Ms. Goldman: It is a pleasure to be able to contribute to a person so knowledgable, as you clearly are. Let me expound. There is more than one type of phosphate. The simplest is ortho phophate, and is tbe type that is in the common phosphoric acid, or household "TSP" (read TriSodium Phosphate), and this animal actually assists in precipitation of most heavy metals, such as Copper. The so-called "complex phosphates", which most commonly are pyrophosphate, which is famed in the memory of most REAL old timers as the electrolyte in the old copper plating baths, and tripoly phophate, which is commonly found in most laundry detergents, and many/most industrial metal cleaners, are chelates, and will complex heavy metals quite nicely, and make waste treatment difficult. And a last comment, the complex phosphates are not totally stable, and their stability is related to pH, the lower the pH, the less stable, and they decompose into ortho phophates. This means that if somebody is batch waste treating a complex phosphate containing solution, they can lower the pH to say, 2, or less, and let the bath sit say 24-48 hours, and then neutralize to pH 9, and all the metals should fall out, some may fall out as the phosphate salt. More than you ever wanted to know. Best, Rudy Sedlak RD Chemical Company *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************