Faced with a problem here at work

[NOT A TA]

First I'll ask if the testing indicates Alum or Aluminum since Aluminum bisulfides (Alum) used in processing is tested for and may be what the test results are showing.

If it is aluminum. You can drop the aluminum by lowering the PH with an acid and raise up the Ph after the drop with a caustic. How big are the aluminum particles? Have you been using any chemicals to treat the water? Are there any sections of aluminum pipe that have chemicaly treated water moving through them? If treated water with low PH is run through aluminum pipes it may be causing the problem.

My initial questions were aimed at discovering the possible sources of the aluminum. Long term, it would probably be more cost effective to snub the source than continually treat for something that might be easy to eliminate at the source.