We have a four or five inquiries a year about pressing potato peel. This peel is a waste product that comes from peeling machines used by potato processors. Three types of peeling equipment are used: abrasive rollers, caustic, and, most commonly, steam peeling.

The peel is very wet, which limits its value as an animal feed. Also the wet weight results is significant haulage costs. By running it through a screw press its value is enhanced, perishability is reduced, and trucking costs are reduced.

Another plus of pressing the peel is that the press liquor can be treated and reused in the peeling process. This is advantageous where water consumption limitations are being faced.

Normally the peel comes to the screw press with 86% to 93% moisture. The lower figure may be the result of the use of an existing screening devise to drop out free water. This device can generally be eliminated by adding a screw press.

Typically the incoming flow of wet peel can be split into a 50:50 split of press cake and press liquor. In testing, we found performance in the range of one-third to two thirds press cake, depending on the air pressure setting of the discharge cone. Press cake moisture of 82% was achieved without difficulty.

With a low cone pressure setting, the press liquor is relatively clear. With high cone pressure a noticeable amount of "mashed potatoes", or starch, will be forced through the screen and into the press liquor. This may or may not be acceptable to the processor, depending on the capacity of his wastewater treatment facility and on whether or not a screen is available to filter the press liquor.

When the press liquor is cleared by running it over a static screen (sometimes called a hydradenser), the tailings from the screen are normally added back to the flow of material going into the press.

The less expensive KP model presses, operating at very low speed, have found acceptance in this market.