Why is the ammonia nitrogen level low and the pH high in water purified by acidic vapor stripping?
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This post was last edited by zxh6267 on 2009-8-15 at 10:15. In our water purification process using acidic vapor stripping (a single-tank, atmospheric-pressure stripping technique), the levels of sulfides have been below 10 mg/l and those of ammonia nitrogen below 20 mg/l – both values are quite low. However, the pH level remains around 9.5； Generally, high ammonia nitrogen levels are accompanied by high pH values. But what causes high pH values when ammonia nitrogen levels are not high? What substances might be responsible for this? Could someone give me some advice? Thank you!
Consider whether the dosage of the corrosion inhibitor used is too high.
Does the process used involve the addition of alkali? If so, the amount of alkali added is high, the ammonia nitrogen level is low, and the pH is high. If this process is not used, it is possible to measure the pH value of the acidic water from each unit separately; generally, the pH value of the hydrogen-added water is higher.
No alkali was added, nor were any other additives such as corrosion inhibitors used.
Generally speaking, problems with upstream devices may be more severe.
The key is to figure out what substance is causing it, so that appropriate measures can be taken to address the issue
It’s probably because the pH value of the upstream device itself is high; the pH value can be measured by taking acidic water samples from each device. It’s probably because they used too much corrosion inhibitor in their system.
The pH value of the acidic water used as raw material is generally between 8.8 and 9.3, but the pH value of the purified water is usually higher than that of the acidic raw material water. What could be the reason for this?
Is it the side-line ammonia extraction process? Was the ammonia not drawn out properly and dissolved back in the water? Otherwise, where would the alkaline substances come from to raise the pH value?
Ammonia is not extracted from the side line; the gas containing amino acids at the top of the tower is fed into the sulfur treatment furnace
This post was last edited by adsl121 on 2009-8-17 at 21:25. It is possible that the low temperature of the acid gas air cooler some time ago caused ammonia salts to crystallize in the pipeline from the stripping tower to the reflux tank; when the temperature of the acid gas air cooler increased again, these ammonia salt crystals dissolved, resulting in an increase in the pH of the purified water, with lower levels of sulfides and ammonia nitrogen