The newly paved 2,000 sq. ft. checkered pathway outside the Dugros Leather (India) factory at Kolkata’s Bantala leather cluster has a story to unfold. The paver tiles gracing the revamped driveway are not to be mistaken for only cement-concrete material. They also contain solid-wastes from the leather manufacturing unit—the same waste that is instrumental in causing stress to the tanneries as well as the environment.
Solidaridad, along with its EU Switch Asia Kolkata project partner, Dugros Leather (India) Pvt Ltd, has successfully completed the first pilot trial, under the revolutionary ‘Waste to Walk’ initiative, at the latter’s premises. Tests conducted on these sludge-incorporated paver blocks to check for their physical property and commercial viability have concluded they have a high load bearing capacity.
The Menace of Solid-Waste
Kolkata Leather Cluster is one of the largest leather clusters of India, housing around 350 tanneries and more than 4,000 leather goods manufacturing units (mostly small & medium enterprises). The industry generates enormous employment as well as export earnings. Despite its huge growth potential, the sector falls in the red category (critically polluting) of the Central Pollution Control Board, Government of India. The transformation of skins/hides to finished leather involves several intensive processes that ultimately releases huge amount of sludge as by-products—including lime sludge, PTP and CETP sludge.
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Disposing of the sludge at landfill sites is both cost-intensive for tanneries and detrimental for the environment. Tanneries incur additional expenses for collecting and transporting sludge, and the accumulated waste at a dumping zone degrades the land and leaches into the ground to contaminate groundwater. This puts the entire surrounding ecosystem at risk. The sludge thus exists as a huge liability on the industry as long as its economic potential remains unrealised.
A Revolutionary Route
Solidaridad approached the solid waste disposal issue as a wakeup call for a market-based solution. Trials were conducted with tile manufacturers for use of sludge as a constituent for making tiles. Paver blocks were thus produced by mixing the solid waste from tanneries and CETP sludge with other constituents such as cement, sand, stone chips etc. The strength of the blocks also demonstrated a high load bearing capacity of 44 N/mm2.
The utilization and conversion of PTP and CETP sludge into paver blocks holds significant potential to revolutionize the industry practices towards ecological restoration and a circular economy. The approach is not only saving tanneries the cost of transportation of sludge, but also creating new business opportunities by tapping into un-utilized resources.
The Math that Matters
In this approach, the tile manufacturers would have to pay approximately INR 1 per kg to the tanneries for transporting the sludge to their premises. The sludge would then be used to partially fill for cement to make bricks, which saves the tile manufacturer approximately INR 70 per batch. It is thus a win-win solution for both the industries. The tannery owners would end up saving approximately INR 4,000 per tonne. The tile makers would also reap a benefit of around INR 35,000 from 5 tonne sludge mixed with cement for manufacturing the tiles. In the process, the environment is also salvaged from the polluting solid-waste of the leather industry and the ecosystem restored.
The ‘Waste to Walk’ Initiative
The ‘Waste to Walk’ initiative has been conceptualised over the last six months by Solidaridad, along with its partners Dugros Leather and Calcutta Leather Complex Tanners Association (CLCTA). Several scientific analyses were conducted and progressive vendors were identified over the course of time to set the tone of the agreement.
The innovative project approaches the solid-waste issue with a two-pronged strategy. It is actively exploring various possibilities of 100% reuse of leather by-products to help minimise the potential threat of pollution on health and environment and focussed on restoring the ecosystem surrounding tanneries. It also strives to make the leather industry more profitably inclusive without losing sight of the Sustainable Development Goals set by the United Nations.
The results of the initiative have been highly appreciated by the key stakeholders, including National Mission for Clean Ganges (NMCG) and CLCTA. The NMCG has also encouraged Solidaridad to scale up the eco-friendly intervention to a larger platform via relevant government bodies such as municipal corporations and State Mission for Clean Ganges.