| 摘要 |
<p>PROBLEM TO BE SOLVED: To adde a small amt. of a chemical agent safe to man and beasts to effectively suppress nitration and to continuously suppress the flotation of activated sludge by denitrification by adding 2-mercaptobenzoimidazole to an activated sludge treatment system. SOLUTION: Waste water is mixed with activated sludge in an aeration tank to be aerated and, subsequently, sludge is separated in a solid-liquid separation tank and a part of the separated sludge is returned to the aeration tank as return sludge and the remainder thereof is discharged as excessive sludge. In this activated sludge treatment method, the flotation of activated sludge is suppressed by adding 2-mercaptobenzoimidazole. This 2- mercaptobenzoimidazole can be added to the arbitrary place of an activated sludge treatment system but is pref. added to the aeration tank. The addition amt. of 2-mercaptobenzoimidazole is different according to an addition position or an adding method but set so as to suppress the nitration reaction of nitrifying bacteria and, in the case of continuous addition, it is pref. to add 2- mercaptobenzoimidazole to inflow raw water in an amt. of 0.5-5mg/l.</p> |
