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Effects of previous drying of sediment on root functional traits and rhizoperformance of emerged macrophytes

《环境科学与工程前沿(英文)》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1427-1

摘要:

• Sediment desiccation alters morphological characteristics of aquatic sediment.

关键词: Fibrous-root macrophytes     Thick-root macrophytes     Nutrients removal     Wet sediment     Dried-rewetted sediment    

Phenolic compounds removal by wet air oxidation based processes

Linbi Zhou, Hongbin Cao, Claude Descorme, Yongbing Xie

《环境科学与工程前沿(英文)》 2018年 第12卷 第1期 doi: 10.1007/s11783-017-0970-2

摘要: Wet air oxidation (WAO) and catalytic wet air oxidation (CWAO) are efficient processes to degrade organic pollutants in water. In this paper, we especially reviewed the WAO and CWAO processes for phenolic compounds degradation. It provides a comprehensive introduction to the CWAO processes that could be beneficial to the scientists entering this field of research. The influence of different reaction parameters, such as temperature, oxygen pressure, pH, stirring speed are analyzed in detail; Homogenous catalysts and heterogeneous catalysts including carbon materials, transitional metal oxides and noble metals are extensively discussed, among which Cu based catalysts and Ru catalysts were shown to be the most active. Three different kinds of the reactor implemented for the CWAO (autoclave, packed bed and membrane reactors) are illustrated and compared. To enhance the degradation efficiency and reduce the cost of the CWAO process, biological degradation can be combined to develop an integrated technology.

关键词: Wet air oxidation     Catalytic wet air oxidation     Phenolic compounds     Heterogeneous catalysts     Mechanism    

Characterization of value-added chemicals derived from the thermal hydrolysis and wet oxidation of sewage

Milan Malhotra, Anurag Garg

《环境科学与工程前沿(英文)》 2021年 第15卷 第1期 doi: 10.1007/s11783-020-1305-2

摘要: Abstract • Hydrothermal treatment can greatly improve resource recovery from sewage sludge. • tCOD removal during WO was ~55% compared with ~23% after TH. • TOC solubilization during hydrothermal treatment followed first-order kinetics. • Solids and carbon balance confirmed loss of organics during thermal hydrolysis. • Reaction pathways for thermal hydrolysis and wet oxidation are proposed. We evaluated the effect of hydrothermal pretreatments, i.e., thermal hydrolysis (TH) and wet oxidation (WO) on sewage sludge to promote resource recovery. The hydrothermal processes were performed under mild temperature conditions (140°C–180°C) in a high pressure reactor. The reaction in acidic environment (pH= 3.3) suppressed the formation of the color imparting undesirable Maillard’s compounds. The oxidative conditions resulted in higher volatile suspended solids (VSS) reduction (~90%) and chemical oxygen demand (COD) removal (~55%) whereas TH caused VSS and COD removals of ~65% and ~27%, respectively at a temperature of 180°C. During TH, the concentrations of carbohydrates and proteins in treated sludge were 400–1000 mg/L and 1500–2500 mg/L, respectively. Whereas, WO resulted in solids solubilization followed by oxidative degradation of organics into smaller molecular weight carboxylic acids such as acetic acid (~400–500 mg/L). Based on sludge transformation products generated during the hydrothermal pretreatments, simplified reaction pathways are predicted. Finally, the application of macromolecules (such as proteins), VFAs and nutrients present in the treated sludge are also discussed. The future study should focus on the development of economic recovery methods for various value-added compounds.

关键词: Hydrothermal pretreatment     Reaction kinetics     Reaction pathway     Sewage sludge     Thermal hydrolysis     Wet oxidation    

Survey of thermal comfort in residential buildings under natural conditions in hot humid and cold wet

Changhai PENG

《结构与土木工程前沿(英文)》 2010年 第4卷 第4期   页码 503-511 doi: 10.1007/s11709-010-0095-1

摘要: Comfort standards (ISO 7730, ASHRAE 55) specify the exact physical criteria for producing acceptable thermal environments, such as temperature, air movement, and humidity limits. These, however, are often difficult to comply with, particularly in hot humid and cold wet seasons in Nanjing, China. Changing expectations of comfort is important in evaluating comfort, since naturally conditioned buildings in Nanjing are not typically air-conditioned. For this objective, a field study was conducted during the summer of 2000 and the winter of 2001. A total of 600 participants each answered a subjective questionnaire. Analyzing these field data shows that in natural conditions, the influence of gender and age on people’s thermal sensations is insignificant compared with six main variables. In addition, people’s thermal discomfort rapidly increases along with growth in relative humidity. Further, the variation of people’s hot or cold sensations is in proportion to that of air movement, and the effect in winter is greater than that in summer. The range of acceptable temperatures in hot humid and cold wet Nanjing is between 14.14°C and 29.42°C.

关键词: thermal comfort     naturally conditioned     hot humid     cold wet     Nanjing    

of carboxymethyl cellulose on morphology of hydroxyapatite nanoparticles as prepared with one-step wet

Ruiqiang LIU,Rattan LAL

《环境科学与工程前沿(英文)》 2015年 第9卷 第5期   页码 804-812 doi: 10.1007/s11783-015-0785-y

摘要: Nano-sized apatite particles (nAP) synthesized with carboxymethyl cellulose (CMC) have shown great application potentials in in situ heavy metal remediation. However, differences in CMC’s properties effects on the size of nAP produced are not well understood. In this paper, two types of CMC, with respective molecular weights (MW) of ~120000 and ~240000 Dalton or respective polymerization degrees of 500 (CMC-500) and 1050 (CMC-1050), were studied in a concentration range of 0.05%–0.5% (w/w) for nAP synthesis. Morphology of the particles was characterized with transmission electron microscopy (TEM). Results showed that 0.05% CMC-500 solution gave an average particle size of 148.7±134.9 nm, 0.25% CMC-500 solution produced particles of 21.8±20.4 nm, and, 0.5% CMC-500 solution contained particles of 15.8±7.7 nm. In comparison, 0.05% CMC-1050 solution produced nanoparticles of 6.8±3.2 nm, 0.25% CMC-1050 produced smaller nAP of 4.3±3.2 nm, and 0.5% CMC-1050 synthesized the smallest nanoparticles in this study, with an average diameter of 3.0±2.1 nm. Chemical composition of the products was identified with X-ray diffraction (XRD) as pure hydroxyapatite. Interactions between nAP and CMC were discussed with help of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopic data. This study showed that CMC at higher concentration as well as higher MW facilitated to produce finer nanoparticles, showing that nAP size could be manipulated by selecting appropriate CMC MW and/or applying appropriate CMC concentration.

关键词: nanotechnology     nanoparticles     apatite     carboxymethyl cellulose (CMC)     particle size    

Performance evaluation on the pollution control against wet weather overflow based on on-site coagulation

Zongqun Chen, Wei Jin, Hailong Yin, Mengqi Han, Zuxin Xu

《环境科学与工程前沿(英文)》 2021年 第15卷 第6期 doi: 10.1007/s11783-021-1400-z

摘要: Abstract • A way for overflow control based on on-site coagulation/flocculation was proposed. • Coagulant and flocculant dose were optimized based on pollutant removal performance. • Settling time of 5 min is enough in a proper transmission distance. • Fast removal of particulate pollutants could be achieved under varied flow. The pollution caused by wet weather overflow in urban drainage systems is a main factor causing blackening an odorization of urban rivers. The conventional overflow treatment based on coagulation/flocculation in terminal drainage systems requires relatively large space and long retention time demand that makes it not applicable in crowded urban drainage systems or under heavy rains. On-site coagulation/flocculation in terminal drainage pipes was proposed in this study which was aimed to transfer the coagulation/flocculation process to the inside of pipes at the terminal drainage system to save space and reduce the retention time of the coagulation/flocculation process. The optimized dose of chemicals was studied first which was 80 mg/L of coagulant and 0.8 mg/L of flocculant. Settling for only 5 min can remove most of the pollutants at 406.5 m of transmission distance. In addition, the relation of wet weather overflow rate and concentration of pollution load on the on-site coagulation/flocculation process was investigated, which indicated that high removal of pollutant was gained at a large range of flow velocity and pollutant concentration. Finally, the study confirmed electric neutralization, bridging, and net capture as the major mechanisms in this process, and further optimization was proposed. The proposed process can reduce much turbidity, chemical oxygen demand, and total phosphorous, but hardly remove soluble ammonia and organics. This work provides scientific guidance to address wet weather overflow in terminal drainage pipes.

关键词: Wet weather overflow     On-site coagulation/flocculation     Fast removal of particulate pollutants    

Removing ammonia from air with a constant pH, slightly acidic water spray wet scrubber using recycled

Ahmad Kalbasi Ashtari, Amir M. Samani Majd, Gerald L. Riskowski, Saqib Mukhtar, Lingying Zhao

《环境科学与工程前沿(英文)》 2016年 第10卷 第6期 doi: 10.1007/s11783-016-0869-3

摘要: Slightly acidic solutions are a practical means of removing ammonia from air Scrubbed NH accumulates in solution as NH and should be an excellent fertilizer Increased air velocity decreased NH removal and increased NH collection Previous research on wet scrubbers has only studied highly acidic scrubbing solutions because of their high ammonia capture efficiencies; however, the high acidity created practical problems. Lower acidity solutions would reduce corrosion, maintenance, and cost; however, designers may need to use strategies for increasing scrubber effectiveness, such as using lower air velocities. The objective of this study was to determine if a spray scrubber with slightly acidic and higher pH scrubbing solution (pH from 2 to 8) could effectively remove NH from NH laden air (such as animal building exhaust air), and also collect this valuable resource for later use as a fertilizer. A bench-scale spray wet scrubber treated 20 ppmv NH /air mixture in a countercurrent contact chamber. First, the solution pH was varied from 2 to 8 while maintaining constant air velocity at 1.3 m·s . Next, air velocity was increased (2 and 3 m·s ) while solution pH remained constant at pH6. At 1.3 m·s , NH removal efficiencies ranged between 49.0% (pH8) and 84.3% (pH2). This study has shown that slightly acidic scrubbing solutions are a practical means of removing ammonia from air especially if the scrubber is designed to increase collisions between solution droplets and NH molecules. The NH removed from the air was held in solution as NH and accumulates over time so the solution should be an excellent fertilizer.

关键词: Ammonia     Spray wet scrubber     Slightly acidic scrubbing solution     Controlled pH     Removal efficiency    

Diversity and vertical distributions of sediment bacteria in an urban river contaminated by nutrients

Xunan YANG, Shan HUANG, Qunhe WU, Renduo ZHANG, Guangli LIU

《环境科学与工程前沿(英文)》 2013年 第7卷 第6期   页码 851-859 doi: 10.1007/s11783-013-0569-1

摘要: The aim of this study was to investigate the benthic bacterial communities in different depths of an urban river sediment accumulated with high concentrations of nutrients and metals. Vertical distributions of bacterial operational taxonomic units (OTUs) and chemical parameters (nutrients: , , dissolved organic carbon, and acid volatile sulfur; metals: Fe, Zn, and Cu) were characterized in 30 cm sediment cores. The bacterial OTUs were measured using the terminal restriction fragment length polymorphism analysis. Biodiversity indexes and multivariate statistical analyses were used to characterize the spatial distributions of microbial diversity in response to the environmental parameters. Results showed that concentrations of the nutrients and metals in this river sediment were higher than those in similar studies. Furthermore, high microbial richness and diversity appeared in the sediment. The diversity did not vary obviously in the whole sediment profile. The change of the diversity indexes and the affiliations of the OTUs showed that the top layer had different bacterial community structure from deeper layers due to the hydrological disturbance and redox change in the surface sediment. The dominant bacterial OTUs ubiquitously existed in the deeper sediment layers (5–27 cm) corresponding to the distributions of the nutrients and metals. With much higher diversity than the dominant OTUs, the minor bacterial assemblages varied with depths, which might be affected by the sedimentation process and the environmental competition pressure.

关键词: heavy metals     nutrients     sediment profile     terminal restriction fragment length polymorphism    

Preparation of rare-earth metal complex oxide catalysts for catalytic wet air oxidation

LI Ning, LI Guangming, YAO Zhenya, ZHAO Jianfu

《环境科学与工程前沿(英文)》 2007年 第1卷 第2期   页码 190-195 doi: 10.1007/s11783-007-0033-1

摘要: Catalytic wet air oxidation (CWAO) is one of the most promising technologies for pollution abatement. Developing catalysts with high activity and stability is crucial for the application of the CWAO process. The Mn/Ce complex oxide catalysts for CWAO of high concentration phenolcontaining wastewater were prepared by coprecipitation. The catalyst preparation conditions were optimized by using an orthogonal layout method and single-factor experimental analysis. The Mn/Ce serial catalysts were characterized by Brunauer Emmett Teller (BET) analysis and the metal cation leaching was measured by inductively coupled plasma torch-atomic emission spectrometry (ICP-AES). The results show that the catalysts have high catalytic activities even at a low temperature (80?C) and low oxygen partial pressure (0.5 MPa) in a batch reactor. The metallic ion leaching is comparatively low (Mn<6.577 mg/L and Ce<0.6910 mg/L, respectively) in the CWAO process. The phenol, COD, and TOC removal efficiencies in the solution exceed 98.5% using the optimal catalyst (named CSP). The new catalyst would have a promising application in CWAO treatment of high concentration organic wastewater.

关键词: torch-atomic emission     Brunauer     Catalytic     process     stability    

Microbial responses to the use of NaClO in sediment treatment

《环境科学与工程前沿(英文)》 2022年 第16卷 第2期 doi: 10.1007/s11783-021-1451-1

摘要:

• Chlorine addition enhanced the release of TOC, TN from the sediment.

关键词: Sediment chlorination     Substance mobility     Microbial response     Community composition     Function    

黄土高原生态重建的水沙效应研究 Article

孙彭成, 吴一平, 杨志峰, Bellie Sivakumar, 邱临静, 刘曙光, 蔡宴朋

《工程(英文)》 2019年 第5卷 第5期   页码 855-864 doi: 10.1016/j.eng.2019.07.014

摘要:

黄土高原是全球土壤侵蚀最为严重的区域之一,也是黄河泥沙的主要来源。自20世纪50年代大规模水土保持措施实施以来,该地区入黄泥沙量持续减少,流域内泥沙来源与输移机制变得更为复杂,对水土保持措施作用下的河流输沙及变异特征的研究一直是学界关注的重点。本文以水土保持治理成效最为显著的黄土丘陵沟壑区的典型区域为研究对象,采用近50年的水沙观测数据,分析水土保持作用下流域水沙关系演变。结果表明,水土保持措施的实施引发流域水沙关系的显著变化,具体表现为幂指数水沙关系中系数的减小和指数的增加,且前阶段指数增加缓慢而后期增加剧烈。幂指数的增加表征新的更加陡峭的水沙关系曲线,意味着流域年际输沙变异程度或将增强。此外,新旧水沙关系曲线存在一个临界交点,在新的水沙关系条件下,低于临界流量的径流将输移更少的泥沙,这也是该地区泥沙输移新的主导状态;然而,大于临界流量的极端径流也有可能引发更强的泥沙输移。因此,本文认为黄土高原的低泥沙输移未必是一种新常态,极端洪水条件下仍有强输沙的可能性而需增强防范。

关键词: 流域水沙关系     生态恢复     黄土丘陵沟壑区     泥沙输移     水沙关系参数    

Air-side heat transfer and friction characteristics of biofouled evaporator under wet conditions

Hui PU, Guoliang DING, Xiaokui MA, Haitao HU, Yifeng GAO,

《能源前沿(英文)》 2010年 第4卷 第3期   页码 306-312 doi: 10.1007/s11708-009-0067-0

摘要: The effects of biofouling on air-side heat transfer and friction characteristics under wet conditions of three biofouled finned tube heat exchangers and one clean finned tube heat exchanger were investigated experimentally. Experimental results indicate that the biofouled fin efficiency of the evaporator decreases by 15.5% compared with the clean evaporator under the condition of the biofouled area ratio of 60% at the inlet air velocity of 2.0m/s; The ranges of friction fouling factor and heat transfer fouling factor are 19.8%―43.1% and ―15.6%―13.1%, respectively; a small quantity of biofouled particles can enhance heat transfer at low Reynolds number, and the enhancement effect decreases with the increase of Reynolds number.

关键词: finned tube     evaporator     fouling     heat transfer     friction    

Red soil for sediment capping to control the internal nutrient release under flow conditions

Lei Xia, Guo Liu, Chunmei Chen, Meiyan Wen, Yangyang Gao

《环境科学与工程前沿(英文)》 2016年 第10卷 第6期 doi: 10.1007/s11783-016-0886-2

摘要: The inhibition of sediment nitrogen (N) and phosphorus (P) release seems necessary. Red soil (RS) was firstly used as sediment capping material under flow conditions. RS capping can effectively reduce the N and P release from sediment. Nitrogen (N) and phosphorus (P) released from the sediment to the surface water is a major source of water quality impairment. Therefore, inhibiting sediment nutrient release seems necessary. In this study, red soil (RS) was employed to control the nutrients released from a black-odorous river sediment under flow conditions. The N and P that were released were effectively controlled by RS capping. Continuous-flow incubations showed that the reduction efficiencies of total N (TN), ammonium (NH -N), total P (TP) and soluble reactive P (SRP) of the overlying water by RS capping were 77%, 63%, 77% and 92%, respectively, and nitrification and denitrification occurred concurrently in the RS system. An increase in the water velocity coincided with a decrease in the nutrient release rate as a result of intensive water aeration.

关键词: Sediment     Red soil capping     Flow conditions     Nitrogen     Phosphorus    

Four kinds of capping materials for controlling phosphorus and nitrogen release from contaminated sediment

《环境科学与工程前沿(英文)》 2022年 第16卷 第3期 doi: 10.1007/s11783-021-1463-x

摘要:

• Lanthanum modified bentonite (LMB) can effectively absorb phosphorus (P).

关键词: Sediment     Eutrophication     Thin-layer capping     Phosphorus     Nitrogen     Aluminum-based P-inactivation agent    

Catalytic wet air oxidation of phenol, nitrobenzene and aniline over the multi-walled carbon nanotubes

Shaoxia YANG,Yu SUN,Hongwei YANG,Jiafeng WAN

《环境科学与工程前沿(英文)》 2015年 第9卷 第3期   页码 436-443 doi: 10.1007/s11783-014-0681-x

摘要: Wet air oxidation (WAO) is one of effective technologies to eliminate hazardous, toxic and highly concentrated organic compounds in the wastewater. In the paper, multi-walled carbon nanotubes (MWCNTs), functionalized by O , were used as catalysts in the absence of any metals to investigate the catalytic activity in the catalytic wet air oxidation (CWAO) of phenol, nitrobenzene (NB) and aniline at the mild operating conditions (reaction temperature of 155°C and total pressure of 2.5 MPa) in a batch reactor. The MWCNTs were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), gas adsorption measurements (BET), fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The functionalized MWCNTs showed good catalytic performance. In the CWAO of phenol over the functionalized MWCNTs, total phenol removal was obtained after 90 min run, and the reaction apparent activation energy was ca. 40 kJ·mol . The NB was not removed in the CWAO of single NB, while ca. 97% NB removal was obtained and 40% NB removal was attributed to the catalytic activity after 180 min run in the presence of phenol. Ca. 49% aniline conversion was achieved after 120 min run in the CWAO of aniline.

关键词: catalytic wet air oxidation (CWAO)     carbon nanotubes (CNTs)     phenol     nitrobenzene     aniline    

标题 作者 时间 类型 操作

Effects of previous drying of sediment on root functional traits and rhizoperformance of emerged macrophytes

期刊论文

Phenolic compounds removal by wet air oxidation based processes

Linbi Zhou, Hongbin Cao, Claude Descorme, Yongbing Xie

期刊论文

Characterization of value-added chemicals derived from the thermal hydrolysis and wet oxidation of sewage

Milan Malhotra, Anurag Garg

期刊论文

Survey of thermal comfort in residential buildings under natural conditions in hot humid and cold wet

Changhai PENG

期刊论文

of carboxymethyl cellulose on morphology of hydroxyapatite nanoparticles as prepared with one-step wet

Ruiqiang LIU,Rattan LAL

期刊论文

Performance evaluation on the pollution control against wet weather overflow based on on-site coagulation

Zongqun Chen, Wei Jin, Hailong Yin, Mengqi Han, Zuxin Xu

期刊论文

Removing ammonia from air with a constant pH, slightly acidic water spray wet scrubber using recycled

Ahmad Kalbasi Ashtari, Amir M. Samani Majd, Gerald L. Riskowski, Saqib Mukhtar, Lingying Zhao

期刊论文

Diversity and vertical distributions of sediment bacteria in an urban river contaminated by nutrients

Xunan YANG, Shan HUANG, Qunhe WU, Renduo ZHANG, Guangli LIU

期刊论文

Preparation of rare-earth metal complex oxide catalysts for catalytic wet air oxidation

LI Ning, LI Guangming, YAO Zhenya, ZHAO Jianfu

期刊论文

Microbial responses to the use of NaClO in sediment treatment

期刊论文

黄土高原生态重建的水沙效应研究

孙彭成, 吴一平, 杨志峰, Bellie Sivakumar, 邱临静, 刘曙光, 蔡宴朋

期刊论文

Air-side heat transfer and friction characteristics of biofouled evaporator under wet conditions

Hui PU, Guoliang DING, Xiaokui MA, Haitao HU, Yifeng GAO,

期刊论文

Red soil for sediment capping to control the internal nutrient release under flow conditions

Lei Xia, Guo Liu, Chunmei Chen, Meiyan Wen, Yangyang Gao

期刊论文

Four kinds of capping materials for controlling phosphorus and nitrogen release from contaminated sediment

期刊论文

Catalytic wet air oxidation of phenol, nitrobenzene and aniline over the multi-walled carbon nanotubes

Shaoxia YANG,Yu SUN,Hongwei YANG,Jiafeng WAN

期刊论文