A Better Understanding Of Biosolids
Biosolids are organic residues resulting from the treatment of commercial, industrial and municipal wastewater (sewage). The products are recycled for use as fertilizer and soil amendment. Agricultural applications of biosolids are regulated and encouraged by the US Environmental Protection Agency and state and local authorities. These standards are based on decades of research and are designed to protect human health and the environment.
What Are Biosolids?
Biosolids are a naturally occurring, beneficial, recycled resource that contains essential plant nutrients and organic matter. They are created by wastewater treatment processes that combine sewage sludge with organic matter from human and animal wastes, as well as pathogens and bacteria. When used as a land-applied fertilizer, they are a good source of essential nutrients for crops (nitrogen and phosphorus), supplementary nutrients (potassium, sulfur, magnesium, calcium, copper, zinc, vanadium and manganese) and a wide array of trace elements necessary for healthy soils. A significant benefit of using biosolids is that they enrich the soil nutrient profile and increase crop yields. However, farmers should note that biosolids do not provide a balanced nutrient uptake for most crops (typically, excess P and insufficient K).
How Are Biosolids Used?
Biosolids are a valuable nutrient and soil conditioner. They provide a wide range of benefits to soil and crops, including increased organic matter, improved soil health, reduced odors, and enhanced water infiltration. They also supply nutrients (N, P and K) that cannot be produced on the farm. This means that farmers must manage their fertilizer program to balance nutrient inputs with crop needs. Depending on how they are used, biosolids can be applied directly to the land as fertilizer, or as a soil amendment. They are also sold in compost or other forms and used as mulch on landscapes. They are usually disposed of at municipal waste landfills, monofills, or engineered landfills. These disposal sites are lined, have groundwater monitoring capabilities and comply with other regulatory design and operational criteria.
What Are The Risks To Human Health And The Environment?
Biosolids can contain many pollutants, including metals such as lead and aluminum, pesticides, fungicides, pharmaceuticals, endocrine disruptors like triclosan and dioxins. Some of these chemicals are highly toxic, and they can affect human health in a variety of ways, such as causing cancer or harming the immune system. One such contaminant is PFAS, or “forever chemicals.” They are found in everything from raincoats to dental floss to non-stick products. They have been linked to serious health problems, and they can also be dangerous for animals.
The EPA is currently awarding grants to scientists who want to learn more about the chemicals in land-applied biosolids and how they can affect human health and the environment. These research projects will seek new information on the occurrence, fate, and transport of these chemicals in biosolids, and their impact on plant growth and the climate. The results will help utilities and states make informed decisions about how to best treat and manage their wastes.