Description

The Frozen Image Centrifuge allows a measurement of sludge compressibility to be obtained in a quick and easy manner. The degree to which a compressible sludge will thicken depends on the individual particles that make up the sludge. If the particles are rigid, the maximum solids concentration is achieved with the particles close packed. But with a flocculent sludge, the flocs will break down and the particles will become compacted, releasing water in the process. It is the compressive forces created by the overlaying particles that causes the flocs to fragment.

Thus the degree to which a sludge is compressed depends on the height of the sludge blanket. The Frozen Image Centrifuge provides an enhanced method for simulating the compressive force. As an example, sludge subjected to 50g force for 5 minutes is the equivalent to the same sludge in a 3.5m deep thickener for one day.

The effect of chemical additives can be rapidly gauged at different effective compressive forces and with different sludge conditions.

Test Method
A sample of known solids concentration is placed in the centrifuge and rotated at the correct speed for the simulated pressure. At discrete times the position of the sludge -supernatant interface can be recorded. The centrifuge is equipped with a flash unit that is synchronised to the position of the sample, this allows the interface to be recorded without interrupting the test.

Technical Specification