A study by the Indian Institute of Technology-Kanpur (IIT-K) carried out during the Covid-19 pandemic has shown that the lockdown ensured at least 50 per cent reduction in chemical concentration in the Ganga river. The study was conducted by a team of scientists from IIT-K to ascertain the impact of restricted anthropogenic activities on the water chemistry resilience of large rivers. The site selected by the team of researchers was downstream of Ganga river at Prayagraj where they studied the impact from March 25 till May 13.
The team analysed the daily geochemical record of the Ganga river which revealed that reduced industrial discharge during 51 days of mandated nationwide lockdown decreased the dissolved heavy metal concentrations by a minimum of 50 per cent. In contrast, inputs from agricultural runoff and domestic sewage like nitrate and phosphate remained almost the same as these sources were not impacted by the nationwide confinement.
The study findings indicated that reduction in industrial wastewater can substantially reduce heavy metal pollution in Ganga water in a short time span of a few months. "The lockdown resulted in a complete shutdown of industrial operations, and in turn, the effluent discharge from various industries was negligible. This industrial discharge usually ends up in nearby water bodies and groundwater despite India's stringent 'zero liquid discharge' laws preventing discharge of untreated effluent in rivers. It is estimated that industrial wastewater contributes nearly 20 per cent of the total volume of wastewater generated in the Ganga basin," the research estimated.
The researchers also quantified that Uttar Pradesh alone contributes 54 per cent of the total industrial wastewater generation in the Ganga basin, especially the stretch between Kanpur and Prayagraj, which hosts an enormous variety of industries.
"We emphasis that of the 764 industries in the entire Indian part of the Ganga basin, 90 per cent of the industries are located in the state of Uttar Pradesh alone, consisting mostly of tanneries (64 per cent) and textiles (9 per cent), sugar (8.2 per cent), paper (4.8 per cent) and industries (32 per cent). Even in terms of industrial wastewater generation, Uttar Pradesh also leads all other states in the Ganga basin, generating 269 million liters per day (MLD), which is 54 per cent of the total wastewater generated in the entire basin," the scientists noted in the study.
The research was supported by the Indo-US Science and Technology Forum (IUSSTF), a bilateral organisation under the Department of Science and Technology (DST), Government of India and US Department of State. It was recently published on the cover of the journal 'Environmental Science and Technology Letters'.