loop

What is Loop? Loop biosolids is a natural soil builder. Using Loop recycles the nutrients in our food back to the land, the same way nature does. It is an endlessly renewable resource that’s good for people, plants, and Puget Sound.

What is Loop?

What is Loop biosolids and how is it made? In this video, staff from King County Wastewater Treatment Division show how they transform raw wastewater into Loop® biosolids. Once we complete the cleaning process, our lucky customers use this endlessly renewable resource to enrich farms, forests, and gardens.

Loop 101

As it has for the past 40 years, King County produces Loop biosolids from solids (the food and poop) recovered during the wastewater treatment process. Gravity separates the solids from the liquids, and then we treat and clean both the liquids and the solids using engineering technology. This engineering technology mimics nature’s cleaning powers. The end result is Loop, a nutrient-rich soil builder. Using Loop recycles the nutrients in our food back to the land, the same way nature does. Harvested plants take nutrients out of the soil, humans eat those nutrients through our food, and then the nutrients are returned to the soil with Loop. Loop is an endlessly renewable resource restoring carbon and nutrients to the land for the good of plants, people, and Puget Sound.

Loop is grounded in rigorous science. Held to rigorous standards under the Clean Water Act, we continuously research and test Loop. For nearly 40 years, we’ve built on Environmental Protection Agency and other national data by teaming with university scientists to evaluate the safety and effectiveness of Loop.

See how Loop is made

Take a tour of King County’s Wastewater Treatment Plants to see for yourself how Loop is made.

What is Loop? How Is Loop made

Loop has enriched Pacific Northwest landscapes as an ingredient in the commercial product GroCo compost since 1976.