(Certified Best Practice by BMPCOE)
Polaroid Corporation - Waltham, MA
Polaroid has developed a two-step carbon and clay filter system which removes oil and detergent from Electrostatic Discharge Machining operation wastewater. The system's initial objective was to maintain or reduce operating costs, and meet the sewer permit requirements set by the Massachusetts Water Resource Authority (MWRA). Acceptable wastewater standards call for less than 15 parts per million of total petroleum hydrocarbons.
During the initial development phases of the project, Polaroid encountered some unique obstacles. Trial system #1 used a coalescing tank and carbon filtration media. However, the carbon media quickly clogged and required frequent and expensive changes. By adding clay to the filtration process, trial system #2 significantly improved the life of the media. However, the wastewater discharge still continued the consumption of water during the process and represented a 5% chance of placing Polaroid in jeopardy for MWRA violations. Trial system #3 addressed the unforeseen benefit of using a closed loop method to run the discharge water back into the rinse tank. This system lowered capital costs, eliminated the possibility of MWRA violations, reduced water consumption by 2,300 gallons per day, and had the added benefit of eliminating wastewater sampling costs.
Benefits from Polaroid's two-step carbon and clay filter system included decreasing water usage, reducing maintenance, and lowering the amounts of non-hazardous materials. Although it met the discharge standards with trial system #2, Polaroid chose to continue modifying and improving the filter system to the point of totally isolating the MWRA process regulations and eliminating the associated environmental liability.