NEW DELHI: There are 522 sewage treatment plants (STP) in the country, of which 79 are non-operational, the Government said today.

In a written reply to a question on number of operational, non-operational and non-conforming STP in Lok Sabha, Union Environment Minister Prakash Javadekar said, "CPCB has carried out an inventorisation exercise of STPs for the country in 2014-15.

"According to their report published in March 2015, 522 STPs having a total capacity of 18883.20 million litres per day (mld) are operational, 79 STPs having a total capacity of 1237.16 mld are non-operational and 145 STPs having a total capacity of 2528.36 mld are under construction in 28 states and union territories in the country."

He also said as per the CPCB report of August 2013, performance evaluation was carried out of 152 STPs constructed under National River Conservation Plan.

Out of the 152, 48 STPs were not complying with the prescribed standards, 63 STPs were complying with the prescribed norms, 32 STPs were not operational and nine STPs were under construction.

"The state government and implementing agencies take corrective measures to ensure adherence to standards of treatment and discharge which include proper operation and maintenance, back-up power arrangements etc," he said.

Replying to another question, Javadekar said Indian Oil Corporation Limited, Paradeep Phosphate Limited (PPL) and EssarSteel India Limited were polluting the air, while PPL and Indian Farmers Fertiliser Corporation Limited were potentially water polluting in nature.

They have installed requisite air pollution control devices and effluent treatment plants respectively, he said.

"CPCB has reported that these industries are complying with the prescribed standards," he said.