Are there toxic materials in the biosolids?
In the Seattle area, industries are required to remove hazardous contaminants before the wastewater is discharged to sewers. (For more details about this program, see King County Industrial Waste Program) The county’s biosolids easily meet EPA’s most stringent standards for safe use on land and crops. Many metals and organic chemicals that are unsafe in large amounts also occur naturally in the environment, and some, such as zinc and copper, are necessary for the health of plants and animals. King County’s biosolids contain only very small amounts of metals and organic chemicals, thanks to the effective monitoring and pre-treatment requirements placed on industries.
