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12401. 题目: Soil carbon and nitrogen accumulation following agricultural abandonment in a subtropical karst region
文章编号: N18091309
期刊: Applied Soil Ecology
作者: Peilei Hu, Shujuan Liu, Yingying Ye, Wei Zhang, Xunyang He, Yirong Su, Kelin Wang
更新时间: 2018-09-13
摘要: Vegetation restoration following agricultural abandonment is an effective method for soil organic carbon (SOC) sequestration. However, SOC dynamics during post-agriculture succession in different soil layers, and its regulation by soil nitrogen (N), are not well understood. We investigated SOC and soil N dynamics during post-agriculture succession at soil depths of 0–10, 10–20, 20–30, and 30–50 cm in a subtropical karst area in southwest China. The succession sequence included grassland (∼9 years), shrubland (∼25 years), secondary forest (∼52 years), and primary forest, with cropland as a reference. In the 0–50 cm soil profile, the SOC and soil N stocks will recover to the primary forest level in ∼74 years at a rate of 112.35 g C m−2 yr−1 and in ∼100 years at a rate of 12.07 g N m−2 yr−1, respectively. The accumulation rate of SOC and soil N was higher in the topsoil (0–20 cm) than in the subsoil (20–50 cm). The estimated time for SOC stock to recover to the primary forest level in topsoil and subsoil was similar (72 and 76 years, respectively), whereas that for soil N stock require more time in topsoil than in subsoil (106 and 89 years, respectively). The higher rate of relative N stock change than that of SOC suggests that progressive N limitation does not occur in the long term following agricultural abandonment. Our results highlight the importance of soil depth and soil N in determining SOC change for secondary succession. Furthermore, the results suggest that, compared to that of previous studies, which considered only surface soil in the karst regions of southwest China, the recovery period of C and N in soil profile may be longer than that assumed previously.

12402. 题目: Effect of aging in field soil on biochar's properties and its sorption capacity
文章编号: N18091308
期刊: Environmental Pollution
作者: Xinhao Ren, Hongwen Sun, Fei Wang, Peng Zhang, Hongkai Zhu
更新时间: 2018-09-13
摘要: Due to its high sorption capacity for different kinds of contaminants, biochar is advocated as a novel remediation strategy for contaminated soils. However, it is not clear how long this extraordinary sorption capacity will be maintained after the biochar is applied to the soil. In this study, a commercial biochar was applied to an agricultural soil, and the sorption of atrazine and phenanthrene on biochar amended soils with different aging periods ranging from 0 to 2 y was investigated. The application of fresh biochar in soil led to an obvious enhancement of the sorption coefficients (Kd) of atrazine and phenanthrene (by 3.13 and 2.93 times at Ce = 0.01 Sw, respectively) compared with the untreated soil. The surface area of biochar first increased and then decreased with aging time. Correspondingly, the sorption of atrazine and phenanthrene on the biochar amended soils first increased and then decreased markedly. Based on the changing trend of the Kd values with aging time, it could be predicted that the sorption capacity of biochar amended soils will decrease to the level of the untreated soil after 2.5 y.
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12403. 题目: Rice root exudates affect microbial methylmercury production in paddy soils
文章编号: N18091307
期刊: Environmental Pollution
作者: Jia-Yin Zhao, Zhi-Hong Ye, Huan Zhong
更新时间: 2018-09-13
摘要: Microbial methylmercury (MeHg) production in contaminated soil-rice systems and its accumulation in rice pose health risks to consumers, especially those in Asia. However, the mechanism responsible for microbial MeHg production in paddy soils is far from clear. While previous studies examined the effect of soil and microbial factors on soil MeHg levels, in this work we explored the impact of rice cultivation itself on microbial MeHg production, focusing on the root exudate organic matter as a potential source of electron donors for microbial methylators. Effects of the cultivation of two rice cultivars, Heigu246 (H-rice) and Neiwuyou8015 (N-rice), on MeHg production in soils were therefore investigated in pot and batch incubation experiments. Soil MeHg levels measured in H-rice treatment during the heading and harvest stages were 18–49% higher than in the control and 23–108% higher than in N-rice treatment. Consequently, MeHg levels in grain, straw, and root were 38%, 81%, and 40% higher in H-rice than those in N-rice, which was mainly attributed to cultivar-specific MeHg production in soils. Results of the batch experiments suggested that root exudate organic matter could be responsible for MeHg production in soils during rice cultivation, by increasing the abundances of potential microbial methylators. For instance, root exudate organic matter increased copy numbers of Hg methylation genes (hgcA) in soils 4.1-fold. Furthermore, the 211% higher concentration of acetate (a key electron donor for microbial methylators) in the root exudate of H-rice could account for the higher MeHg production under H-rice than N-rice cultivation. Our results suggest that root exudate organic matter, especially acetate, as its key component, contributes to the elevated soil MeHg concentrations during rice cultivation. The proposed mechanism provides new insights into the elevated risk of MeHg production in contaminated soil-rice systems, as well as cultivar-specific MeHg bioaccumulation.
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12404. 题目: Dynamic variations in dissolved organic matter and the precursors of disinfection by-products leached from biochars: Leaching experiments simulating intermittent rain events
文章编号: N18091306
期刊: Environmental Pollution
作者: Mi-Hee Lee, Yong Sik Ok, Jin Hur
更新时间: 2018-09-13
摘要: Biochar-leached dissolved organic matter may have a substantial impact on the water quality of receiving water surrounded by biochar-amended fields. In this study, we tracked variations in the spectroscopic characteristics and the disinfection by-products formation potentials of dissolved organic matter (DOM) leached during sequential extraction for three different biochars (BCs), which simulates DOM from BC-amended fields during intermittent rain events. The optical properties of DOM were more dependent on the BC types with different origins (sludge, corn, and rice) rather than on the extraction time. A large amount of DOM was released during the initial period of the extraction (1 day), which was equivalent to 52–60% of the total cumulative organic carbon during 17 days of extraction. The relative contribution of the initial extraction to the total cumulative amounts was greater for the formation potential of trihalomethanes (THMs) per BC (71–82%) compared to those of haloacetic acids (HAAs) or dissolved organic carbon (DOC), suggesting that the leaching behaviors of disinfection byproducts (DBP) precursors from BCs may be different from those of DOC (i.e., bulk DOM). Among the three BCs, corn BC-derived DOM exhibited the highest formation potentials of THMs and HAAs per BC for both the initial and the total cumulative extraction. The specific (or DOC-normalized) THMs formation potential was positively correlated with the ratios of terrestrial humic-like to fulvic-like components, implying condensed aromatic structures could operate as a surrogate for THMs formation of BC-derived DOM. This study provided insight into dynamic leaching behaviors of DOM from BCs and the formation potentials for THMs and HAAs in BC-amended fields under intermittent rainfall.
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12405. 题目: Distribution patterns of organic pollutants and microbial processes in marine sediments across a gradient of anthropogenic impact
文章编号: N18091305
期刊: Environmental Pollution
作者: A. Zoppini, N. Ademollo, L. Patrolecco, L. Langone, S. Lungarini, W. Dellisanti, S. Amalfitano
更新时间: 2018-09-13
摘要: Marine sediments are part of the hydrological cycle and the ultimate storage compartment of land-derived organic matter, including pollutants. Since relevant microbially-driven processes occurring at benthic level may affect the quality of the overall aquatic system, the necessity for incorporating information about microbial communities functioning for ecosystem modelling is arising. The aim of this field study was to explore the links occurring between sediment contamination patterns by three selected class of organic pollutants (Polycyclic Aromatic Hydrocarbons, PAHs, Nonylphenols, NPs, Bisphenol A, BPA) and major microbial properties (Prokaryotic Biomass, PB; total living biomass, C-ATP; Prokaryotic C Production rate, PCP; Community Respiration rate, CR) across a gradient of anthropogenic pollution. Sediments were sampled from 34 sites selected along 700 km of the western coastline of the Adriatic Sea. Organic contamination was moderate (PAHs <830 ng g−1; NPs <350 ng g−1; BPA <38 ng g−1) and decreased southward. The amount of PAHs-associated carbon (C-PAHs) increased significantly with sediment organic carbon (OC), along with microbial functional rates. The negative relation between PCP/CR ratio and OC indicated the shift toward oxidative processes in response to organic pollution and potential toxicity, estimated as Toxic Equivalents (TEQs). Our outcomes showed that sediment organic contamination and benthic microbial processes can be intimately linked, with potential repercussions on CO2 emission rates and C-cycling within the detritus-based trophic web.
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12406. 题目: Effect of sample holding time on bioaccessibility and sediment ecotoxicological assessments
文章编号: N18091304
期刊: Environmental Pollution
作者: Kara E. Huff Hartz, Federico L. Sinche, Samuel A. Nutile, Courtney Y. Fung, Patrick W. Moran, Peter C. Van Metre, Lisa H. Nowell, Marc Mills, Michael J. Lydy
更新时间: 2018-09-13
摘要: The ecotoxicological effects of hydrophobic organic compound (HOC) contamination in sediment are often assessed using laboratory exposures of cultured invertebrates to field-collected sediment. The use of a sediment holding time (storage at 4 °C) between field sampling and the beginning of the bioassay is common practice, yet the effect of holding time on the reliability of bioassay results is largely unknown, especially for current-use HOCs, such as pyrethroid insecticides. Single-point Tenax extraction can be used to estimate HOC concentrations in the rapidly desorbing phase of the organic carbon fraction of sediment (i.e., bioaccessible concentrations), which relate to sediment toxicity and bioaccumulation in invertebrates. In this study, repeated measurements of bioaccessible concentrations (via Tenax), were made as a function of sediment holding time using pyrethroid-contaminated field sediment, and Hyalella azteca 10-d survival and growth was measured concurrently for comparison. Similarly, bioaccessible concentrations and 14-d bioaccumulation were measured in Lumbriculus variegatus as a comparison using the legacy HOCs, polychlorinated biphenyls (PCBs). While the bioaccessible and bioaccumulated PCB concentrations did not change significantly through 244 d of holding time, the bioaccessible pyrethroid concentrations were more varied. Depending on when pyrethroid-contaminated sediments were sampled, the bioaccessible pyrethroid concentrations showed first-order loss with half-lives ranging from 3 to 45 d of holding, or slower, linear decreases in concentrations up to 14% decrease over 180 d. These findings suggest that at least for some contaminants in sediments, holding the sediments prior to bioassays can bias toxicity estimates.
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12407. 题目: Reactive nitrogen losses via denitrification assessed in saturated agricultural soils
文章编号: N18091303
期刊: Geoderma
作者: Giuseppe Castaldelli, Nicolò Colombani, Elisa Soana, Fabio Vincenzi, Elisa Anna Fano, Micol Mastrocicco
更新时间: 2018-09-13
摘要: The aim of the present study was to quantify nitrate (NO3) removal via denitrification in an intensively cropped lowland of the Po River delta (Northern Italy). These agricultural lands are characterized by fine textured soils, generally poor of labile organic matter and amended mainly with synthetic fertilizers. Laboratory core incubations in water saturation conditions were performed on two contrasting soil types distinguished by different soil textures (silty-loam and silty-clay) either amended with NO3 alone or a combination of NO3 and acetate. Denitrification was evaluated by concomitant measurements of NO3 consumption and N2 production via N2:Ar analyses by Membrane Inlet Mass Spectrometry (MIMS).The water-logged soils showed higher capacity to reduce NO3 to N2 when supplied with acetate as an organic substrate, while, without acetate amendment, NO3 removal was limited due to lack of labile organic substrates. Transient nitrite (NO2) accumulation was documented in acetate amended mesocosms, due to concurrent presence of elevated pH values and use of highly oxidized substrates (like acetate).This study suggests that agricultural practices aimed to increase the availability of labile organic matter, such as acetate, are beneficial in buffering reactive N excess in soils and to reduce NO3 leaching towards groundwater and surface-water.

12408. 题目: Synergistic effect of ferrate (VI)-ozone integrated pretreatment on the improvement of water quality and fouling alleviation of ceramic UF membrane in reclaimed water treatment
文章编号: N18091302
期刊: Journal of Membrane Science
作者: Jing Liu, Zhenghua Zhang, Qianhua Chen, Xihui Zhang
更新时间: 2018-09-13
摘要: A novel ferrate (VI)-ozone integrated pretreatment process was proposed and applied herein for the first time in reclaimed water treatment. We demonstrated the synergistic effect of the ferrate (VI)-ozone integrated process in terms of •OH generation and its double-win effects on the improvement of water quality and fouling alleviation of ceramic ultrafiltration (UF) membrane. The concentration of •OH in the ferrate (VI) (0.15 mM)-ozone (10 mg/L) integrated case was almost 3-fold higher compared to the ferrate (VI) (0.15 mM) case, while no obvious •OH was detected in the pre-ozonation case (10 mg/L) in Milli-Q water. The reclaimed water quality was remarkably enhanced with the maximum removal efficiencies of 70.5% (DOC), 80.5% (UV254), 25.6% (protein) and 65.5% (polysaccharide) in influent achieved by the integrated pretreatment of ozone (10 mg/L) and ferrate (0.15 mM). Biopolymers (molecular weight (MW) of 20–2000 kDa) were the main removed organics with the best removal efficiency of 92.6%. Additionally, membrane fouling was effectively mitigated and the normalized trans-membrane pressure (TMP) was maximally decreased by 89.5% obtained after the integrated pretreatment of ozone (10 mg/L) and ferrate (0.15 mM). The statistical analysis results demonstrated that the increased particle size and the effective reduction of organic matters with ferrate-ozone integrated pretreatment led to a porous fouling layer with high permeability and thus a remarkable reduction of TMP and resistances, which was also in agreement with the modeling results that cake blocking was significantly alleviated.
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12409. 题目: Utilization of the saccharification residue of rice straw in the preparation of biochar is a novel strategy for reducing CO2 emissions
文章编号: N18091301
期刊: Science of The Total Environment
作者: Jiajun Hu, Hongcheng Guo, Xiahui Wang, Min-tian Gao, Guodong Yao, Yiu Fai Tsang, Jixiang Li, Jianfang Yan, Saiwei Zhang
更新时间: 2018-09-13
摘要: Once rice straw has been bioconverted into biofuels, it is difficult to further biodegrade or decompose the saccharification residue (mainly lignin). Taking into account the pyrolysis characteristics of lignin, in this study the saccharification residue was used as a raw material for the preparation of biochar (biochar-SR), a potential soil amendment. Biochar was prepared directly from rice straw (biochar-O) with a yield of 32.45 g/100 g rice straw, whereas 30.14 g biochar-SR and 30.46 g monosaccharides (including 20.46 g glucose, 9.11 g xylose, and 0.89 g arabinose) were obtained from 100 g of rice straw. When added to liquid soil extracts as a soil amendment, almost nothing was released from biochar-SR, whereas numerous dissolved solids (about 70 mg/L) were released from biochar-O. Adding a mixture of biochar-SR and autotrophic bacteria improved soil total organic carbon 1.8-fold and increased the transcription levels of cbbL and cbbM, which were 4.76 × 103 and 3.76 × 105 times those of the initial blank, respectively. By analyzing the soil microbial community, it was clear that the above mixture favored the growth of CO2-fixing bacteria such as Ochrobactrum. Compared with burning rice straw or preparing biochar-O, the preparation of biochar-SR reduced CO2 emissions by 67.53% or 37.13%, respectively. These results demonstrate that biochar-SR has potential applications in reducing the cost of sustainable energy and addressing environmental issues.
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12410. 题目: Response of phosphorus fractions to land-use change followed by long-term fertilization in a sub-alpine humid soil of Qinghai–Tibet plateau
文章编号: N18091209
期刊: Journal of Soils and Sediments
作者: Xiaolei Sun, Meng Li, Guoxi Wang, Marios Drosos, Fulai Liu, Zhengyi Hu
更新时间: 2018-09-12
摘要: Purpose: Identification of phosphorus (P) species is essential to understand the transformation and availability of P in soil. However, P species as affected by land use change along with fertilization has received little attention in a sub-alpine humid soil of Tibet plateau. Materials and methods: In this study, we investigated the changes in P species using Hedley sequential fractionation and liquid-state 31P-NMR spectroscopy in soils under meadow (M) and under cropland with (CF) or without (CNF) long-term fertilization for 26 years in a sub-alpine cold-humid region in Qinghai–Tibet plateau. Results and discussion: Land-use change and long-term fertilization affected the status and fractions of P. A strong mineralization of organic P (OP) was induced by losing protection of soil organic matter (SOM) and Fe and Al oxides during land-use change and resulted in an increase of orthophosphate (from 56.49 mg kg−1 in M soils to 130.07 mg kg−1 in CNF soils) and great decreases of orthophosphate diesters (diester-P, from 23.35 mg kg−1 in M soils to 10.68 mg kg−1 in CNF soils) and monoesters (from 336.04 mg kg−1 in M soils to 73.26 mg kg−1 in CNF soils). Long-term fertilization boosted P supply but failed to reclaim soil diester-P (from 10.68 mg kg−1 in CNF soils to 7.79 mg kg−1 in CF soils). This may be due to the fragile protection from the combination of SOM with diester-P when long-term fertilization had only improved SOM in a slight extent. Conclusions: These results suggest that SOM plays an important role in the soil P cycling and prevents OP mineralization and losses from soil. It is recommended that optimization of soil nutrient management integrated with SOM was required to improve the P use efficiency for the development of sustainable agriculture.

12411. 题目: Different pathways of nitrogen and phosphorus regeneration mediated by extracellular enzymes in temperate lakes under various trophic state
文章编号: N18091208
期刊: Environmental Science and Pollution Research
作者: Chunlei Song, Xiuyun Cao, Yiyong Zhou, Maurizio Azzaro, Luis Salvador Monticelli, Marcella Leonardi, Rosabruna La Ferla, Gabriella Caruso
更新时间: 2018-09-12
摘要: Several Italian and Chinese temperate lakes with soluble reactive phosphorus concentrations < 0.015 mg L−1 were studied to estimate nitrogen and phosphorus regeneration mediated by microbial decomposition and possible different mechanisms driven by prevailing oligo- or eutrophic conditions. Leucine aminopeptidase (LAP), beta-glucosidase (GLU) and alkaline phosphatase (AP), algal, and bacterial biomass were related to trophic and environmental variables. In the eutrophic lakes, high algal and particulate organic carbon concentrations stimulated bacterial respiration (> 20 μg C L−1 h−1) and could favor the release of inorganic phosphorus. High extracellular enzyme activities and phosphorus solubilizing bacteria abundance in sediments accelerated nutrient regeneration. In these conditions, the positive GLU-AP relationship suggested the coupling of carbon and phosphorus regeneration; an efficient phosphorus regeneration and high nitrogen levels (up to 0.067 and 0.059 mg L−1 NH4 and NO3 in Italy; 0.631 and 1.496 mg L−1 NH4 and NO3 in China) led to chlorophyll a peaks of 14.9 and 258.4 μg L−1 in Italy and China, respectively, and a typical algal composition. Conversely, in the oligo-mesotrophic lakes, very low nitrogen levels (in Italy, 0.001 and 0.005 mg L−1 NH4 and NO3, respectively, versus 0.053 and 0.371 mg L−1 in China) induced high LAP, while low phosphorus (33.6 and 46.3 μg L−1 total P in Italy and China, respectively) led to high AP. In these lakes, nitrogen and phosphorus regeneration were coupled, as shown by positive LAP-AP relationship; however, the nutrient demand could not be completely met without the supply from sediments, due to low enzymatic activity and phosphorus solubilizing bacteria found in this compartment.

12412. 题目: β–Cyclodextrin Functionalized Biochars as Novel Sorbents for High-performance of Pb2+ Removal
文章编号: N18091207
期刊: Journal of Hazardous Materials
作者: Hai-tao Zhao, Shuai Ma, Sheng-yang Zheng, Shu-wen Han, Fen-xia Yao, Xiao-zhi Wang, Sheng-sen Wang, Ke Feng
更新时间: 2018-09-12
摘要: The aim of this study was to synthesize the functionalized biochars with β–cyclodextrin (β–CD), compare the two kinds of adsorption capability, and try to explore the possible mechanism for the adsorption Pb2+ by β–CD functionalized rice straw and palm biochars in the aquatic environment. The performance of the functionalized biochars was matched against the activated and raw biochars. Rice straw biochar loaded with β–CD performed better than functionalized palm biochar with the adsorption capabilities of 130.60 mg/g and 90.30 mg/g at Pb2+ concentration of 3000 mg/L and 2000 mg/L, respectively. Maximum adsorption capability of functionalized rice straw and palm biochars from the Langmuir isotherms were all fitted out to be 131.24 mg/g and 118.08 mg/g for Pb2+. Kinetics and thermodynamics are combined to investigate the Pb2+ removal by the two functionalized biochars, e.g, Pb2+ is mainly removed by chemical process for functionalized palm biochar, whereas by both physical and chemical factors for functionalized rice straw biochar.

12413. 题目: Protein: Polysaccharide ratio in exopolymeric substances controlling the surface tension of seawater in the presence or absence of surrogate Macondo oil with and without Corexit
文章编号: N18091206
期刊: Marine Chemistry
作者: Kathleen A. Schwehr, Chen Xu, Meng-Hsuen Chiu, Saijin Zhang, Luni Sun, Peng Lin, Morgan Beaver, Cameron Jackson, Oscar Agueda, Charles Bergen, Wei-Chun Chin, Antonietta Quigg, Peter H. Santschi
更新时间: 2018-09-12
摘要: Amphiphilic substances can interact with oil in the water to form emulsions and aggregates; dispersants are designed to form emulsions to prevent oil droplets from coalescing and stabilize them in a suspension. Amphiphilic extracellular polymeric substances (EPS) concentrated at the air-water interface where surface tension was measured to determine their propensity for formation of emulsions and/or aggregates. Here we investigated mechanisms governing the self-assembly and phase separation for protein-polysaccharide-oil-dispersant interactions through measurements of surface tension, chemical composition, and confocal microscopy. EPS colloid fractions from treatments of WAF (water accommodated fraction of oil), CEWAF (chemically enhanced WAF using the dispersant Corexit), and a control mesocosm were examined. In analyzing the size fractions of water column samples, it was found that treatments with oil and/or Corexit showed EPS with enhanced protein:polysaccharide carbon-based ratios and lower surface tension (SFT), suggesting the effective bioemulsifying effects of proteins. In addition, EPS model constituents of protein slightly increased SFT at low concentrations of less than a few mg/L, but decreased it at higher concentrations of 8 mg/L or more. These model molecules appear to be more efficient than Corexit in inducing the self-assembly of micelles in the seawater even when only very low concentrations of these constituents are present. Our results suggest that EPS are more efficient than Corexit at forming micelles. Results from this study provides mechanistic insights into the fate and distribution of oil in the surface ocean.

12414. 题目: Synergistic strengthening mechanism of hydraulic selection pressure and poly aluminum chloride (PAC) regulation on the aerobic sludge granulation
文章编号: N18091205
期刊: Science of The Total Environment
作者: Zhe Liu, Ning Li, Min Gao, Jiaxuan Wang, Aining Zhang, Yongjun Liu
更新时间: 2018-09-12
摘要: This study aimed to enhance aerobic granulation by the integration of hydraulic selection pressure (HSP) and poly aluminum chloride (PAC) regulation. Based on an investigation of sludge characteristics, microbial aggregation and extracellular polymeric substances (EPS) secretion, the synergistic mechanisms of HSP and PAC regulation were revealed. For granule formation, HSP primarily improved the cell hydrophobicity and extracellular protein production, while PAC regulation markedly neutralized the surface charge of cells and reduced the interaction energy between them. In addition, biomass retention was also facilitated by the PAC dosing. Notably, the results of total interaction energy and flocculating ability imply that prior HSP screening could significantly promote PAC regulation on microbial aggregation. To optimize the balance between granule formation and reactor performances, five kinds of integrated strategies for HSP and PAC regulation were conducted in batch test. According to the results, 4.3 g/L initial mixed liquor volatile suspended solids (MLVSS) was preferred before the addition of PAC.
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12415. 题目: Enhancement of anaerobic digestion sludge dewatering performance using in-situ crystallization in combination with cationic organic polymers flocculation
文章编号: N18091204
期刊: Water Research
作者: Qiandi Wang, Weijun Zhang, Zhaoyi Yang, Qiongying Xu, Peng Yang, Dongsheng Wang
更新时间: 2018-09-12
摘要: Anaerobic digestion (AD) has been widely used in sludge treatment for biogas recovery, organic fraction stabilization, and sludge reduction. However, after AD, sludge filterability is extremely deteriorated due to the release of biopolymers and the formation of fine particles. AD sludge is generally rich in nutrients, mainly ammonium nitrogen and phosphates, that result from biopolymer degradation. We designed a conditioning process that combines the in-situ crystallization of magnesium ammonium phosphate (MAP), as a skeleton builder, with organic polymer flocculation. We show that crystallized MAP can bind with extracellular polymeric substance fractions to increase sludge floc density. The molecular structure and electrical charge of organic polymers importantly influence sludge particle flocculation and aggregation. We found that cationic polyacrylamides form flocs that aggregate with branching structures which are characterized by a larger size and a more compact structure. Simultaneous crystallization and flocculation produced by a magnesium–organic polymer gel improved AD dewaterability more than the separate addition of magnesium ions and organic polymers. The method of sludge conditioning that we propose was tested by extensive use in different AD sludge conditioning protocols. The method reduces the ammonium nitrogen load in AD liquor and increases the suitability of the biosolids for use as land fertilizer.
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12416. 题目: The role of influent organic carbon-to-nitrogen (COD/N) ratio in removal rates and shaping microbial ecology in soil aquifer treatment (SAT)
文章编号: N18091203
期刊: Water Research
作者: Liron Friedman, Hadas Mamane, Dror Avisar, Kartik Chandran
更新时间: 2018-09-12
摘要: Soil columns simulating soil aquifer treatment (SAT), fed with synthetic secondary effluent by intermittent infiltration of flooding/drying cycles, were characterized for nitrogen and organic carbon removal, and microbial ecology and biokinetics. The columns differed in the ratio of chemical oxygen demand (COD) to the summed NH4+, NO2 and organic nitrogen—2 (C/N2) or 5 (C/N5). Chemical profiles along the column demonstrated a preference for COD oxidation over nitrification and coupled denitrification, with higher nitrogen loss (57% vs. 16%) in the C/N5 column. Unexpectedly, significant dominance of the genus Nitrospira over the genus Nitrobacter and ammonia-oxidizing bacteria (AOB) was strongly correlated at column depths where NH4+ removal occurred. Moreover, the Nitrospira profile had the strongest correlation to the profile of NH4+ (positive) and NO3 (negative), strongly indicating complete ammonia oxidation. 16S sequencing analysis of the topsoil in C/N2 vs. C/N5 columns revealed double the abundance of microbial aerobic potential (64% vs. 32%) vs. one-third the denitrification potential (13% vs. 31%). The concentrations and degradability levels of organic carbon were the most influential parameters shaping community structure. Niche differentiation within the biofilm attached to the soil is suggested to have an important role in the process's anoxic activity and nitrogen removal.
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12417. 题目: Formation of odorous and hazardous by-products from the chlorination of amino acids
文章编号: N18091202
期刊: Water Research
作者: Zuo Tong How, Kathryn L. Linge, Francesco Busetti, Cynthia A. Joll
更新时间: 2018-09-12
摘要: The formation of odorous aldehydes and N-chloraldimines, and also nitriles, which are potentially hazardous to human health, was investigated in studies of the chlorination of amino acids (AAs) in both operational drinking water treatment plants and laboratory-based experiments. In the drinking water treatment plants studied, the concentration of total free AAs did not significantly change after treatment, even though good removal of DOC was observed. However, free AAs still contributed less than 3% of total nitrogen in the treated drinking waters, and no aldehydes, N-chloraldimines or nitriles of interest were detected in the treated waters, presumably due to the low concentrations of the precursor AAs in these water samples. Laboratory formation potential experiments showed that carboxylic acids can form from the degradation of aldehydes and nitriles. Volatile carboxylic acids could result in odour issues and some carboxylic acids may be of potential health concern. Therefore, carboxylic acids should also be considered as potential by-products of interest in distribution systems with long contact times of ≥ 7days. A higher proportion of nitrile formation, and promotion of carboxylic acid formation, was observed when the chlorine to AA ratio was greater than 4 compared to when this ratio was 2.8, indicating that the Cl:AA ratio is an important factor in DBP formation pathways. This suggests that results from laboratory formation studies undertaken at these low Cl:AA ratios cannot be directly applied to ‘real’ water systems, which typically have Cl:AA ratios that are orders of magnitude higher than 4. Laboratory formation potential experiments also showed that the short-term rate of formation of aldehydes and N-chloraldimines was reduced in the presence of ammonia, although formation over longer timescales (e.g. 7 days) was not significantly different between chlorination and chloramination experiments. Therefore, the use of chloramination instead of chlorination does not appear to reduce the formation of these by-products from AAs.
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12418. 题目: Ceramic membrane fouling by dissolved organic matter generated during on-line chemical cleaning with ozone in MBR
文章编号: N18091201
期刊: Water Research
作者: Huifang Sun, Hang Liu, Siyu Wang, Fangqin Cheng, Yu Liu
更新时间: 2018-09-12
摘要: Ceramic membrane bioreactor (MBR) has attracted increasing interest due to its high flux, long membrane life-span and excellent resistance to hash operation conditions. Although ozone has been used for chemical cleaning of ceramic membranes, it is still unclear about the role of dissolved organic matter (DOM) generated during on-line chemical cleaning with ozone in the development of membrane fouling in ceramic MBR. This study clearly revealed that the released DOM could considerably induce irreversible membrane fouling, and humic acid like-substances (HAL) with molecular weight (MW) of about 500 Da were mainly responsible for the observed membrane fouling. A strong positive relationship existed between the membrane fouling rate of supernatant and the rejection level of HAL evidenced by a high correlation coefficient (R2) of 0.99. Meanwhile, the results also showed that biopolymers with MW greater than 10 kDa were easily rejected by the ceramic membranes used, leading to the development of membrane fouling. However, the high ozone concentration helped to reduce the generation of biopolymers. The organic fractions with MW less than 500 Da in the DOM (e.g. building blocks, low-MW acid and low-MW neutrals) could pass through the ceramic membranes used, i.e. their contributions to the observed membrane fouling could be considered insignificant. Consequently, it appeared from this study that membrane fouling associated with the DOM generated by ozone during on-line chemical cleaning should not be ignored in the design and operation of ceramic MBR towards long-term process sustainability.
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12419. 题目: Roles of hydrophobic and hydrophilic fractions of dissolved organic matter in sorption of ketoprofen to biochars
文章编号: N18091117
期刊: Environmental Science and Pollution Research
作者: Lin Wu, Ningwei Yang, Binghua Li, Erping Bi
更新时间: 2018-09-11
摘要: Hydrophobic acid (HoA) and hydrophilic neutral (HiN) are two major fractions of dissolved organic matter (DOM). Their role in the sorption of ketoprofen (KTP) to wheat straw-derived biochars pyrolyzed at 300 °C (WS300) and 700 °C (WS700) was investigated to further probe the mechanisms responsible. WS700 has much higher pore volume and specific surface area (SSA) than WS300. Loading of HoA and HiN resulted in surface coverage of biochars. HoA with larger molecular size led to more pore blockage of biochars than HiN. Higher HoA binding affinity also caused a stronger competition with KTP on biochars. These factors reduced the accessibility of sorption sites for KTP, and significantly inhibited KTP sorption to biochar of lower SSA (i.e., WS300) by HoA. Water solubility (Sw) of KTP was slightly enhanced (3%) in the presence of HoA. In contrast, the presence of HiN reduced (22%) Sw of KTP. The decreased Sw of KTP by HiN exerted a more dominant influence than its competitive and loading effects, thus led to apparent enhanced sorption of KTP, especially to biochar of higher SSA (i.e., WS700). The results demonstrated the diverse effects of HoA and HiN on KTP sorption, which is helpful in understanding pharmaceutical-DOM-biochar interactions and environmental behaviors of pharmaceuticals.

12420. 题目: Performance, microbial community and fluorescent characteristic of microbial products in a solid-phase denitrification biofilm reactor for WWTP effluent treatment
文章编号: N18091116
期刊: Journal of Environmental Management
作者: Fei Han, Dong Wei, Huu Hao Ngo, Wenshan Guo, Weiying Xu, Bin Du, Qin Wei
更新时间: 2018-09-11
摘要: Microbial products, i.e. extracellular polymeric substance (EPS) and soluble microbial product (SMP), have a significant correlation with microbial activity of biologically based systems. In present study, the spectral characteristics of two kinds of microbial products were comprehensively evaluated in a solid-phase denitrification biofilm reactor for WWTP effluent treatment by using poly (butylene succinate) (PBS) as carbon source. After the achievement of PBS-biofilm, nitrate and total nitrogen removal efficiencies were high of 97.39 ± 1.24% and 96.38 ± 1.1%, respectively. The contents of protein and polysaccharide were changed different degrees in both LB-EPS and TB-EPS. Excitation-emission matrix (EEM) implied that protein-like substances played a significant role in the formation of PBS-biofilm. High-throughput sequencing result implied that the proportion of denitrifying bacteria, including Simplicispira, Dechloromonas, Diaphorobacter, Desulfovibrio, increased to 9.2%, 7.4%, 4.8% and 3.6% in PBS-biofilm system, respectively. According to EEM-PARAFAC, two components were identified from SMP samples, including protein-like substances for component 1 and humic-like and fulvic acid-like substances for component 2, respectively. Moreover, the fluorescent scores of two components expressed significant different trends to reaction time. Gas chromatography-mass spectrometer (GC-MS) implied that some new organic matters were produced in the effluent of SP-DBR due to biopolymer degradation and denitrification processes. The results could provide a new insight about the formation and stability of solid-phase denitrification PBS-biofilm via the point of microbial products.
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