Bad_Odour

Aeration
By aerating the water sufficiently it is possible to blow off the hydrogen suphide. While this method is usually more costly in terms of the initial capital outlay on the necessary equipment such as pumps, especially for domestic applications, the advantage is that it is a low maintenance system and no chemicals are added to the water. Basically the water is pumped through a fine nozzle to create a spray of fine droplets in a tank where fresh air passes through the spray and the hydrogen sulphide can escape to the atmosphere. The spray water is collected in a storage tank and if necessary can be filtered further should there also be iron in solution in the water that precipitates out when the water is aerated. Alternatively the water in the storage tank can be allowed to stand for a period of 24 hours during which iron precipitate will settle out of the water and the sludge can be drawn off through a valve at the bottom of the tank from time to time.

Chlorine Dosing
The hydrogen sulphide can be precipitated out o solution using a strong oxidative agent such as chlorine introduced into the water by means of a dosing feeder which is basically a pump dosing the required amount of chlorine for a particular flow of water. The water will need to be retained in a storage tank for at least 24 hours to allow enough time for the hydrogen sulphide to settle out. Filter will be required to remove both the precipitate in the water as well as the added chlorine which is typically removed using am activated carbon filter. Apart from the extra control required to run the dosing feeder, one disadvantage of this method is the possible production of trihalomethanes that can be produced by chlorine coming into contact with organic material in the water. Trihalomethanes have been suspected as possibly being carcinogenic. To reduce the chlorine requirement the water can be aerated first as in the previous method. An advantage of this system is that if there is also iron in the water it will definitely also precipitate out together with hydrogen sulphide.

Potash Filtration
A filter containing the inorganic chemical compound potassium permanganate (KMnO4), a water soluble salt and strong oxidizing agent, can be used to oxidize the hydrogen sulphide to precipitate it out of solution. Sometimes chlorine is used in the filter instead of potassium permanganate but in both cases it is usually difficult to ensure a uniform rate of removal of hydrogen sulphide as the oxidant will gradually become exhausted and if the amount of hydrogen sulphide in the water varies it can give inconsistent results, especially as the removal rate is generally quite low in the first place. Again, the chlorine and the potassium permanganate will need to be removed from the treated water using an activated carbon filter as potassium permanganate is very easily leaves stains that are very difficult to remove.