Evaluating options to meet current and future BNR limits
Garver evaluated the Complex A aeration basins at Dallas Water Utilities’ Central WWTP for combining treatment flow and return activated sludge (RAS) streams, alternative diffuser technology, and the existing clarifiers. All of which, Garver used to provide recommendations for improvements. The existing activated sludge system consisted of 12 separate aeration basins with separate RAS and tube diffusers. DWU planned to replace the tubular diffusers with disc diffusers and identify modifications to the aeration basins that would improve oxygen transfer, biological loading capacity, plug flow conditions, and future conversion to biological nutrient removal (BNR). Garver evaluated four BNR conversion alternatives to be compatible with DWU’s master plan of decommissioning trickling filters. This evaluation included a CFD model of the basins to identify baffling to improve plug flow conditions and process modeling to identify improvements in organic loading capacity. The chosen design combined the 12 trains into six, adding baffles, and replacing diffusers with nine-inch disc membranes.
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