EQUIPMENT AND PROCESS FOR TREATING SEWAGE

摘要

PROBLEM TO BE SOLVED: To provide sewage treatment equipment capable of automatically controlling aeration in an optimum state and suppressing wasteful consumption of energy. SOLUTION: This sewage treatment equipment 2 is provided with: a secondary treatment vessel 5 into which sewage subjected to primary treatment is introduced and which is used for subjecting the introduced sewage to secondary treatment and discharging the resulting treated water to the outside; an aerator 7 for supplying air into the secondary treatment vessel 5; and an automatic controller 10 for controlling the aeration; wherein the secondary treatment vessel 5 is further provided with a dissolved oxygen concentration (DO) detector 11 for detecting DO in inflow water and an oxidation-reduction potential(ORP) detector 20 for detecting ORP of the inflow water, and also the automatic controller 10 is provided with a CPU 21 and used for controlling the DO so as to be a specified value when the aeration is performed, and also controlling on-off of the aeration and the amount of air for the aeration, on the basis of signals from the outside. In the aeration stage, when characteristics considered as those indicating completion of nitrification is read out in an ORP variation curve plotted on the basis of detected values by the ORP detector 20, the aeration is stopped and in a non-aeration stage, when characteristics considered as those indicating completion of denitrification is read out in the ORP variation curve, the aeration is restarted.