The National Green Tribunal’s (NGT) latest order setting aside Centre’s 2017 notification relaxing the effluent discharge standards for sewage treatment plants (STPs)in smaller cities has made it imperative for the state government to upgrade about 50 STPs.
The 2015 draft, based on a report by the expert committee, had set stricter standards for seven parameters. In the final notification (2017), the biochemical oxygen demand (BOD) limit was relaxed for biochemical oxygen demand (BOD) from 10 mg per litre to 30, total suspended solids from 20 to 100 mg per litre, faecal coliform from 100 mpn/100 ml to 1000 mpn/100 ml. The limits for chemical oxygen demand (50 mg/litre), total nitrogen (10 mg/litre) and ammoniacal nitrogen (5 mg/litre), were removed altogether. For major cities like state capitals and metros, the ministry did not dilute the norms.
In its order on a petition by Nitin Shankar Deshpande, the NGT noted that the standards were sought to be diluted by the 2017 notification and stressed the need for revised standards to protect the water quality of the rivers/streams. Stating that there was no justification for diluting standards for areas other than mega and metropolitan cities, it said: “The water quality standards are required to be same for the population of major cities or other cities. Major population of this country will be affected by diluted standards and only persons. Standards recommended for mega and metropolitan cities will also apply to the rest of the country.” Sources in KSPCB and BWSSB said except for the Kengeri STP and three others under construction the remaining plants in the state capital have to be upgraded to comply with the latest NGT order. “Throughout the state, the existing STPs have been built as per the older designs and comply with old parameters. We need a full scale upgradation and build infrastructure like anaerobic and anoxic tanks to the existing STPs,” the official said.
At present, the state government has 50 STPs and has target of building another nine by 2020. “Besides that, we have proposed 16 other STPs in smaller cities. All these will come up as per the NGT standards,” an official said. The NGT’s latest order also sets limit for phosphorous, which causes eutrophication, at 1 mg per litre. Asked about the measures required, a BWSSB official said they have already drawn up Rs 2,000 crore plan to upgrade the STPs. “We have sought time till 2021,” he said. Asked about the STPs in smaller cities like Hubballi and Mysuru, Urban Development Department Secretary Anjum Parvez said the government is adopting sequential batch reactors (SBR) technology in the new STPs. “Nitrogen and phosphorous will be well within the limits defined by the rules in the new STPs. The existing STPs will be upgraded in a time-bound manner,” he said.