| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to completely suppress the occurrence of odor from sludge dewatering cake by separately using alkali metal derivatives of pyrithion as a first agent and at least one kind of compound which is selected from a chlorite, zinc chloride and hydrogen peroxide as a second agent jointly. SOLUTION: At the time of deodorizing the sludge dewatering cake which is formed by the dewatering treatment of first sedimentation sludge by gravitational treatment of sewage, and excess sludge and concentrated sludge in activated sludge treatment, the alkali metal derivatives of pyrithion as the first agent, at least one kind of compound which is selected from a chlorite, zinc chloride and hydrogen peroxide as the second agent are separately added and mixed. Thereby, the deodorization is achieved and the deodorization effect can be maintained for a long period. Sodium pyrithion is preferably used as the alkali metal derivatives of pyrithion and the quantity of the alkali metal derivative of pyrithion to be used is set to 0.03-3 g to 1 kg of the solid material before the dewatering or the solid material of the sludge dewatering cake.
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