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Innovative hydrodynamic clarification as pre-treatment for RO


We describe a novel and rapid in-line clarification method that does not require sedimentation or filtration. Innovations include rapid coagulation, floc conditioning, and pin floc separation. Spiral mixing structures with custom shear rates are developed to enhance aggregation kinetics of colloidal particles, resulting in 50% reduction in coagulant dosage to achieve the same turbidity reduction, and floc conditioning to create dense uniformly sized pin floc. Fluidic separation structures with designed size cut-off and efficiency are developed for hydrodynamic separation of the pin floc, eliminating sedimentation, and reducing process time from hours to minutes. The ability to treat neutrally buoyant suspensions makes this method ideal for seawater which has high organic content. Resulting water quality is shown to be comparable to permeate waters from MF systems. The fluidic separation structures are modular in design and highly scalable for throughput by parallelization. Other applications include municipal water, waste water reclaim, industrial water, and all instances where this generic capability to separate neutrally buoyant particles may be used to rapidly reduce TSS loading. Compared to conventional 20MGD installations, this innovation is estimated to reduce capital cost by 30-70%, operations and maintenance cost by 30-40%, and land use by 58-77%.


Lean, M.; Kole, A.; Hsieh, H. B.; Seo, J.; Voelkel, A. R.; Chang, N. E.; Melde, K. Innovative hydrodynamic clarification as pre-treatment for RO. 13th Annual Water Reuse & Desalination Research Conference; 2009 May 18-19; Huntington Beach, CA.