Reducing Waste from Solvent Sink Parts Washers
So you have 14 solvent sink parts washers. They clean well, but waste management is a problem. The sink company replaces the solvent every four weeks and now you just found out that you are a hazardous waste Large Quantity Generator. What can you do? Fortunately, there are several steps that can be taken to reduce waste and save money.
How dirty is the solvent in the sink? If the solvent is still cleaning your parts well, do not change the solvent. There is no rule that says solvent must be changed out every four weeks. Only replace the solvent when it no longer cleans. Run some tests and see how long the solvent will last. Some sinks may be used more than others. Periodically moving sinks from light to heavy wash loading areas will extend the solvent life by sharing the cleaning load between all sinks.
Is there a filter on the solvent sink? Many newer solvent sinks will filter solids from the solvent as the pump recirculates the solvent. Instead of replacing the solvent, some companies have found that only the filter needs to be replaced to keep the solvent sink working. If the solvent sink is leased, the supply company can often replace existing sinks with filter type sinks. If your company owns the sinks, consider purchasing new sinks with filters or refitting the sinks with filters.
Use the solvent sinks in stages. If solvent sinks are used in pairs, the solvent will last longer. One sink is the first stage washer; very dirty parts are washed here. The second sink is the final washer. The solvent in the first stage will become very dirty, but even dirty solvent will remove heavy grease and grime. The final wash sink will stay clean; the clean solvent will remove any grime left on the part after it has passed through the first stage. When the solvent in the final washer gets too dirty for final cleaning, it can be replaced with clean solvent. The dirty solvent removed from the final washer is used to replace the solvent in the first stage sink. Only the very dirty solvent from the first stage sink is shipped offsite as waste. This type of cleaning is called two-stage washing; this process can reduce solvent usage and waste generation significantly.
Finally, why use solvent? There are a number of cleaning solutions that can replace solvents such as mineral spirits. Many of these chemicals are not hazardous. Using nonhazardous solutions may be your solution to reducing hazardous waste, providing a safer workplace, and saving money.