A bioreactor apparatus for processing waste, comprising a cylindrical
pressure vessel having an inlet end and an exit end, an internally
rotating main shaft having spaced apart ends, and a plurality of paddles
and agitator bars attached to and extending radially from the shaft. At
least some of the plurality of paddles and/or agitator bars extend
radially outward from the shaft and form a helical spiral pattern when
viewed from either of the spaced apart ends.