Aeromonads in Drinking-Water Supplies: Their Occurrence and Significance

Traditionally, bacteriological monitoring of drinking-water supplies has focused on the detection of Escherichia coli and related coliform bacteria. However, attention has recently been given to the occurrence of biofilms and associated organisms which occur in distribution systems. One group of bacteria which have been isolated from water supply systems are the Aeromonads. This group is gaining increased recognition as they have been implicated as causal agents of gastro-enteritis in humans and are indicators of regrowth potential. In order to obtain a better insight into these organisms and their relationship with other parameters, a number of laboratory and field-based studies were undertaken. These included (a) comparison of isolation media, (b) examination of biofilms, (c) temperature growth studies, (d) toxicity testing, and (e) sampling and analysis at treatment works and in distribution systems.     

Integrated Catchment Management Planning

Catchment management plans represent the National Rivers Authority's vision for the water environment. With the National Rivers Authority being organized by hydrological regions, the catchment is seen as the natural management unit, and catchment plans offer the means to integrate the Authority's work programme with those of other agencies. Catchment plans summarize relevant data and include an agreed action programme to optimize catchment uses, produced after wide consultation; they complement local authority statutory plans, are current for five to ten years, and will be reviewed regularly during this period. The catchment planning process is seen by the National Rivers Authority as a medium for promoting discussion, resolving conflict, assigning priorities, and setting targets by which progress on key issues can be monitored.     

The Health Effects of Low-Contact Water Activities in Fresh and Estuarine Waters

Four studies were carried out at separate locations to investigate the relationship between health effects and low-contact water sports, and intensive microbiological sampling was conducted in parallel to the health studies at each site. The two sports examined were marathon canoeing and rowing.
The extremes of water quality were at the estuarine sites on the River Torridge, where pollution levels varied from a geometric mean faecal coliform value of 62/100 ml at the Appledore/Instow site to 4613/100 ml at the Bideford site.
A comparison of 'exposed' and 'unexposed' groups, 5–7 days after exposure, showed that the health effects of low-contact water sports are minimal, within the water quality ranges which were studied.     

The Sirofloc Process at Redmires Water-Treatment Works

The first use of the Sirofloc process in an operational water-treatment works, outside Australia, was commissioned in 1988 by Yorkshire Water at Redmires, Sheffield. The plant represents a major advancement in the development of a new type of treatment process for drinking water.
This paper describes the new treatment process and the method and reasons adopted in developing a full-scale plant. The first four months of operation are reviewed, with particular attention to the water quality produced and the performance of the plant. Further areas for development in improving the performance of the process are identified.     

A Replacement Outfall for Peterhead

The paper describes the design and construction of an outfall into Sandford Bay, Peterhead, on a highly-exposed stretch of the NE coast of Scotland.
The outfall forms part of a drainage system that was installed in the early 1970s to reduce pollution in Peterhead Bay and to accommodate increased flows from oil-related development. It replaces the original outfall, which failed in 1979 due to wave action.
Stability of the new steel-pipe outfall, which was installed by the bottom pull method, is ensured by burial within an excavated rock trench, backfilled and armoured with graded stone.
The exposed location of the site was demonstrated during construction work when bad weather and adverse sea conditions delayed completion by one year.
The paper concludes that the full significance of prevailing sea and weather conditions, and consequently reduced working 'windows', should be taken into account in the planning and programming of outfall work, to reduce the risk of damage to a partially completed and unprotected outfall.     

Controlling Nitrate Leaching in Water Supply Catchments

S prings from a catchment to the north east of Bath to provide up to 80 per cent of the water supply to a population of 96 000. A review in 1984 suggested that within a few years nitrate concentrations in these sources could exceed the limit for drinking water (11.3 mg N/1). Nitrate was being leached from agricultural land and when an opportunity arose to alter the largely arable farming on part of the catchment, guidelines were devised to reduce nitrate leaching. This paper describes the guidelines and the effects of their implementation.     

Effect of semi-rigid connections on steel column strength

A review has been made of all available experimental data relating to the moment versus in-plane rotational behaviour of practical beam-to-column connection types as used in steel frames. This has clearly shown that all forms of connection possess some stiffness which will act as partial restraint to the column's ends. Moreover this restraint has been found to be a non-linear function of connection deformation. Methods of mathematically describing connection data have been reviewed and an improved representation based on the use of cubic B-splines proposed. This possesses the advantage that it will not give an (incorrect) negative connection stiffness. Using this technique to model connection behaviour a computer program for the maximum strength analysis of steel columns has been written. This is based on a Newton-Raphson incremental finite element approach and incorporates features such as initial lack of straightness and spread of yield through the cross-section including the effects of residual stresses. The results of some preliminary analyses, which demonstrate the increases in column strength and reduction in column deformation that result from a consideration of actual joint behaviour, are presented.     

UK Drinking Water: A European Comparison

Introduction of the drinking-water Directive has resulted in a much more quantified approach to drinking-water quality. Increased attention from environmental groups and the media, together with occasional breaches of the limits, have resulted in a loss of confidence in the product. Infringements depend upon the stringency of the limits and the quality of available raw water. The UK is one of the few EC countries having to use a high proportion of surface water. The Directive has now been fully implemented in all member states, but information on compliance is poor. Only the UK and Ireland produce compliance reports. Published papers indicate that infringement problems exist throughout the Community, particularly for pesticides, nitrate, lead, coliforms and iron. Nevertheless, drinking water is of very high quality within the EC, and UK supplies compare very favourably with the rest.     

Changes in Plant community at Foxcote Reservior Following Use of Ferric Sulphate to Control Nutrient Levels

I n an attempt to control planktonic algal growth in I n an attempt to cosntrol planktonic algal growth in Foxcote water supply reservoir, which is supplied by eutrophic waters from the river Great Ouse, ferric sulphate has been used to reduce ortho-phosphate concentrations in the pumped inlet water. Internal recycling of sediment-bound nutrients retarded the expected algal control for almost three years. During the third year, a marked change in the ecology of the reservoir occurred, and planktonic algae were largely replaced by prolific growths of filamentous species and rooted macrophytes. While the changed flora have caused their own problems, the reservoir is now less prone to closure due to intractable water treatment problems.     

The potential role of biofuels within the built environment

For most of man's life on earth the bulk of his energy needs have been met by the combustion of wood. The advent of the Industrial Revolution and the mining of coal in 18th century England led to dependence upon initially fossil, and later fossil and fissile, fuels within the industrialized nations and fuelwood consumption rapidly declined. Biomass (organic plant matter) has, however, continued to provide the main energy supply to the developing world.

With the present day necessity to conserve fossil fuel reserves, particularly oil, renewable biomass energy sources are' once again being examined with everincreasing interest, both in the West and in Communist bloc countries, as well as in the Third World. The potential contribution of biofuels (fuels derived from biomass) within both developed and developing nations is examined, particularly with respect to their utilization within the built environment.