Developing Scientific Aspects of Water Treatment

Severn Trent Water is currently undertaking an extensive capital programme to enhance water-treatment facilities at many of its major plants, and this work is underpinned by the need to apply robust, cost-effective solutions utilizing modern treatment technology.
The paper describes various aspects in the development of these functional designs in relation to treatment objectives, technical innovation and value engineering, drawing examples from Severn Trent schemes and particularly from the redevelopment of the Birmingham water-treatment plant.     

Frankley Water-Treatment Works Redevelopment: Pilot-Scale Studies

The redevelopment of Frankley water-treatment works (maximum flow 450 Ml/d), which supplies soft upland-derived water to the Birmingham area, will enable iron, manganese, colour, turbidity and natural aluminium levels to be significantly reduced below the EC drinking water quality Directive.
This paper describes the pilot studies which led to the decision to build what is presently believed to be the largest dissolved-air flotation plant in the world.
The studies demonstrated, amongst other things, the effectiveness of ferric sulphate for treating coloured upland waters; the viability of stablization using carbon dioxide and lime to prevent pH variation in the distribution system; that a membrane press was the most appropriate dewatering process, and that the treated water would reduce the particulate lead concentrations in properties containing lead service pipes.
Costing £0.5 million and equating to approximately 1% of redevelopment cost, the pilot study was considered to be excellent value.     

Chlorination and Drinking Water Quality - an Operational Overview

A vailable national guidelines for disinfection practice, and for the examination of bacteriological quality, are reviewed, together with the legislative requirements of the EC 'Drinking Water'Directive. Problems of impracticability, vagueness, and ambiguity are identified.
Experience of the maintenance of bacteriological quality in large, lowland, surface water and ground-water supply areas is given with reference to the behaviour of disinfectant residuals, trihalomethanes, nitrite, and aesthetic parameters. The way forward in terms of the management of distribution systems and water treatment is discussed.