Resource detail

Challenge: Alumina refineries across the world face the environmental challenge of disposing red mud in a safe manner. Red mud is a hazardous chemical waste, which is usually dumped in large dumping sites that are generally as large as football grounds. Red mud tends to become airborne and causes eye sores, dust allergies and has the potential for caustic contamination.

In the mid 1980s efforts were made to tackle the menace by dry mud stacking whereby red mud was stored in mounds. In fact Belgaum Alumina Refinery became the first Indian refinery to ever do so. Black cotton soil from adjoining areas was used to cover the exposed surface and sprinklers were installed to keep the area moist. At that point, this was the most cost effective solution and used minimal land for waste management.

However the procedure for waste disposal was not a sustainable one because the problems would resurface during the dry season, due to the very property of red mud. When wet red mud becomes sticky and starts to dry, clodding and crusting occur. The surface becomes hard and develops cracks of reticular design due to the swelling and shrinking property of its finer fraction. During the dry season, the surface material turns loose and powdery, eventually becoming airborne. The dust nuisance was kept in check, almost for a decade by covering the exposed surface with imported cotton soil and moistening the surface with water, a process known as 'Turfing.' This was not only an expensive and cumbersome process but was also leading to wastage of useful resources that could have been put to better use.

Initiative: A reliable long term solution to the problem was sought for the safe and cost effective disposal of red mud. HIL initiated a project with TERI, New Delhi. A bacterial culture was isolated from the one ton of fresh mud which was sent to TERI for laboratory evaluation. It generated acid and neutralized soda. The promotion of soil generation through the application of fungi called mycorrhiza was suggested and a six month trial was followed. During the trial period:

♦ Red mud pond was tilled and terraces were formed through reduction of slope of the dump

♦ Industrial waste gypsum, farmyard, manure, microbial counts and vermicompost were mixed with the soil.

♦ Select species of trees such as Prosopis julifora, Acacia nilotica, Pongamia pinnata and grass species like Sesbania sesban were planted in pits.

The red mud pond transformed within a matter of 6 months and the chemistry of the red mud changed drastically as the pH reduced. With the success of the experiment, the vegetation project was extended to the adjacent 4 hectares of land in the next two years. The outcome was positive and the experiment was a success.

Table: Change in red mud characteristics at a depth of 45 cm

Outcome/Benefits: With the success of this experiment, a once dry barren and hazardous site was transformed into a non hazardous lush green cover. Dust storms were minimized as the red mud was no longer left loose to be airborne. The project thus provided a long term sustainable solution.

Since there was no more requirements of sprinklers to keep the surface land moist, consumption of electric energy was also reduced. It was thus a very cost effective alternative. The black cotton soil was also not required anymore and hence there was preservation of precious quality natural resource.

It also led to effective utilization of the garbage generated in the plant premises. The waste produced was now being effectively utilized for creating vermicompost or manure to increase the fertility of the red mud soil.

Commercially tested: Yes