Marine sewage treatment with biological filter

A marine sewage disposal system for use on board a vessel comprising:

• (a) a central aeration chamber having air diffusers supplied with air from a blower and being positioned to supply air from the bottom of said chamber upwardly toward the top, said chamber adapted to receive sludge to a top level therein,
• (b) a pair of biological filters, one positioned to each side of said aeration chamber and contiguous therewith, the bottom of said aeration chamber communicating with the bottom of each of said biological filters to supply aerated sludge to said biological filters, each of said biological filters having a plurality of buoyant plastic hollow spheres retained in filter tiers on foraminous grating so that as the liquid flows up through the spherical filter tiers some of the sludge and entrapped sewage waste solids will separate from the liquid by gravity settling and dissolved oxygen is supplied to bacteria on said biological filters by liquid convection and oxygen diffusion,
• (c) an inverted T-shaped crossover pipe connecting said filters with the horizontal portion of the T-shaped crossover which lies below the top level of sludge in said aeration chamber and the upper end of the vertical leg of the T-shape is above the level of sludge in said aeration chamber, and
• (d) a chlorine contact tank connected to receive clarified liquid from the upper end of said inverted T-shaped crossover pipe by a flexible exit pipe to transfer clarified liquid from said biological filters to the chlorine tank for treatment with chlorine from a source of chlorine, prior to discharge.