Wet well aeration

[Fred3]

I'm new to wastewater and I was wondering about the ups and downs of lift station wet well aeration. I have heard that some cities are doing this, but there's not a lot of info on the internet about it. I did find a discussion on eng-tips from 2002 and it looked as if it was unheard of at that time. My thoughts are:

ups
1. prevent it from turning septic
2. prevent grease cap from forming
3. decrease BOD at plant headworks

downs
1. cost
2. strip out more H2S and cause more odor issues

And I was wondering what the oxygen content of air is before and after it is blown though an aeration basin. If it is still relatively high O2, would it be wise to inject the "used" air from the wet well into the force main to further aerate the pumped sewage and remove the fowl air from the wet well?

 

[theci]

No matter what the Oxygen concentration is in the air, you can not inject air into a forcemain because (1)a forcemain is designed for fluid only, and injected air will compete with fluid flow; (2) injected air will not aerate sewage much since injected air will tend to stay together as air pockets, to aerate you need some kind of diffuser; (3) air in forcemain may cause forcemain and pump failure; etc.

To me,

Ups:
1. prevent it from turning septic
2. prevent grease cap from forming
3. decrease BOD at plant headworks (This is not really a benefit in my opinion becuase it will not decrease BOD much with so low biosolid concentration existing in the wet well.)

Downs:
1. cost
2. strip out more H2S and cause more odor issues (Increase air flow rate of odor control system)
3. Dissolved gases in water may cause cavitation and then damage pump.

theci