Chennai Metrowater is preparing to increase production from the two Nemmeli desalination plants as storage in the city’s five drinking-water reservoirs falls to nearly 37% of their combined capacity. Replacement of reverse osmosis membranes at the 110-million-litre-a-day (mld) plant is expected to finish by the end of October, while work at the 150-mld plant is scheduled for completion by the end of November, according to officials.
The five reservoirs together hold nearly 3,700 million cubic feet less water than they did on the same day last year, The Hindu reported. Metrowater has assessed that the city’s daily supply can be sustained for another five months using available resources, including water from Veeranam tank. The agency is also expecting the Northeast monsoon to improve reservoir storage by the end of the year.
Chennai’s water system has a designed supply capacity of 1,712 mld, but the city is currently receiving 1,272 mld of drinking water. The Nemmeli plants are contributing between 175 mld and 180 mld, accounting for nearly 15% of the city’s total demand.
At the 110-mld plant, 6,543 of the 7,056 reverse osmosis membranes have been replaced over the past two years. The facility is currently producing 95 mld and is expected to reach its full capacity by the end of October. The 150-mld plant is presently producing 85 mld and is expected to reach its designed output by the end of November after its membrane replacement work is completed.
Reverse osmosis membranes are a critical part of the desalination process because they remove dissolved salts and other impurities from seawater. The replacement components were sourced from the Netherlands, Germany and the United States. Delivery delays linked to geopolitical issues slowed the planned increase in production, officials said. Contractors have now airlifted the reverse osmosis and ultrafiltration membranes to accelerate the remaining work.
The desalination plants currently supply south Chennai and the southern suburbs. Metrowater officials said that once the 150-mld plant is operating at full capacity, additional water can be conveyed into the network serving central parts of the city.
The planned increase comes as the city uses multiple sources to maintain supply during a period of lower reservoir storage. Water from abandoned quarries in Sikkarayapuram and Erumaiyur is also being pumped into the city’s water-supply system, officials said.
The immediate milestones for Chennai’s water network are the completion of membrane replacement at the 110-mld plant by October end and the restoration of full production at the 150-mld plant by November end. Metrowater’s assessment also depends on available resources and the expected contribution of the Northeast monsoon to reservoir storage.
