Acetic acid and methyl acetate are the main suspects when we talk about odour nuisance. Acetic acid especially has a low odour threshold value; in other words, you don't need much of it to cause odour nuisance.
However, the fact that you can smell it and experience it as being unpleasant does not mean that it is a harmful. The odour of acetic acid with which the site is associated with from time to time is neither harmful nor poisonous. It is comparable with a concentrated form of household vinegar. But the odour is unpleasant and as a result, undesirable.
One of the major causes of odour nuisance results from the water treatment plant. This mainly occurs during the fist stage of the process, in the buffer basins. Here, the fairly warm waste water flows together and is mixed rather intensely. Possible residual volatiles may then cause odour nuisance.
Production units too can attribute to the odour nuisance. Incidents inside the plant such as leaks can also cause odour nuisance.