Brownian transport of self-propelled overdamped microswimmers (like Janus particles) in a <?format ?>two-dimensional periodically compartmentalized channel is numerically investigated for different <?format ?>compartment geometries, boundary collisional dynamics, and particle rotational diffusion. The resulting time-correlated active Brownian motion is subject to rectification in the presence of spatial asymmetry. We prove that ratcheting of Janus particles can be orders of magnitude stronger than for ordinary thermal potential ratchets and thus experimentally accessible. In particular, autonomous pumping of a large mixture of passive particles can be induced by just adding a small fraction of Janus particles.