There are about 16,000 wastewater treatment plants in the US. The input to these plants includes both residential and industrial discharges. The industrial dischargers are referred to as Significant Industrial Users (SIU’s) in EPA parlance. The wastewater treatment plants’ effluent is regulated by the federal Clean Water Act and as augmented by state and local regulations. It is in their interest to limit the heavy metals from the SIU’s. The concentration of the allowed metals are set forth in permits negotiated between the two parties. SIU’s are subject to fines for violating the terms of their permits.
The concentration levels reported by the continuous monitoring at the outlet of the metal finishers and others discussed in the Industrial Heavy Metals section will be accessed via the internet and displayed on PCs at the downstream wastewater treatment plant. There are opportunities for installing monitoring at the treatment plant and in the distribution system that feeds into the plant. Also there are applications for optimizing the treatment processes within the plant.
 McIlvaine Company, Northfield IL.