2nd Generation ATAD Provides Superior Treatment

In a bold move to modernize its wastewater treatment, Bowling Green, Ohio, installed the state’s first second-generation Autothermal Thermophilic Aerobic Digestion (ATAD) system—ThermAer—in 2004. The upgrade expanded the plant’s capacity from 6 to 10 MGD and replaced an inefficient, odor-prone coarse-bubble aeration system. What resulted was a leap forward in performance, achieving a remarkable 72% solids reduction and completely eliminating odor complaints—all at an impressively low treatment cost of $109 per dry ton (as of 2009).

ThermAer uses high-temperature aerobic digestion, driven by microbial heat, to pasteurize biosolids and deliver Class A output. Innovative process improvements, such as alternate-day feeding for pathogen kill and in-system ammonia removal via the SNDR™, enhanced both efficiency and environmental compliance. The integrated BiofiltAer™ odor control system, including a Strobic fan, cut odor emissions to undetectable levels while reducing biofilter size and energy consumption by the equivalent of 500 horsepower.

With a hands-free, operator-friendly control system and no need for raw sludge storage tanks, the Bowling Green installation has set a new standard for low-cost, high-performance, and community-friendly biosolids management.