Re: Activated Sludge Process plants

Activated sludge plant:  This type of secondary sewage treatment involves
cultivation of sewage-eating microorganisms.  The waste is aerated and
allowed to settle as the bacteria digest the sewage and form aggregates.
These aggregates settle out of the tank.  Some of this "activated sludge"
is then used to inoculate a new batch of the sewage from primary treatment.
The remainder is landfilled, as it is no longer acceptable practice to
send this sludge to the ocean.

Tests:  Microbiological tests typically involve counting of Total bacteria
and Viable bacteria in various stages of the process.  Chemical and
physical tests are usually performed to make sure the microorganisms are
getting enough of the needed nutrients and that they are growing well:
Oxygen content, permanganate, organic nitrogen, suspended solids, optical
density.

For more info, see Atlas, R.M. and R. Bartha.  MICROBIAL ECOLOGY.  Benjamin
Cummings Publishing, Menlo Park, CA.  (2nd edition, 1987)

Good luck!

jackie