Abstract: A process for treating effluent water of a poultry processing plant for reuse in that plant. According to the present invention, a treatment of the effluent with a strong oxidant and with a substance to reduce the pH to less than 5.2 pH units, and preferably about 3.0.+-.0.5 pH units causes a floc to form together with a destruction of bacteria and a breaking of the oils and greases. The floc contains the impurities such that the water separated from the floc is sufficiently purified for reuse in certain processing steps in the plant. In the case of treating effluent water from the poultry chiller tank(s), the product water can be reused in the tank(s). In the preferred form of the process, formation of the floc is enhanced by the addition of an anionic polymer or other thickener/strengthener, and separation is achieved by dissolved air flotation techniques. A final filtration can be utilized after a readjustment of the pH to near neutral to match new water to be used in the plant.