Monitoring waste odours

People really notice unpleasant smells and will complain if there is a problem. Its vital that waste companies monitor odour emissions from their sites to rectify any potential issues before they become a nuisance.

The Environment Agencys biowaste sector performance report, published earlier this year, revealed that odour was the main reason for the breach of permits in the biowaste industry in 2011. Plus, a number of large organics recycling companies have recently faced or are facing legal action about the odour levels at specific sites from the public.

The most useful odour testing technique for the waste management industry is the human nose which is UKAS accredited and recommended by the EA. This method is better than chemical testing because the human nose can detect lower concentrations of odour from mixed organic waste processing plants such as composting sites. Plus, the results provide direct feedback about how smells are perceived by people which is particularly beneficial in odour nuisance cases.

Sampling

Odour samples are taken from the source of emissions on-site and sent to laboratories that specialise in the human nose technique. The samples are presented over a range of dilution settings to a group of six panellists simultaneously alongside an odour-free gas as a reference point. The panellists are asked to report how sure they are that they can smell anything from the gases emitted from each sample. The responses of the panellists from the range of dilution settings are used to calculate the concentration of the odours in internationally recognised European Odour Units.

If the panel finds the 50% odour detection threshold and the levels are in breach of the sites permit are detected, the site should take investigative action. To manage odour levels on an ongoing basis, companies in the waste industry can use the human nose test to measure the efficiency of the systems used to reduce odours such as biofilters.

Utilising the human nose in odour monitoring sounds old fashioned, but it is actually an accurate and effective technique. It is being used more and more in the waste management sector and is useful because members of the public detect odours coming from waste sites via their sense of smell.