Biological wastewater treatment usually works best in a pH range from 7.0 - 8.0. Remember that this is the "best" range in a general sense. In making bioaugmentation products, we have used strains with pH ranges from 3.0 (Thiobacillus) to 11.0 (alkanophilic Bacillus).
The most pH sensitive process tends to be ammonia removal or nitrification. Ammonia Oxidizing Bacteria (AOB) do best at a pH of 7.2 - 8.2 where the free ammonia (NH3-N) is present but is still soluble in water.
Now for pH adjustment - most systems use strong chemistry:
So remember that you have choices in adjusting pH and buffering the system. Alkalinity or buffering capacity is a key consideration in wastewater treatment especially if you require ammonia oxidation. AOB/NOB activity consumes approximately 7.1 mg alkalinity as CaCO3 per mg ammonia fully oxidized. Other processes in the nitrogen cycle can release alkalinity back into the water.
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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