Ours does the exact same thing. We call it the ammonia "ball" We have had to go in the pipe every few months and chisel it out. From our understanding it is the hardness coming out due to the pH change. We switched to ammonium sulfate in hopes to correct this problem.
Do you have results of the switch yet? I'm going to guess that your change will do the trick. Ammonium sulfate is acidic so you shouldn't be doing any calcium precipitation.
I work in the industrial world and have worked in WWT and other parts of our processes. We have many scrubbers that need NaOH added to maintain pH. In our plants with high water calcium we always get gypsum buildup from doing essentially cold lime softening. During maintenance down days in our process we add citric acid to the scrubber water and recirculate that for hours. Organic acids like that are good at removing the calcium buildup. Our scrubbers are high in sulfate based on the process so gypsum (CaSO4) is our problem.
Im at a drinking water plant. The injection pipe goes straight from the raw tank to the treated tank so we would not 1. be able to circulate acid for hours. 2 we wouldn't have anywhere to put the waste (acid) afterwords and 3 same with waste... trying to flush said pipe to remove acid would also be problematic as again it goes straight into finished tank that then goes straight into the distribution system.
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u/watergatornpr 2d ago
Ours does the exact same thing. We call it the ammonia "ball" We have had to go in the pipe every few months and chisel it out. From our understanding it is the hardness coming out due to the pH change. We switched to ammonium sulfate in hopes to correct this problem.