Abstract: The present invention includes: a laundry wastewater tank that temporarily stores laundry wastewater from a plant facility; a biological treatment tank in which the laundry wastewater from the laundry wastewater tank is aerated and mixed with activated sludge; a treated water tank that stores the treated laundry wastewater that has been biologically treated; and a treatment preparation supplying device that supplies a laundry wastewater biological treatment preparation to the biological treatment tank. The laundry wastewater biological treatment preparation is introduced when a change in water quality that deteriorates the biological treatment in the biological treatment tank is detected. Thus, biological treatment can be performed stably.

Abstract: A process (S1) for producing freeze-dried sludge includes: an acclimatization step (S10) of imposing a load on cells of a microorganism in activated sludge to acclimatize the cells; a production increase step (S21) of subjecting the activated sludge to a production increase operation in which production of an extracellular polymer by the cells is increased after the acclimatization step (S10); and a freeze-drying step (S30) of freeze-drying the activated sludge after the production increase step (S21).

Abstract: The present invention includes: a laundry wastewater tank that temporarily stores laundry wastewater from a plant facility; a biological treatment tank in which the laundry wastewater from the laundry wastewater tank is aerated and mixed with activated sludge; a treated water tank that stores the treated laundry wastewater that has been biologically treated; and a treatment preparation supplying device that supplies a laundry wastewater biological treatment preparation to the biological treatment tank. The laundry wastewater biological treatment preparation is introduced when a change in water quality that deteriorates the biological treatment in the biological treatment tank is detected. Thus, biological treatment can be performed stably.