pH lower in aeration process

Question

We are facing pH issue in STP water aeration tank. Feed pH: 7.5 after entering water in aeration process it down up to 6.0 , normally in aeration pH goes little up.

Gary Brown · Accepted Answer

Hi, you may be observing the effects of nitrification (conversion of ammonia to nitrates under aerobic conditions) since alkalinity is consumed. If the inflow alkalinity is low and is also being consumed, the pH can decline
check out these parameters, you may need to add alkalinity, typically lime or soda ash, 
if you have the knowledge and capabilities, you can create anoxic conditions and stimulate denitrification, this counters alkalinity consumption during nitrification
good luck

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