Aqueous chemical baths and rinse water are processed at a pretreatment facility where acidity is neutralized and dissolved copper is removed prior to discharge to a POTW. In 1991, the treatment produced 1417 tons of metal hydroxide sludge, a RCRA F006 hazardous waste.
Two processes were identified for chemical use reductions. HCl is used to prepare surfaces, with simple process experimentation and inexpensive equipment changes the team determined how to minimize use of HCl. An important step was the use of Electron Spectroscopy for Chemical Analysis (ESCA) to determine when sufficient surface preparation was accomplished.
An additional project decreased the carbonate usage in developing solutions. Together these projects reduced the usage of HCl by 90% in cleaning processes, developing and stripping solutions by 40%, reducing the amount of lime need for neutralization by 75% and the generation of sludge by 47%.
Hazardous sludge generation was reduced from peek 1991 levels by about 670 tons per year.
Details of Reductions
Additional Information :
The total cost savings based on reduced material purchases and reduced waste disposal came to $630,000 per year. There were minimal expenditures on equipment, the savings paid for the investment in time in well less than a year.