A rotating annular crossflow filter shears radially outward flowing axial
feed between counter-rotating coaxial centrifugal impellers. A radial
impedance of flow at the impeller periphery slows the radially outward
flow and increases residence time of feed between the impellers. Shear
lift ejects solids from the boundary layer at the filter surface, and
ejected solids collect by centrifugation at the impeller periphery, where
they thicken into a sludge and are extruded. Gases, oils, floating
solids, and fractions having a specific gravity less than water evolve
into radial vortices and are sucked radially inward and out from between
the impellers by an axial pump. Three way phase separation proceeds
continuously in one pass through a simple mechanical device having a long
residence time for feed in the processing zone.
Opposing rugose portions of counter-rotating impeller surfaces cause audio
frequency pressure pulses. At the impeller periphery, the pressure pulses
milk liquid out of sludge. At the portion of the radial passage prior to
the filter, pressure pulses evolve gases and degassed cavitation bubbles
inactivate microbes. Degassing of the high energy forced periodic
cavitation bubbles between the impellers removes the cushion of
noncondensibles which would otherwise absorb energy on compression,
therefore implosion becomes extremely violent and a barrage of high
pressure pulses and ultraviolet light pulses inactivates microbes.
Applications include field water purification, municipal and industrial
wastewater degassing and sludge thickening, swimming pool filtration,
effluent dewatering, wine and beverage degassing and clarification, fruit
crushing, olive oil dewatering, produced brine and drilling mud
processing, manure slurry dewatering and degassing, and recovery of
solvents and fine suspended solids from fluid mixtures such as wastewater
from machining operations.