Which of the following is NOT part of the silver recovery exemption criteria?

• A. Less than 500 gallons per month
• B. Treated on-site within 90 days
• C. Silver concentration less than 5 mg/L
• D. The solution is non-hazardous for silver

Answer: (D)

Understanding when silver-bearing wastes qualify for the silver recovery exemption involves limits that keep handling small and manageable. The exemption applies if the waste is produced in a limited amount (less than 500 gallons per month), is treated on-site within 90 days, and has a silver concentration below 5 mg/L. These criteria are about controlling volume, ensuring timely on-site treatment, and keeping silver content at a low level to minimize risk.

The statement about the solution being non-hazardous for silver isn’t part of those criteria. The exemption isn’t based on silver itself being non-hazardous; instead, it relies on the overall waste being small in quantity, treated promptly on-site, and having low silver concentration.