SMALL SUPPLY SYSTEMS EFFECT OF VARIABILITY OF RAW WATER QUALITY Final Report to the Department of the Environment 667-S DoE Contract PECD 7/7/198
Report No DWI0014

Mar 1988

EXECUTIVE SUMMARY

Every processing plant operating as an independent unit, whether it is a waterworks, sewage works, engineering factory or retail warehouse, needs to be able to handle a varying load. Every kind or business is under continuous pressure to improve economic efficiency. The key to success lies in Providing the right combination of capital equipment, operational resources and stock holding together with a management system capable of achieving optimum results under all conditions. If the load is well enough characterised, it should be possible to predict the performance to be expected under different conditions and to set performance standards. It may even be possible to contemplate an allowable degree of under-performance or even an acceptable failure rate at times of peak load.

The concept is not new, but it was this which prompted the initiation of this research related to small water supplies.

This is the second of two related reports. The first reviewed what was known about the variability of water quality at small supply sources. This report reviews treatment processes appropriate to small supplies and how they may be selected according to the nature of the source.

It has been found that in the design of small treatment works, there is no systematic methodology for describing the variability of raw water quality and only the most rudimentary methods of selecting processes and designing plant to take account of the variability of the source. The same situation is found in the design of large waterworks and indeed of process plants of all kinds. In many process industries the approach is to control feedstock quality or, where it is a natural material to homogenise it. It has been found that variability is so little regarded in the design or process plant that even an adequate means of describing it does not exist.

The report makes suggestions for further work, not necessarily to be sponsored by the Department of the Environment.

Copies of this report may be available as an Acrobat pdf download under the 'Pre 2000 Reports' heading on the DWI website.