A decanter system for separating liquid from solids in an aqueous mixture in a tank, comprising: a) a structure at least partially submersible in said aqueous mixture in said tank, said structure having screening extending over at least a portion of the outer surface thereof defining thereby a screen structure for carrying out said separating and having an open interior, said screen structure defining an area within said tank, said screen structure including a water outlet comprising openings for removal of screened water from within said screen structure and being constructed such that water cannot pass from outside of said screen structure to inside of said screen structure without passing through said screening; said screen structure further comprising a baffle lifting column connecting to a pipe and extending through a bottom and a top of said screen structure and being attached thereto, said baffle lifting column being hollow and having the openings exposed to said open interior; and said pipe directly connecting to a flexible hose connecting said baffle lifting column to an effluent outlet control valve; b) a lifting mechanism attached to said screen structure and comprising a lifting apparatus attachable to said baffle lifting column of said screen structure for raising and lowering said screen structure vertically with respect to said tank, said lifting apparatus further comprising a winch, a cable, a pulley, and a winch drive; and c) a control mechanism governing said lifting mechanism for regulating the vertical position of said screen structure with respect to said tank. a) a structure at least partially submersible in said aqueous mixture in said tank, said structure having screening extending over at least a portion of the outer surface thereof defining thereby a screen structure for carrying out said separating and having an open interior, said screen structure defining an area within said tank, said screen structure including a water outlet comprising openings for removal of screened water from within said screen structure and being constructed such that water cannot pass from outside of said screen structure to inside of said screen structure without passing through said screening; said screen structure further comprising a baffle lifting column connecting to a pipe and extending through a bottom and a top of said screen structure and being attached thereto, said baffle lifting column being hollow and having the openings exposed to said open interior; and said pipe directly connecting to a flexible hose connecting said baffle lifting column to an effluent outlet control valve; screening extending over at least a portion of the outer surface thereof defining thereby a screen structure for carrying out said separating and having an open interior, said screen structure defining an area within said tank, said screen structure including a water outlet comprising openings for removal of screened water from within said screen structure and being constructed such that water cannot pass from outside of said screen structure to inside of said screen structure without passing through said screening; said screen structure further comprising a baffle lifting column connecting to a pipe and extending through a bottom and a top of said screen structure and being attached thereto, said baffle lifting column being hollow and having the openings exposed to said open interior; and said pipe directly connecting to a flexible hose connecting said baffle lifting column to an effluent outlet control valve; b) a lifting mechanism attached to said screen structure and comprising a lifting apparatus attachable to said baffle lifting column of said screen structure for raising and lowering said screen structure vertically with respect to said tank, said lifting apparatus further comprising a winch, a cable, a pulley, and a winch drive; and c) a control mechanism governing said lifting mechanism for regulating the vertical position of said screen structure with respect to said tank.