Bubble Diffuser for WWTP

[aida2011]

Dear all

I have installed bubble diffusers to replace surface aerators for our WWTP. This is one of the cost saving initiative since bubble diffusers consume less energy than surface aerators. However, after using bubble diffusers, the results of WWTP had turned bad, prompting us to run aerators as backup. According to the supplier, the air from blower is more than sufficient to maintain the bacteria.

My question is, the air from blowers is very hot, which is 90 deg.C. Can this hot air kill the bacteria under water? What should be the temperature of air?

Thanks

Miss Aida Hanani
Malaysia

 

[bimr]

The air is heated from passing through the blower. The air is generally cooled by the time it passes through the pipes and enters into the aeration basin. In any case, the amount of heat is not substantial and will not change the temperature of the wastewater which should be a maximum of 35-40°C for the activated sludge process.

Generally, the volume of air supplied for mixing (to maintain the solids in suspension) is greater than the amount required for biological treatment. The minimum air volume required is generally 37 cubic meters/minute per 1000 square meters of aeration basin floor area. As an example, if your basin is 5,000 meters square, than you need a minimum of 185 cu m/min of aeration.

To advance diffuser projects, salespeople will sometimes promote the aeration requirements for the biological process rather than for mixing. That is misleading at best.

You should also have some spare diffuser capacity as there will be a loss in capacity as the diffusers foul.

 

[aida2011]

Dear Bimr

Thanks for your insightful answer.

So, the bacteria most likely did not die due to the hot air. Actually I was planning to install aftercooler (using cooling water) after the blower to cool down the air, so thanks for your reply, probably I need not to, or need to study further.

In your opinion, which is better, individual pond aerators or bubble diffusers?

Best regards

Miss Aida Hanani
Plant Engineer

Malaysia

 

[bimr]

The pond aerator would probably have less maintenance, but again, you need adequate power to keep the solids in suspension.

 

[geesamand]

Pond aerators can vary widely in performance.

Is it a pond, or concrete ditch? What kind of aerators did you have before?