The aeration system is a fine bubble diffusion system and involves no mechanical aeration. Four blowers send air heated to about 120 degrees F to an air mixing manifold system in the aeration tank. The air is heated to increase the mixed liquor temperature to avoid possible freezing during the cold months of the year. The air enters through the top of the manifold while mixed liquor is pumped through the bottom. The air and mixed liquor mixture is then discharged through one of twelve jets thus creating a turbulent mixing action. The air loading is tapered with the first four tanks receiving 168 lbs/O2 per day and the last eight receiving only 64.7 lbs/O2 per day. The aeration unit was design to handle a maximum BOD5 loading of 3824 lbs/day.
Previously the plant had trouble with foaming sludge but it is believed that they were over correcting At the time there was more than one operator controlling the inlets to the aeration tanks, and due to differences in opinions, a consistent operating technique was never decided upon. One operator would set the air loading and RAS recycle rate and the other would change it to values that he thought were more appropriate. The tank was constantly being tampered with and as a result efficiency was far less than what is being achieved today.