs) and the PFAS sorption increased with increasing perfluorocarbon chain length with 0.60 and 0.83 log K OC units per CF2 moiety for C3–C10 PFCAs and C4, C6, and C8 PFSAs, respectively. The effects of cation treatment and SOM bulk net charge were evident for many PFASs with low to moderate sorption (C5–C8 PFCAs and C6 PFSA). However for the most strongly sorbing and most long-chained PFASs (C9–C11 and C13 PFCAs, C8 PFSA and perfluorooctane sulfonamide (FOSA)), smaller effects of cations were seen, and instead sorption was more strongly related to the pH value. This suggests that the most long-chained PFASs, similar to other hydrophobic organic compounds, are preferentially sorbed to the highly condensed domains of the humin fraction, while shorter-chained PFASs are bound to a larger extent to humic and fulvic acid, where cation effects are significant.
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32110. 题目: Toxicity screening of biochar-mineral composites using germination tests
文章编号: N18052911
期刊: Chemosphere
作者: Jan Mumme, Josephine Getz, Munoo Prasad, Ulf Lüder, Jürgen Kern, Ond?ej Ma?ek, Wolfram Buss
更新时间: 2018-05-29
摘要: This study assessed the properties and toxicity (water cress germination trials) of 38 waste-derived, novel biochar-mineral composites (BMCs) produced via slow pyrolysis and hydrothermal carbonization (hydrochars). The biochars were produced from sewage sludge and compost-like output (CLO) by varying the type of mineral additive (zeolite, wood ash and lignite fly ash), the mineral-to-feedstock ratio and the carbonization process. While pure hydrochars completely inhibited germination of water cress, this effect was ameliorated by mineral additives. Seedlings grew best in pyrolysis chars and while wood ash addition decreased plant growth in many cases, 1:10 addition to CLO doubled germination rate. The factors responsible for the phytotoxicity can be attributed to pH, salinity and organic contaminants. Importantly, while pure minerals inhibited germination, conversion of minerals into BMCs reduced their inhibitory effects due to buffered release of minerals. Overall, mineral wastes (e.g., combustion ashes) and waste biomass can be used safely as sources of nutrients and stable organic carbon (for soil carbon sequestration) when converted into specific biochar-mineral composites, exploiting synergies between the constituents to deliver superior performance.

32111. 题目: Enhanced hexavalent chromium removal performance and stabilization by magnetic iron nanoparticles assisted biochar in aqueous solution: Mechanisms and application potential
文章编号: N18052910
期刊: Chemosphere
作者: Shishu Zhu, Xiaochen Huang, Dawei Wang, Li Wang, Fang Ma
更新时间: 2018-05-29
摘要: The superiority of the nanoscale zero valent iron (nZVI) assisted biochar (BC) composites compared to traditional nZVI and its application feasibility are still unclear. This study aimed to provide valuable information for practical application. Firstly, the Fe/BC mass ratio of 2:1 during the preparation of nZVI-BC was proved obtaining the complete Cr6+ removal. Then, results revealed that the initial pH value tuned Cr6+ removal performance via varying existing Cr6+ species, surface charge, and chemical states of iron nanoparticles (NPs). Improvement of colloidal stabilization and positive surface charge attributed to enhancement of Cr6+ removal of nZVI-BC. The Cr6+ removal process was well described using pseudo-second-order kinetic. By Langmuir isotherm model, the maximum removal capacity (58.82 mg g-1) was determined. Moreover, the multiple evidences (XRD, XPS, FTIR, and TEM results) explained the mechanisms of Cr6+ removal (i.e. electrostatic force, complexes, metal reduction, and precipitates on the edges). Little inhibitory effect of coexisting anions (SO4 2-, PO4 3-, and NO3 -) and well regeneration ability (82.2% removal efficiency after five cycles using acid washing), along with well Cr6+ removal efficiencies of real contaminated water (electroplating wastewater, tannery wastewater and groundwater) treatment, suggested nZVI-BC was considered as a superior and cost-effective choice for Cr6+ included polluted water treatment.
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32112. 题目: Groundwater contamination and land drainage induce divergent responses in boreal spring ecosystems
文章编号: N18052909
期刊: Science of The Total Environment
作者: Kaisa Lehosmaa, Jussi Jyv?sj?rvi, Jari Ilmonen, Pekka M. Rossi, Lauri Paasivirta, Timo Muotka
更新时间: 2018-05-29
摘要: Degradation of freshwater ecosystems has engendered legislative mandates for the protection and management of surface waters while groundwater-dependent ecosystems (GDEs) have received much less attention. This is so despite biodiversity and functioning of GDEs are currently threatened by several anthropogenic stressors, particularly intensified land use and groundwater contamination. We assessed the impacts of land drainage (increased input of dissolved organic carbon, DOC, from peatland drainage) and impaired groundwater chemical quality (NO3 --N enrichment from agricultural or urban land use) on biodiversity and ecosystem functioning in 20 southern Finnish cold-water springs using several taxonomic and functional measures. Groundwater contamination decreased macroinvertebrate and bacterial diversity and altered their community composition. Changes in macroinvertebrate and bacterial communities along the gradient of water-quality impairment were caused by the replacement of native with new taxa rather than by mere disappearance of some of the original taxa. Also species richness of habitat specialist (but not headwater generalist) bryophytes decreased due to impaired groundwater quality. Periphyton accrual rate showed a subsidy-stress response to elevated nitrate concentrations, with peak values at around 2500 μg L-1, while drainage-induced spring water brownification (increased DOC) reduced both periphyton accrual and leaf decomposition rates already at very low concentrations. Our results highlight the underutilized potential of ecosystem-level functional measures in GDE bioassessment as they seem to respond to the first signs of spring ecosystem impairment, at least for the anthropogenic stressors studied by us.
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32113. 题目: Manure digestate storage under different conditions: Chemical characteristics and contaminant residuals
文章编号: N18052908
期刊: Science of The Total Environment
作者: Yun Li, Hang Liu, Guoxue Li, Wenhai Luo, Ying Sun
更新时间: 2018-05-29
摘要: In this study, chemical characteristics and contaminant residuals in livestock manure digestate were investigated during storage under different conditions. Results show that storing digestate openly under the mesophilic condition (30 ± 1 °C) led to water evaporation and thus considerable mass reduction. As a result, concentrative effect occurred to increase the contents of organic matter, nutrients, and heavy metals during digestate storage. By contrast, ammonium (NH4 +) concentration in digestate decreased over storage period. The concentrative effect and NH4 + reduction could be mitigated by storing digestate with coverage and/or under psychrophilic conditions (e.g. 15 ± 1 °C). Regardless of storage conditions, organic matter was further biodegraded, thereby reducing the residuals of antibiotics in digestate. Antibiotic removal was more notable when digestate was stored under mesophilic conditions. Nevertheless, additional processes to control heavy metals and antibiotics in digestate are still necessary before agricultural applications.
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32114. 题目: Biochar enhances plant growth and nutrient removal in horizontal subsurface flow constructed wetlands
文章编号: N18052907
期刊: Science of The Total Environment
作者: Kuno Kasak, Jaak Truu, Ivika Ostonen, Jürgen Sarjas, Kristjan Oopkaup, P??rn Paiste, Margit K?iv-Vainik, ?lo Mander, Marika Truu
更新时间: 2018-05-29
摘要: Biochar has shown great potential as an amendment to improve soil quality and promote plant growth, as well as to adsorb pollutants from water. However, information about the effect of biochar on the wastewater treatment efficiency in horizontal subsurface flow (HSSF) constructed wetlands (CWs) is still scarce. In this study, we assessed the effect of biochar amendment on the purification efficiency of pretreated municipal wastewater in planted (Typha latifolia) experimental horizontal subsurface flow filters filled with lightweight expanded clay aggregates (LECA). The addition of wood-derived biochar (10% v/v) to LECA significantly increased plant biomass production and enhanced the wastewater treatment efficiency of the planted filters. Both the aboveground plant biomass and belowground plant biomass were higher (1.9- and 1.5-fold, respectively) in the filters of the LBP (LECA + biochar + plants) treatments compared to the LP (LECA + plants) filters. The water pH was significantly lower in the planted filters (LBP < LP < LB-LECA + biochar). The efficiencies of TN and TP removal from wastewater were highest in the LBP filters (20.0% and 22.5%, respectively), followed by the LP (13.7% and 16.2%, respectively) and LB (9.5% and 15.6%, respectively) filters. More N and P were incorporated into the plant biomass from wastewater in the presence of biochar in the filter medium. The study results confirm that biochar can be an advantageous supplement for planted HSSF CWs to enhance the treatment efficiency of these systems.
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32115. 题目: Arsenic speciation dynamics in paddy rice soil-water environment: sources, physico-chemical, and biological factors - A review
文章编号: N18052906
期刊: Water Research
作者: Prasanna Kumarathilaka, Saman Seneweera, Andrew Meharg, Jochen Bundschuh
更新时间: 2018-05-29
摘要: Rice is the main staple carbohydrate source for billions of people worldwide. Natural geogenic and anthropogenic sources has led to high arsenic (As) concentrations in rice grains. This is because As is highly bioavailable to rice roots under conditions in which rice is cultivated. A multifaceted and interdisciplinary understanding, both of short-term and long-term effects, are required to identify spatial and temporal changes in As contamination levels in paddy soil-water systems. During flooding, soil pore waters are elevated in inorganic As compared to dryland cultivation systems, as anaerobism results in poorly mobile As(V), being reduced to highly mobile As(III). The formation of iron (Fe) plaque on roots, availability of metal (hydro)oxides (Fe and Mn), organic matter, clay mineralogy and competing ions and compounds (PO4 3- and Si(OH)4) are all known to influence As(V) and As(III) mobility in paddy soil-water environments. Microorganisms play a key role in As transformation through oxidation/reduction, and methylation/volatilization reactions, but transformation kinetics are poorly understood. Scientific-based optimization of all biogeochemical parameters may help to significantly reduce the bioavailability of inorganic As.
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32116. 题目: Determining major factors controlling phosphorus removal by promising adsorbents used for lake restoration: A linear mixed model approach
文章编号: N18052905
期刊: Water Research
作者: A. Funes, F.J. Martínez, I. ?lvarez-Manzaneda, J.M. Conde-Porcuna, J. de Vicente, F. Guerrero, I. de Vicente
更新时间: 2018-05-29
摘要: Phosphorus (P) removal from lake/drainage waters by novel adsorbents may be affected by competitive substances naturally present in the aqueous media. Up to date, the effect of interfering substances has been studied basically on simple matrices (single-factor effects) or by applying basic statistical approaches when using natural lake water. In this study, we determined major factors controlling P removal efficiency in 20 aquatic ecosystems in the southeast Spain by using linear mixed models (LMMs). Two non-magnetic -CFH-12 and Phoslock - and two magnetic materials -hydrous lanthanum oxide loaded silica-coated magnetite (Fe-Si-La) and commercial zero-valent iron particles (FeHQ)- were tested to remove P at two adsorbent dosages. Results showed that the type of adsorbent, the adsorbent dosage and color of water (indicative of humic substances) are major factors controlling P removal efficiency. Differences in physico-chemical properties (i.e. surface charge or specific surface), composition and structure explain differences in maximum P adsorption capacity and performance of the adsorbents when competitive ions are present. The highest P removal efficiency, independently on whether the adsorbent dosage was low or high, were 85–100% for Phoslock and CFH-12 , 70–100% for Fe-Si-La and 0–15% for FeHQ. The low dosage of FeHQ, compared to previous studies, explained its low P removal efficiency. Although non-magnetic materials were the most efficient, magnetic adsorbents (especially Fe-Si-La) could be proposed for P removal as they can be recovered along with P and be reused, potentially making them more profitable in a long-term period.
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32117. 题目: Impact of inorganic ions and natural organic matter on arsenates removal by ferrate(VI): Understanding a complex effect of phosphates ions
文章编号: N18052904
期刊: Water Research
作者: Jan Kola?ík, Robert Prucek, Ji?í Tu?ek, Jan Filip, Virender K. Sharma, Radek Zbo?il
更新时间: 2018-05-29
摘要: Arsenic compounds are carcinogenic to humans and are typically removed from contaminated water using various sorbents. The ionic composition plays a significant role in arsenate removal efficiency during the process of water remediation. Here, we quantify the effects of natural ions (chlorides, nitrates, carbonates, sulfates, and phosphates) and humic acid on the removal of arsenates by ferrate(VI) at pH = 6.6. In the experiments, the initial concentration of arsenates was 10 mg L-1 (as As) and the concentrations of ions varied in the range from 5 to 100 mg L-1 of element in ionic form and humic acid. The achieved results show that only phosphate ions had principle influence on the efficiency of arsenate removal by ferrate(VI). The effect of phosphates was elucidated by applying transmission electron microscopy, energy-dispersive X-ray spectroscopy, and low temperature in-field 57Fe M ssbauer spectroscopy to solid samples, prepared under different weight ratios of ferrate(VI), arsenates, and phosphates. These results show three crucial effects of phosphates on the arsenate removal mechanisms. At low P:As weight ratio (up to 1:1), the incorporation of arsenate ions into the crystalline structure of γ-Fe2O3/γ-FeOOH nanoparticles was found to be suppressed by the presence of phosphates. Thus, arsenates were mainly adsorbed onto the surface of γ-Fe2O3/γ-FeOOH nanoparticles. Further increase in the P:As weight ratio (more than 1:1) resulted in the competition between arsenates and phosphates sorption. With the increased concentration of phosphate ions, the number of arsenates on the surface of γ-Fe2O3/γ-FeOOH nanoparticles was reduced. Finally, the complexation of iron(III) ions with phosphate ions occurred, leading to a decrease in the arsenates removal efficiency, which resulted from a lower content of precipitated γ-Fe2O3/γ-FeOOH nanoparticles. All these aspects need to be considered prior to application of ferrate(VI) for arsenates removal in real natural waters.
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32118. 题目: Interaction of calcium, phosphorus and natural organic matter in electrochemical recovery of phosphate
文章编号: N18052903
期刊: Water Research
作者: Yang Lei, Bingnan Song, Michel Saakes, Renata D. van der Weijden, Cees J.N. Buisman
更新时间: 2018-05-29
摘要: To address the issues of eutrophication and the potential risk of phosphorus (P) shortage, it is essential to remove and recover P from P-containing streams to close this nutrient cycle. Electrochemical induced calcium phosphate (CaP) precipitation was shown to be an efficient method for P recovery. However, the influence of natural organic matter (NOM) is not known for this treatment. In this paper, the behavior of NOM and its effect on CaP precipitation was studied. In contrast to studies where NOM hindered CaP precipitation, results show that the interaction of NOM with CaP improves the removal of P, independent of the types of NOM. The P removal at the average increased from 43.8 ± 4.9% to 58.5 ± 1.2% in the presence of 1.0 mg L-1 NOM. Based on the yellow color of the CaP product, NOM is co-precipitated. The bulk solution pH with and without buffers has totally different effects on the precipitation process. Without buffer, CaP precipitates on the cathode surface in a wide pH range (pH 4.0–10.0). However, the precipitation process is completely inhibited when the bulk solution is buffered at pH 4.0 and 6.0. This is probably due to neutralization of OH - by the buffers. Regardless of the presence or absence of NOM and solution pH, the recovered products are mainly amorphous CaP unless the electrolysis time was increased to seven days with 4.0 A m-2, in which crystalline CaP formed. These findings advance our understanding on the interaction of Ca, P and NOM species for the application of electrochemical method for P recovery from real wastewater.
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32119. 题目: New insights into the formation of silver-based nanoparticles under natural and semi-natural conditions
文章编号: N18052902
期刊: Water Research
作者: Andreas Wimmer, Anna Kalinnik, Michael Schuster
更新时间: 2018-05-29
摘要: For the first time, the natural formation of silver-based nanoparticles (Ag-b-NPs) was studied in field investigations of two pre-alpine lakes in Germany that contain geogenic silver traces in the sub-ng L-1 range. Light-sensitive microorganisms most likely accumulate and transport these silver traces from deeper water layers to the surface. At the surface of the eutrophic lake, approximately 40% of total silver (5.7 ng L-1) consisted of Ag-b-NPs, whereas in the oligotrophic lake with similar enrichment of silver species, no Ag-b-NPs were detected. Additional lab experiments with nature-related Ag(I) concentrations in the lower-ng L-1 range and natural organic matter with total organic carbon values of ≤5 mg L-1 revealed that, contrary to common interpretation in the literature, Ag-b-NPs are also or even preferably formed in the dark. Particle size increases gradually with increasing reaction time, showing that Ostwald ripening occurs even at such low particle concentrations. When sulfide ions are present, smaller Ag-b-NPs with a narrower size distribution are formed.
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32120. 题目: The dependence of chlorine decay and DBP formation kinetics on pipe flow properties in drinking water distribution
文章编号: N18052901
期刊: Water Research
作者: Yingying Zhao, Y. Jeffrey Yang, Yu Shao, Jill Neal, Tuqiao Zhang
更新时间: 2018-05-29
摘要: Simultaneous chlorine decay and disinfection byproduct (DBP) formation have been discussed extensively because of their regulatory and operational significance. This study further examines chemical reaction variability in the water quality changes under various hydrodynamic conditions in drinking water distribution. The variations of kinetic constant for overall chlorine decay ( k E ) and trihalomethane (THM) formation were determined under stagnant to turbulent flows using three devices of different wall demand and two types of natural organic matters (NOM) in water. The results from the comparative experiments and modeling analyses show the relative importance of wall demand ( k w ), DBP-forming chlorine decay ( k D ), and other bulk demand ( k b ' ) for pipe flows of Re = 0–52500. It is found that chlorine reactivity of virgin NOM is the overriding factor. Secondly, for tap water NOM of lower reactivity, pipe flow properties (Re or u) can significantly affect k E , the THM yield (T), formation potential (Y), and the time to reach the maximum THM concentration ( t max ) through their influence on kinetic ratio k D ( k b ' + k w ) . These observations, corroborating with turbidity variations during experiments, cannot be explained alone by chlorine dispersion to and from the pipe wall. Mass exchanges through deposition and scale detachment, most likely being flow-dependent, may have contributed to the overall chlorine decay and DBP formation rates. Thus for the simultaneous occurrence of chlorine decay and DBP formation, model considerations of NOM reactivity, pipe types (wall demand), flow hydraulics, and their interactions are essential.
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