The smell says it all 

The cool, neutral air in the laboratory immediately puts all your senses at ease. The heat and humidity of Kuching's tropical climate keeps one’s olfactory senses constantly on alert, so the refuge of the lab provides a welcomed if unexpected relief. We are in Malaysia's first odour laboratory, and here a neutral atmosphere is an absolute necessity.

The laboratory has been established as part of the implementation of an environmental management system in Kuching, an important aspect of which is to regularly monitor the results of efforts to improve the environment. In Kuching there is a particular focus on improving water quality in the heavily polluted River Sarawak and its tributaries.

Inexpensive method of measurement

COWI's Ib Larsen, Chief Technical Adviser for the environmental management project, comments: "At present chemical analyses of the water are made in the river, but if the monitoring programme is to be expanded to the entire city drainage and sewer system then more economical monitoring methods are needed. The water – especially in drains and tributaries – smells. And the smell indicates that pollution in the water is at a serious level. Until we here in the laboratory can say that the water no longer smells, there is no point in implementing costly, complex chemical analyses."

In collaboration with Danish company dk-Teknik, the project has therefore developed a simple monitoring method whereby once a month a group of test persons sniffs the water samples that have been collected from drains and watercourses.

Odour limit values

The only equipment used in the laboratory is a table, some brown glass bottles and a few measuring beakers. The odorous water is mixed with clean water in a variety of concentrations in the brown bottles, which individuals from the test group then sniff to determine at what concentration the smell completely disappears. An advanced computer program compensates for any variations in olfaction on the part of the individual test persons. In this way the odour limit value, or TON value, can be determined.

Adds Ib Larsen: "What matters is to find a monitoring method which can follow the quality of the water in the easiest, cheapest way, but which at the same time is reasonably reliable. In Denmark we would consider a TON value over 50 to be excessive. Samples from the drains in some of Kuching's wetland areas show TON values up to 6,300. That is the equivalent of taking 6,299 bottles of pure water and mixing them with one bottle of waste water – and still being able to smell it."

"The smell is the right place to start. If odour monitoring results show a drop of 50 per cent, it reasonably indicates that pollution has fallen by a similar amount. The day that the water no longer smells will be the day when we can say that we have already come a long way. But only then does it make economic sense to adopt more sophisticated monitoring techniques of actual pollution levels."

Published: 27.10.2004
By: Janne Toft Jensen, jaje@cowi.dk