The Tamil Nadu Water and Drainage Board’s (TWAD) proposal to set up a 60 MLD Sea Water Reverse Osmosis (SWRO) plant at Kuthiraimozhi village in Ramanathapuram has been recommended for CRZ clearance by the Expert Appraisal Committee (EAC) of the Environment Ministry after a modified proposal was submitted.
The proposal was earlier not cleared owing to the location being within the eco-senstive zone of the Gulf of Mannar Marine National Park, to be precise, only 25 metres from its boundary.
The TWAD filed a modified proposal to the EAC for clearance submitting that the intake and brine disposal point has been shifted away the eco-sensitive area.
Under the earlier proposal, the project site was supposed to be located at Latitude 09°07’28.35” N and Longitude: 78°26’30.77” E. As per the revised proposal, the project is now proposed to be located at Latitude 09° 07’ 8.27” N and Longitude 78°25’ 28.73” E
The Committee also noted that the intake and brine disposal point has been shifted away from eco-sensitive area. The Committee noted that the revised proposal requires intake flow of 139 MLD instead of 154.8 MLD. The EAC had earlier asked the TWAD to look at the possibility of reusing the brine water fully by giving it to authorised salt pan agencies instead of discharging it into the sea.
According to the minutes of meeting, the EAC was informed by the TWAD that it proposed to create a series of artificial lagoons filled with brine from the desalination plant and ‘drastically reduce’ the brine disposal into the sea. The artificial lagoons are proposed for 1 metre shallow depth to collect the brine and the surplus to be utilised either by Tamil Nadu Salt Corporation Ltd or private salt pan owners at Periasamy Puram, about 10 kms from the proposed desalination plant.
The EAC noted the submissions that brine discharge will reduce from 94.52 MLD to 42 MLD with the new technology proposed, of using Counter Flow Reverse Osmosis (CFRO) instead of Conventional Sea Water Reverse Osmosis. “In CFRO Plant, the recovery rate will be 64% as against 45% for conventional Plant,” the TWAD submitted.
The project proponent further informed the EAC that brine discharge into the sea will only be for two months when salt pans are non-operational and will be stored in the lagoons or other applications for the remaining 10 months.
“The Committee appreciated the project proponent for coming out with good model with reduced brine discharge by way of creating artificial lagoons using the brine, which will help as foraging grounds for migratory birds,” according to the minutes.
The EAC, however, urged the TWAD explore the possibility of zero brine discharge from the plant and develop the plant as a model project for others to follow suit.