Treatment of waste waters containing heavy metals, contaminants or excess turbidity

Removal of metal ions and organic compounds dissolved or suspended in water.

  • Clay has been used as a low cost adsorbent to assist with cost effective removal of metals and organic compounds from wastewaters.
  • The calcium bentonite clays have a high capacity to bind metal ions dissolved in solution. This adsorption, the binding of chemicals to clay surfaces, is a rapid process and the binding is strong.
  • Once these metals are bound to the clay they can be rapidly separated from water by removing the clay.
  • The clay can then be flocculated by adding special flocculating chemicals; these cause the clay to form large aggregates that can be easily removed form water.
  • Metal ions including copper, zinc, lead, mercury and cadmium bind strongly to the charged surfaces of the clay and can be removed from the water as metal/clay complex.
  • Similar process occurs with a range of organic chemicals, which also bind strongly onto the clay surface. These include industrial dyes, solvents, herbicides, pesticides and other toxins.

The process of clay binding to the chemicals and then being separated from water by removing the clay is illustrated below.