ROTOR RETROFIT OPTIMIZES AERATION SYSTEM

The aeration and mixing of mixed liquor suspended solids in aeration channels has long been accomplished by the use of mechanical surface aerators such as the horizontal brush type rotor. Horizontal brush type rotors can be effective but alternative technologies have been developed which can meet the required mixing and aeration requirements more efficiently. The City of Massillon, Ohio, when faced with the challenges of designing a major wastewater treatment plant expansion, selected an innovative vertical mixer technology developed in the Netherlands to meet the aeration channel mixing needs. This mixing system coupled with a fine bubble diffused air aeration system and a custom aeration control system, to meet the aeration channel aeration needs, provided significant energy savings while still maintaining the racetrack effect commonly used in aeration channels without the use of turning vanes. The system is able to minimize the energy needed for mixing and yet provide propulsion of the tank contents across the fine bubble diffusers and facilitate the mixing of the incoming primary effluent and RAS streams. The system has proven to be very effective in the retrofitting of existing aeration channels.