Part of the wastewater treatment process is the treatment and processing of biological solids from the water. Each year, Troutdale's Water Pollution Control Facility produces more than 3 million gallons of digested sludge in its lagoon. This results in nutrient-rich organic materials called biosolids. In the past, biosolids were viewed as waste and disposal options included landfill or burial, incineration, and dumping at sea. Now there is a much better option.
Biosolids are approximately equivalent to a 5-4-1 commercial fertilizer. It improve soils by providing organic matter, which improves the “tilth” or physical conditioning of the soil. Good soil tilth means that soils are easy to dig in and work up, easy for seedlings to emerge from, and easy for plant roots to move through.
During the summer months, the WPFC's 3,500 gallon tanker trucks apply biosolids to local hay or alfalfa fields. Anecdotal evidence suggests farmers have better results with our biosolids than commercial fertilizer.
In fact, farmers have been successfully using biosolids to grow crops for decades. Biosolids are regularly monitored to meet strict federal and state regulations and have been used safely for decades. Hundreds of academic and scientific studies have shown that biosolids are a safe and responsible alternative to chemical fertilizers. In addition, soil samples are taken periodically to conform with Oregon Department of Environmental Quality (DEQ) standards.
In 2020, almost 3.5 million gallons of biosolids were hauled to local farms, the highest amount in a single season. Our overall goal is to remove more from the lagoon than we put in, for greatest efficiency.
For more information, contact Biosolids Coordinator Liz Welch at 503-666-8377.