at a cost of 48.66/m3 (US$1.03/m3). The water to industries is sold at a rate of 60/m3 (US$1.27/m3). At the end of the 25-year agreement, the plant will be transferred to the state government. With an installed capacity to produce 100 million liters of drinking water per day, it is the largest such plant in India. Commercial operations began on 25 July 2010, and average production has been 90 MLD. Operations Reverse osmosis (RO) technology is employed at the plant to desalinate the sea water, which contains up to 6.4 ppm aluminium and about 50 NTU of turbidity. Energy recovery units help increase the efficiency of the system by recovering kinetic energy from the brine solution and transferring the same to the desalinated water that has passed through the osmotic membrane. Pre-treatment of the raw sea water includes coagulation-flocculation, gravity, and pressure filtration. The filtered water is then pumped to the plant where it undergoes various preliminary treatments before being passed through the RO trains. The water is then forced through the RO membranes at high pressure. The membranes retain the salts and pass on the desalinated water to the next stage, namely, the post-treatment process. The treated water is then flavoured and stored in a 20 MLD underground water tank, from where it is pumped to the Red Hills reservoir and then released into the city grid. The RO technology of the plant produces 100 MLD of desalinated water from 273 MLD of sea water. Components The plant consists of 8,600 sea water reverse osmosis (RO) membranes, 248 pressure vessels, 115 pressure exchangers, 5 high-pressure pumps, 16 pressure filter vessels, electrical, automation and control systems and 1,200 m of HDPE pipelines of 1,600 mm diameter. The CMWSSB laid a 33 km pipeline at a cost of 930 million (US$20 million) to carry the treated fresh water from Minjur to Red Hills. The project also included infrastructure for the collection of seawater, including a 110 kV/22 kV sub-station built by the Tamil Nadu Electricity Board for uninterrupted power supply to the desalination plant. Before construction of the plant, studies were also conducted on the environmental impact on the livelihoods of fishermen and other communities and the impact of high saline discharge on the fisheries and turtle nesting. Seawater intake system A reinforced concrete cylindrical intake well of 5 m diameter and 4 m height has been installed nearly 600 m