Earthworms Help Municipal WWTP Overcome High-Strength Wastewater Challenges Through Vermifiltration

WALLA WALLA, Wash., Dec. 4, 2025 /PRNewswire/ -- In a unique step forward in sustainable, low-energy wastewater treatment, the City of Walla Walla has an unlikely partner - earthworms. The system leverages worms and microbial ecosystems to treat wastewater, delivering robust removal of some of the most persistent pollutants — while significantly reducing capital and operational costs.

Check out a short video about it here.

Vermifiltration is emerging as a powerful eco-engineering solution. Unlike conventional treatment plants that depend on energy-intensive aeration, polymers, flocculants or chemical additives, vermifiltration technology harnesses nature's proven engineers — earthworms — to break down organic matter. The process is gravity-driven, low pressure, and requires minimal external energy, translating into lower energy costs.

Key benefits realized at the municipal site include:

• High removal efficiency: Significant reductions in BOD, TSS, and other contaminants.
• Persistent chemical remediation: Effective sequestration and decomposition of some of the hardest to treat pollutants and toxic compounds.
• Regulatory compliance: The plant, which had wrestled under previous technology trials, returned to compliance under the vermifiltration process.
• Cost savings: Thanks to minimal infrastructure needs, simple operation, and nearly chemical-free processing, the system offers compelling capital and operational cost benefits compared to traditional methods.
• Eco-engineering and by-product reuse: The filtered effluent can be further polished or used for irrigation; and the system produces nutrient-rich biomass (worm castings) that can support agriculture or landscaping.

Perca, Inc. is a Walla Walla, Washington based company focused on vermifiltration - specializing on hard to treat constituents. At the heart of ongoing earthworm innovation is the one-of-a-kind "Vermitech Innovation Center" (VIC), Perca's dedicated R&D facility in Walla Walla, WA. There, science continues to refine the vermifiltration design — optimizing variables such as bed composition, hydraulic loading, and earthworm species to maximize treatment performance under real-world municipal loading.

"As regulators focus more on hard-to-treat and emerging chemical pollutants, traditional wastewater systems are reaching their limits," said Dr. George Damoff, Chief Science Officer at Perca. "Our vermifiltration system offers a nature-based, cost-effective, and scalable alternative — one that not only cleans water but regenerates ecosystems."

The success at this WWTP shines a light on the future of sustainable wastewater management — where eco-engineering, lower energy demand, and nature-based innovation combine to deliver regulatory compliance and system resilience.

About Perca:
Perca is a cleantech firm based in Walla Walla, Washington, specializing in low-cost, nature-based wastewater treatment. Its proprietary Drilo2 system employs earthworms, microbial communities, and natural filtration to treat and detoxify water - removing up to 99% of contaminants.

"Pioneering green-technology systems for advanced water treatment. Restoring healthy ecosystems worldwide through innovation and sustainability. Making a meaningful, tangible difference in the world—one drop of water at a time."

Learn how Perca can improve your wastewater treatment performance:

Internet: www.perca.net 

SOURCE Perca, Inc.