When life sprouts in the form of a seedling, breaking through
hardened layers of chemical sludge, it is a victory for nature against environmentally
unsustainable human practices. TERI’s researchers have replicated this
success at the inorganic-sludge-loaded sites of industries located on the coast
of Gujarat. One could not imagine any type of flora surviving on these wastelands
heavily laden with chlor alkali sludge, formed because of the alkaline- and
chloride-rich sediments emanating from industrial discharge. The shortage of
water in these coastal areas only worsened the conditions.
The task in front of TERI researchers was to green the toxic
chemical basin. TERI’s endeavour has carpeted the chemical bed with lush
green plantation— Jatropha curcas (the bio-diesel plant), neem,
Paras pepal, aloe vera, acacia, salicornia, and casuarinas.
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| ‘Before and after’: a dumping site
loaded with chlor alkali sludge (left) and the same site post-intervention
by T E R I (right) |
The dump yard of troubles
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| A vertical profile of different layers of a wasteland |
The chemical waste at these sites was a health hazard for the residents and
a burden on nature. The solid wastes ensured zero biological activity and the
coastal wind was sweeping fugitive emissions over residential areas.
Attempts to grow any vegetation proved futile as the seeds came in direct contact
with sea water: the high saline substrate made germination difficult. The waste
area also contaminated the low water table. The site had extremely high pH (11.7)
and electrical conductivity (74.4 mS/cm2) as compared to the near
neutral pH (7.0) and electrical conductivity (near 1 mS/cm2) of normal
soil. These values affected the availability of several important nutrients
to plants.
The endeavour
TERI’s project team isolated microbes inhabiting the sites and screened
their targeted functional properties. This was done because these microbes had
successfully withstood the onslaught of chemical sludge. These microbes were
then multiplied in mass and strategies to apply them to the sludge were devised.
As a parallel initiative, partially tolerant plant species were chosen and inoculated
with selected mycorrhizae at the time of planting. This was done in a specially
designed landscape to overcome highly stressful substrate properties.
In the process, changes also took place in the quality of the sludge. This
was made possible by the mycorrhizal biofertilizer—a group of naturally
occurring fungi that provide tolerance and strength to the stressed flora. The
biofertilizer enhanced nutritional uptake, enabling the plant to get phosphorus
and nitrogen. Mycorrhizal fungi, due to their inherent properties, resist drought
and harsh climatic conditions, they make the new foliage hardy enough to withstand
a revival of the most adverse conditions.
Watering was done in stages: initially with sweet water, followed by a combination
of sweet water and sea water, and then only with sea water. The purpose was
to strengthen the plants and acclimatize them to harsh conditions.
Donning multiple roles
The technological innovation that successfully reclaimed the toxic wasteland
had many other roles to play as well. First, the new vegetation reduced fugitive
dust emissions and improved the physico-chemical properties of the substrate,
thereby marking their return to near-normal levels. Both groundwater leaching
and fugitive dust emissions (causing air and water contamination) reduced significantly
and the biggest surprise was when old seeds, planted during earlier unsuccessful
trials, started germinating.
Beneficiaries
The technological breakthrough has a positive effect on the socio-economic situation
of the region. For example, there is now a demand for nurseries to raise seedlings,
which eventually will create employment opportunities as well as thicken and
expand the green cover in the region. Companies under pressure to adapt to eco-friendly
practices can successfully replicate this technology at their own premises.
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Chemical-sludge-laden sites
revegetated with economic plantations |
Applications/benefits
The mycorrhizal technology is easily replicable and uses local material and
plants. It is extension-friendly, cost-effective, environmentally safe, and
yields economic benefits. One of the plants that grows on the sludge-laden wasteland
– Jatropha curcas – can yield bio-fuel oil, which can be
blended with diesel. If Jatropha is grown over similar degraded sites
elsewhere, it will immensely help the fuel sector. Casuarina, which is also
grown on the sludge, has proven its potential in paper manufacturing. Plants
such as salicornia (a source of edible oil; also used in salads as a delicacy)
and aloe vera (valued in the cosmetics industry) proved highly adaptable with
microbial combinations.
The cost of nursery preparation on a one-acre (0.40 hectare)
area, using TERI’s technology, is 33 400 rupees. The plantation cost per
acre is 178 300 rupees and its maintenance costs 22 200 rupees. Physical requirements
such as water, soil, and clay would cost extra. Although environmental benefits
have not been analysed in terms of monetary gains, revenue generation from Jatropha
plantations would be about 8000 rupees per acre per year after maturity.
