NSF Engineering Research Center
and in Partnership with Industry
Definition
Sludge means any solid, semi-solid, or liquid waste generated from a municipal, commercial, or industrial wastewater treatment plant, water supply treatment plant, or air pollution control facility exclusive of the treated effluent from a wastewater treatment plant.
As used by the EPA, sludge identifies a waste generated from one of several specific processes (in this case the removal of contaminants from air or water) and not the characteristics of the waste. In addition, note the following about the EPA definition of sludge:
·     May be a solid, semi-solid, or liquid.
·     Generator of waste must be municipal, commercial or industrial entity.
·     May be generated as a result of wastewater treatment, treatment of a water supply, or an air pollution control device.
·     It does not include the treated effluent (or discharge) from a wastewater treatment plant.
At CASFER, we plan on repurposing this sludge, by extracting the active nitrogen from it and converting it into usable nitrogen-based fertilizer! One step on our path to a Nitrogen Circular Economy!