Delhi tries bio-enzymes to solve air pollution: Will it go from smog to bog?

The Delhi government is exploring the use of bio-enzymes to address air pollution, with a pilot project conducted in Rohini and Wazirpur showing a reduction in particulate matter pollution by 30–55 per cent.

"While the application of bio-enzymes for wastewater treatment and reducing contamination at landfill sites is known, this is possibly the first instance of using this method to combat air pollution in India," said Podilapu Mounica Kavya, senior executive (operations), R.R. Geocycle Pvt Ltd, the firm that conducted the pilot in December 2023.

During the pilot, a solution created by dissolving the bio-enzymes in water in a 1:5,000 ratio was sprayed across Rohini and Wazirpur using the anti-smog guns of the Municipal Corporation of Delhi (MCD) and the Public Works Department (PWD) in three eight-hour cycles from 16 to 24 December, a report submitted by the firm to the Delhi Pollution Control Committee (DPCC) said.

The results revealed a 55 per cent drop in PM2.5 levels and a 32 per cent decrease in PM10 levels on average, it said.

However, within three hours of discontinuing spraying of the bio-enzymes, PM2.5 levels again rose by 62 per cent and PM10 levels by 51 per cent on average.

Continuous spraying of the solution for seven hours showed better results, with the PM2.5 and PM10 levels dropping by 60–65 per cent.

The concentration of nitrogen dioxide and sulfur dioxide also decreased notably, while ozone levels showed an increase, according to the report.

Indonesia has also experimented with bio-enzymes to control air pollution in Jakarta and Bali.

R.R. Geocycle's Kavya said the cost of bio enzymes is Rs 2,000 per litre and spraying them across Delhi would amount to an expenditure of Rs 40 crore over 45 days.

Mukesh Khare, a professor at IIT-Delhi and a researcher on air pollution issues, said that using bio-enzymes to reduce air pollution is unheard of.

He said that while algae screens (bio filters) are used in the West for localised air purification, this bio-enzyme approach is innovative.

Khare, however, cautioned about the potential impact of bio enzyme spraying on ecology. He stressed the need for an academic committee to review it.

Nehal Mevadaa, senior executive (operations) at R.R. Geocycle claimed spraying of bio-enzymes has no health impact whatsoever. He added the enzymes are sourced from the Raipur Bio Enzyme Bank.

Vivek Chattopadhyaya, principal programme manager of the Air Pollution Control Cell at the Centre for Science and Environment (CSE), suggested testing the bio enzyme-based technology indoors and comparing results to rule out the impact of meteorological conditions and other interventions.

He too, like Khare, emphasised the necessity of ensuring the safety of bio-enzymes.

The effect on the respiratory system and other organs in animals and humans should be determined and a credible third party should certify the technology before widespread use, Chattopadhyaya said.

Unfavourable meteorological conditions combined with vehicular emission, paddy straw burning, lighting of firecrackers and other local pollution sources contribute to hazardous air quality levels in Delhi NCR every winter.

Delhi's air quality ranks among the worst in the world's capital cities.

A report by the Energy Policy Institute at the University of Chicago in August 2023 had said that air pollution is shortening lives in Delhi by almost 12 years.