Pollutant Management

pollutant-001smBentonite clays have a long history of use as sealants used to contain leachates from landfill and other dumps, cap and seal these and other sources of potential pollutants. Use as barriers to restrict movement of groundwater to or through contaminated sites or movement of contaminated water from contaminated soils.

The Watheroo calcium bentonite has a high cation exchange capacity and an affinity for metal ions, hydrocarbons and range of other chemicals. This means that they will bind and restrict movement of these chemicals in groundwater or surface systems. This dual capacity of very low permeability and adsorption of pollutants makes them very effective as barrier treatments and as adsorbents for these pollutant management applications.

Watheroo bentonite is available as screened granules, this makes them easy to handle and deliver to treatment areas. Granules have very high clay content, over 80 %. They will hydrate to form a plastic barrier with very low permeability and resistant to cracking, or being compromised by ground movement.

Calcium bentonites have less swelling capacity compared to the sodium bentonites. This means that they are less subject to drying and cracking and also diffusion of pollutants through hydrated clay slurry.

Figure 1. Hydrated bentonite layer, uncompacted, very low permeability, plastic layer

Figure 1. Hydrated bentonite layer, uncompacted, very low permeability, plastic layer.

Figure 2. Granules of calcium bentonite.

Figure 2. Granules of calcium bentonite.

See analyses for content, CEC, PSD, permeability.

Summary of previous work on saponite, Monash, Churchman

(EP A-542-R-98-005 July 1998 www.epa.gov. Evaluation of subsurface engineered barriers at waste sites.)