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31961. 题目: Impact of organic matter types on surface charge and aggregation of goethite
文章编号: N18062101
期刊: Colloids and Surfaces A: Physicochemical and Engineering Aspects
作者: Stefan Dultz, Heiko Steinke, Robert Mikutta, Susanne K. Woche, Georg Guggenberger
更新时间: 2018-06-21
摘要: In order to assess the mobility and function of Fe oxihydroxides in terrestrial and aquatic environments, knowledge of the parameters and conditions determining aggregation and the size of formed aggregates is crucial. Here we study the impact of different organic matter (OM) types on the aggregation of goethite (α-FeOOH) with particular focus on the relevance of surface charge (SC). Synthetic goethite was reacted with galacturonic acid (GA), polygalacturonic acid (PGA), and tannic acid (TA) as model substances as well as with natural dissolved OM (DOM) from a litter (Oi-DOM) and a humified horizon (Oa-DOM). The SC of goethite was adjusted at pH 4 and 6 by the adsorption of organic acids and DOM to equal positive and negative SC as well as point of zero charge (pzc). Aggregation was traced by laser light scattering and sedimentation experiments. Aggregation of all goethite-OM associations depended on OM type and could well be explained by SC. Associations of goethite with OM rich in acidic groups (PGA, Oi-DOM, and Oa-DOM) followed the aggregation behavior of pure goethite. Largest aggregates with diameters up to 7 μm formed at pzc, whereas smaller ones ( 0.4 μm) developed at positive or negative SC. Organic substances rich in acidic functional groups interacted strongly with goethite at high additions, thus favoring charge reversal and limiting aggregate growth. For OM with low acidity (TA and GA), adsorption on goethite was incomplete even at high additions. These associations remained close to pzc and, hence, were susceptible to aggregation with maximum diameters at 6 μm. Aggregation was possibly also promoted by the exposure of less polar moieties exposed at the goethite-OM interface. Our data suggest that aggregation in environmental systems such as soils is driven by the nature and acidity of ubiquitous OM, which determines SC by the extent of adsorption to mineral surfaces.
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31962. 题目: Differences in long-term vs short-term carbon and nitrogen sequestration in a coastal river delta wetland: implications for global budgets
文章编号: N18062003
期刊: Organic Geochemistry
作者: R.D. DeLaune, J.R. White, T. Elsey-Quirk, H.H. Roberts, D.Q. Wang
更新时间: 2018-06-20
摘要: Coastal wetlands can serve as a considerable sink for carbon (C) gases. However, the capacity for wetlands to serve as more permanent C and N sinks over the long term is less clear given the time dependence of sediment deposition, organic matter decomposition, and anthropogenic land use change. In this study, we compare the short-term (decadal scale) and long-term (millennial scale) C and N accumulation rates estimated using 137Cs and radiocarbon dating of vibracores collected from a freshwater coastal wetland in the Louisiana Mississippi River deltaic plain (Atchafalaya River delta). The mean short-term (60 yr) sediment accumulation rate was 1.4 cm/yr while the mean rate of long-term (100–1000 yr) sediment accumulation was an order of magnitude lower at 0.12 cm/yr. Annual rates of C and N accumulated over the past several thousand years were approximately 10% of that over the past 60 years after correcting for bulk density. These results are similar to other coastal wetlands and suggest that time scale must be considered in determining the relative permanence of C and N storage in coastal wetland soils. This difference is especially important for assessing the role of C cycling in relation to global change models and N cycling related to water quality in accurately quantifying the role of coastal deltaic fresh water wetlands in regulating these biogeochemical cycles.
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31963. 题目: Biochar from Different Carbonaceous Waste Materials: Ecotoxicity and Effectiveness in the Sorption of Metal(loid)s
文章编号: N18062001
期刊: Water, Air, & Soil Pollution
作者: Mariano Simón, Inés García, María Diez-Ortiz, Verónica González
更新时间: 2018-06-20
摘要: In this study, biochar produced by pyrolysis of urban pruning wood (Bpw) and sewage sludge (Bss) were characterized and investigated as adsorbents for the removal of Cu(II), Pb(II), Zn(II), and As(V) from contaminated solutions. Both types of biochars showed different physical-chemical properties and metal(loid) content. In Bss, Cu, Zn, and Pb concentrations exceeded the upper limit of the common ranges in soils. However, when they were tested for their effect on soil invertebrates, neither of the biochar was expected to exert negative effects as long as the dose applied as an amendment was ≤ 4.8 t ha-1. For an assessment of the effectiveness of biochar in the immobilization of metal(loid)s, three contaminated solutions with acidic pH and different pollutant concentrations were added to both types of biochar. Precipitation as oxy-hydroxides and the formation of complexes with active functional groups of the organic matter were the main mechanisms of metal(loid) fixation by the biochar, with increased precipitation and a rising pH. Both types of biochar were effective at immobilizing Pb and Cu, while Zn showed less effectiveness in this regard and As the least. The high P content of the biochar from sewage sludge favored Pb fixation, presumably forming complexes with phosphates, while competition between phosphate and arsenate ions decreased As adsorption by Fe compounds. The metal(loid)s immobilized by biochar from urban pruning wood were more bioavailable

31964. 题目: Tillage system change affects soil organic carbon storage and benefits land restoration on loess soil in North China
文章编号: N18061906
期刊: Land Degradation & Development
作者: HaoWang , ShulanWang , YujiaoZhang , XiaoliWang , RuiWang , JunLi
更新时间: 2018-06-19
摘要: Soil organic carbon (SOC) is a core indicator of soil quality. A proper tillage system can improve SOC accumulation and benefit land restoration. This improvement is especially significant in loess soil, which is undergoing serious degradation in China. In this study, we chose a field that was used for crop production and used a traditional moldboard plow with crop residue removal (CT) for over 10 years. We then carried out a long‐term field experiment (2007–2015) and changed the tillage system from a moldboard plow with crop residue removal to either a moldboard plow with buried straw system (BT), a no‐tillage with straw mulch system (NT), or a subsoiling with straw mulch system (ST) to evaluate the effect of tillage system change and the effects of tillage systems on SOC storage. Tillage system change influenced SOC content, NT, ST, and BT showed higher values of SOC content and increased 8.34, 7.83, and 1.64 Mg·C·ha 1, respectively, compared with CT. Among the 3 changed tillage systems, NT and ST showed a 12.5% and 11.6% increase in SOC content then BT, respectively. Tillage system change influenced SOC stratification ratio values, with higher value observed in BT and NT compared CT but ST. Therefore, in loess soil, changing tillage system can significantly improve SOC storage and change profile distribution. The NT and ST treatments showed a more marked SOC increase, but the increase value in stratification ratio with NT still needs attention, and our results is meaningful for soil quality improvement and land restoration.

31965. 题目: Ferrate(VI) oxidation of polychlorinated diphenyl sulfides: Kinetics, degradation, and oxidized products
文章编号: N18061905
期刊: Water Research
作者: Jing Chen, Xinxin Xu, Xiaolan Zeng, Mingbao Feng, Ruijuan Qu, Zunyao Wang, Nasri Nesnas, Virender K. Sharma
更新时间: 2018-06-19
摘要: This paper presents oxidation of polychlorinated diphenyl sulfides (PCDPSs), dioxin-like compounds, by ferrate(VI) (FeVIO4 2 , Fe(VI)). Kinetics of the reactions of Fe(VI) with seventeen PCDPSs, differ in number and positions of chlorine atoms (from 2 to 7), were investigated at pH 8.0. The second-order rate constants (k, M 1 s 1) of the reactions varied with the numbers and positions of chlorine atoms and appeared to be related with standard Gibbs free energy of formation (ΔfG0) of PCDPSs. Degradation experiments in the presence of ions and humic acid demonstrated complete removal of PeCDPS by Fe(VI) in minutes. Pathways of the reaction were investigated by identifying oxidized products (OPs) of the reaction between Fe(VI) and 2,2′,3’,4,5-pentachlorodiphenyl sulfide (PeCDPS) at pH 8.0. Pathways of oxidation involved major pathway of attack on sulfur(II) by Fe(VI) in steps to yield sulfoxide type products, and subsequent breakage of C-S bond with the formation of sulfonic acid-containing trichloro compound. Minor pathways were hydroxylation of benzene ring and substitution of chlorine atom with hydroxyl group. Estimation of toxicity of OPs of the oxidation of PeCDPS by Fe(VI) suggested the decreased toxicity from the parent contaminant.
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31966. 题目: Impact of chlorination on silver elution from ceramic water filters
文章编号: N18061904
期刊: Water Research
作者: Bonnie A. Lyon-Marion, Anjuliee M. Mittelman, Justine Rayner, Daniele S. Lantagne, Kurt D. Pennell
更新时间: 2018-06-19
摘要: Applying silver nanoparticles (nAg) or silver nitrate (AgNO3) to ceramic water filters improves microbiological efficacy, reduces biofilm formation, and protects stored water from recontamination. A challenge in ceramic filter production is adding sufficient silver to achieve these goals without exceeding the maximum recommended silver concentration in drinking water. Silver release is affected by silver type, application method, and influent water chemistry. Despite a lack of data, there is an assumption that chlorinated water should not be used as influent water because it may increase silver elution. Thus, the objective of this work was to systematically evaluate the impact of chlorinated water (0–4 mg/L free chlorine residual, FCR) on silver release from ceramic filter disks painted with casein-coated nAg, painted with AgNO3, or containing fired-in nAg over a range of ionic strength (IS = 0–10 mM as NaNO3) in the presence or absence of natural organic matter (NOM). Influent deionized water containing chlorine increased silver release 2–5-fold compared to controls. However, this effect of chlorine was mitigated at higher IS (≥1 mM) or in the presence of NOM (3 mg C/L). For filter disks painted with nAg or AgNO3, silver release increased with increasing IS (with or without chlorine), and effluent concentrations remained above the World Health Organization (WHO) guideline of 0.1 mg/L even after 30 h (80 pore volumes, PVs) of flow with a background solution of 10 mM NaNO3. Silver speciation (nAg vs. Ag+) was monitored in effluent samples from painted or fired-in nAg filter disks. Results indicated that in general, greater than 90% of the eluted silver was due to Ag+ dissolution rather than nAg release. Additionally, a filter disk prepared with fired-in nAg exhibited a lower % released in the nanoparticle form (nAg = 5% of total Ag in effluent) compared to painted on nAg (nAg = 14% of total Ag in effluent). The findings of this study suggest that chlorinated influent water has minimal impact on silver elution from ceramic filters under simulated natural water conditions, and thus, the recommendation to avoid the use of chlorinated water with ceramic filters is not necessary under most conditions.
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31967. 题目: Insights into the simultaneous removal of Cr6+ and Pb2+ by a novel sewage sludge-derived biochar immobilized nanoscale zero valent iron: Coexistence effect and mechanism
文章编号: N18061903
期刊: Science of The Total Environment
作者: Zeng-Hui Diao, Jian-Jun Du, Dan Jiang, Ling-Jun Kong, Wen-Yi Huo, Cui-Mei Liu, Qi-Hang Wu, Xiang-Rong Xu
更新时间: 2018-06-19
摘要: Cr6+ and Pb2+ are both highly toxic pollutants and commonly co-exist in some industrial effluents and contaminated waters. In this study, simultaneous removal of Cr6+ and Pb2+ by a novel sewage sludge-derived biochar immobilized nanoscale zero-valent iron (SSB-nZVI) was systematically investigated. It was well demonstrated that a porous structure was successfully formed on the SSB-nZVI when the starch was used as an additive. A synergistic effect on the adsorption and reduction over the SSB-nZVI was achieved, resulting in nearly 90 and 82% of Cr6+ and Pb2+ removal within 30 min, respectively. Cr6+ was reduced prior to Pb2+. A low pH could accelerate the corrosion of nZVI as well as phosphate leaching. When Malachite green was added as a coexisting organic pollutant, its effective removal was found due to the formation of a Fenton-like system. The SSB-nZVI could be run consecutively three times with a relatively satisfactory performance. Most of Cr6+ was converted into Cr2O3 and Cr(OH)3 on the SSB-nZVI surface, whereas most of Pb2+ species existed as Pb(OH)2 (or PbO). A possible reaction mechanism on the SSB-nZVI involved the adsorption, reduction and precipitation of both Cr6+ and Pb2+ over the particles. Present study sheds light on the insight of the fate and transport of Cr6+ and Pb2+ in aquatic environment, as well provides helpful guide for the remediation of coexistence of pollutants in real applications.
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31968. 题目: Humic-Like Substances (HULIS) in Aerosols of Central Tibetan Plateau (Nam Co, 4730 m asl): Abundance, Light Absorption Properties, and Sources
文章编号: N18061902
期刊: Environmental Science & Technology
作者: Guangming Wu, Xin Wan, Shaopeng Gao, Pingqing Fu, Yongguang Yin, Gang Li, Guoshuai Zhang, Shichang Kang, Kirpa Ram, Zhiyuan Cong
更新时间: 2018-06-19
摘要: Humic-like substances (HULIS) are major components of light-absorbing brown carbon that play an important role in Earth’s radiative balance. However, their concentration, optical properties, and sources are least understood over Tibetan Plateau (TP). In this study, the analysis of total suspended particulate (TSP) samples from central of TP (i.e., Nam Co) reveal that atmospheric HULIS are more abundant in summer than that in winter without obvious diurnal variations. The light absorption ability of HULIS in winter is 2–3 times higher than that in summer. In winter, HULIS are mainly derived from biomass burning emissions in South Asia by long-range transport. In contrast, the oxidation of anthropogenic and biogenic precursors from northeast part of India and southeast of TP are major sources of HULIS in summer.
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31969. 题目: Modeling soil organic carbon dynamics in temperate forests using Yasso07
文章编号: N18061901
期刊: Biogeosciences
作者: Zhun Mao, Delphine Derrien, Markus Didion, Jari Liski, Thomas Eglin, Manuel Nicolas, Mathieu Jonard, and Laurent Saint-André
更新时间: 2018-06-19
摘要: Facing global changes, modeling and predicting the dynamics of soil carbon stock of forest ecosystems is vital but challenging work. Yasso07 is considered as one of the most promising models for such a purpose. We aim at examining the prediction accuracy of Yasso07 on soil carbon dynamics over the whole French metropolitan territory at a decennial time scale. We used the dataset from 101 RENECOFOR sites network, which encompass most of the French temperate forests. The data include (i) measured yearly litter quantity from aboveground organs part from 1994 to 2008, and soil carbon stocks twice at an interval of ca. 15 years (early 1990s versus around 2010). Using Yasso07, we simulated the stock changes (tCha-1yr-1) per site and compared them with the measured ones. We carried out meta-analyses to reveal the variability in litter biochemistry between different tree organs for conifers and broadleaves. We also performed sensitivity analyses to explore Yasso07’s sensitivity to inputs, including litter carbon quality and initial carbon stocks. At the national level, the simulated annual carbon stock changes (ACC, +0.45±0.09tCha-1year-1, mean±standard error) stayed in the same order of magnitude with the observed ones (+0.34±0.06tCha-1year-1). The correlation between predicted and measured ACC remained weak (R <0.1). There was significant overestimation for broadleaves sites and underestimation for conifers sites. Sensitivity analyses showed that the final carbon stock was weakly affected by litter carbon quality, but a strongly affected by simulation length to investigate and initial soil carbon quality. We revealed both interest and challenges of applying Yasso07 for temperate forests, which reflected the whole state-of-the-art of soil carbon modelling due to lacking knowledge or data on soil and litter carbon quality and fine root litter quantity, rendering high uncertainties for model inputs.

31970. 题目: Temporal response of soil organic carbon after grassland‐related land‐use change
文章编号: N18061801
期刊: Global Change Biology
作者: Wei Li, Philippe Ciais, Bertrand Guenet, Shushi Peng, Jinfeng Chang, Vincent Chaplot, Sergey Khudyaev, Anna Peregon, Shilong Piao, Yilong Wang, Chao Yue
更新时间: 2018-06-18
摘要: The net flux of CO2 exchanged with the atmosphere following grassland‐related land‐use change (LUC) depends on the subsequent temporal dynamics of soil organic carbon (SOC). Yet, the magnitude and timing of these dynamics are still unclear. We compiled a global data set of 836 paired‐sites to quantify temporal SOC changes after grassland‐related LUC. In order to discriminate between SOC losses from the initial ecosystem and gains from the secondary one, the post‐LUC time series of SOC data was combined with satellite‐based net primary production observations as a proxy of carbon input to the soil. Globally, land conversion from either cropland or forest into grassland leads to SOC accumulation; the reverse shows net SOC loss. The SOC response curves vary between different regions. Conversion of cropland to managed grassland results in more SOC accumulation than natural grassland recovery from abandoned cropland. We did not consider the biophysical variables (e.g., climate conditions and soil properties) when fitting the SOC turnover rate into the observation data but analyzed the relationships between the fitted turnover rate and these variables. The SOC turnover rate is significantly correlated with temperature and precipitation (p < 0.05), but not with the clay fraction of soils (p > 0.05). Comparing our results with predictions from bookkeeping models, we found that bookkeeping models overestimate by 56% of the long‐term (100 years horizon) cumulative SOC emissions for grassland‐related LUC types in tropical and temperate regions since 2000. We also tested the spatial representativeness of our data set and calculated SOC response curves using the representative subset of sites in each region. Our study provides new insight into the impact grassland‐related LUC on the global carbon budget and sheds light on the potential of grassland conservation for climate mitigation.

31971. 题目: Degradation of methadone by the sunlight/FC process: Kinetics, radical species participation and influence of the water matrix
文章编号: N18061701
期刊: Chemosphere
作者: Ming-Chi Hsieh, Sri Chandana Panchangam, Webber Wei-Po Lai, Angela Yu-Chen Lin
更新时间: 2018-06-17
摘要: Free chlorine sunlight photolysis (sunlight/FC) markedly enhances the degradation rate of methadone, a synthetic opioid used medically, over that obtained using sunlight alone. The pseudo-first-order rate constants of methadone degradation under acidic conditions ([methadone] = 0.2 μM, [free chlorine] = 4 μM, and pH = 4) for sunlight/FC and sunlight photolysis are 7.0 ± 1.1 × 10-2 min-1 and 1.4 ± 0.2 × 10-2 min-1, respectively. The improved methadone degradation can be attributed to the production of HO and reactive chlorine species (RCS) during sunlight/FC photolysis. HO and RCS predominantly accounted for degradation during sunlight/FC photolysis under acidic and neutral conditions, while direct photolysis was the major contributor towards methadone degradation in alkaline conditions. The initial pH (pH 4–11) and free chlorine concentration (1–6 μM) significantly influenced the overall degradation efficiency of methadone. The presence of HCO3 -, Cl- and dissolved organic matters, which may competitively react with HO and RCS, retard the degradation of methadone in synthetic wastewater. Consequently, a 50% lower methadone degradation rate was observed when deionized (DI) water was replaced with tap water. These results emphasize the need to consider different water matrices when applying sunlight/FC photolysis for water treatment.
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31972. 题目: Removal of precursors of typical nitrogenous disinfection byproducts in ozonation integrated with biological activated carbon (O3/BAC)
文章编号: N18061610
期刊: Chemosphere
作者: Jian Zheng, Tao Lin, Wei Chen, Hui Tao, Yiwen Tan, Baiwen Ma
更新时间: 2018-06-16
摘要: The O3/BAC process has been widely used in drinking water treatment to improve the removal of dissolved organic matters (DOMs), including the precursors of nitrogenous disinfection byproducts (N-DBPs). In this study, the removal of N-DBP precursors by biological activated carbon (BAC) filters with different usage time of granular activated carbon (GAC) was investigated. Results showed that the BAC filter with 6 years of usage time of GAC (old BAC filter) had a poor performance in the removal of precursors of N-DBPs such as dichloroacetonitrile (DCAN; an average of only 4.7%), dichloroacetamide (DCAcAm), and trichloronitromethane (TCNM) when compared with the BAC filter with 1 year of usage time of GAC (new BAC filter). Particularly, the organic fraction >10 kDa and the percentage of autochthonous substances were increased in the effluent of the old BAC filter. The red shift of the fluorescence peaks was evident in the excitation–emission matrix spectrum of the effluent from the old BAC filter. The abiotic adsorption of precursors by the old BAC filter was less. In addition, less amino acids and polysaccharides were removed, but more amino sugars and proteins were produced because of microbial metabolism. The metabolism strength of the attached biofilm decreased with increased operation time of the BAC filter. The relative abundance of Sphingomonas significantly decreased in the biofilm of the old BAC filter. The diversity of microbial community in the old BAC filter was higher, but the equitability was lower than those of the new BAC filter. The less removal of N-DBP precursors by the old BAC filter was attributed to the changes in abiotic adsorption capacity and microbial metabolism properties, in which soluble microbial products played an important role.

31973. 题目: Ultraviolet photosensitized transformation mechanism of microcystin-LR by natural organic matter in raw water
文章编号: N18061609
期刊: Chemosphere
作者: Qiyuan Sun, Tianfang Zhang, Feifeng Wang, Changqing Liu, Chunshan Wu, Rong-rong Xie, Yuyi Zheng
更新时间: 2018-06-16
摘要: Microcystins (MCs), produced by cyanobacterial blooms in eutrophic water, are common toxic metabolites and a potential threat to human health. However, the mechanism of MC photodegradation by photosensitizers in raw water remains unclear. In photodegradation and quenching experiments, this study investigates the photosensitized degradation of microcystin-LR (MC-LR) by fulvic acid (FA, a kind of dissolved organic matter with natural photosensitizing properties) under ultraviolet (UV) light irradiation. The photodegradation mechanisms of FA are also explored. The photodegradation process of MC-LR by FA was consistent with second-order reaction kinetics. The degradation rate of MC-LR in FA decreased from 80% to 55% as the pH increased from 3 to 9, because the binding ability of FA to MC-LR reduces as the pH increases. Given that FA can both inhibit and promote MC-LR degradation depending on its concentration, the optimum initial FA concentration for degrading MC-LR was determined as 9.86 mgC·L-1. The excited triplet state of FA (3FA ) accounted for 50.12% of the MC-LR loss; the remaining loss (49.88%) was contributed by reactive oxygen species and direct photolysis. This implies that the main pathway of MC-LR degradation is reaction with 3FA . The MC-LR degradation rate is 36% higher under UV irradiation than that under simulated sunlight irradiation.

31974. 题目: Formation of regulated and unregulated disinfection byproducts during chlorination of algal organic matter extracted from freshwater and marine algae
文章编号: N18061608
期刊: Water Research
作者: Chao Liu, Mahmut S. Ersan, Michael J. Plewa, Gary Amy, Tanju Karanfil
更新时间: 2018-06-16
摘要: Seasonal algal blooms in freshwater and marine water can increase the input of algal organic matter (AOM) to the pool of dissolved organic matter. The impact of bromide (Br-) and iodide (I-) on the formation of regulated and unregulated disinfection byproducts (DBPs) was studied from chlorination of AOM solutions extracted from three species of cultured isolates of freshwater and marine algae (Microcystis aeruginosa (MA), Synechococcus (SYN), and Alexandrium tamarense (AT)). Comparable concentrations of DBPs were formed from three types of AOM. In the absence of Br-, trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetaldehydes (HALs) were the main groups of DBP formed, and haloacetonitriles (HANs) were formed at lower concentrations. In contrast, the formation of iodinated THMs was <8 nM (1.7 μg/L) since most of initial I was oxidized to iodate. Increasing initial Br concentrations increased the formation of THMs and HANs, while concentrations of total organic halogen and HAA remained stable. On the contrary, total HAL concentrations decreased due to the instability of bromated HALs. Decreasing the specific UV absorbance (SUVA) value of AOM favours bromine substitution since bromine more preferentially reacts with low reactivity organic matter than chlorine. Increasing the pH enhanced the formation of THMs but decreased the formation of HANs. Concentrations of HANs and HALs decreased at high pH (e.g., 9.0), high initial chlorine concentration and long reaction time due to the decomposition. Based on the cytotoxicity calculations, unregulated HANs and HALs were the main contributors for the total toxicity of DBPs measured, even though based on the weight regulated THMs and HAAs predominated.
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31975. 题目: Investigation on extracellular polymeric substances, sludge flocs morphology, bound water release and dewatering performance of sewage sludge under pretreatment with modified phosphogypsum
文章编号: N18061607
期刊: Water Research
作者: Quxiu Dai, Liping Ma, Nanqi Ren, Ping Ning, Zhiying Guo, Longgui Xie, Haijun Gao
更新时间: 2018-06-16
摘要: Modified phosphogypsum (MPG) was developed to improve dewaterability of sewage sludge, and dewatering performance, properties of treated sludge, composition and morphology distribution of EPS, dynamic analysis and multiple regression model on bound water release were investigated. The results showed that addition of MPG caused extracellular polymeric substances (EPS) disintegration through charge neutralization. Destruction of EPS promoted the formation of larger sludge flocs and the release of bound water into supernatant. Simultaneously, content of organics with molecular weight between 1000 and 7000 Da in soluble EPS (SB-EPS) increased with increasing of EPS dissolved into the liquid phase. Besides, about 8.8 kg kg 1DS of bound water was released after pretreatment with 40%DS MPG dosage. Additionally, a multiple linear regression model for bound water release was established, showing that lower loosely bond EPS (LB-EPS) content and specific resistance of filtration (SRF) may improve dehydration performance, and larger sludge flocs may be beneficial for sludge dewatering.
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31976. 题目: Surface properties of activated sludge-derived biochar determine the facilitating effects on Geobacter co-cultures
文章编号: N18061606
期刊: Water Research
作者: Peng Zhang, Shiling Zheng, Jia Liu, Bingchen Wang, Fanghua Liu, Yujie Feng
更新时间: 2018-06-16
摘要: Biochar has been reported to facilitate direct interspecies electron transfer (DIET) in co-cultures between Geobacter metallireducens and Geobacter sulfurreducens, a model defined co-culture system. In this study, the biochar derived from the activated sludge with different pyrolysis temperature was added to the co-cultures, the ethanol metabolism rates (Re) and succinate production rates (Rs) of co-culture with biochar-800 were 1.05- and 1.42-fold higher than that without addition. The results suggested that the conductivity of the biochar did not correlate with the facilitating effect of the biochar on the co-culture metabolism. Furthermore, the surface functional group and surface charge of biochar may also influence the facilitating effect on the interspecies electron transfer between the two Geobacter cells. Based on these results, it supported that the electron transfer depending on the charging and discharging process of the surface functional groups might play a major role in facilitating the direct electron transfer process by the biochar derived from activated sludge here. This study could shed light on the better understanding of the bacteria-biochar electron transfer system and the potential utilization of the biochar in the environmental wastewater treatments.
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31977. 题目: Diapycnal dissolved organic matter supply into the upper Peruvian oxycline
文章编号: N18061605
期刊: Biogeosciences
作者: Alexandra N. Loginova, S?ren Thomsen, Marcus Dengler, Jan Lüdke, and Anja Engel
更新时间: 2018-06-16
摘要: The Eastern Tropical South Pacific (ETSP) hosts the Peruvian upwelling system, which represents one of the most productive areas in the world ocean. High primary production followed by rapid heterotrophic utilization of organic matter supports the formation of one of the most intense oxygen minimum zones (OMZ) in the world ocean where dissolved oxygen (O2) concentrations reach well below 1 molkg 1. The high productivity leads to an accumulation of dissolved organic matter (DOM) in the surface layers that may serve as a substrate for heterotrophic respiration. However, the importance of DOM utilization for O2 respiration within the Peruvian OMZ remains unclear so far. Here, we evaluate the diapycnal fluxes of O2, dissolved organic carbon (DOC), dissolved organic nitrogen, dissolved hydrolysable amino acids (DHAA) and dissolved combined carbohydrates (DCCHO) and the composition of DOM in the ETSP off Peru to learn, whether labile DOM is reaching into the core of the OMZ and how important DOM utilization might be for O2 attenuation. The observed diapycnal 2 flux (50mmolO2m 2day 1 at max) was limited to the upper 80m of the water column, the flux attenuation of ~1 molL 1day 1, was comparable to previously published O2 consumption rates for the North and South Pacific OMZs. The diapycnal DOM flux (31mmolCm 2day 1 at max) was limited to ~30m water depth, suggesting that the labile DOM is already utilized within the upper part of the shallow oxycline off Peru. The analyses of DCCHO and DHAA composition support this finding, suggesting that DOM undergoes comprehensive remineralization already within the upper part of the oxycline, as the DOM within the core of the OMZ was found to be largely altered. Estimated by a simple equation for carbon combustion, aerobic respiration of DCCHO and DHAA, supplied by diapycnal mixing (0.46 molL 1day 1 at max), could account for up to 38% of the diapycnal O2 supply in the upper oxycline, which suggests that DOM utilization may play a significant role for shape of the upper Peruvian oxycline.

31978. 题目: Dimethyl phthalate elimination from micro-polluted source water by surface discharge plasma: Performance, active species roles and mechanisms
文章编号: N18061604
期刊: Journal of Hazardous Materials
作者: Tiecheng Wang, Guangzhou Qu, Xianqiang Yin, Qiuhong Sun, Dongli Liang, Xuetao Guo, Hanzhong Jia
更新时间: 2018-06-16
摘要: Plasticizer pollution brought huge risks to ecological environment and human health. Surface discharge plasma (SDP) was employed to eliminate plasticizer in natural water, with dimethyl phthalate (DMP) as a typical plasticizer. Experimental results showed that DMP degradation efficiency reached 82.8% within 60 min’s SDP treatment, and the elimination process fitted well the first-order kinetic model. Low initial DMP concentration, alkaline condition, and low natural organic matter content were all conducive for DMP degradation. The contributions of OH radical and O2 to DMP elimination were 91.9% and 78.1%, respectively. Total organic carbon (TOC), UV–vis spectroscopy, and atomic force microscopy analysis demonstrated that DMP molecular structure was destroyed after the SDP treatment, and some small molecular fractions were generated. Approximately 47.8% of TOC and 73.5% of COD were eliminated after 60 min’s SDP treatment. Phthalic acid monomethyl ester, phthalic acid, o-phthalic anhydride, acetic acid, formic acid, and oxalic acid were detected as the byproducts. Carbon balance analysis among these intermediates showed that total carbon content was approximately 4.64 × 10-2 mmol before treatment, and it was 4.578 × 10-2 mmol after treatment, suggesting that some C-containing intermediates still existed but not detected. DMP degradation pathways in the SDP system were proposed.

31979. 题目: Effect of surface modification on carbon nanotubes (CNTs) catalyzed nitrobenzene reduction by sulfide
文章编号: N18061603
期刊: Journal of Hazardous Materials
作者: Qi Liu, Han-Qing Zhao, Lei Li, Pan-Pan He, Yi-Xuan Wang, Hou-Yun Yang, Zhen-Hu Hu, Yang Mu
更新时间: 2018-06-16
摘要: Carbon nanotubes (CNTs) could be directly used as metal-free catalysts for the reduction of nitroaromatics by sulfide in water, but their catalytic ability need a further improvement. This study evaluated the feasibility of surface modification through thermal and radiation pretreatments to enhance catalytic activity of CNTs on nitrobenzene reduction by sulfide. The results show that thermal treatment could effectively improve the catalytic behaviors of CNTs for the reduction of nitrobenzene by sulfide, where the optimum annealing temperature was 400 °C. However, plasma radiation pretreatment didn’t result in an obvious improvement of the CNTs catalytic activity. Moreover, the possible reasons have been explored and discussed in the study. Additionally, the impacts of various operational parameters on nitrobenzene reduction catalyzed by the CNTs after an optimized surface modification were also evaluated. It was found that the rate of nitrobenzene removal by sulfide was positively correlated with CNTs doses in a range of 0.3–300 mg L-1; the optimum pH was around 8.0; higher temperature and sulfide concentration facilitated the reaction; and the presence of humic acid exhibited a negative effect on nitrobenzene reduction.
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31980. 题目: Evaluation of fouling in nanofiltration for desalination using a resistance-in-series model and optical coherence tomography
文章编号: N18061602
期刊: Science of The Total Environment
作者: Jongkwan Park, Sungyun Lee, Jeongyeop You, Sanghun Park, Yujin Ahn, Woonggyu Jung, Kyung Hwa Cho
更新时间: 2018-06-16
摘要: Resistance-in-series models have been applied to investigate fouling behavior. However, it is difficult to model the influence of morphology on fouling behavior because resistance is indirectly calculated from the water flux and transmembrane pressure. In this study, optical coherence tomography (OCT) was applied to evaluate the resistance of the fouling layer based on fouling morphology. Sodium alginate, humic acid, and bovine serum albumin (BSA) with high salts concentrations (conductivity: 23 mS/cm) were used as model foulants. At the same total fouling resistance, BSA showed the highest cake layer thickness (BSA (114.5 μm) > humic acid (53.5 μm) > sodium alginate (20.0 μm)). However, a different order was found for the cake layer resistance (BSA > sodium alginate > humic acid). This indicates that fouling thickness is not correlated with cake layer resistance. According to the Carman–Kozeny equation, fouling layer porosity decreased in the following order: humic acid (0.30) > BSA (0.21) > sodium alginate (0.20). In addition, we provided a specific value that was calculated using the ratio between the fouling thickness and cake layer resistance. The results show that alginic acid induced a stronger cake layer resistance, despite its thin fouling layer, whereas BSA showed a relatively low potential for inducing cake layer resistance. The results obtained in this study could be used for estimating and predicting fouling behavior.
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