METHOD OF SEWAGE BIOLOGICAL TREATMENT BY AERATION AND EQUIPMENT FOR MAKING THE SAME

摘要

A method for the secondary treatment of sewage (and apparatus therefor) having a step in which sewage is circulated around a system having a riser and a downcomer communicating with each other at their upper and lower ends and in which an oxygen-containing gas is supplied to the sewage as it passes through the downcomer. The method is intended for use in the aeration and/or digestion steps in the secondary treatment of sewage. The riser and downcomer are preferably located in a shaft extending into the ground for at least 40 meters below a basin containing the sewage.