Abstract

The paper describes a novel drop shaft system that relies on the use of a selfactivating, non-powered and no moving part air intake control system to prevent instabilities and provide smooth transitions between air-entrained vortex flow modes and pipe full operating modes. This allows more compact drop pipe arrangements to be deployed within a single drop structure, also providing for maintenance access. These systems therefore do not require auxiliary maintenance or air shafts resulting in significant project cost savings. Further optimization of the system has involved the use of compact hydraulic break, rotary flow energy dissipation structures at the base of the vertical drop pipes resulting in a space efficient and effective system for controlling flows into deep tunnels. The operational characteristics of the novel drop shaft system including the basis for more effective flow control and elimination of unstable flow conditions are described in detail in this paper. The paper also includes case studies of its successful application in a number of deep tunnel schemes and at a wastewater treatment plant.

Authors

R.Y.G. Andoh, H. Carter, C. Osterrieder, N. Raymond & M.A. Stein

Abstract

Faced with the challenge of addressing Combined Sewer Overflow (CSO) issues, the City of Saco, Maine, adopted an approach which involved improving the transport and management of excess wet-weather flows by implementing a scheme that applied advanced vortex technologies for both flow control and water quality improvement. The application of vortex technology at Saco utilizes vortex flow regulators in the upstream diversion chambers to regulate maximum flows to the existing wastewater treatment plant in order to avoid hydraulic overloading and the diversion of excess combined sewer flows to the new CSO treatment facility. The new facility utilizes an advanced hydrodynamic vortex separator (HDVS) that incorporates a novel non-powered, self-activating and self-cleansing CSO floatables control screening system and accomplishes primary treatment equivalency, disinfection, floatables capture and grit removal all in one vessel. The underflow from the CSO facility comprising sewer debris and solids including grit, sediments, settleable organic solids and floatables, is returned to the headworks at the treatment plant and the clarified, screened and disinfected overflow is discharged to the receiving environment (Saco River) after de-chlorination. The ability to perform several essential unit processes (i.e. Sedimentation, Screening, Disinfection and Grit Removal) all in one vessel resulted in significant savings in the overall project scheme costs on account of the more compact design of the advanced HDVS system coupled with the elimination of additional tanks and vessels that would have been required with the conventional approach. Analytical results from post-construction compliance monitoring have confirmed the efficacy of the system.

Authors

M. G. Faram, J. M. Saker & V. M. Story

Abstract

This paper presents a study of UK water industry capital equipment selection, focusing in particular on behaviour in relation to sewerage/combined sewer overflow (CSO) and wastewater-associated investment activities. Valuable new insights into the perspectives of different parties, including water service providers (WSPs), design consultants and construction companies, are provided. Through analysis of over 200 questionnaires, equipment selection is confirmed to be multi-organisational, with different parties dominating different roles. Among the selection criteria, service and quality are found to be valued as parameters worth paying for. Relationships and sustainability considerations are also found to be important, although views on whether sustainability benefits will be paid for are divided. While interparty alignment of views is generally good, there are occasional discrepancies at the individual water region level. It is suggested that optimisation might derive from recognising the significance of intangible components of the supplier offering, and managing relationships to allow these to be capitalised upon.

Authors

Robert Y.G. Andoh,Michael G. Faram and Kwabena Osei

Abstract

Globally, the water and wastewater industry faces major challenges, both in developed and developing world regions. The developed world has enjoyed the benefits of the foresight of prior generations, with major strides gained in public health simply from innovations such as the humble sewer which has contributed more to human health than all developments in the medical field. Challenges faced in different regions are diverse in nature, magnitude and scale. Some are local in nature but others such as the impacts of Climate Change are truly global. The paper examines the status and evolution of innovations within urban water management (with particular reference to stormwater management) including impacts of regulation, barriers to innovation, current trends and paradigms. It is argued that there is a need to change the way we approach urban water management challenges, particular if the goal is to achieve more sustainable development in an increasingly urbanizing world.

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.