32 | ROCKY MOUNTAIN WATER SEPTEMBER 2020
and for how long to fire. An air bubble about the size of a
softball is released and moves to the surface, resuspending
solids in the tank.
Another feature that Creaghe likes is the insignificant oxygen
transfer (low ORP) environment, which enables the large
bubble air mixing to work in anaerobic, anoxic, and aerobic
applications. Even though the large bubble is made up of air,
the oxygen in the bubble remains in the bubble and doesn’t
transfer to and aerate the surrounding mixed liquor.
The Loveland plant is rated at 12 mgd (capacity) and
typically processes about 6 mgd. It has 13 people in technical
services (maintenance) and nine operators.
The large air bubble system handles mixing for 14 baffled
anaerobic and anoxic zones. It also helps Loveland meet
Colorado Department of Public Health and Environment
Regulation 85 effluent nutrient limits.
“We’re typically at 13 mg/L for total inorganic nitrogen
(the limit is 15 mg/L) and 0.2 mg/L for phosphorous (the
The stationary system
mixers and the out-of-
required to keep them
running. The system also
uses less power.