range from about 6 000 to about 15 000 microns wide by about 50 000 to about 75 000 microns long and are spaced about 1 500 to about 8 000 microns apart it is understood however that any other arrangement of perforations may be used without departing from the scope of the invention so long as the structural integrity of the drum 214 is maintained the drum 214 is surrounded by a fine filtration media 218 while stainless steel wire woven cloth with pore sizes ranging from about 50 to about 200 microns can be advantageously used as the media 218 in the preferred embodiment the present invention is not limited thereby and it should be understood that other media such as synthetic woven materials or monofilament screens can also be used also it is preferred that the media 218 be attached to the drum 214 in such a manner that it may be quickly and easily replaced for example in the preferred embodiment one end of the media 218 is bolted to the drum 214 a shaft mount not illustrated is welded to this end and a shaft not illustrated is attached as by spot welds if the media is stainless steel wire woven cloth to the other end of the media 218 the media 218 is wrapped around the drum 214 and the shaft is inserted into.