Sea as source of drinking water? Mumbai civic body mulls plant
The Brihanmumbai Municipal Corporation (BMC) authorities plan to set up a desalination plant near Gorai beach, amid the growing need for an alternative potable water source due to changing patterns of rainfall.
The desalination plant will purify seawater into potable water.
Maharashtra minister for environment Aaditya Thackeray on Monday gave a go-ahead to the project and has directed the BMC to prepare a feasibility report by reviving the civic body’s 2007 plan.
The 2007 desalination proposal was meant to provide an alternative water source owing to poor rainfall in the catchment areas of the dams that supply water to Mumbai.
Later in 2016-17, the BMC had initiated the process to set up two desalination plants – one in south Mumbai and another either in the suburbs or anywhere in the Mumbai Metropolitan Region (MMR). The plants were supposed to have a capacity of processing 100 million litres per day (MLD) of seawater into potable water. However, later, the project was put on hold due to high cost.
P Velrasu, additional municipal commissioner (AMC), BMC, said, “The cost for a desalination plant has been optimised because of evolution of technology. The cost of construction of the plant is the same as that of a dam. It is estimated to cost around Rs 1,800 crore to construct a 200 MLD plant.”
“We had to find a sustainable solution because of changing patterns of rainfall. We cannot go on constructing dams by cutting trees. We need a back-up plan,” he added.
At present, seven lakes such as Bhatsa, Vaitarna, Middle Vaitarna, Modak Sagar, Tulsi, Tansa and Vehar supply drinking water to Mumbai. The lakes are located in Mumbai and neighbouring Thane and Palghar districts. The civic body supplies 3,750 million (m) litres (l) of water daily, as compared to the demand of 4,200 ml.
BMC officials said they would collect seawater samples from the west coast in north Mumbai for setting up the desalination plant.
Initially, a pilot project will be undertaken, which will cater to 5% of Mumbai’s drinking water needs, and later the capacity will be successfully augmented to 200 MLD.
“A suitable plot will be considered for the project on the west coast as the Port Trust authorities own land on the east coast. We plan to acquire a plot owned by the government owing to the cost factor,” said a BMC official, requesting anonymity.
The BMC has zeroed in on a plot near Gorai beach for the project. However, a final call will be taken after the submission of the feasibility report.
“An Israeli company has been tasked to submit the feasibility report, which was involved in a similar 650 MLD-capacity plant in Israel. It will take around three years to construct the plant,” said Velrasu.
Dubai is the first city in the world to construct a desalination plant.
Chennai, which has three such plants, had constructed its first project in 2003 that supplies 90 MLD of water to the city.
Rakesh Kumar, director of Council of Scientific & Industrial Research-National Environmental Engineering Research Institute (CSIR-NEERI), said, “If it is possible to have desalination plant to convert seawater into potable water worldwide, it is certainly possible in Mumbai also. This is the future if we have to deal with shortage of water. However, these are costlier options, and it again brings back to the problem of how we handle our water resources. This does brings us back to the discussion of how we should be doing water conservation.”