The Effect of Ozonation on Particle Removal in Drinking-Water Treatment

The effect of the introduction of additional process stages in a surface-water treatment plant was studied in order to investigate how particle removal could be optimized. Particle counting is considered to be a useful indicator of treatment performance. This paper is based on results which were obtained from trials on a water-treatment plant treating surface water; these consisted of a combination of modifications to existing full-scale plant and a specially constructed pilot plant.     

The Impact of Electricity at Work Regulations on the Operation of a Water Company

Since 1 April 1990, the Electricity at Work Regulations 1989 have placed legal requirements on employers, employees and the self-employed to take precautions against the risk of death or injury from electricity in work activities. This paper (a) examines the requirements, (b) reports on an initiative by the Lee Valley Water Company, and (c) proposes a management strategy for an organization to comply with the legislation.     

Desalination: the State of the Art

Desalination technology is applied in many areas of the world to provide fresh water from brackish or seawater sources. The paper reviews the technology which is available and discusses both distillation and membrane processes. Indications of capital and operating costs are provided.     

The East Kent Chalk Aquifer during the 1988-92 Drought

Groundwater resources of Chalk aquifers may become depleted during drought periods; major causes of this depletion include reductions in the aquifer transmissivity and the interaction between aquifers and rivers. In the East Kent aquifer there are certain catchments where difficulties are encountered in maintaining yields but, in other catchments, drought periods have little effect on the available resources. A mathematical model is developed to help understand the flow processes within the aquifer system, and the model is used to predict the consequences of possible abstraction scenarios.     

Thermal Drying of Sewage Sludge

Over the next decade the UK will experience significant, imposed changes in the quantity of sewage sludge produced and in the means available for its disposal. Existing practices are being reappraised and new technologies are being explored to cope with a predicted 40% increase in the quantity for disposal. Thermal drying of sludge undoubtedly has a role to play in coping with this demand.
The two principal process types, i.e. direct and indirect heat application, are appraised in depth and a comparison is drawn. A case study is identified to examine the energy demands of the process, including the potential for heat recovery and for resource reuse. The environmental impact of a typical process is also examined.     

Maintaining Groundwater Supplies during Drought Conditions in the Brighton Area

The very low level of recharge to the chalk of the South Downs, which provide Brighton with its water supply, has meant that the groundwater levels are very low. Despite this, no restrictions have been necessary since February 1991. This is perhaps due to the instigation of public information campaigns, together with media coverage of the drought, as well as a successful programme of leakage control. This paper looks at how the growth of public water supply has been accommodated operationally while ensuring that groundwater quality is maintained. Options for the future expansion of supply, and their cost-effectiveness, are also considered.     

Surface-Water Abstraction Controls in Scotland

ABSTRACT The system of abstraction controls for irrigation in Scotland is one of local control orders where, to limit abstractions from any particular watercourse, the river purification authority must apply for an order from the Secretary of State for Scotland to cover abstractions from that one watercourse and its catchment. This contrasts sharply with the heavily protective system in England and Wales where the National Rivers Authority has statutory powers to license all abstractions. The purpose of this paper is to examine the abstraction control system in Scotland with a view to highlighting its advantages and limitations, and to suggest ways by which the system can be improved or made more effective.     

Habitat Creation Opportunities for Landward Coastal Re-alignment: Essex Case Studies

Relative sea-level fluctuations during the Holocene period have combined with medieval to present saline floodplain embanking to reduce the inter-tidal saltmarsh area in Essex from 40 000 ha to 4400 ha. The present loss by erosion is estimated at 2%/annum for the country, and the reduction in these areas is not only detrimental to related habitats but has caused an increasing requirement for flood-defence financial investment.
Recent initiatives by the Ministry of Agriculture, Fisheries and Food, the Environment Agency and English Nature have created mechanisms and opportunities to develop sustainable flood-control structures where coastal re-alignment has been the preferred option.
The Orplands frontage covers 2 km of sea wall which have been deliberately breached to allow 40 ha of rare saltmarsh to re-establish. At Abbotts Hall, an arable field of 20 ha has been converted to its former saltmarsh by creek re-establishment and tidal inundation by reversal of existing sluices. These two schemes have (a) regenerated habitats for halophytic and semi-halophytic plants, marine and brackish invertebrates, and (b) provided roost, feed and breeding areas for birds and nursery areas for marine fish fry. Apart from flood control and habitat creation, particular features were incorporated to provide niche locations for targeted types of wildlife.     

Requirements for Quality System Certification to BS 5750 with Reference to the Water Industry

Quality assurance for the water industry and its suppliers is being seen to be of ever-increasing importance as a means of meeting the demands of customers and giving confidence to regulators. The creation of the Water Industry Certification Scheme demonstrates the industry's increased level of commitment to quality assurance.
This paper considers the requirements and benefits of certification of quality systems with particular reference to the BS 5750/EN 29000/ISO 9000 series of standards. The requirements for certification in the water industry are discussed in terms of corporate policy, what is stated in the standard, and how the requirements of some elements of the standard might be interpreted by a certification body.     

Development of the Sludge Thermal-Drying Option for South West Water

Sewage-sludge production in South West Water is predicted to more than double, to about 50000 dry tonnes per annum, by the turn of the century. Staff of South West Water Services have carried out a strategic review of sludge utilization and treatment options, and have developed a strategic planning computer model to assist in the financial evaluation of the many options which are available. The strategy allows for the provision of new raw sludge thermal-drying facilities for the anticipated increase in sludge production.
Trials were carried out with an indirect dryer system to develop and investigate the operational issues and use of the dried raw product. The initial trial produced a fluffy, low-density material with poor storage and handling characteristics, apparently associated with the high-fibre content of the sludge. The process has been modified to include pelletization.