Office of Technical Assistance Executive Office of Environmental Affairs Commonwealth of Massachusetts

Summary

Hyde Tools, a division of Hyde Manufacturing Corp., installed a filtration system to recycle the quench oils used in its heat treating process. This system reduced the firm's water consumption, cut back on testing and permitting costs, and eliminated the need for out-of-house reclamation of quench oils. The project cost $25,805 to implement, and it yielded a favorable net present value in excess of $15,000 over its ten-year economic lifetime.

Background

Hyde Tools of Southbridge, Massachusetts is a 300-employee firm with two lines of products: an industrial tool line featuring machine blades, saw blanks and hand knives; and a trade line of knives, scrapers and other surface preparation tools designed for do-it-yourself home improvement projects.

Hyde's knife and scraper blades are stamped out of high-carbon steel, sent through a vibratory degreaser, loaded into racks, then propelled via robotics through a heat treatment process. In the heat treatment process, the blades are submerged in a molten salt tank at temperatures ranging from 1600 to 1800 degrees, then plunged into a 500-gallon tank of quench oil. The quench oil is removed from the parts in a wash tank and two rinse tanks. The blades are then ground and polished, and the tools are assembled, packaged and shipped.

Prior to the implementation of in-house quench oil recycling, the heat treatment process generated approximately 12 drums of oily water every six weeks. These were sent out for reclamation and water removal.

Toxic Use Reduction

In 1988, the firm instituted a systematic plan to attain zero discharge of water pollution within three to five years. At that time, company management realized that eliminating the use of toxic chemicals in Hyde's processes would not only be cost-effective, but would also help ensure the health and safety of workers and the public, while guaranteeing that the firm would exceed compliance requirements.

With the help of plant engineers, Hyde Environmental Manager Douglas DeVries drafted a plan for attainment of the zero discharge goal. DeVries decided to deal first with discharge from the heat treatment process. After considerable analysis, he determined that in-process recycling was the answer.

Toxics Use Reduction Modification

After collecting and reviewing proposals from various vendors of filtration and wastewater recycling systems, DeVries chose a filtration model capable of recycling the wash and rinse water as well as the quench oil. The new system is composed of a transfer pump, a bag filter for capturing excess dirt, and two heated cone-bottom reclamation tanks in which suspended solids and water can be separated from the quench oil. This new system eliminates the need to pump oil into drums and send them out for reclamation, reduces the total cost of reclaiming quench oils, and conserves wash and rinse waters by filtering and recirculating them.

The purchase cost of Hyde's oil recycling system was $20,055. The vendor trained Hyde employees to use and monitor the system at no additional cost. In-house installation costs amounted to approximately $5,000.

Results

Reductions Achieved: Hyde was able to reduce the amount of oil sent off site for reclamation by 1,730 gallons per year. The project also reduced water usage in the wash process by 19,200 gallons per year.

Economics: Purchase and installation costs for Hyde's new filtration and recycling system totaled $25,055. Hyde also installed an alarm system that automatically shuts off the unit's pump when the oil/water combination in the sump nears capacity. The purchase and installation cost of this safety system was $750, bringing the total up-front cost to $25,805.

The new system has reduced Hyde's purchases of quench oil by $4,844 every year. In addition, Hyde saves $8,760 in water bills, $4,200 in NPDES permits and $300 in laboratory testing costs each year. The only new expenditures associated with the system are the filtercake purchase and disposal costs, which total $2,800 per year. Thus, the payback period for the investment is about 2.5 years. This does not take into account the potential $2,500 per day fines or the potential liability associated with discharging into the sewer.

OTA has conducted a more fine-toothed economic analysis which shows that the project yields a favorable net present value of $15,229 over its 10-year economic lifetime. (See Figure 1.) In net present value analysis, any project which shows a positive value is considered favorable.