What are biosolids? Biosolids are the nutrient-rich by-product
of municipal wastewater treatment. The City of Portland treats
raw sewage solids (often called sludge) to meet stringent U.S.
Environmental Protection Agency (EPA) standards for pathogen
reduction, vector attraction reduction, and pollutant levels
before they can be called biosolids and used beneficially. Why
recycle biosolids? Recycling biosolids through land application
returns a useful resource to the land. Biosolids are rich in
nutrients and organic matter that aid the growth of farm crops,
gardens, forests and parks. Biosolids can also restore
vegetation to soil disturbed by mining or topsoil removal. The
City of Portland once landfilled its biosolids, which is an
expensive and unsustainable practice. Beneficial reuse of
biosolids frees up finite landfill space and replenishes the
soil with valuable nutrients and organic matter. Biosolids can
also offset the use of commercial fertilizers, which are
produced by a fossil fuel-intensive process.