For quantifying odours, the two most common parameters are hydrogen sulphide and the odour unit. The available knowledge about both these parameters lacked a sound scientific basis and their relevance to sewage treatment was not understood. This lack of understanding caused the water industry to unnecessarily escalate spending on odour abatement, and this spending was set to increase because local authorities are adopting tougher, quantitative standards based on one or both of these parameters.
The project, undertaken by WRc in conjunction with six water utilities, provided a scientific basis for using and interpreting odour parameters in sewage treatment so that intensity and offensiveness of odour is taken into account in setting abatement objectives. The guidance on use of common odour parameters relevant to sewage treatment is essential to avoid dramatic and uncontrolled increases in capital spending. The outcome also contributed to reducing the growing costs of odour monitoring by enabling better application of low cost monitoring techniques.
The study established a more scientific approach for setting and evaluating odour standards. This has helped significantly in minimising capital investment required for odour control and allow local authorities to set odour targets that are justified and achievable without the need for massive capital investment. The study also reduced current monitoring costs by indicating those conditions under which it was possible to use the cheaper sulphide monitoring for quantifying odour problems.