Bentonite Wastewater Treatment
All Bentonite clay used in wastewater treatment is not the same. There is sodium bentonite and there is calcium bentonite. What’s the difference? Bentonite clay found in many places around the world is mostly calcium bentonite. Calcium bentonite is significantly less efficient for wastewater treatment. The reason that sodium bentonite is more effective than calcium bentonite is due to two things, the surface area and to the charge. The surface area of sodium bentonite clay is larger than Calcium bentonite giving it a significant advantage for adsorbing oils, grease, and metals. This also provides better encapsulation of contaminates in the wase water.
Sodium Bentonite vs Calcium Bentonite: Ionic Charge Difference
The ionic charge on the sodium ion is +1. This is less than the charge on the calcium ion which is +2. What this means is that the sodium ion on the surface of the clay particles is not held as tightly as a calcium ion because of the lower charge. Therefore, the sodium ion is more available for ion exchange with other ions. The other ions, along with oils, grease, suspended solids, and metals are adsorbed onto the floc particle, encapsulated and then separated in a filter. When compared side by side in jar testing the difference can often be visible.