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Biosolids

Land applying biosolids
Environment, Great Lakes, and Energy

Biosolids

Biosolids are nutrient-rich organic solid, semisolid, or liquid residues that can be land applied for beneficial reuse. They are generated during primary, secondary, or advanced treatment of domestic sanitary sewage through one or more controlled processes that reduce pathogens and vector (flies, mosquitos, rodents) attraction. These processes include, among others, anaerobic digestion, aerobic digestion, and lime stabilization. The terms "Biosolids" and sewage sludge are defined in Part 31, Water Resources Protection of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended; however biosolids are only the portion of sewage sludge that have undergone adequate treatment to permit their application to land. Industrial sludges and septage are land applied under different programs and are excluded from the biosolids definition.

Contact us

Each county has a specific biosolids coordinator assigned; find your county biosolids program staff.

Laws & rules

On June 18, 1997 the governor signed 1997, PA 29. Act 29 amended the Natural Resources and Environmental Protection Act, 1994 PA 451 (NREPA) by amending section 3101 (MCL 324.3101) and by adding sections 3131, 3132, and 3133 providing for a fee-based statewide biosolids management program. These changes to part 31 of NREPA provided new ability to better manage the land application of sewage sludge (biosolids) and sewage sludge derivatives.

The Part 24 Biosolids Rules of Part 31, Water Resources Protection, of the NREPA, became effective on November 2, 1999. The rules establish standards consisting of general requirements, pollutant limits, management practices and operational requirements for the beneficial land application of biosolids.

The state statute and Rules are consistent with the federal title 40, Code of Federal Regulations, Part 503 rule.