Ari,f I agree with most voted answer. Regards
I do not know biological systems used for heavy metal removal. As I colleague said maybe there are some metal that is incorporated to the cell and removed as excess sludge. But it hapens when we have exceptional conditions as pH, temperature, etc. I would recommend a chemical treatment followed by...
As some colleagues already said there is a difference between blowers and air compressors. May be you can share witu us dissolved oxygen content in the aeration tank, tank dimensions and type and flow per diffuser. With this information we can help you.
Regards
Ademar