05401402 is referenced by 45 patents and cites 37 patents.

A method of treating sewage sludge is provided, in which the sludge is mixed with an alkaline material in such a way as to provide intimate surface contact that enables the alkaline material to permeate even small particles of the sludge, and to deliver the resultant product in a granular, scatterable form. The sludge and alkaline material are delivered to a mixing chamber and are confronted therein with a screw type mixer having generally helical flighting carried by a shaft, with the mixer being rotatably driven in generally horizontal arrangement to convey the mixture toward an outlet, with the mixture that is being mixed being maintained at a level in the mixer such that a spiral rolling action is imparted to the sludge and alkaline additive by the flighting engaging particles of sludge and rolling those particles up over the rotating shaft of the screw mixer. The rate of addition of sludge and additive into the mixer and/or the speed to rotation of the rotating screw in the mixer can be automatically adjusted as a function of the level of sludge being mixed in the mixer. The level of sludge may be reflected by various types of sensing means, such as torque load on the motor driving the screw shaft, visual detection devices, limit switch devices, etc. Preferably, two such helical screw mixers are provided working in opposition to each other.

Title
Process and apparatus for treating sewage sludge
Application Number
749988
Publication Number
5401402
Application Date
March 30, 1994
Publication Date
March 28, 1995
Inventor
Richard W Christy
Ambler
PA, US
Paul G Christy
Devon
PA, US
Agent
Paul & Paul
Assignee
RDP Company
PA, US
IPC
C02F 11/18
C02F 11/14
View Original Source