the main pollutantsReading time:
Exept for very specific IWW cases, odorous compounds emitted by water treatment systems fall into four major groups :
- reduced sulphur compounds :
- hydrogen sulphide : H2S;
- mercaptans : CH3SH…;
- organic sulphides : CH3–S–CH3, CH3–S–S–CH3 (for the most common)…;
- nitrogen compounds :
- ammonia : NH3;
- amines : CH3NH2, CH3–NH–CH3 (for the most common)…;
- volatile fatty acids :
- e.g. formic and butyric acids;
- aldehydes and ketones.
Both reduced sulphur and nitrogen groups are responsible for the strongest smells found in urban water treatment plants that are not operated in conjunction with any industry or with sludge heat treatment. In the latter case, there may be strong odours caused by aldehydes.