The Voraxial® Grit Separator a New Technology for the 21st Century

The Hillsborough County Water Department (Department) in Tampa, Florida, in its ongoing program to reduce the amount of grit which reaches the Northwest Regional Residuals Recovery Facility (NWRRRF), issued a research purchase order to EnviroVoraxial® Technology, Inc. (EVTN) to perform a demonstration program for the removal of grit using a Voraxial® Grit Separator. The patented Voraxial® Grit Separator is a technology that produces a high centrifugal force to separate solids and liquids based on their specific gravities. The impeller in the Voraxial® Grit Separator produces a vortex in the fluids flowing through the unit with the heavier materials being drawn to the outside of the vortex, while the lighter materials are drawn to form a central core. A specially designed manifold at the exit of the separation chamber is utilized to collect the separated streams.The objective for this project is to demonstrate and document the grit removal efficiency of the Voraxial® Grit Separator at the headworks of the Northwest Regional Water Reclamation Facility (Northwest). The goal is to evaluate the separation efficiency for the total grit quantity in the wastewater and for a series of grit particle size ranges based on a sieve analysis of the collected samples.A VAS4000GS Voraxial® Grit Separator was installed at the Northwest headworks during November 2003 and performance tests were conducted from February through July 2004. The test data showed that the grit at Northwest is typical of that found in the southeast with a high amount of sugar sand.Testing demonstrated that high efficiency grit removal could be achieved with the reject flow as low as five percent (5%) of the total flow. The Overall Efficiency obtained at an operating speed of 3150 rpm varied from 81% to 89%, by weight, over the entire range of grit particle sizes in the influent wastewater. The entire range of sizes includes those for sugar sand. The performance at 3150 rpm is superior to the present state-of-art for grit removal equipment. The performance of the VAS4000GS Voraxial® Grit Separator exceeded that for Vortex-type separators. The data also showed excellent performance for removal of sugar sand.In summary, this test program has demonstrated that the Voraxial® Grit Separator is a very efficient grit removal device. The Voraxial® Grit Separator achieved excellent Overall Efficiency and the data shows that the separator can remove sugar sand efficiently.