NOVELTY - The sewage treatment unit (1) has inflow pipe having suction inlet for primary treated water, an inflow separation tank (2) with an inlet (3) connected to other-end of inflow pipe, electrolysis treatment tank (7), floating tank(s) (8-10), an outflow separation tank (11) with outlet for secondary treated water connected to floatation tank, floating scum outlet and floating scum return pipe.    USE - For isolating or decomposing pollutant in wastewater ejected from kitchens, restaurants, hotels, home or food-processing factory.    ADVANTAGE - The sewage treatment unit has low grease trapping-processing capacity, but increases processing capacity and processing speed. The sewage treatment unit is small, has simple structure, consumes less installation space, easy to maintain and economical. The sewage disposal method enables to synergistically prevent accumulation of floating scum and sedimentation sludge.    DETAILED DESCRIPTION - The sewage treatment unit (1) has inflow pipe having suction inlet for primary treated water, processed by grease trap formed in one end of the inflow pipe, an inflow separation tank (2) with an inlet (3) connected to other-end of inflow pipe, electrolysis treatment tank (7) connected to the inflow separation tank, floating tank(s) (8-10) connected to the electrolysis treatment tank, an outflow separation tank (11) with outlet for secondary treated water connected to floatation tank, floating scum outlet formed in the side wall of electrolysis treatment tank(s) at the height substantially same as outlet, and floating scum return pipe (19) connected to the floating scum outlet for returning the floating scum to the grease trap. An INDEPENDENT CLAIM is also included for sewage treatment method.    DESCRIPTION OF DRAWING(S) - The figure shows an outline block diagram of the sewage treatment unit.    sewage treatment unit (1)    inflow separation tank (2)    inlet (3)    electrolysis treatment tank (7)    floatation tanks (8-10)    outflow separation tank (11)    secondary-treated-water return pipe (13)    floating scum outlet (18)    floating scum return pipe (19)