Disinfection using chloramines is a very effective way to treat water because the process offers extended disinfection into very long distribution networks. Chloramination also helps reduce the formation of trihalomethanes (THM's) in the water treatment process caused by reactions with organic materials. It also lessens taste and odour concerns.
Chloramination involves the addition of chlorine and ammonia, typically at a 3-5:1 ratio. The ammonia can be added before chlorination, concurrently, or after chlorination. Additionally, the greatest formation potential for chloramines is between pH 7 to 8.5.
There are some limitations with chloramination including:
They do not oxidize iron or manganese
They are less effective at high pH
They must be produced on site
Excess ammonia in the distribution network may cause nitrification; not enough ammonia causes the production of undesirable dichloramines
Metcon Solution Metcon can provide a complete metering and control solution for chloramination. One of the highlights of our offering is the advanced chloramination controller from ASA - Chemscan. This analyzer is designed specifically for the application is unique because it measures free ammonia, true monochloramines and total chlorine. This takes a lot of the guess work out of setting up chlorine to ammonia ratios as it continuously provides the control and feedback to regulate ammonia feed.