Overview

A key part of municipal wastewater treatment is a biological process, referred to as secondary treatment.  High volume blowers are used to feed air into large tanks in order to provide optimal conditions for biological growth and treatment.  These aeration blowers use a great deal of electricity – energy demand from this equipment has a very high associated cost each and every month.

Details

The District recently completed a project to replace two existing 150 horsepower centrifugal blowers, that were in service since 1993.  After detailed engineering analysis, new 75 horsepower high speed turbo blowers were selected for installation.  This is a relatively new type of aeration blower that operates with a wider range of air flow and can be controlled to match the precise oxygen demand within the process tanks.   The smaller blowers are sized appropriately for current and future conditions, and by design they use far less electricity to run.  The result was a very significant reduction in energy use at the plant.

The District looked at all available technologies before selecting turbo blowers manufactured by APG Neuros.  Accurate dissolved oxygen monitoring equipment and automated valves were installed as part of the project to control delivery of air to the aeration basins and maintain consistent dissolved oxygen concentrations.  On completion of the integrated project, we achieved an annual energy savings of approximately twenty-five percent.  The project cost was also partially offset by an energy efficiency rebate from Southern California Edison.