large scale lab mimic of the impellor was used to confirm that precipitate of the desirable size could be made at the large scale and that the subsequent plate filter could remove solids under a gravity fed mode fig1 shows the particle size of material originating from the large scale vessel and compares it to that derived from the small scale vessel clearly large precipitate dominates the particle size distribution indicating that the design of the impellor and plate filter used in the newly configured mixing step can form precipitate of the desired size when this material was applied to the plate filter the precipitate was largely retained on the 200 u03bcm mesh a 350 mm 200 u03bcm mesh was able to handle 5 litres of precipitated lysate in less than 1 minute the sieve or mesh 10 is most clearly seen in fig1 it comprises a filter mesh 12 which is spot welded to a support mesh 14 to provide it with significant rigidity the filter mesh is a stainless steel wire mesh disc with apertures not shown of 200 u03bcm this is supported on the support mesh which is also made of stainless steel and is a 1 6 mm aperture mesh both are 316 grade stainless steel a mesh seal 16 allows the sieve or mesh to be correctly aligned and seated on a filter plate 20 by sitting it in a recessed portion 46 the sieve or mesh forms.