Implementing an Odor Control Program for a Centralized Sludge Processing and Loading Facility

The City of Garland, Texas needed to upgrade the solids processing facilities at their Rowlett Creek Wastewater Treatment Plant. The upgrades included replacing belt filter presses (BFPs) with centrifuges; replacing gravity belt thickeners with rotary drum thickeners (RDTs); converting anaerobic digesters to mixed sludge holding tanks; and other improvements. By upgrading the sludge processing equipment, the City was able to minimize the cost of odor control for these facilities.The equipment upgrades and process modifications required varying methods of odor control, including biotrickling filters, carbon adsorbers, and organic media biofilters. With the change in processes, determining the appropriate design odorant concentrations required innovative field testing. Dispersion modeling was used to determine the effectiveness of carbon adsorbers and stack discharge prior to bidding so that the City could make an informed decision on certain additive alternate bid items. The design process included prequalifying odor control manufacturers and interviews to select vendors for the systems.This paper discusses the interaction with the biosolids process design; minimization of odor control costs; determining appropriate odorant concentrations and design airflows; technology selection and design; construction and performance testing.