Odor Control System – College Township, Centre County, PA

Herbert, Rowland & Grubic, Inc. (HRG) has a long partnership with the University Area Joint Authority (UAJA) that goes back more than 20 years. Together, we have received national recognition for work that pushed the boundaries of our industry. Many times over the years, UAJA has been able to rely on us to offer creative, innovative solutions and expertise that similar firms don’t offer. That was the case again when they turned to us with a unique challenge: controlling odor from their treatment plant in College Township.

The population in this area has been increasing for years, and contractors have been building new homes closer and closer to the facility. As people moved in near the plant, UAJA began hearing objections from residents about the odor, and they took quick action to address the community’s concerns.

Few firms have experience addressing odor complaints, but HRG has a certified Odor Assessor on our team. We worked with UAJA and the community to develop a long-lasting, high-performance solution that eliminated odor complaints and minimized energy consumption.

We completed an odor control study to determine what was causing the issue and evaluate different solutions. We conducted extensive public outreach and designed a solution that eliminates odor for the community while minimizing costs and operational demands for the authority.

Our study included:

• Development of a state-of-the-art complaint/inspection tracking system
• Field observation and sample collection (on-site and within the surrounding perimeter)
• Laboratory testing (via Penn State University), analysis, and data interpretation
• Air dispersion modeling (assisted by our subconsultant Material Matters)
• Evaluation of the existing odor control system’s efficacy
• Evaluation of alternative odor remediation systems (including a budgetary cost comparison)

We determined that the composting biofilter and the dewatering facility ventilation stack were the largest contributors to the facility’s odor issues and began identifying potential solutions using air dispersion modeling. We evaluated multiple odor control technologies and selected an enclosed, concrete vessel with down-forced filtration and an inorganic media biofilter. Our design offered several benefits:

• Biofilters are the most cost-effective choice when ventilation rates exceed 50,000 cfm, and the air exchange rate required for UAJA’s composting operation is more than 100,000 cfm.
• The enclosed system controls moisture, pH, and temperature better, optimizing overall performance and reliability
• Inorganic media has a lower biofilter footprint than organic media
• Inorganic media is a more permanent solution, offering a 20-year life expectancy versus the 3-5 year replacement cycle associated with organic media
• Inorganic media is recyclable when returned to the manufacturer
• The upper layer of media can easily be removed and replaced if significantly fouled, thanks to the down-forced filtration design
• Electrical consumption is lower because lower static pressures are required
• The system outlet can be directed through a stack to improve air dispersion
• The system uses vacuum conditions to minimize fugitive odor emissions

UAJA’s odor control system came online in June 2020, and it is producing great results. More than 99% of the Hydrogen Sulfide is removed prior to stack dispersion, and more than 90% of the overall odor is removed. The authority has received no odor complaints since the system began operating.