Today in 1935, US Patent 2009382 A was issued, an invention of George Blaufuss, for his beer “Filter.” There’s no Abstract, although in the description it includes these claims:

The object of the present invention is to generally improve and simplify the construction and operation of filters of the character described; to provide a filter in which a filtering medium such as diatomaceous earth, or the like, is used and applied to the surface of a cylinder to form a thick filter cake through which the liquid to be filtered must pass; to provide means for continuously removing impurities collected on the surface of the filter cake and also a portion of the filter cake so as to gradually decrease the thickness of the cake; and further, to provide means for continuously discharging the impurities and material removed from the surface of the filter cake.