Sludge is an organic solid, semi-solid, or liquid by-product of publicly owned treatment works. (For infomation about waste resulting from industrial processes, please contact the Waste Management Program) Sludge characteristics vary depending on each treatment facility’s wastestream and the processes that are used. In general, sludges are composed of water, organic matter, nutrients (such as nitrogen, phosphorus, calcium, and magnesium), and micro-nutrients such as zinc and iron.
Sludges meeting EPA standards for beneficial use are referred to as Biosolids. Like animal wastes, biosolids are a part of the natural cycle of life. They have nutrient and soil-enhancing properties making them a practical choice for a variety of beneficial uses. There has been significant research on the beneficial use of biosolids, and history has demonstrated, in the United States and other regions of the world, high quality biosolids can be beneficial soil additives and plant nutrients when properly applied. Concerns about biosolids relate primarily to the quality of the material and its impact on human health, soil productivity, groundwater, surface water, and adjacent land uses.
To ensure sludges which are used as biosolids are treated and managed in a manner that protects both human health and the environment, Congress directed EPA to develop a comprehensive national Sewage Sludge Program aimed at reducing risks and maximizing the beneficial uses of sludge. In February of 1993, EPA issued its sewage sludge use and disposal regulation, 40 CFR Part 503, commonly referred to as the "503s". For more information, check out EPA's Biosolids Program (Please note, this link will take you out of SD's web site).
As part of EPA's implementation for the 503s, it has developed a permitting program for biosolids to ensure biosolids are beneficially reused in an environmentally safe manner. South Dakota has received delegation of the biosolids permitting program from EPA. For more information about biosolids reuse and permitting in South Dakota, contact Tina McFarling at (605) 773-3351.
Beneficial Uses for Biosolids
As stated above, biosolids have many beneficial uses:
- Farmland: for the production of a wide range of crops. Biosolids help build up soils and can serve as a partial replacement for fertilizers.
- Forest Land: to enhance forest productivity and to condition soils in reforestation projects.
- Land Reclamation Projects: to build up barren soils in areas such as mine tailings, abandoned sand and gravel pits.
- Public Works Projects: along highways, in parks, on airport runways.
- Landscaping Projects and Golf Course