Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/1085636
TAMIL NADU • Water demand of Chennai projected to reach 1.6 million m3/d while supply is 840,000 m3/d • New desalination capacity of 150,000 m3/d and 400,000 m3/d has been mooted • Potential offshore plant of 10,000 m3/d under discussion Tamil Nadu state was an early adopter of desalination tech- nology and boasts India's two biggest plants. They are both in capital city Chennai, produc- ing a third of the city's total water supply. The 100,000 m3/d plants, at Minjur and Nem- meli, were procured by Chennai MetroWater to reduce depend- ence on the seasonal monsoon. Minjur Desalination Plant, lo- cated in Kattupalli village, north of the city, was inaugurated in 2010. It is operated by Chennai Water Desalination Ltd, a special purpose vehicle of Indian com- pany IVRCL Infrastructure & Projects and Befesa Agua of Spain, under a 25-year design, build, own, operate, transfer (DBOOT) contract. The plant has faced prob- lems. Critics highlight that no cost-bene' t analysis of delivery by an alternative means, such as a public-private partnership, was ever carried out. And they argue that the existing arrange- ment puts extra ' nancial burden on the government. "There have been lots of problems with water quality and leakage, the consor- tium has been trying to sell the asset to other bidders but no one is interested because of concerns over quality," adds Earth Water Group chief operating o™ cer Hariharan Subramaniam. The second plant, at Nemme- li, about 35 km south of Chennai, was delayed by several years of political wrangling. There were execution hurdles. The planned output was even- tually cut from 300,000 m3/d to 100,000 m3/d. Commercial operation began in 2013. The water demand of Chennai and its urban catchment is projected to reach 1.6 million m3/d this year. However, supply cur- rently hovers at around 840,000 m3/d. Chennai MetroWater wants to bridge this gap by add- ing new capacity at Nemmeli of 150,000 m3/d and 400,000 m3/d. The 150,000 m3 plant will cost INR 1,26 billion and is to be jointly funded by Germany's KfW and the Tamil Nadu government. The design and build contract was tendered in 2016 but the pro- ject has been held up by a court case related to the procurement process. The plant of 400,000 m3/d, costing INR 1.8 billion, will be funded by Japan International Coopera- tion Agency (JICA). Tamil Nadu's embrace of innova- tive desalination technology could break new ground with the proposed construction of India's ' rst o¡ -shore desalination plant - potentially to be located at least 40 kilometres o¡ coast at Ennore, a Chennai neighbour- hood. A detailed proposal for the 10,000 m3/d plant, that would cost up to INR 2 billion to build, was submitted by the National Institute of Ocean Technology in 2017 for consideration by the national government. The plant will utilise low- temperature thermal desalination, harness- ing the temperature di¡ erence between surface water and deep seawater to evaporate at low pressures. The vapour is condensed using colder deep-sea water. The process avoids the pollution associated with existing RO plants which includes release of chemicals and brine into the ocean. Research- ers are now assessing whether the plant can be powered using electricity produced by ocean thermal energy conversion technology. the pollution associated with existing RO plants which includes release of chemicals and brine into the ocean. Research- ers are now assessing whether the plant can be powered using electricity produced by ocean thermal energy conversion technology. Marina Beach in Chennai, Tamil Nadu, is six kilometres long. Desalination plants are located to the north, in Minjur, and in the south of Chennai, at Nemmeli 760k m3/d Chennai's water demand gap 22 In Site March 2019 Water. desalination + reuse