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RE: 4-cell municpal lagoon

Jerry — Thu, 19 Jul 2007 17:56:33 GMT

Timers would work also. Your alga growth during the day will supply oxygen. So set the timers to run at night.

Low DO in the second cell appears to be stratification(turnover). However if the blowers were running at all, this wouldn't be the problem.

RE: 4-cell municpal lagoon

TerryF — Thu, 19 Jul 2007 17:19:47 GMT

Peter,

You could put a variable speed drive on your floating aerator and then run the aerator only as fast as necessary to maintain a DO of say 1-2mg/l. The variable speed drive will use some power itself but the slower speed of the aerator will save much more if the speed can be reduced substantially.

Odour is obviously one quality measure but it would seem that your BODs are currently pretty good as well.

TerryF

4-cell municpal lagoon

Peter McCarthy — Thu, 19 Jul 2007 13:35:43 GMT

The local town has a 4-cell (equal volume) municipal aerated lagoon. Cells 1 and 2 are separated by baffel with window. Cells 3 and 4 are in separate in-ground basin, and are also separated by baffle. First two cells have diffused aeration. Third and forth cells have floating aspirators. DO out of 2nd cell has dropped to 0.6 mg/l this summer but no odor. DO out of 4th cell is 4 mg/l.

Town is interested in saving energy. They could turn second blower on feeding Cells 1/2 to provide more air, if required. Anyone with lagoon systems out there with similar DO. At what DO in Cells 1/2 or 3/4 would you decide to turn more air on in Cells 1/2? Would you use odor as your guide?

BOD removals over 90 % through ponds. Effluent TSS is less than 20 mg/l.