Iron Sludge Holding Tank

[bccwwes]

Looking for options to fix an iron sludge holding tank for a water treatment plant ahead of a sludge press. The existing tank has a 22 deg sloped bottom and the inlet is turned 90 deg to try and mix the incoming flow from the treatment plant (clarifiers and filter backwash). When drawing sludge to the day tank for the press the tank has a tendency to "rat hole" quickly. Thick sludge feeds briefly then watery material.

Options under consideration include mechanical mixers to mix and then resettle the tank periodically, air mixing of the tank and installing a bottom scraper system.

Any thoughts on these options? Any other suggestions?

 

[bimr]

If you have a large installation, then a continuous flow thickener would be appropriate.

Lacking a sludge scraper, 55 degrees is the typical minimum angle of repose for solids.

For a small operation, you probably would want a batch operation using a tank to decant the dilute wastewater.

Perhaps a large bulk tank with mixers to keep the solids in suspension. You could then pump to a smaller tank with conical bottom where you can decant off excess water before dewatering.