J. Y. Sharma , Grace Lhouvum , Suresh Chauhan , Banwari Lal , T. P. Singh , Varghese Paul

Abstract

Bauxite residue, also known as red mud, is a by-product of the Bayer Process. Bauxite is composed principally of the monohydrate and trihydrate forms of alumina in varying proportions. The research study was conducted to rehabilitate used red mud ponds of INDAL (Indian Aluminium Company Ltd.), Belgaum, Karnataka, India, by identifying suitable trees, grasses, and legume species as well as amenders, including bacteria and mycorrhizae, to improve the physico-chemical condition of red mud deposits and convert it to a substrate. Amenders such as gypsum, FYM (farmyard manure), fly ash/vegetative dust in different proportions, forming three basic combinations, A, B, and C, were developed. These three combinations were then treated with the bacteria and mycorrhizae both alone, and in combination, to form twelve treatments and one control. The research study showed that there is remarkable change in the physical and chemical properties of red muod after amendment, which provides the platform for plantation growth. The best combination found for treating red mud ponds was: Red mud + 20% FYM + 10% Gypsum + 15% Fly ash + Bacteria + Mycorrhizae for four tree species, Prosopis julijlora, Acacia nilotica, Pangamia pinnata and Melia azedarach, and three grass/legume species Brachiaria mutica, Chloris gayana, and Sesbania sesban.

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Suresh Chauhan , Jitendra Vir Sharma , Banwari Lal , Varghese Paul

Abstract

Based on the findings of the research trials on the rehabilitation of red mud conducted by TERI, New Delhi, a field experiment was implemented on pilot basis over 1.08 ha of the red mud pond at INDAL, Belgaum, Karnataka. Optimum combination, identified in the trials i.e., Red mud + 25% FYM + 15% Gypsum + 5% Vegetative dry dust + Bacteria + Mycrorrihaza, was used for the field experiment. Five tree species, i.e., Prosopis juliflora, Pongamia pinnata, Acacia nilotica, Leucaena Leucocephala and Albizia lebbek and five grass/legumes species i.e., Brachiaria mutica, Chloris gayana, Sesbania sesban, Brachiaria decumbens and Stylosanthes scabra, identified through the research trials, were grown in the experimental plot. The findings reveal remarkable changes in physical and chemical characteristics of red mud after amendment, which provides conducive medium for plants to grow. After thirteen months, among the tree species, Leuacaena leucocephala species showed maximum average growth rate and low mortality, while among the grass/legumes, all the five species gave good growth and survival. The micronutrients contents increased and alkalinity of the red mud decreased up to seven months from the start of the experiment. However, after seven months there was reduction in the micronutrients contents and increase in the alkalinity of the red mud, which is due to the uptake of micronutrients by the plants.

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