Authors

D.A. Phipps, R.M. Alkhaddar and M.G. Faram

Abstract

In recent years, various proprietary treatment technologies have evolved to reduce the polluting impact of urban run-off on receiving watercourses. The majority are ‘flow-through’ devices, designed to intercept and store pollutants in submerged chambers for later removal and safe disposal. Frequently, the performance of such systems is described solely in terms of ‘ability to remove pollutants from the inflow’, usually at specified discrete flowrates. However, it is suggested that this is insufficient to give a true assessment of performance and a critical parameter that is often overlooked is chamber ‘retention efficiency’, the ability of a chamber to retain stored pollutants once collected. In the current study, this parameter is investigated experimentally for a range of chamber configurations. Cylindrical chambers with different inlet orientations, internal components and hence flow dynamics are considered. The study identifies retention efficiency as being a major differentiator between designs, and concludes that chambers in which captured pollutants are stored in regions that are hydraulically isolated from the main treatment area are likely to be the most effective in practice.

Authors

Darrell A. Egarr, Michael G. Faram, Timothy O’Doherty, David A. Phipps, Nicholas Syred

Abstract

A Hydrodynamic Vortex Separator (HDVS) has been modelled using Computational Fluid Dynamics (CFD) in order to predict the residence time of the fluid at the overflow and underflow outlets. A technique which was developed for use in Heating, Ventilation and Air Conditioning (HVAC) was used. The results have been compared to those determined experimentally. It is shown that in using CFD, it is possible to predict the mean residence time of the fluid and to study the response to a pulse injection of tracer. It is also shown that it is possible to apply these techniques to predict the mean survival rate of bacteria in a combined separation and disinfection process.

Authors

D.A. Egarr, M.G. Faram, I. Guymer, T. O’Doherty, N.Syred

Abstract

The fluid residence time characterisation of a 3.4m diameter Hydrodynamic Vortex Separator (HDVS) has been carried out over a range of flowrates. Computational Fluid Dynamic (CFD) modelling has also been undertaken for the same conditions and validated against the experimental results, for which reasonable correspondence has been found. Using the results from the CFD modelling and batch inactivation results from the disinfection of secondary treated wastewater, it is shown that the theoretical performance of a HDVS as a contact vessel for disinfection can be predicted.

Authors

D.A. Egarr, M.G. Faram, I. Guymer, T. O’Doherty, N.Syred

Abstract

The fluid residence time characterisation of a 3.4m diameter Hydrodynamic Vortex Separator (HDVS) has been carried out over a range of flowrates. Computational Fluid Dynamic (CFD) modelling has also been undertaken for the same conditions and validated against the experimental results, for which reasonable correspondence has been found. Using the results from the CFD modelling and batch inactivation results from the disinfection of secondary treated wastewater, it is shown that the theoretical performance of a HDVS as a contact vessel for disinfection can be predicted.

Authors

D. Egarr, M.G. Faram, T. O’Doherty, D. Phipps and N. Syred

Abstract

A Hydrodynamic Vortex Separator (HDVS) has been modelled using Computational Fluid Dynamics (CFD) in order to predict the residence time of the fluid at the overflow and underflow outlets. A technique which was developed for use in Heating, Ventilation and Air Conditioning (HVAC) was used to determine the residence time and the results have been compared with those determined experimentally. It is shown that in using CFD, it is possible to predict the mean residence time of the fluid and to study the response to a pulse injection of tracer. It is also shown that it is possible to apply these techniques to predict the mean survival rate of bacteria in a combined separation and disinfection process.