Conversion of Sewer Sludge to Electricity and pure drinking water

Sewer sludge (refers to the solids separated during the treatment of municipal waste water) are heated in a boiler to a temperature where it emits water vapours. Water vapours are then taken to water purifier set up where it is purified and made drinkable.

The remaining part of sludge is taken put in furnace. Output is high temperature, high pressure steam which is having enough power to rotate turbines which in turn generates electricity.

These guys are capable enough to make this process happen with sewer sludge. Cities like, Mumbai being the sea-shore city, Don't Municipal Corporation find any of the process to make this process happen from sea water? They should have such plants which can take care of this scarcity issue. These cities are facing water issues sicne many decades. I learnt, "The Nemmeli Desalination Plant is a reverse osmosis, water desalination plant at Nemmeli, Chennai, on the coast of the Bay of Bengal that supplies water to the city of Chennai. The production cost of treated water at the plant has been worked out to INR 30 per kilolitre of water"