NOVELTY - Waste treatment system (I) comprises a waste-receiving pit; separator(s) for waste materials having specific gravity less than or equal to and above that of water; crusher(s) to produce liquid product; acetogenic fermenter(s) receiving liquid product; methanogenic fermenter(s); and liquid feed line(s).    USE - (I) is used for treating unsorted municipal solid waste, e.g., food scraps, yard waste, organic materials, paper, cardboard, rags, plastic material, glass, wires, light gauge metallic containers, heavy metal pipes, iron castings.    DETAILED DESCRIPTION - (I) comprises a waste-receiving pit (102); first separator(s) (104) for separating one waste material with a specific gravity equal to or less than or equal to that of water and a second waste material with a higher specific gravity than water; crusher(s) (106) for receiving and crushing the first waste material; acetogenic fermenter(s) (326) which receive the liquid product from the crusher(s) and for anaerobic acetogenic fermentation; methanogenic fermenter(s) (328) which receive the fermented effluent from the acetogenic fermenters and for anaerobic methanogenic fermentation; and liquid feed line(s) (172) which feed the effluent(s) into the system's device(s) or subsystem(s).    INDEPENDENT CLAIMS are also included for the following:    (1) a separation apparatus (120) for collected waste comprising an open-topped receptacle for receiving the waste and a bottom end with a sink portion for receiving a waste material with a larger specific gravity than water; a conveyor (136) with its bottom end within the sink portion and its top end extending out of the receptacle to convey the waste material from the sink portion to a collecting device outside the receptacle, and another conveyor with its bottom end at another portion of the receptacle which is at a level higher than that of the sink portion to convey articles to another collecting device; a barrier-defining member above the first conveyor permitting delivery of the waste material by the first conveyor and defining a barrier for articles introduced into the receptacle by directly contacting the first conveyor in the sink portion; and liquid injection nozzles within the receptacle for injection of liquid streams into the liquid in the receptacle to impart lateral movement on articles in the liquid; and    (2) a liquid-carrying waste treatment apparatus comprising a tubular body which defines a flow path between a liquid inlet and outlet; and high pressure liquid nozzles within the tubular body at the corners and arranged to inject an axial jet of pressurized liquid into the distal section. The tubular body consists of a section proximal to the inlet and a section distal. The sections are connected at ends to form corners at their point of contact.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a system of the invention.    Waste-receiving pit (102)    Separator (104)    Crusher (106)    Filtration and separation subsystem (108)    Separation apparatus (120)    First conveyor (136)    Acetogenic fermenter (326)    Methanogenic fermenter (328)