REMOVAL OF NITROGEN COMPONENT FROM WASTE WATER IN FINAL SEWAGE DISPOSAL PLANT

摘要

PURPOSE:To effectively remove a nitrogen part from waste water in a final sewage disposal plant, in treating inflow sewage by aeration, by adding alkali to said sewage in advance of or in the middle stage of said aeration step. CONSTITUTION:Waste water in a final sewage disposal plant ordinarily contains 20-30ppm a nitrogen part. In this regard, said waste water is not suited to irrigation water, but drained to rivers. Such is the present condition. Said waste water is now aerated, and alkali in an amount of 1-1.5mol equivalent to ammoniac nitrogen in the waste water is added to the waste water before or during said aeration to discharge said ammoniac nitrogen as free ammonia to the atmosphere. Hence, the nitrogen part in the waste water is reduced to about a third, so that the waste water becomes suitable as irrigation water. As alkali, caustic soda, caustic potassium, sodium carbonate, milky lime, etc. may be used.