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Silver Management Program

Silver Management Program

The goal of Boulder's silver reduction program is to reduce the amount of silver entering the city's wastewater treatment facility. Boulder's 75th Street Wastewater Treatment Facility is unable to treat or remove metals such as silver. Treated wastewater is discharged to Boulder Creek while solids that settle out during the treatment process are applied to agricultural land as a soil amender.

Silver Sources

The primary source of silver is from the discharge of untreated or improperly treated silver-bearing fixer from photographic material processing such as development of silver bearing film, x-ray film and photographic paper.

Why Recover Silver?

  • Conserve natural resources and protect Boulder's watershed.
  • Save money.
  • And, it's the law:
    • Boulder Revised Code 11-3 Industrial and Prohibited Discharges requires that all facilities generating waste photographic fixer treat for silver removal prior to discharge to the sanitary sewer. Discharges from silver treatment systems may not exceed 100 mg/L. The alternative to on-site treatment is to have the fixer transported off-site for disposal. Failure to comply with regulations is a violation of law and can result in penalties up to $1,000 per day for each violation.

Off-Site Disposal

Several local vendors offer fixer pick-up services. If your practice generates only small quantities of fixer, it may be more cost-effective and efficient to have the fixer transported off-site for silver removal. By opting for off-site disposal, you are guaranteed 100 percent recovery of silver in x-ray fixer.

When storing fixer for off-site treatment or disposal, remember to:

  1. Collect and store the fixer in a closed plastic container.
  2. Label the container "Hazardous Waste - Used Fixer" along with the date the fixer was first added to the container.
  3. Keep your records of the volume and frequency of off-site fixer disposal for a minimum of three years.

On-Site Disposal

You can purchase or lease a silver recovery unit to remove silver from spent fixer. Canister units are usually sufficient for removing silver from small volumes of fixer and can be used alone or in series. Electrolytic units are also available and can be followed by a canister to ensure as much silver as possible is recovered. Talk with a silver recovery service about what will work best for your practice. After a specified interval, the canister of the plated silver is shipped to a metal reclaimer where the captured silver is recovered. The treated fixer can be discharged to the drain with permission from the City of Boulder Industrial Pretreatment Program.

If your office uses a silver recovery unit, remember to:

  1. Check the unit daily for leaks, spills and overflows.
  2. Periodically, check the flow rate of solution to the recovery system. Typically, a lower flow rate and a longer retention time will maximize silver recovery.
  3. If using an electrolytic unit, check the appearance of the silver plate. The plate should be tan to brown and grainy. Consult your user's guide for specific guidance.
  4. Test the silver concentration of the treated fixer monthly. The test can be performed with an analytical test kit or a lab analysis. Periodic testing will tell you how effective your unit is at capturing silver and will alert you to recovery unit problems.
  5. Record test results in a silver recovery log.

 

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