Automatic marine sewage treatment through a pair of tanks with salt water based sewage fed to the first tank after removal of solids above a predetermined size. Circulation means responsive to liquid levels in the tanks cause batch transfer of liquids from the first tank to the second tank and multiply...http://www.google.fr/patents/US4009104?utm_source=gb-gplus-shareBrevet US4009104 - Marine sanitation method and device
