TAKING AERATION TO A NEW OTE LEVEL

The highest power consumption at a wastewater treatment plant is tied to the aeration system; consequently, optimizing oxygen requirements in addition to operating efficient equipment are important elements in keeping operating costs down. For Inland Empire Utility Agency (IEUA), both oxygen optimization and efficient equipment were key elements in their evaluation of aeration equipment for their Regional Water Recycling Plant No. 4 (RP-4). IEUA evaluated Parkson Panels and Aerostrip strip diffusers as potential aeration equipment to replace their existing large surface aerators. The equipment would be implemented as part of two projects. The first project consisted of energy reduction improvements to the existing 7 mgd facilities. These improvements included the addition of primary clarifiers, replacement of the aeration equipment, and replacement of the UV system with chlorination. The second project will follow within 5 years and increase plant capacity to 14 mgd. The increased capacity will be achieved by reconfiguring the racetrack aeration basins to parallel plug flow aeration basins. A multi-phased approach was taken to the selection of the aeration equipment. In the first phase, a present worth analysis was conducted to determine if there was a similarity in cost between the Parkson Panel and the Aerostrip™ strip diffusers. Based on the similarity in present worth costs, an evaluated bid was prepared as part of the energy reduction project to select a diffuser. Aerostrip™ won the bid primarily based on power savings which were achieved using a clean water oxygen transfer efficiency (OTE) of 50% at average conditions. To validate the bid values, clean water shop testing and field pressure testing were performed. With the Aerostrip™ diffuser, an OTE of 50% was achieved at a SWD of 16 feet which is 60 – 70% higher than the OTE of conventional membrane disks at the same depth.