Ten leading wastewater treatment plant manufacturers have joined forces to form an industry focus group within British Water. An independent and non-commercial panel, the group will work closely with the government and regulators, such as the Environment Agency (EA), addressing issues including best practice and compliance. Several initiatives will be launched during the year. The group will also contribute to the European panel.

Tom Stephenson, professor of Water Sciences at Cranfield University and a director of British Water, chairs the focus group. Talking exclusively to WWT, Professor Stephenson discusses the industry and the group’s aims.

Is the package treatment plant industry changing?

TS: Yes, things are changing in a very positive way. Ten of the leading package sewage treatment plant manufacturers have formed the independent Focus Group at British Water. They include Balmoral, Biwater, Clearwater, Copa, Conder, Hepworth, KEE, Klargester, Titan and WPL.
The group will be addressing key issues and driving the industry forwards in terms of best practice and compliance.
British Water is the leading trade organisation representing the collective interests of the UK water and wastewater industry, at home and overseas. One of the group’s first initiatives is to create a code of practice, for the loading of wastewater treatment systems.

What are the aims and
objectives of the code of practice?

TS: The code sets out a new, universal set of loading criteria for wastewater treatment systems. It gives guidance in assessing all types of loads and provides a consistent, sizing/data approach. In addition, it contains the best available advice and is supported by the leading package wastewater treatment plant manufacturers and by British Water.

How was the code of
practice derived?

TS: Available loading charts were examined by the focus group. Categories were redefined, data consolidated and collective expertise was used in their compilation.

What prompted its creation?

TS: There was a need for a code of practice that reflected current trends and lifestyles, provided a consistent message and presented data in a user-friendly format. Modern habits have changed and are no longer in line with textbook loading. As well as fulfilling these needs, the code is a positive contribution to reducing pollution from decentralised sanitation by considerably reducing the risk of under-sizing a plant.

Why does loading present such problems?

TS: Because wastewaters differ so much, from one site to another. Manufacturers can now provide consistent guidance notes to assist in the selection of a plant and the risks from under-sizing should be greatly reduced. Under-sizing leads to poor performance and can be hazardous, affecting the immediate neighbourhood and larger environment. Consents are becoming more stringent, as reflected in the recent introduction of ammonia figures in the loading guide, and compliance has to be the top priority.

What could a typical loading example be?

TS: Hotels provide interesting examples. If we take a four or five-star hotel and identify the nature of business – the number of rooms, quality of meals served, additional facilities like a leisure and health suite, laundry provisions – adding up these activities gives base criteria from which a manufacturer can recommend a plant. Compare these results to motorway accommodation
that just provides a basic meal, and you have two very different specifications.

So when sizing a plant, are there any golden rules that should be followed?

TS: Yes – declare everything. Don’t be tempted to under-size, always design for the maximum load. You should always consider the future potential of your business and look at every activity on site. Most plants will be in the ground for 20 years or more and the business could change an awful lot in that time. It is simply a false economy to under-size and select on lowest capital cost. All aspects of maintenance should also be considered for the life of the plant.

In addition to under-sizing, can any other factors affect a plant’s performance?

TS: Modern detergents and cleaning agents can be detrimental to performance. Treatment plants are based upon biological processes and while they can deal with a certain amount of products in reasonable quantities, large doses of any chemical can be a problem – for example, in the case of heavy laundry usage. Such applications need to be considered at design stage.

Who is responsible for
ensuring a plant meets its consents?

TS: The person whose name is on the consent is wholly responsible for sizing, professional maintenance and for the removal of sludge by a licensed waste disposal contractor. Most people do not realise this.

How will the code of
Practice benefit the end user?

TS: If best available advice is followed, the end user will benefit from a plant that is fit for the purpose. The system should perform well, without creating odour or unsightly pollution, and fulfil all expectations – now and, hopefully, in the future.

Will the focus group be
introducing any other

TS: Yes, there are several others in the pipeline. The group is currently putting together a servicing code of practice, which should be available to all engineers before the end of the year, incorporating a training programme for service engineers. It is also providing input to a European group, which will have an influence on the new European Standard

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