Thermal-Distillation and Reverse-Osmosis Case Studies

During the past eight years, interest in thermal-distillation and membrane-separation processes has increased in the UK. Whilst distillation is a mature technology, and reverse osmosis has had setbacks in the last decade, both processes continue to be developed. To illustrate this development, two case studies have been selected.     

Commissioning and Operation of the Thames Water Ring Main

In order to achieve the earliest possible benefits of the investment in the Thames Water ring main, in late 1989 it was recognized that it was necessary to establish a commissioning team. The remit for the team was to progressively commission the ring main to match the construction programme, without risking the integrity of the daily water supply.
This paper describes the methods, accountability, and achievement of the commissioning project.     

Water Quality and Management Strategies in London's Docklands

Regeneration and changes in land use in London's Docklands have resulted in new water quality requirements. Areas previously occupied by docks now form part of redevelopment projects which have made a feature of the water.
The paper describes a project to provide water that is aesthetically pleasing and of a quality suitable for water contact recreational activities.
An extensive programme of water sampling and analysis was carried out to gain an understanding of the processes affecting water quality, including the monitoring of algal growth. The river is the main source of nutrients in the docks, which results in large concentrations of algal biomass and bacterial contamination. The principal strategy is to limit light via artificial mixing systems supplemented by limiting the inflow of nutrients from the river.
The results from the water sampling programme have been used to build a 3D computer model with a supporting graphic information system to attain (a) qualitative evaluations of management and development options, and (b) short-term predictions of changes in water quality.     

ANOMALOUS RESPONSE IN THE HALIFAX PROCESS

The Halifax process was first proposed as a means of minimising the bulking of activated sludge. In one system using this process, bulking continued to occur. An analysis of the process, using dynamic modelling tools, predicted that the process contains the potential for effluent quality to become worse as the hydraulic loading to the process is reduced — contrary to common experience with more conventional layouts.     

The Management and Creation of Beaches for Coastal Defence

The creation and management of beaches using natural mobile materials can often provide a cost-effective and environmentally appropriate coastal defence. This paper summarizes recent practical endeavours in beach creation and management. Reference is made to the natural sources of beach building materials and to the numerical and physical models that may be employed to assist in the definition both of material transport paths and their magnitude. Risk analysis is noted to be a necessary part of the beach design process together with an appraisal of the coastal hydrodynamics and topographical constraints of the site of interest. The techniques that have been employed to recycle beach materials on some frontages are described, with comments on bypassing materials around obstructions. The paper describes the important considerations to be made when material is being imported to a beach, and notes some of the presently used techniques. Important points are drawn out for the future of beach creation and management, and a number of research needs and administrative difficulties are highlighted.     

Investigation of River Flow Failure at Sleaford

The River Slea through Sleaford is fed by groundwater emanating from the Lincolnshire Limestone. In recent years, the springs have dried up periodically, causing failure of river flow through the town. The Slea is a main feature of the town and, when flowing, a valuable visual amenity. Conversely, when it is not flowing, progressive water quality deterioration in ponded sections reduces the river corridor to an eyesore. The paper describes investigations into the cause of the problem and how to overcome it.     

Developments in Structured-Wall Plastics Sewer Pipes and a Method of Testing Their Resistance to Damage

Structured-wall plastics sewer pipes rely upon the structural configuration of their walls to enhance their stiffness, whilst saving on material. Their properties and performance vary widely with the type and material from which they are made, and opinion is divided as to the acceptability of these products for sewerage systems. The UK water industry and the Committee for European Normalisation are actively developing standards for them, but there are a number of performance-related concerns which need to be addressed if they are to be accepted in the UK.
A test, which measures a pipe's resistance to being damaged, has been developed at the University of East London, and preliminary results confirm a wide variation in performance.     

Fluvial Flood Forecasting

This paper describes some of the latest developments in real-time fluvial flood-forecasting systems which utilise quantitative weather radar information. Rain-gauge, flow-measuring stations, weather radar and other sources of information are fully integrated by the real-time flood-forecasting system and provide flood warnings for civil protection. The systems have been commissioned in various regions within the UK and are undergoing continuous development in conjunction with the UK water industry and through close involvement with various European partners via the auspices of the European Union.     

Satisfying the Water Supply Demand of the Channel Tunnel

When Europe's largest civil-engineering construction site, the Channel Tunnel, requested a guaranteed source of water during 1988, the Folkestone District Water Company was experiencing the first signs of the drought conditions which were to prevail for the next three years. Whilst infrastructure changes allowed for supplies to be made available to the Channel Tunnel contractors, the increasing reduction of resources meant that an alternative supply of water was required.
The solution to the problem was to utilize desalination by reverse osmosis of sea water taken from the English Channel. The process design and operation of this most arduous of feed water is discussed, demonstrating the successful application of this technology.