Invisible Odor Control: Providing Plant-Wide Odor Control Treatment Facilities at an Advanced Municipal WWTP While Minimizing Negative Aesthetic Impacts

An odor control facilities plan was developed for the Alexandria Sanitation Authority (ASA) Advanced Wastewater Treatment Facility Upgrade Program. Various odor control technologies were evaluated in pursuit of ASA's aggressive odor control and aesthetic goals on a relatively tight site.The ASA plant is located in an attractive residential area, adjacent to the District of Columbia. ASA took an active role in communicating, with city officials and community groups, the progress for the existing facility upgrade. Design of a plant-wide odor control system was a key facet in public presentations of the ASA upgrade project.Design workshops with ASA and design consultants were used to flush out key decision-making issues. An aggressive fenceline impact Dilutions-to-Threshold (D/T) goal of 2 D/T (1 hour average) at the property line was agreed upon by all parties as the foundation for the odor control design. Odor sampling and analysis was conducted to identify major odor sources. Industrial Source Complex Dispersion Short Term (ISCST3) Dispersion Modeling was performed with the existing and future site plans and odor sources in order to assess odorous impacts by unit process/facility. Isopleths, showing D/T contours by source, were used by ASA and CH2M HILL to prioritize odor sources that required containment and treatment to meet odor control goals.ASA requested that all odor control treatment system components be centrally located in a new solids processing building. The Authority also requested that the aesthetic impacts of the treatment systems and ductwork be minimized.The designed treatment system provides particulate, ammonia, and hydrogen sulfide scrubbing for priority odor sources. In addition, the designed system enclosed the scrubber treatment systems in a new solids processing building and provided architectural canopies and buried ductwork to minimize aesthetic impacts.