Bentonite is an absorbent clay that has aluminium properties and is formed out of volcanic ash. While commonly found in beauty products to absorb high amounts of oil in the skin, bentonite is also often used in large quantities in various drilling and construction applications. This form of bentonite, when it is liquefied into slurry, must be disposed of carefully and properly to avoid compromising the safety of the people who may be exposed to it.
Leave the bentonite in whatever strength you have it in. Adding any more water to the bentonite slurry will just make more slurry for you to get rid of.
Contact your local hazardous waste disposal agency to find out the specifications for liquid disposal. Ask the agency whether your area terms slurry as a liquid or not.
Keep the bentonite away from any drainage or sewer systems where it can enter into circulation with other water.
Cover the bentonite slurry with a fresh layer of soil daily. You can use this method until all but the clay at the bottom of the slurry is used up.
Provide the clay to a water cleaning processor. The high level of bentonite in the clay can be used to purify heavy metals that are found in contaminated water.
Contact a liquid waste disposal company if to remove all of the bentonite slurry if it is qualified as liquid waste in your area.
Make arrangements to have the slurry picked up before the actual end of the bentonite use so you won't have the slurry sitting around.
Do not abandon leftover slurry. It is your responsibility to handle it safely.