OPTIMIZING CLARIFIER INLET AND OUTLET ARRANGEMENTS LEADS TO IMPROVED PERFORMANCE AND BIG SAVINGS

Secondary clarifier performance at Michelson Water Reclamation Plant (MWRP) has been the subject of many studies over the last decade. Improving the performance of the clarifiers is crucial for enhancing the performance of the plant in general and the downstream tertiary filters in particular. The secondary clarifiers also represent the main treatment capacity bottleneck in the activated sludge process at the plant. Increasing secondary clarifier capacity would unlock the capacity of the whole treatment plant and increase the production of recycled water.In 2001, Irvine Ranch Water District (IRWD) initiated a project to optimize the secondary clarifiers. The project included field testing, mathematical modeling, design and construction of clarifier modifications and performance verification testing. Based on the field-testing and mathematical modeling, the most cost effective modifications were identified, designed and constructed. A parallel comparison between a modified and an unmodified clarifier indicated that modifications have improved performance and reduced effluent suspended solids concentration by more than 80 percent. Stress testing indicated that modifications have increased clarifier capacity significantly, by approximately 30 percent from 13.5 mgd to 17.5 mgd. As a result of the improved performance, the District revised its plan of building two new secondary clarifiers to building only one new secondary clarifier.