CFD Model Proves to be Useful Tool for Anoxic Channel Modifications at MWRD

摘要

Increasingly stringent nutrient limits for wastewater discharge is requiring many facilities toincorporate upgrades for increased nutrient removal. Increased nutrient removal typicallyinvolves the use of anoxic or anaerobic reactors to provide a selective environment for organismscapable of accumulating or removing nutrients. Anoxic and anaerobic reactors can be negativelyimpacted by return flows containing dissolved oxygen. Many return flows are kept in suspensionby air mixing systems, which entrain dissolved oxygen. In converting existing systems toincorporate anoxic or anaerobic reactors, it is beneficial to provide mixing and suspension ofreturn flows without the use of air. Design of mixing systems without the use of air, is greatlyenhanced by the use of Computational Fluid Dynamic (CFD) modeling. CFD models allow aneconomic means of assessing the geometries and energy requirements of specifically designedfluid mixing systems. This paper provides an overview of the design, construction, and operationof a unique anoxic mixing system installed at Metro Wastewater Reclamation District’s(MWRD), Robert W. Hite Treatment Facility (RWHTF), North Secondary Complex, whichfacilitated combining return flows of Return Activated Sludge (RAS) and Primary Effluent (PE)while minimizing dissolved oxygen impacts to their nutrient removal process.