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Gustafson LLC Moves to Zero-discharge

When Gustafson LLC, a manufacturer of agricultural equipment, moved from Eden Prairie to its new Shakopee facility at the beginning of 2000, it took the opportunity to make its operations more environmentally friendly. The primary goal of this undertaking was to minimize chemical use and chemical toxicity within the plant. This led to the ultimate goal of achieving zero-discharge of process wastewater and eliminating the need to hold an Industrial Discharge Permit.

The need to discharge tumbling wastewater has been eliminated through the use of a dry deburring dust, rather than water, in the vibratory deburring units. All water-soluble coolant is shipped off-site for recycling and the non-contact cooling water used to cool the facility's two spot-welders is discharged to the storm sewer under an NPDES permit. (Please note, installation of a chiller to reuse non-contact cooling water is preferable to storm sewer discharge.)

The largest hurdle Gustafson faced in achieving zero-discharge status was to eliminate discharge from the 3-stage phosphating line used to prepare parts for painting. First, Gustafson replaced the first stage alkaline cleaner with a neutral cleaner. The neutral cleaner is easier and safer to work with. It can be kept at 120-130 oF, rather than 150-160 oF, which allows the tank to be more versatile in its uses. The company currently cleans plastic and fabrics with the neutral cleaner. In addition, the neutral cleaner doesn't react with the primer nor have bacteria problems the way the alkaline cleaner did. Next, Gustafson evaluated the raw material being received by the company and considered the fabrication process and desired finish, in order to determine what amount of cleaner was needed. Beginning with the least aggressive cleaning method and progressing to the most aggressive method, the company then conducted bench testing on all of the substrates. Through bench testing, the company discovered that in order to achieve their desired cleaning results, only a 5% solution of cleaner is needed, rather than the 12-13% solution that the chemical supplier recommends.

The second stage in the line is a dead rinse and the third stage is the phosphating acid. By spray rinsing the parts over the baths and balancing the rinsing with evaporation, the company has conserved water and eliminated the need to discharge wastewater from the tanks.

Although it has not yet been needed or performed, reclamation of the cleaner and phosphating acid will involve skimming of the oil, removing of solids (through precipitation and/or filtration), evaporating the liquid to a concentrated cleaner and then reformulating. The adoption of these procedures has allowed Gustafson to avoid the need to discharge their 900-gallon tanks two times per year. The company has nearly eliminated the use of lacquer thinner in the plant by replacing it with a dilute solution of the neutral cleaner. Gustafson found that the keys in implementing their pollution prevention strategies were:

1. Finding a chemical supplier that was willing to work with the company.
2. Bench testing to determine the minimum amount of chemical needed to obtain the desired results of parts treatment.
3. Support of management.

As of yet, the company has only seen the cost savings resulting from not holding an Industrial Discharge Permit, including the associated monitoring costs. After the new system has been refined, the company expects to see cost savings of 25-30% resulting from labor savings through production efficiency improvements, energy cost savings from process refinements and saved chemical costs.