Anaerobic Bacteria

Question:

We are continually having a reoccurrence of anaerobic bacteria in our system. We dumped the entire system, thoroughly cleaned it with peroxide, and months later, we are there again. One of my arguments is heat in the first stage (phosphate). Range is 90–140°F and it might average 108°F. I am arguing that temperature should be at least 130–135°F. Also, have some dragout issues into the other stages, especially rinse stage. Can you offer any advice on this problem? Am I correct in assuming part of the problem is a temperature issue with the sludge and low temps providing a breeding ground for the bacteria, especially when there is carryover to the rinse stage (ambient temperature)? Any help would be appreciated. C.L.

Answer:

The first step to the elimination of any bacteria problem is to dump the existing system and make sure it is given a very thorough cleaning that includes bleach and a final rinse at the end. I am not sure if peroxide is strong enough to kill all the bacteria, especially if it is just a consumer-grade hydrogen peroxide. Careful attention will have to be given to recesses and corners that would normally be more difficult to access. Without this, it is likely the problem will continue to come back.

You are correct to consider temperature. Many microorganisms will thrive in warm areas, while they may not survive in a hotter environment. This could be all you need, however, some bacteria can live at extremely high temperatures.

Another means of combating anaerobic bacteria is to add oxygen to their environment. Air bubbling into the tank may be enough to keep the dissolved oxygen at a high enough level to eliminate the bugs. This could present problems with an immersion tank due to foaming, but it could be possible to either change to a lower foaming cleaner or use an anti-foam until you are sure you eliminated the problem.