PURPOSE: To solve the various problems relating to the dust treatment brought with garbages by separating a solid matter and a liquid component in a mixture and treating the solid matter and liquid component separately prior to the treatment in a sewage treating facility or a waste water treating facility.

CONSTITUTION: After the garbages 1 generated in a home and a restaurant are subjected to pulverization to be muddy form by a disposer 3 (size of pulverized matter is ≤5mm, preferably ≤1mm), the garbages are combined with the living waste water 5 incorporating a night soil, the sludge water of a sewage purifier, and industrial waste water are fed into the suspended solid (SS) separator 11 by exclusive draining pipe 9. The separated liquid portion in this device is fed into the activated sludge tank 13 and is subjected to the sludge treatment. However, SS is previously separated from the liquid component the capacity of the activated sludge tank 13 can be smaller than that of the previous method. The solid portion 15 formed by the SS separator 11 and an excess sludge 17 from the activated sludge tank 13 are fed into the sludge concentrator 19 and concentrated.