Below is a table showing pollutant concentration limits for biosolids. The Ceiling Concentration values provides the maximum levels of heavy metals that may be in a land applied Biosolid. If a Biosolid contains metal levels greater than these amounts, alternative disposal methods such as either land filling or incineration must be used.
The Exceptional Quality values provide maximum pollutant concentration levels allowable for heavy metals to meet one of the requirements of an "exceptional quality" Biosolid. Pollutant concentrations must be below the Exceptional Quality levels for a Biosolid to be bagged, sold or given away for use on a lawn or home garden. The linked graphs illustrate: 1) statewide averages of heavy metals relative to both the Ceiling Concentration and Exceptional Quality, and 2) statewide trends in the level of heavy metals contained in Michigan biosolids since 1981. The graphs demonstrate the positive correlation between pollutant levels and the implementation and enforcement of industrial pretreatment programs by municipal wastewater treatment facilities.