Sump Agitation

[NOLAengineer]

Hi everyone,

I've been asked to help resolve a solids build-up issue in a sump pit that collects a slurry stream from the plant's river water clarifiers. Attached is a drawing with the sump dimensions (25x25x15) and the pump location. The normal liquid level is ~5ft above the sump floor. The suction basin for the pump is approximately 4' below the sump floor. The pump is a Hazleton Vertical Slurry Pump. Currently, there is a separate line diverted from the pump discharge to the pump suction area, but it doesn't seem to have prevented the solids from settling around the pump suction.

In order to prevent the solids from settling in the sump, I'm conisdering installing an agitator or a perforated pipe at the bottom of the sump whose water flow will suspend the the solids in the river water. Does anyone have any recommendations for one over the other? I'm concerned that the pipe could become plugged from the solids. Does anyone have any hydraulic agitation design literature or any literature approximating the amount of fluid needed to agitate X amount of ft3? Any information would be greatly appreciated.

Eric

 

[cheute79]

I have no literature to offer, but perhaps a water treatment equipment vendor will. I suggest, however, that you know your sludge: what it the loading of sludge, on average, in the sump? (wt% solids, both wet and dry - this'll get you a feeling for waters of hydration), settling time characteristics (for the heaviest fraction, and to optical clarity in the supernate), etc. This stuff varies signficantly based on the source. Obviously sand settles fast, clays will pug up your inlet quickly, and heavily hydrated compounds look bad but will flow and pump readily. You might even find that adding electrolytes or ions will provide some favorable fluidizing or fractional settling benefit. Even single-digit ppm quantities of alumina, ferric salts, etc. can change the characteristics dramatically. I'd call your water treatment chemical vendor and a water treatment equipment supplier, like Walker Equipment Co, Aquatech, and others. Dimensions and sketches don't really tell much of a story.