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Technical Papers Library

Browse the library of technical papers authored by Hydro International's water experts for information on stormwater, wastewater and combined sewer overflow research. 

For papers about best management practices for the water industry, browse Hydro's White Papers Library located in the Press Centre.

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file icon Experimental study of a hydrodynamic vortex separatorhot! 03/16/2009
Authors
D A Egarr, MG Faram, T O’Doherty
Abstract
A hydrodynamic vortex separator (HDVS) has been studied under laboratory conditions by using a specifically designed rig. Pressure tapping points placed at eight locations, six external and two internal, have revealed an even radial pressure distribution on the outer walls and central shaft. The ability of the HDVS to separate particulates has been studied. The particulates have been characterized by measurements of particle diameter and settling velocity, which have allowed efficiency cusps to be plotted against dimensionless groups used by other researchers. Owing to an unsatisfactory reduction of the data to a single curve by plotting the efficiency against dimensionless groups, an efficiency law has been determined based on the logistic equation and describes the separation efficiency in terms of the inlet flowrate, volume of the separator, and particle diameter and density.
file icon Assessment of laboratory test protocols for determining the pollutant removal capabilities of stormwhot! 09/16/2008
Authors
K. Osei, R.Y.G. Andoh, J. MacKinnon and M.G.Faram
Abstract
Laboratory testing of stormwater separators can overcome many of the technical challenges associated with field testing. With laboratory testing, sediment characteristics and the flow rates at which a device is tested are known and measurable before, during, and after the test. This controlled environment ensures that test programmes can be set up to meet specific objectives, and data can be obtained in a repeatable and timely fashion. However there are differences in laboratory test protocols that can have a significant bearing on test results which, if overlooked, can result in invalid comparisons being made between different systems. This paper looks at two protocols for testing separators in the laboratory, normally referred to as the Direct Test Method and the Indirect Test Method. The test methodologies are described and the similarities and differences shown. Results from tests on a stormwater treatment separator using the two protocols are presented. The results show that for the same sediment gradation and flow rate, a difference of over 20% in measured removal efficiency is possible. They also show that the Direct Test Method produces outputs that are more consistent, conservative and representative of the removal efficiencies expected for stormwater treatment separators.
file icon Efficiency testing of a hydrodynamic vortex separatorhot! 09/16/2008
Authors
D.A. Phipps, R.M.Alkhaddar, E. Loffill, R.Y.G Andoh and M.G. Faram
Abstract
The factors affecting the overall efficiency for the removal of a solid from an influent stream of water by an HDVS (Hydrodynamic Vortex Separator) have been examined using a combination of solids capture/washout experiments and dye tracer studies. The overall solids removal efficiency of the device is a function of loading rate (overall flow). The efficiency can be considered in terms of the balance between initial capture of the sediment and any subsequent re-entrainment. Tracer studies have shown that a well-designed device offers almost complete separation into a mobile and quiescent zone, with slow exchange between the two. This enhances both sediment capture and its subsequent retention.
file icon Laboratory and Field Tests of the Up-Flo Filterhot! 09/16/2008

Authors: Robert Pitt, Uday Khambhammettu, Robert Andoh, Lisa Lemont, Kwabena Osei, and Shirley E. Clark

Abstract: The Up-Flo stormwater filter technology, developed under the US EPA’s Small Business Innovative Research (SBIR) program, incorporates elements of a treatment train approach including screening, sedimentation and high-rate filtration in a compact modular device. The Up-Flo™ Filter is a passive, modular proprietary upflow filtration system that incorporates multiple elements of a treatment train into a single, small-footprint device. The device uses a sedimentation sump and screening system to pre-treat stormwater runoff before it flows up through the filter media where final polishing via filtration occurs. A high-capacity siphoning bypass safeguards against upstream ponding/flooding during high-flow events. The siphon also serves as a floatables baffle to prevent the escape of floatable trash and debris from the Up-Flo™ Filter chamber. The Up-Flo™ Filter during normal operation. The Up-Flo™ Filter has undergone extensive testing, including laboratory and field testing of a prototype and fullscale unit. This paper describes some of these tests, especially relating to the flow treatment capacity of the filter. Comparisons of the different test protocols that are being followed during current full-scale testing are also made.

file icon Physical characterisation and hydrograph response modelling of vortex flow controlshot! 09/16/2008
Authors
J. P. LeCornu, M. G. Faram, D. S. Jarman, and R. Y. G. Andoh
Abstract
Urban drainage networks require accurate, reliable flow control systems for their effective operation and minimisation of flood risk. Different types of flow control produce different hydraulic characteristics, having implications to system design in particular relating to upstream storage utilisation. Vortex flow controls (VFCs) present particular opportunities, producing desirable hydraulic characteristics while also having large clearances compared to other devices. This paper describes the implementation of advanced flow control characterisation procedures and techniques allowing VFCs in particular to be characterised within a period of a few hours. The results are shown to correspond with those collected using conventional methods. Work is also described relating to the development and application of a model to allow storm hydrograph response modelling of storage-flow control combinations. It is demonstrated how the use of a VFC can lead to significantly more efficient storage utilisation compared to when a simple orifice plate is used. Further to this, it is found that system recovery times can be significantly improved, with gains of in excess of 35% being obtained. Initial verification of the simulations shows a favourable correspondence with test outputs produced by others.

 

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