An Illinois circuit board manufacturer has a wastewater treatment system that operates at 130 gpm daily. The waste streams contains mainly copper and lead plus other heavy metals, found in solder and flux. The system operates by collecting wastewater from the various sumps (etching, plating, etc.) in an equalization tank. The stream is then fed to three treatment tanks. In the first tank, acid/ferrous sulfate/ organic coagulant mixture is added. Caustic is added in the second tank to raise the pH and precipitate metal hydroxides. In the third tank, a polymeric flocculent is added to enhance sedimentation in the clarifier. Overflow from clarifier is neutralized, pumped through a sand filter into a holding tank and finally released to the sewer. Sludge from the clarifier is collected in a sludge holding tank and dewatered in a filter press. The waste is hauled away as a hazardous material.

Laboratory tests showed that a dose of 500 mg/L of AQUASIL^® AMX-5M is sufficient to bring the quality of treated water into compliance with local regulations. As the pH of the raw water is about neutral, AQUASIL^® AMX-5M was added directly in the dry form, without prior or post pH adjustments. The treatment produced large, dense floc that settled efficiently. Moreover, the AQUASIL^® Treatment also reduced the concentration of phosphorus, COD, and total dissolved solids. The treated water is of excellent quality and can be reused.

The AQUASIL^® treatment eliminated the need of all liquid chemicals, neutralization tank, and sludge thickening, produced a very clear treated effluent that meets municipal standards, and generated non-hazardous waste as defined by Resource Conservation and Recovery Act (RCRA).