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What is Biosolids Recycling?

We all know about recycling metal, glass, plastic and paper and why it is important for the environment. But few of us know about biosolids recycling. Biosolids recycling is a process of returning nutrients and organic matter back to where there materials came from--the soil.

Biosolids are a resource that is reclaimed during the treatment process of municipal wastewater.

Everyday millions of us flush used water down sinks, bathtubs, showers, and toilets. This wastewater ends up at a wastewater treatment plant, where the organic matter and nutrients in the wastewater are removed during the treatment process. After treatment to remove pathogens (i.e., disease-causing organisms) and reduce odor potential, the organic matter and nutrients become biosolids. Once this treatment is accomplished, biosolids are analyzed for beneficial properties and contaminant levels to ensure that the product is safe and beneficial.

Biosolids benefits include:

• add organic matter to soil
• improve soil properties
• provide plant nutrients
• increase crop yields
• reduce soil erosion

Wastewater treatment and biosolids recycling is good for the environment. Discharge wastewater could have a very detrimental effect on lakes and rivers if nutrients and organic matter were not removed from the wastewater. These nutrients and organic matter, however can have a very positive effect on soil and plant growth. Treated biosolids contain essential plant nutrients and organic matter, which make it an excellent fertilizer and soil amendment.

The recycling of biosolids is regulated and supported by the U.S. Environmental Protection Agency (U.S. EPA) and the Minnesota Pollution Control Agency (MPCA).

Biosolids uses include:

• agriculture
• forestry
• landscaping & gardening
• land reclamation & soil improvement

Biosolids Recycling in Agriculture

Extensive modern-day agriculture is largely dependent on farm chemicals and limited rotations of just a few crop species. While this type of agriculture had resulted in a bonanza of crop yields over the years, it has also left some areas with depleted soil fertility, degraded soil structure and eroded topsoil.

Biosolids recycling can provide many of the plant nutrients needed to restore soil fertility, including nitrogen, phosphorus, and trace minerals. Many of these nutrients are organic, "slow-release" nutrients, which can improve the crop yields over soluble chemical fertilizers. The organic matter in biosolids can improve the soil structure and tilth, reduce soil erosion and increase moisture retention.

Over twenty years of research by the University of Minnesota and the U.S. Department of Agriculture at the Rosemount Experiment Station has shown that biosolids recycling in agriculture is a safe and beneficial practice that results in improved crop yields.

Biosolids Recycling in Forestry

Over the years, we have put a considerable pressure on our forest resources due to increased demands on forest products (paper, building materials, etc.). While the demand for forest products is growing, many acres of forests are being taken out of production for uses such as recreational/vacation areas and suburban/rural housing. Consequently, pressure to intensify timber harvesting remains very high.

To supply our ever increasing need for forest products, foresters are investigating ways to increase forest productivity. The use of biosolids in forestlands and on tree farms as a fertilizer and soil conditioner has resulted in rapid tree growth and increased timber production. A secondary benefit is a more productive forest, which can provide more food and cover for wildlife. The use of biosolids to grow trees is common in many states and is expected to increase in Minnesota.

Biosolids Recycling in Land Reclamation and Soil Improvement

Soils are often drastically disturbed where mining or construction activities take place. If left unchecked, soils disturbed by these activities can result in severe erosion and nearby surface waters can be impacted. Biosolids have been used to reclaim distributed areas such as strip mines, tailings basins, rock dumps, sand/gravel pits, large construction sites, and road right-of-ways. Biosolids work to improve soil stability on steep slopes, promote rapid growth of vegetative cover, and reduce erosion.