Vegetable and potato processors benefit from the water cleaning and recycling capability of centrifuges. Capacities from 1-150 m3/hr can be processed using the Hiller range of starch recovery centrifuges.
Centrifuge equipment in the potato industry fall into five main areas:
Units are installed to recover saleable starch from the wash water used in the cutting or slicing process at crisp and chip manufacturers. We find that 100 tonnes of potatoes processed produces approximately 2 - 3 tonnes of saleable starch, and a solids cake discharge of 60% dry solids can be produced. The starch yield is less in the case of straight cut chips and we find that approximately 0.3 - 0.5% of the potato tonnage being processed presents itself as starch which can be recovered at 60% dry solids.
The MSE Hiller centrifuge is well suited to cold water starch dewatering and can lead to:
A typical example from site
After grit removal and primary sedimentation, the underflow was thickened in a cone thickener prior to land disposal by tanker. A centrifuge was installed and cakes of up to 40 - 55% ds were easily achieved without flocculant addition. The product was saleable to farmers as an animal feed additive. In this case abrasive peelers were used in the process.
Similar results have been achieved from sludges derived from Dissolved air floatation DAF) units at potato processing factories and factories where no pre thickening takes place at all. When steam peeling is used one cannot expect such a high dry solids content of the cake, nevertheless the resultant cake 20 - 25% is still truckable. Some factories do nothing more than screen to 7 mm and pump the whole flow of factory effluent through the decanter centrifuge which has the result of removing 98 -99% of suspended solids and a reduction of 50 - 60% in COD.
The MSE Hiller centrifuge is ideally suited for effluent derived from potato processing. Clients who have used belt presses have complained of high maintenance costs in comparison to centrifuges. It is to be noted that centrifuges have also replaced rotary vacuum filters and plate and frame presses at several sites for similar reasons. Nevertheless, there are still many potential clients who do not consolidate their effluent and incur high charges from their Water Authority.