Chennai: Water, water, everywhere and all of it for industry to use

Industries in two major hubs in Chennai now have a neat solution to their water problems. The Chennai Metropolitan Water Supply and Sewerage Board, the State-run utility, will recycle the city’s sewage to drinking water standards and supply it for industrial use.

Two tertiary water treatment plants, run by private sector companies for the utility, Metrowater, will take partly treated sewage, process it to drinking water standards and pipe the water to the industrial hubs. The recycled water will be sold to industrial units by Metrowater. Apart from creating a new source of water, the move also reduces environmental pollution as the partially treated sewage will not be let out into nearby canals as is being done now.

One project of 45 million litres a day (mld) was inaugurated in North Chennai at Kodungaiyur last week by Chief Minister Edappadi K Palaniswami. Another of a similar size will soon start operations in the western part of the city at Koyambedu. Metrowater had bid out these projects to private sector EPC contractors who will operate and maintain the plants for 15 years.

The one in North Chennai is operated by BGR Energy and was formally inaugurated last week. The other at Koyambedu, to be inaugurated soon, is by the city-based multinational integrated water and waste-water player VA Tech Wabag.

Addressing shortage

Apart from benefiting industry, the projects also address Chennai’s drinking water shortage significantly. Together, the two units’ capacity is about 90 mld, equal to 15-20 per cent of the drinking water being supplied to the city. That means industry will not have to compete for the equivalent quantity of fresh water supplied for drinking purposes. This is critical because industrial units have always lost out to citizens’ needs in the competition for water during times of shortage. Units, particularly large continuous process industries, have had to shut down for lack of water on several earlier occasions. Effectively, Chennai will get an additional string to its bow in strengthening its tenuous water security.

Read: A problem of ‘plenty’

The city’s primary source is rainwater which replenishes ground water and the reservoirs. But monsoon can play truant as has been seen repeatedly in the past, including in the last few months when the reservoirs ran dry. For the same reason, supply can be disrupted from the other major source — river water from neighbouring States.

For now, the one dependable source is the two desalination plants of 100 mld each — one in Minjur in North Chennai and the other to the south of the city on the East Coast Road. These convert sea water to drinking water using reverse osmosis. Similarly, the two sewage water recycling plants provide another sustainable source of clean water even if it is only for industrial use.

These, however, will bring down pressure on drinking water supply. The units will take the secondary treated sewage – raw waste water held in a pond for waste to settle and aerated – from Metrowater facilities. This partly treated sewage will then be processed by the two tertiary treatment plants.

According to Rajiv Mittal, Managing Director, VA Tech Wabag, the treatment involves a dual media filtration process, chemical dosing, followed by ultrafiltration to remove colloidal particles, reverse osmosis to remove dissolved salts and micro organisms and finally ozone treatment to disinfect the water.

The final product is clean water of potable standard. From Koyambedu a 60-70 km pipeline will move the water to industrial units in Sriperumbudur region, a hub for automobile, auto components and diverse manufacturing industries. The pipeline infrastructure is already in place.

According to officials in the know, water from the North Chennai plant will be sent by a 20-km pipeline to industries and power plants in Manali and Ennore, a hub for large petrochemical, fertilisers and other continuous process industries. It was also recently decided to extend the pipeline beyond the Ennore creek to supply water to the North Chennai Thermal Power Stations and the Ennore Port, revealed the official.

The official said the unit will process about 200 mld sewage and recover about 45 mld clean water.

A senior executive from one of the companies in Manali said the user unit will buy the treated water from Metrowater at about Rs 80 per kilolitre. In fact, units have already started entering into purchase agreements for the water.

The deal offers multiple tangible and intangible benefits. While industrial units feel the price is steep, they are not unhappy, said the executive. The recycled water will be an assured source of supply and of established quality. For now, petrochemical and other units in Manali area alone bring in over 1,000 tanker loads of water. With piped water supply, vehicular pollution and tanker traffic on the roads will come down. Also, the industrial units are saved the trouble of treating the water inhouse. The facility by Metrowater is a welcome step, said officials.