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National Information |
Biosolids
What are Biosolids?
Biosolids are, in effect, a slow release nitrogen fertilizer with low concentrations of other plant nutrients. In addition to significant amounts of nitrogen, biosolids also contain phosphorus, potassium, and essential micronutrients such as zinc and iron. Many western soils are deficient in micronutrients. Biosolids are rich in organic matter that can improve soil quality by improving water holding capacity, soil structure and air and water transport. Proper use of biosolids can ultimately decrease top soil erosion.
When applied at agronomic rates (the rates at which plants require nitrogen during a defined growth period), biosolids provide an economic benefit in addition to their environmental benefits. Colorado State University agronomists have shown continuous application of three dry tons per acre every other year to dryland wheat produces comparable yields, higher protein content, and larger economic returns compared with the use of 50-60 pounds per acre of commercial nitrogen fertilizer.
How do Biosolids differ from Sewage Sludge?
Most simply, biosolids is the new name for what had previously had been referred to as sewage sludge. Biosolids are primarily organic treated wastewater materials from municipal wastewater treatment plants -- with the emphasis on the word treated -- that are suitable for recycling as a soil amendment. Sewage sludge now refers to untreated primary and secondary organic solids. This differentiates biosolids which have received stabilization treatment at a municipal wastewater treatment plant from the many other types of sludge that exist (such as oil and gas field wastes) that cannot be beneficially recycled as soil amendments.
What are the Reuse/Disposal Options?
The only options for reuse/disposal of biosolids are incineration, surface disposal, landfilling, or recycling as soil amendments. Incineration is very expensive. Landfilling and surface disposal are really temporary solutions to a permanent problem. Because biosolids are a valuable resource, recycling as soil amendments is the preferred disposal option.
What are the Traditional Practices in this Region?
Before about 25 years ago, the traditional practice in this Region was to landfill or incinerate what was then called sewage sludge. During the past quarter century the practice changed to recycling biosolids as soil amendments. Region 8 recycles 85% of the biosolids generated in the six state Region. Data from 1996 indicated that 90% of the facilities meet the more restrictive Table III requirements (see 40 CFR Part 503).
What are the Federal Requirements?
The EPA in 1993 set forth requirements for management of all biosolids generated during the process of treating municipal wastewater, commonly called the 503 rule. The 503 rule encourages the beneficial reuse of biosolids and establishes strict standards under which wastewater residuals can and cannot be beneficially recycled as soil amendments. The EPA believes that biosolids are an important resource that can and should be safely recycled. The 503 rule is designed to protect public health and the environment. Most of the requirements were based on the results of extensive multimedia risk assessment and on more than 25 years of independent research. The 503 rule establishes standards for pathogen destruction and for levels of metals that can be present in biosolids. It also governs the stability of the materials by reducing the attraction of vectors (such as flies), agricultural practices, site restrictions, and crop harvesting restrictions.
How can I get More Information?
U.S. EPA
Robert Brobst (8P-W-P), Biosolids Coordinator
U.S. Environmental Protection Agency, Region 8
1595 Wynkoop Street
Denver, Colorado 80202-1129
Telephone:(303) 312-6129 or 1-800-227-8917 ext. 6129
Email: brobst.bob@epa.gov
FAX: 303-312-6116
State Contacts for the Biosolids Program
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