We have a problem with a very rapidly growing slime build up that has been shown to consist of fatty acids. We treat pulp wastewater. It grows during TMP production but not BCTMP production. We think its the use of Hydrogen Peroxide during BCTMP production that inhibits its growth. It can be seen growing on the primary treatment influent coarse filter and also in the DAF clear water tank. The main concern however is that it grows on the fill of our equalisation tank cooling tower (led to the collapse of the cooling tower in 10 days of operation!). Has anyone any experience with this and how to treat it?

Thanks

Agree that it is probably bacterial polysaccharide/gluten slime  - this can be dissolved using a hydrolase enzyme additive or by oxidation (electrolytic; hdyrogen peroxide, permanganate, etc). Chemical oxidation priorto main TMP treatment would probably be counter-productive - so I'd look at the enzyme addition as it should not adversely affect the TMP process.

JKD:

I have dealt with this many times, only a few times in a cooling tower, but most often in equalization tanks and aeration basins. It is due to high bacterial growth on starch and fermentation of this to organic acids (fatty acids).  Nutrients (nitrogen and/or phosphorus) are probably low before nutrient addition, so the "slime" is a polysaccharide build-up due to low nutrients. You will need to control this using an oxidant like chlorine or peroxide. Some mills use a high pH shock (pH >9) regularly (every week or two) to control this.

Hope that this helps.