Waste Treatment Process for Electroless Copper

The spent electroless copper bath is deactivated at the overflow by the automatic addition of hydrogen peroxide (H2O2) to prevent copper from plating out in the drain lines, causing the lines to become blocked. Caustic (NaOH) and formaldehyde (HCHO) are then added to the deactivated electroless copper solution in a batch treatment process. Powdered aluminium or aluminium fines are added to precipitate out the copper as metallic copper. The copper concentration (<1 ppm) can be made stable for several days if necessary. The metallic copper is filtered out and salvaged. The mother liquor is neutralised (pH 6·5–9·0) and discharged. United States patent applied for, 07–345865.