Apparatus and method for sensing the quality of dewatered sludge

A method of sensing the quality of dewatered sludge comprising the steps of:

• (a) introducing and then compressing said dewatered sludge within a closed end hollow cylinder using a piston driven under a predetermined torque;
• (b) sensing the density of said compressed, dewatered sludge;
• and
• (c) withdrawing said piston from said compressed dewatered sludge and measuring as a function of time the distance moved by said piston and the torque required to retract said piston from said compressed dewatered sludge.

A cake sensing apparatus comprising:

• (a) cylinder means for receiving a cake material therein, said cylinder means having an opening adapted to have a fluid source connected thereto, said cylinder means being comprised of:
• (i) a hollow cylindrical shell having at least one opening through the side wall thereof;
• (ii) first and second end plates sealing the two ends of said shell;
• (b) piston means in said cylinder means for compressing against and withdrawing from material in said cylinder, said piston means comprising:
• (i) a piston head within said cylinder;
• and
• (ii) a piston rod connected to said piston head, extending through said first end plate, and having indexing markings thereon for determine the position of said piston rod within said cylinder;
• (c) density sensing means connected to said cylinder means for sensing the density of compressed cake material within said cylinder;
• and
• (d) torque motor means connected to said piston means moving said piston means toward and away from cake material in said cylinder means and for determining the amount of torque required to move said piston means, said piston rod being connected to said torque motor means.