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The rehabilitation process was initiated through rigorous experimental trials at the nursery level and then implemented at the red mud ponds of HINDALCO at

Belgaum in Karnataka and Muri in Jharkhand. The restoration process was initiated through nursery trials by importing three tonnes of red mud from HINDALCO, Belgaum, to TERI’s research centre at Gual Pahari, Haryana, in 2000/01. The main objective of the nursery trials was to identify the best suitable amenders, such as farmyard manure (FYM), gypsum, vegetative dry dust, bacteria, and mycorrhizae, with the correct dosage, as well as the tree, grass, and legume species suitable for the rehabilitation of red mud ponds. To improve the physicochemical condition of red mud deposits and convert the deposits into substrates that can support vegetation to grow and survive, appropriate soil amenders, such as acid-producing bacteria and mycorrhizae, were produced. During the nursery trials, amenders, along with bacteria and mycorrhizae, were used to form 12 different combinations and one control. Data on the height, girth, number of leaves, and biomass of the tree

From muck to moolah

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A case study of HINDALCO, Belgaum and Muri

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Plateau of red mud pond

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Bund

DrainDrain

Pongamia pinnata

Prosopls juliflora

Acacia nilotlca

Bracharla mutica

Sesbanla sesban

Rhodes grass

Figure not to scale

For over 10 years, The Energy and Resources Institute (TERI) has been engaged in the ecological restoration of industrial waste, especially of red mud (aluminium waste). TERI, with the help of Hindustan Aluminium Company Ltd (HINDALCO), successfully developed and standardized the vegetation protocol to rehabilitate the red mud pond worldwide.

Front view of plantation pattern on the terraces at the red mud pond at Belgaum, Karnataka.

species, as well as the number of tufts and leaves for grass and legume species was collected on a monthly basis for a year and then, analysed statistically. Among the 13 different combinations, including the control, of red mud with various soil amenders, a combination of red mud with 25% FYM, 15% Gypsum, 5% vegetative dry dust, bacteria, and mycorrhizae was found to be the most suitable and, therefore, recommended for the implementation of research trial at Belgaum in 2002/03.

Immediately after the completion of nursery trials in 2003, a field trial experiment was started in 1.08 hectare area of the red mud pond at Belgaum. The implementation work was conducted in three phases—earthwork, preparation of amenders, and plantation activities. The earthwork was started by tilling the red mud pond into terraces and then, reducing the slope of the dumps to about 7–10 degrees using a JCB machine. Four terraces—80 m long and 30 m, 40 m, 30 m, and 35 m wide, respectively—were created. After the creation of the terraces, the dry mud surface was tilled to a depth of 10–15 cm. This broke the mud columns and loosened up the mud considerably,

but still left relatively large hard clods of loosely packed mud. The tilling process was followed by the levelling of the surface. Levelling was done with the help of a heavy wooden plank attached to a tractor. The levelling process crushed the brittle lumps of the mud into finer materials and compacted the surface. After levelling, pits of size 60 cm x 60 cm x 60 cm were dug with spacing of 3 m x 3 m. The mixing of mycorrhizae and bacteria was done during the plantation activity. A combination of gypsum, FYM, and rice husk with bacteria and mycorrhizae was prepared for filling the pits, stacked on the top of the red mud pond, and allowed to decompose. Based on the results of the nursery trials, tree species, viz. Prosopis juliflora, Acacia nilotica, Pongamia pinnata, Albizia lebbeck, and Leucaena leucocephala, were planted to vegetate the problematic area. The tree species were planted alternately on all the four terraces. These species are multipurpose and capable of meeting the diverse requirements of the local people, apart from being a good nitrogen fixer and having high tolerance to alkaline conditions. Besides the tree species, four grass/legume species viz. Brachiaria mutica, B. decumbens, Stylosanthes scabra (three grass species), and Sesbania sesban (legume) were also planted. In between the two rows of tree plantations, one row of grass/legume species was also planted.

Monitoring, evaluation, and data collection were carried out on a quarterly

basis. Overall, the survival of the tree species till the first year was recorded to be nearly 80%, but it sharply declined after the fourth year. This was due to various reasons, such as extensive growth of grass. This resulted in the abundant production of grass seeds, providing ideal conditions for rodents and other burrowing animals to feed and make their burrows under the thick growth. These animals started destroying the root zones of the adjoining trees, leading to their mortality and drastic reduction in their numbers in the experiment plot.

In spite of the successful rehabilitation of red mud ponds at Belgaum, there were some gaps in this entire exercise. For example, there was a need to study the role of different pit sizes for the development of root zone system, which was not taken into account in the present study and the impact of various irrigation types on plantation survival, as well as to try out some more species, apart from the five tree and four grass/legume species, and test some more soil amenders in different dosages. Keeping all these important factors in mind and to analyse the impact of all these factors on the plantation on the red mud, a similar initiative was undertaken with the help of HINDALCO at Muri.

In Muri, the main focus was on the gaps of the previous research work. A research trial on a two-hectare area of the red mud pond was conducted. The aim was to standardize the vegetation protocol to rehabilitate the red mud ponds worldwide. In this case, a Random Block Design (RBD) experiment was laid by taking two pit types (normal pit and pit with augur hole), two irrigation types (hand watering and drip irrigation), four pit mixtures (including vermicompost and different proportion of gypsum), and five tree (Terminalia arjuna, Bauhinia variegata, Acacia nilotica, Pongamia pinnata, and Albizia lebbeck), and two grass (Pennisetum pedicellatum and Stylosanthes) species. The research plot was first levelled and then, divided into four equal plots during April 2007. Further, the entire boundary of the research area was fenced with poles and wires to protect the

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Pongamia pinnata

Prosopls juliflora

Acacia nilotlca

Bracharla mutica

Sesbanla sesban

Rhodes grass

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30 M

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Bund

Figure not to scale

Pongamia pinnata

Prosopls juliflora

Acacia nilotlca

Bracharla mutica

Sesbanla sesban

Rhodes grass

35 M

30 M

40 M

30 M

Bund

Figure not to scaleSide view of the plantation pattern on the terraces at the red mud pond at Belgaum, Karnataka.

young plantation from cattle and human interference. The pit digging work started after the fencing was done in June 2007. Two sizes of pits—normal pit (45 cm x 45 cm x 45 cm) and pit with augur hole (45 cm x 45cm x 90 cm)—were created equally in the entire research area. Mixing of amenders, tree plantation, and sowing of grass species was done in July 2007 during the monsoon. After completing the plantation activities, drip irrigation systems were installed in plot number 1 and 2, while the other two plots were watered manually.

For monitoring and evaluation, a framework was developed and followed regularly on a monthly basis to measure the growth parameters of the established tree species, including survival rate, height, collar diameter, girth at breast height, crown cover, and number of leaves and branches, as well as of the grass species, such as height and number of tufts. The result of analysing the data of almost two years (till May 2009) was found to be

encouraging. The findings of this research work revealed remarkable changes in the physical and chemical characteristics of red mud. While the nutrient content increased, the pH value decreased after amendment. The research work confirmed that gypsum and vermicompost, along with acid-producing bacteria, could create a suitable medium for plants to grow on aluminium waste. Among the three mixtures with one control, the combination 20% gypsum + 10% vermicompost + red mud + bacteria was found to be most suitable for the vegetation to grow in the aluminium waste. Among the five selected tree species, the performance of Albizia lebbeck and Acacia nilotica was the best, under all the different combinations. Both tree species survived 100% and attained maximum growth, crown diameter, and high tolerance to the adverse conditions in all the treatments and under both irrigation types, as compared to the rest of the three species. In addition, both grass species showed tolerance to

adverse conditions and had good survival and growth rates.

For the successful establishment and growth of the plantation, the main focus was on the correct choice of species, soil working methods, plantation techniques, soil amenders with appropriate dosage, and other management practices suited to the specific mine waste dumps and local edaphic and climatic conditions. However, there is still a huge scope for improvement in this area, which can be attained by focusing on the maximum utilization of rainwater; efficient and cost-effective soil working and planting techniques; soil amenders along with appropriate dosage; spot treatment only at the planting site; soil treatment up to a deeper zone and not confined to only 10–15 cm; keeping minimum salt concentration in the active zones of young plants through leaching; and so on. n

By Suresh Chauhan, Fellow, Forestry and Biodiversity Group, TERI.

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Red mud