Report No FR0060

APPLICATION OF CONTOUR MAPPING OF HYDROGEN SULPHIDE
LEVELS TO ODOUR CONTROL AT SEWAGE TREATMENT WORKS

Feb 1990

SUMMARY

I OBJECTIVES

A major objective of the work is to investigate the suitability of using low level hydrogen sulphide readings to produce a map of odour around a sewage works. It is hoped that by studying the relationship between hydrogen sulphide levels on the site and hydrogen sulphide levels in the downwind plume it will be possible to identify the major source of odour on the site.

It was also necessary to develop techniques for analysis of the data to produce contour maps of hydrogen sulphide levels.

II REASONS

Methods of identifying odours and their causes on sewage treatment works are available. However, a more quantitative approach to the process would be ideal. A major difficulty arises in determining the odour emission rate from area sources. An alternative is to develop a method of measuring the dispersion pattern of odorous plumes from a works which can be related back to the emission rate E. Additionally, if a profile is produced with sufficient resolution, it should be possible to use it as a tool for pinpointing sources of odour production.

III CONCLUSIONS

This technique allows us to identify sources of odour and the dispersion patterns both around sewage treatment works and the surrounding areas. As yet no attempt has been made to evaluate emission rates from the contour profiles, but the method of identifying odour sources has been refined.

IV RECOMMENDATIONS

WRc recommends that this technique of analysing the dispersion of odours be used in investigations into odour problems on wastewater treatment facilities.

V RESUME OF CONTENTS

This report describes a method of illustrating the dispersion patterns of odorous gases from a series of sources on a sewage treatment works. The experimental procedure is detailed and the limitations of the computer model used are outlined.

Two treatment works were visited and the results of these site investigations constitute the main body of the report- A discussion of the results highlights the effectiveness of the contour profiles in identifying sources of odour release on the works.

Limitations of the technique are discussed and some possible improvements are suggested.

Copies of the report are available from FWR, price 15.00, less 20% to FWR Members.