PURPOSE: To effectively recover blood components contained in blood washing waste water and utilize them as effective resources by adding a strongly acidic liq. to the waste water, agitating them to adjust the water to ≤4pH, further adding strong alakli, and agitating them to flocculate the blood components at a predetermined pH.

CONSTITUTION: In the treatment of waste water from a process of washing organic blood discharged by butchering livestock, a strongly acidic liq. is added to the waste water contg. blood compenents and agitated to adjust the waste water to ≤4pH. A strongly alkaline liq. of slaked lime or the like is then added to the water and agitated to flocculate the blood components at 9W10pH. By adding a suitable polymer flocculant to the waste water at that state and agitating them, the blood components are flocculated further assuredly. The blood components recovered can be utilized as resources such as feedstuff and fertilizer, and the purified waste water can be recycled to the washing process.