All the operations are carried out in different ways in large scale, intermediate and small-scale plants. The methods employed invariably influence the yield of oil and its quality. In the large scale plant, all the processing operations are fully mechanised, with sophisticated conveyance systems. The use of screw expellers in oil separation and the recapturing of oil by a sludge centrifuge for further clarification enables over 90% of the oil to be extracted (Hartley, 1988, Chap. 14). However, there is a contention that screw expellers are generally too expensive, such that small-scale processors find it difficult to embrace the technology (Badmus, 1991).