Activated Carbon & Chloramine Combine to Cause Odor Issues
By: Michael UrbansWe recently had a troublesome water odor problem. We used Calgon F-600AR+ activated carbon for the treatment of PFAS/PFOA in a North Carolina community. The water was odor free prior to treatment but within a couple months it developed an objectionable odor similar to H2S.
After many phone calls with our frustrated dealer, we turned to our supplier, Calgon Carbon, for answers.
Highlighted below is Calgon’s response:
- Retained samples were tested for H2S Peak Release and the results were 0.2 ppm.
- With time, GAC filters can turn biological – a biofilm grows on the surface of the media.
- The microbial communities found in these biofilms are a function of the water matrix the filters treat.
- In this case, the influent water was potable water with chloramine disinfection residual.
- Water sources with chloramine typically have elevated levels of ammonia/nitrate in the water due to the use of chloramines.
- When chloramines come in contact with the GAC, the oxidant is quenched and the nutrients in the water then encourage biological growth.
- The likely cause is sulfur reducing bacteria establishing itself on the GAC media and then leading to the formation of hydrogen sulfide. Hydrogen sulfide is the “rotten egg” smell waters can sometimes emit.
Our customer replaced the coal base, F600AR+, with catalytic coconut carbon and the problem went away.