How Does Formalin Recycling Work?
You’ve been using formalin for years and are thinking about recycling it. That’s a great idea that will save you money!
While formalin itself is not expensive, it is expensive to dispose of. You could simply dump it down the drain, but if anyone finds out you’d have a major public relations problem on your hands.
It doesn’t take a lot of training or special knowledge to recycle formalin. Here are the basics:
Formalin
Formalin is used to fixate or “fix” tissue. The formalin binds to enzymes and crosslinks proteins to stop tissue from decaying. Formalin is consumed in the “fixing” process when it is incorporated into the tissue. The result is a deplete formalin solution is eventually no longer concentrated enough to fix tissue.
Formalin is generally used at 10% concentration. After use, it is typically in the 7-8% concentration range.
Most formalin has buffers added to give it a neutral pH. This is the so-called “neutral buffered formalin” or NBF.
Contaminants
High boiling contaminants in formalin include fat, paraffin, protein, biological materials, and buffer salts. The formalin also has excess water that needs to be removed in order to bring the solution back to the original 10% concentration.
Recycling Formalin
To recycle formalin, choose a solvent recycler that uses fractional distillation by temperature. If the concentration is too low, the tissues will decay. However, if the concentration is too high the tissue will be tough to cut.
It is critical the recycler is able to consistently bring the formalin concentration back very close to 10%.
Formalin will distill over. Once all the formalin has been distilled into the pure formalin container, the recycler will automatically stop and cool down.
All that’s left in the boiler is excess water with some fat, protein, biological materials, and buffer salts.
If the test indicates that the formalin is too concentrated or too dilute, there is a handy table that shows how to adjust the formalin concentration by adding water or concentrated formalin.
Anatech is a well-respected company in all things histology. Their test kit is very accurate and has a long shelf life.
Pure Formalin
The formalin will be 99.9% pure and 10% concentration. You can use it anywhere you would use new formalin, including in the tissue processor and surgicals.
Recovery Rate
The recovery rate for formalin is about 80%. That means you will only need to buy 20% of the formalin you did before recycling!
Waste disposal
The boiler waste from a quality recycler should not contain any formalin – not even trace amounts. Since the boiler waste does not contain formalin, it is suitable for drain disposal. The waste is mostly water with some fat, protein, biologicals, and salts.
Boiler waste that contains formalin should be disposed of as hazardous waste. Make sure to check with manufacturers about your boiler waste.
Also, make sure you choose a recycler the guarantees there is no formalin in the waste.
Re-buffering Formalin
Formalin contains buffer salts to maintain the correct pH for staining. The formalin recycling process removes the buffer salts along with the contaminants. After recycling, you should add buffer salts.
Buffer salts are inexpensive and available for purchase through most histology supply catalogs. You can also find recipes for neutral buffer salts online if you prefer to make your own.
Anatech makes a buffer salt that is already in liquid form. There is no need to dissolve the solid buffer salts, so it is a great option for re-buffering.
Checking your formalin concentration
We recommend testing your recycled formalin with a kit from Anatech LTD. Each kit is good for more than 100 tests.
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