An experimental investigation of conditions affecting the agitation and removal of manure solids from a liquid manure holding tank

Model studies were conducted on the effects of tank shape, internal obstructions, and agitation time on the removal of manure slurries from liquid manure holding tanks. Peat moss was used to simulate cow manure. The models were constructed to one fifth scale, and the relationships between model and prototype were developed from Prandtl's mixing length theory. The results of the tests conducted in the models were expressed as the percentage of the loaded solids remaining in the tank after each cycle of agitation and removal by pumping of the suspended solids. From the standpoint of manure removal, these tests showed no significant difference between circular and rectangular tanks, long and short agitation periods, and the presence or absence of cover support columns. A dividing wall baffle in the rectangular tank significantly reduced the quantity of manure which could be removed in a suspended state.