Treatment of sewage sludge
OwnerJohannes S. Terblancheinventor
Life of this patent
Estimating the term…
Abstract
Sewage sludge is mixed with organic material such as woodchips in a three screw mixer so that moving masses are created in the mixing compartment, there being a shearing action at the interfaces between the masses. The mixer includes the mixing compartment and a holding compartment into which dewatered sludge is continuously charged. There is a gate between the compartments which is opened when it is desired to convey sludge from the holding compartment to the mixing compartment. The shearing action results in the organic material being coated with a thin layer of sludge without the formation of dewatered sludge lumps which would rot instead of composting.
Claims9
A method of mixing dewatered sewage sludge with an organic material thereby smearing said sludge over said organic material so as to form a coating thereon, which method comprises charging said sludge and said organic material into a mixer, feeding a first mass of sludge and organic material at a first velocity and feeding a second mass of sludge and organic material in the same direction as the first mass of sludge and organic material but at a second velocity, there being an interface between the first and second masses at which interface there is a shearing action between the two masses, feeding a third mass of sludge and organic material in the opposite direction to the first and second masses thereby creating interfaces between the second and third masses and between the first and third masses at which interfaces a shearing action takes place.
A means for mixing dewatered sewage sludge with an organic material comprising a mixer and a source of dewatered sewage sludge and a source of an organic material, said mixer comprising a casing defining an elongate mixing compartment, a first screw for displacing a first mass of sewage sludge and organic material along said compartment at a first velocity, a second screw for displacing a second mass of sewage sludge and organic material along said compartment at a second velocity different than said first velocity so that there is an interface between the first and second masses at which a shearing action takes place, a third screw, for moving a third mass of sewage sludge and organic material along said compartment, wherein said first and second masses are moved in the same direction and said third mass is moved in the opposite direction to the first and second masses whereby there is an interface between said second and third masses and between the first and third masses at which interfaces a shearing action takes place, a holding compartment for receiving dewatered sludge, and a gate having a closed position in which it prevents sludge in the holding compartment from reaching the mixing compartment and an open position in which it permits movement of dewatered sludge from the holding compartment to the mixing compartment.
Dependencies are inferred from the claim text.