DIFFUSED AERATION ODOR CONTROL SYSTEM

The City of Concord, New Hampshire, decided on an integrated approach for the aeration system and new odor control facilities by implementing a fine bubble diffused aeration system to supply process air and to treat offensive odor emissions from a portion of the liquid treatment train at the Hall Street Wastewater Treatment Facility (WWTF). The bioscrubbing of odorous air by the activated sludge system has been practiced for over thirty years for odor mitigation. However, due to several design and operational concerns, e.g., equipment corrosion, adverse impacts on process operation and performance, air volume balance between the odorous airflow to be treated and airflow demand for the activated sludge process, the use of activated sludge scrubbing for odor control has been limited.During the design of this facility, those and other issues inherent to diffused aeration odor control systems were evaluated and effectively incorporated into the design. The construction of this facility was completed in July 2000. The results of the performance testing showed that there was significant removal of odorous compounds, particularly hydrogen sulfide, in the aeration tank. After almost one year of operation, the diffusion of odorous air containing hydrogen sulfide and other contaminants to the aeration tank has not resulted in any noticeable operational difficulties.