ATAD Provides Increased Capacity With No Odors

Faced with persistent odor complaints and limited space, Douglas County Sewer District #1 in East Wenatchee, Washington, turned to the ThermAer second-generation Autothermal Thermophilic Aerobic Digestion (ATAD) system to modernize its biosolids treatment. Located between the Columbia River and a main thoroughfare, the plant could not expand its footprint, so engineers retrofitted existing infrastructure—including converting an aeration basin into two ThermAer reactors and repurposing old ATAD tanks into SNDR™ reactors.

The new ThermAer system, commissioned in 2009, brought dramatic improvements: 60–67% volatile solids reduction, a 50% boost in solids handling capacity, and complete odor elimination, a game-changer for nearby residents and businesses. Walking and biking traffic near the site has returned, a testament to the community’s support. ThermAer’s real-time ORP monitoring, jet aeration, and BiofiltAer™ odor control ensure precise process control and air quality compliance. A CoolAer™ heat exchanger helps optimize downstream nitrification and dewatering performance, with anticipated cake solids of 35%—a significant improvement over the prior 25%.

Fully automated and low-touch, the ThermAer upgrade turned a once-controversial plant into a quiet neighbor and a model of modern biosolids treatment in a growing, space-constrained community.