Do you have an ‘air to water’ cooling tower for your glycol cooling system? Most small breweries do not (they use ‘air to air’ coolers), but you’ll know it if you do. It’s a big rain storm in a box with a big fan outside near your glycol chiller.
The idea behind these ‘air to water’ cooling towers is to cool water used to cool the refrigerant used to cool the glycol. 3 closed loop systems!
The water loop in a system like this is an ideal breeding ground for bacteria, algae, and mold. So we add a ‘biocide’ to the water to inhibit growth of these nasties. If these were allowed to grow they will create a slime on the heat exchange surfaces leading to a decrease in energy efficiency. These slimes can even plug the water tubes inside the chiller.
So, my point of all of this is these biocides can be a significant problem for a wastewater treatment plant, especially if the brewery has their own treatment system.
Packaging line conveyor lubricants can also pose a similar problem. We don’t want the conveyors becoming slimy with growth, so often times the lubricant will come with a growth inhibitor.
What can you do about it?
- Use these chemicals at recommended concentrations. This saves money in chemical cost as well as downstream savings at the treatment system.
- You can talk to your chemical provider about other options that are maybe less toxic to your wastewater system.
- Another option is to not send these waters to your wastewater plant. Send them straight out to the sanitary sewer if possible.
The point is to be aware. Trace amounts of biocide in wastewater can lead to odd problems with unknown origins in a wastewater plant.