CLEAR OPTIONS

India is adopting new sewage wastewater treatment technologies that are more efficient, but it must choose the ones that best meet local needs

ATUN ROY CHOUDHURY, NEHA SINGH, P SANKAR GANESH, RESHAM BHALLA, K MAHALAKSHMI AND K SANDHYA

WASTEWATER TREATMENT and recovery are critical to address water scarcity and environmental pollution. Indian cities currently treat only 28 per cent of the 72,368 million litres of sewage they generate every day, as per the latest data released by the Central Pollution Control Board in December 2022.

While the country clearly needs to increase its treatment capacity, it also needs to upgrade the currently employed wastewater treatment processes for more efficient technologies. Most sewage treatment plants in the country rely on outdated technologies such as the activated sludge process, planted drying beds, soil biotechnology and upflow anaerobic sludge blanket reactors that have a treatment efficiency of around 65 per cent and are cumbersome to set up and manage.

The story is slowly changing with several states in recent years opting for newer technologies that have treatment efficiency of around 80 to 90 per cent.

Almost all the sewage treatment plants set up in Andhra Pradesh and Telangana after 2018 are based on two such technologies— sequencing batch reactors (sbrs) and moving bed biofilm reactors (mbbrs). Telangana's capital Hyderabad, in a first, recently upgraded an existing sewage treatment plant that releases its effluent into the Durgam Cheruvu Lake with sbr technology. Bihar has replaced most of its obsolete and inferior sewage treatment plants with sbrs. Similar upgrades are also reported in Maharashtra, Goa, Haryana, West Bengal and Uttarakhand.