Do filter based solvent recyclers work?

by brblog on July 16, 2019

Q: Do filter based recyclers work?

Yes and no….mostly no.

There are commercial filter recyclers available for alcohol and formalin. There are no filter recyclers for xylene on the market.

Alcohol – What does a filter recycler do?

With use, the alcohol concentration gradually gets weaker due to water absorbed from the tissue and carry over from the previous alcohol station. Eventually the concentration becomes so weak that the used alcohol must be changed to fresh alcohol of the original strength.

Filtering removes contaminants such as stain, fat, protein and biologicals.

Alcohol Filtering

Filtering does not increase the concentration of the alcohol!

If the waste alcohol and filtered alcohol have the same weak concentration then it is still as unusable as when you took the weak alcohol out of service.

Yes, filtering is fast, easy and cheap. That’s why people try it. It even makes the solvent look clean. Too good to be true, right? Right.

Where on the tissue process or stainer would you use weak concentration alcohol? Clearly you wouldn’t.

Choose a recycler that distills solvents by temperature and guarantees purity/concentration. It will remove all the stain, fat, proteins and biologicals. More importantly, it will increase the alcohol concentration to 95%. Dilute it to the correct concentration and use anywhere on the stainer/tissue processor that does not require 100% alcohol.

Formalin – What does the filter recycler do?

Formalin is used to “fix” tissue or stop it from decaying. It is actually consumed in the fixing process. With use, the formalin concentration gradually decreases until the concentration is no longer able to “fix” tissue. At this point the weak, used formalin is changed for fresh, full strength formalin.

Filtering removes contaminants such as stain, fat, protein and biologicals.

Filtering does not increase the concentration of the formalin at all!

Formalin Filtering

You stopped using the formalin because it was too weak. Filtering does not improve the concentration. So filtered formalin can’t be reused.

Yes, filtering is fast, easy and cheap. That’s why people try it. It even makes the formalin look clean. But the concentration is too low for the formalin to be used.

Choose a recycler that distills formalin by temperature and guarantees purity/concentration. It will remove all the stain, fat, proteins and biologicals. More importantly, it will increase the concentration to full strength (10%) so that you can use the recycled formalin again and again.

Posted in Histology, Histology Solvent Recycling, solvent recovery, Solvent Recycling

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