Question: “I wanted to ask you if you could help us understand what Cad-Con 1000™ does to the alloy tank water? Could you please explain technically how the Cad-Con neutralizes the active metals left in the water and how best to determine if the water has been treated so that we can be certain it’s ok to discharge it in the sewer?”



Alloy tank wastewater is water that has been in direct contact with liquid and solid 117 alloy for some period time long enough to contaminate it to the point that it needs to be replaced.  Depending on the chemical components of the original tap water, the used alloy tank water will contain some concentration of each of the alloy constituents; Bismuth, Indium, Lead, Tin and Cadmium.  It will also contain traces of the abrasives, polishes and other chemicals used in the generating and polishing processes as well as microscopic particles of the plastics or glass that the lenses are made of.  Although there are at least 5 metals in the wastewater, Cad-Con 1000™ is formulated to target cadmium and lead primarily because these two metals are toxic to humans, animals and the environment, and are regulated by the EPA and State environmental agencies.

Cad-Con 1000™ works in two ways to ensure that these two toxic metals are removed from the water and can be safely disposed of.  First, it chemically attracts and stabilizes the metals in the water by forming new chemical compounds that are insoluble.  In other words, the metals become chemically bound to the particles of Cad-Con 1000 and separate from the water as the particles are filtered or settled out.  Secondly, Cad-Con 1000™ regulates and maintains the pH of the sediment within a range where cadmium and lead are the most stable.  Once the sediment is removed from the water, so are the metals and the clear water should be virtually free of toxic metals and suitable for discharge.  The sediment can be separated either by filtration or settling and collected in filters or as a sludge and sent to a recycler where the metals including the cadmium and lead are recovered through a smelting process.  Or the sediment can be disposed on in an industrial landfill where the Cad-Con 1000™ will maintain the optimum pH indefinitely.  In addition to forming insoluble compounds, regulating the pH of the sediment is crucial to how Cad-Con 1000™ controls the leachability of the toxic metals over time. Because of this, the cadmium and lead remain locked in the sediment in the landfill.

In order to verify compliance of the water for discharge to a drain, do the following:

  1. First you need to know the discharge limits required by your local sewer authority for your location.  If you do not know, you need to contact them and ask for that information.  I will assume that cadmium (Cd) and lead (Pb) are the only two constituents you will need to be concerned with, but there may be others. Get a list of discharge limits and contact PSI if you have questions.
  2. Contact an environmental laboratory and ask for sample bottles needed to test for Total Cd, Total Pb and any other metals required by your sewer authority.
  3. Treat your alloy tank water in accordance with the instructions provided by your supplier. Check and record the pH of the water before treatment and after treatment.
  4. Allow the treated water to rest in the treatment bucket undisturbed for 5 days.  This ensures that the sediment has thoroughly separated from the water.
  5. With unused rubber gloves on, fill the sample bottles by dipping into the surface of the treated water.  DO NOT disturb the sediment or get any alloy or sediment on the gloves or in the sample.  Seal the jars and deliver them to the lab in accordance with their instructions.
  6. You should receive the laboratory results within 10 days.  Compare the results to the limits established by the sewer authority.  If the lab results are less than the discharge limits, your discharge is in compliance.  You should keep a file on your testing results and perform your alloy tank water treatment the same way each time.  Also, it is a good idea to test your discharge water and verify your compliance periodically, say every 6 months.  Keep an ongoing file of your compliance testing.

If your results exceed the sewer discharge limits, the treated water does not comply and the treatment process should be reviewed by an environmental professional who can recommend appropriate modifications to your process.  If this happens, please contact PSI at or call 800-237-8154.