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Constructed wetlands for wastewater treatment in cold climate--A review

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Journal of Environmental Sciences 2017年第7期29卷 293-311页

作者： Mo Wang Dong Qing Zhang Jian Wen Dong soon keat tan College of Landscape Architecture Fujian Agriculture and Forestry UniversityFuzhou 350002China Nanyang Environment&Water Research Institute 1 CleanTech Loop#06-10637141Singapore School of Civil and Environmental Engineering Nanyang Technological University639798Singapore

Constructed wetlands（CWs） have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option ***,the application of CW for wastewater treatment in frigid climate presents special *** treatment of wastewater relies largely on biological processes,and reliable treatment is often a function of climate *** date,the rate of adoption of wetland technology for wastewater treatment in cold regions has been slow and there are relatively few published reports on CW applications in cold *** paper therefore highlights the practice and applications of treatment wetlands in cold climate.A comprehensive review of the effectiveness of contaminant removal in different wetland systems including：（1） free water surface（FWS） CWs;（2） subsurface flow（SSF） CWs;and（3） hybrid wetland systems,is *** emphasis of this review is also placed on the influence of cold weather conditions on the removal efficacies of different *** strategies of wetland design and operation for performance intensification,such as the presence of plant,operational mode,effluent recirculation,artificial aeration and in-series design,which are crucial to achieve the sustainable treatment performance in cold climate,are also *** study is conducive to further research for the understanding of CW design and treatment performance in cold climate.

关键词： Constructed wetlands Wastewater treatment Nutrient Cold climate

Rheological properties of dense natural cohesive sediments subject to shear loadings

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International Journal of Sediment Research 2014年第4期29卷 454-470页

作者： Wen-yu YANG Guo-liang YU soon keat tan Hua-kun WANG State Key Laboratory of Ocean Engineering School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong University Maritime Research Centre School of Civil and Environmental EngineeringNanyang Technological University

Cohesive sediments exhibit complex rheological behaviors that are non-Newtonian and time-dependent when subjected to external *** paper presents the results of an investigation on the rheological properties of three types of dense cohesive sediments,collected from the mouth of the Yangtze River,the shoal of the Hangzhou Bay,and the Yangcheng Lake in China.A set of rheological parameters(including viscosity,yield stress,etc.) was studied based on experiments that were conducted with a RheolabQC *** of the flow curves,shear stress-time responses,and yield stresses were *** solid-liquid transition of the dense cohesive sediments occurred both in the shear rate ramp tests and the shear stress ramp *** transition was not direct,but it was mediated by a transitional deformation regime or stress *** the Herschel-Bulkley model and Carreau model were able to describe the rheological behavior of dense cohesive sediments,and the empirical expressions for calculating the parameters in these models were obtained by a dimensional and regression *** yield stresses determined by the shear stress ramp test and by the vane method were compared and *** influence of the water content on the rheological properties of dense cohesive sediments was considered.

关键词： Rheology Cohesive sediment Solid-liquid transition Thixotropy Yield stress

Application of constructed wetlands for wastewater treatment in tropical and subtropical regions(2000–2013)

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Journal of Environmental Sciences 2015年第4期27卷 30-46页

作者： Dong-Qing Zhang K.B.S.N.Jinadasa Richard M.Gersberg Yu Liu soon keat tan Wun Jern Ng Advanced Environmental Biotechnology Centre Nanyang Environment & Water Research Institute Nanyang Technological University Department of Civil Engineering University of Peradeniya Graduate School of Public Health San Diego State University

Constructed wetlands（CWs） have been successfully used for treating various wastewaters for decades and have been identified as a sustainable wastewater management option for developing countries. With the goal of promoting sustainable engineered systems that support human well-being but are also compatible with sustaining natural（environmental）systems, the application of CWs has become more relevant. Such application is especially significant for developing countries with tropical climates, which are very conducive to higher biological activity and productivity, resulting in higher treatment efficiencies compared to those in temperate climates. This paper therefore highlights the practice,applications, and research of treatment wetlands under tropical and subtropical conditions since 2000. In the present review, removal of biochemical oxygen demand（BOD） and total suspended solid（TSS） was shown to be very efficient and consistent across all types of treatment wetlands. Hybrid systems appeared more efficient in the removal of total suspended solid（TSS）（91.3%）, chemical oxygen demand（COD）（84.3%）, and nitrogen（i.e.,80.7% for ammonium（NH）4-N, 80.8% for nitrate（NO）3-N, and 75.4% for total nitrogen（TN））as compared to other wetland systems. Vertical subsurface flow（VSSF） CWs removed TSS（84.9%）, BOD（87.6%）, and nitrogen（i.e., 66.2% for NH4-N, 73.3% for NO3-N, and 53.3% for TN）more efficiently than horizontal subsurface flow（HSSF） CWs, while HSSF CWs（69.8%）showed better total phosphorus（TP） removal compared to VSSF CWs（60.1%）. Floating treatment wetlands（FTWs） showed comparable removal efficiencies for BOD（70.7%）,NH4-N（63.6%）, and TP（44.8%） to free water surface（FWS） CW systems.

关键词： Constructed wetlands Treatment Nutrient Removal Tropical

Lagrangian modeling of tidal bores passing through bridge piers

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Lagrangian modeling of tidal bores passing through bridge pi...

Experimental Study of a Circular Cylinder with Grooved Surface

第九届国际水动力学会议

作者： soon keat tan Maritime Research Centre School of Civil and Environmental EngineeringNanyang Technological University

The process of tidal bore passing through bridge piers is numerically simulated in an open channel using a pure Lagrangian method,*** Particle Hydrodynamics（SPH）.Due to its "gridless" feature,SPH is intrinsically wellsuited for the complex hydrodynamic simulation when the fluid encounters a *** behavior of bores propagation along the channel is illustrated herein and includes the bore’s free surface properties and flow field,and in particular,the intricate behavior of unsteady flow during the passage of tidal *** generation of shock waves between the structures can be clearly observed in the numerical *** vortical structures behind the bore front are generated as the bore propagate through the constriction.

关键词： tidal bore SPH undular bore

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Experimental Study of a Circular Cylinder with Grooved Surfa...

Socio-Environmental Impact of Water Pollution on the Mid-canal (<i>Meda Ela</i>), Sri Lanka

中国造船工程学会船舶力学学术委员会第九届全体会议

作者： Bo Zhou Yehan Qi Diankai Sun soon-keat tan School of Naval Architecture Dalian University of Technology School of Civil and Environmental Engineering Nanyang Technological University

New experiments were performed to measure the force and flow characteristics of a circular cylinder with grooved surface roughness in a range of Reynolds numbers,7.43×10 to 7.99×*** main aim of this study is to obtain a better understanding of the drag reduction mechanism of surface roughness,thorough quantitative measurement of the flow field around the cylinder using Particle Image Velocimetry(PIV).The findings of the study revealed that a grooved cylinder produces a lower drag coefficient that was about 0.75 times of that of a smooth cylinder.

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Journal of Water Resource and Protection 2012年第7期4卷 451-459页

作者： K. B. S. N. Jinadasa S. K. I. Wijewardena Dong Qing Zhang Richard M. Gersberg C. S. Kalpage soon keat tan Jing Yuan Wang Wun Jern Ng Department of Chemical and Process Engineering University of Peradeniya Peradeniya Sri Lanka Department of Civil Engineering University of Peradeniya Peradeniya Sri Lanka Graduate School of Public Health San Diego State University Hardy Tower Campanile San Diego USA Nanyang Environment & Water Research Institute (NEWRI) Nanyang Technological University Singapore City Singapore Nanyang Environment & Water Research Institute (NEWRI) Nanyang Technological University Singapore Singapore Works Department Kandy Municipal Council Kandy Sri Lanka

Unplanned urban population growth in developing countries such as Sri Lanka exert pressures on the sectors of water supply, sewage disposal, waste management, and surface drainage in the cities as well as their surrounding areas. The Mid-canal is considered the most polluted surface water body in the Kandy district of Sri Lanka and contributes significantly to pollution of the Mahaweli River. Health problems in the nearby population may well be associated with environmental degradation and related to deteriorated water quality. The overall objectives of this study were to identify the socio-economic status of the community settled along the Meda Ela banks, and to examine the current water quality status of the Meda Ela and possible impacts of the nearby residents on water quality. Additionally, we propose remedial measures concerning wastewater and solid waste disposal to improve environmental conditions in this area.

关键词： Meda Ela Sri Lanka Environment Pollution Water Quality

THEORETICAL,NUMERICAL AND EXPERIMENTAL STUDY OF WATER HAMMER IN PIPE SYSTEM WITH COLUMN SURGE CHAMBER

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Journal of Hydrodynamics 2003年第5期15卷 20-28页

作者： tan soon keat ENV-NTU Environmental Engineering Research Centre

A new kind of governing equations for water hammer based on the elasticcolumn theory was proposed and adopted to analyse water hammer phenomenon in the pipe system with avertical column surge chamber and water level fluctuation in the surge chamber during pressuretransient. The wrongness existing in the classical governing equations for water hammer wasanalysed. A typical reservoir-valve pipe system was chosen as an example to verify the new governingequations numerically and experimentally. The finite difference method based on the method ofcharacteristics was used to solve numerically the nonlinear characteristic equations. The temporalevolutions of transient volume flux and head and of water level fluctuation for various surgechamber configurations were worked out, assuming that the air in the surge chamber are *** relevant experiment was conducted to verify the new governing equations and numerical *** numerical and experimental results show that the new governing equations are valid and theconventional assumption that the pressure head at the base of a surge chamber equals that of thestatic head above it during pressure transient is not always valid. The surge chamber generallyreises the period of transient pressure wave in pipe system, reduces the maximum pressure envelopeand lifts the minimum envelope substantially. The water level fluctuation in the surge chamber wasnumerically and experimentally observed. Increasing the size of the surge chamber and/or decreasingthe initial air pressure in the surge chamber enhance the effectiveness of the surge chamber insuppressing pressure wave.

关键词： water hammer vertical column surge chamber pipe system

HYDRODYNAMIC CHARACTERISTICS AND OPTIMIZATION DESIGN OF EFFICIENT AXIAL-FLOW BLAST WITH LOW NOISE AND ENERGY SAVING

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Journal of Hydrodynamics 2002年第4期14卷 40-46页

作者： tan soon keat School of Civil and Structural Engineering Nanyang Technological University

Based on the demand on efficient axial-flow blast with low noise and energy saving, a blade was designed through the application of the unequal work distribution principle and the exponential twisted camber was used to shape blades. Then, the hydrodynamic characteristics of blades were studied and the strengths and vibrations of blades and hydro-dynamic noise of blast were analyzed. Furthermore, the software of optimization design of axial-flow blast was developed. Finally, the HMF-T40No.20 axial-flow blast used in large textile conditioner system of cotton spinning industry was designed, which could meet the required total safety and environmental requirements as the corresponding test demonstrates. The study is beneficial to designing axial-flow blast.

关键词： Acoustic noise Design Noise abatement Optimization Software engineering Turbomachine blades

RESEARCH ON STABILITY OF INTERFACE OF JET CONTAINING SUSPENDED SOLID PARTICLES

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Applied Mathematics and Mechanics(English Edition) 2000年第7期21卷 741-746页

作者：周泽宣 tan soon keat 林建忠 School of Civil and Structural Engineering Nanyang Technological University 637898 Singapore Department of Mechanics Zhejiang University 310027 Hangzhou P R China

The stability equation of interface of two-phase jet and the corresponding particle-gas disturbance velocity ratio equation are derived by means of the phase-coupled model. The stability nares of interface of two-phase jet for different particle properties and the corresponding particle-gas disturbance velocity ratio curves are given out through numerical computation. Further, several important conclusions on effect of particle property on growth and propagation of disturbance of interface of two-phase jet and particle disturbance property me presented on the basis of analyses of the obtained stability curves and particle-gas disturbance velocity ratio curves. These important conclusions can play a guiding role in studying development of two-phase jet and executing artificial controls over it in project practice.

关键词： stability of interface suspended solid particles particle disturbance property phase-coupled model jet shear layer