Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Subs' cleaner sewage system under trial

A SEWAGE treatment process developed by consultant Pell Frischmann is to be trialled for use in nuclear submarines, which must meet new NATO restrictions on effluent discharge.

The UK Ministry of Defence believes Pell Frischmann's catalytic wet air oxidation (CWAO) technology could help meet new NATO environmental standards.

These will place tougher limits on emissions from naval ships when they come into force next year.

Space aboard fighting ships is at a premium, so the Royal Navy is looking for the most lightweight and compact treatment process possible.

Pell Frischmann project director Chris Sweeney said that it is also looking for an automated process.

Pell Frischmann's CWAO involves heating sewage or bilge water contaminated with oil at temperatures of 200infinityC to 250infinityC. It is pressurised at 70bar to maintain it in liquid state.

The effluent is then passed over a catalyst which triggers rapid oxidation. After 10 to 30 minutes chemical oxygen demand is reduced from 40,000mg/litre to 30mg/litre, with contaminants converted to CO 2and water.

The technology was developed by British Gas (BG) to treat effluents produced on offshore gas platforms in the North Sea.

It has been taken forward by Pell Frischmann, which bought BG Technology's water process business in 2000.

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.