Proposed STP to treat wastewater flowing through Coimbatore International Airport may be inadequate to address pollution

The Coimbatore Corporation’s plan to establish a two-million-litres-per-day (2 MLD) sewage treatment plant (STP) to treat wastewater flowing through a natural stream and passing through the premises of Coimbatore International Airport may be insufficient to address the pollution concerns, experts say.

Siruthuli, which is conducting a pilot study on bioremediation to address sewage contamination in the stream, reported through real-time flow monitoring using sensors that the waterway currently conveys approximately 10.1 MLD of wastewater. The stream originates near the CODISSIA Trade Fair Complex and flows toward Avinashi Road. Two stormwater drain networks in the vicinity also discharge into the stream, with the combined flow continuing toward the airport, crossing Avinashi Road, passing through the airport premises, and ultimately reaching Achankulam.

L. Cibi Mahiban, a project researcher, said the stream receives untreated effluent from adjacent residential and commercial establishments. “Recent laboratory analyses recorded a biochemical oxygen demand (BOD) concentration of 244 mg/L, substantially exceeding the permissible limit of 10 mg/L, and a chemical oxygen demand (COD) level of 805 mg/L, well above the standard of 50 mg/L,” he said.

R. Ilangovan, former Vice-Chairman of the Tamil Nadu Water Resources Cell and a researcher specialising in urban water bodies, claimed that the Corporation’s similar STPs at urban lakes are underperforming.

“The current facilities are burdened by elevated energy consumption and significant operational costs. Deployment of advanced treatment technologies, alongside strict maintenance protocols, is imperative to ensure effective and sustainable wastewater treatment,” he said.

Corporation Commissioner M. Sivaguru Prabakaran said, “although the stream’s flow exceeds the current capacity of the STP, the plant will be designed for future expansion. Once the city’s underground drainage works are completed, the stream’s flow will decrease, allowing the STP to treat wastewater efficiently.”