DuPont develops RO-based water treatment plant

DuPont has come up with a new form of water treatment plant, in an effort to address the rising water shortage in the country.

“Rising ground water shortage, urbanisation and heightened industrial activities have all put a strain on municipal corporations’ ability to meet the water demand,” said H.P. Nanda, Global Vice-President and General Manager, DuPont Water Solutions.

This problem is accentuated by the demand from residential users and industry, the latter needing much larger quantities. Also, for industry, there are government mandates on usage of water.

“Industrial water users in India are finding it more challenging to manage their water utility because of reduced access to reliable, low-cost water sources, as well as the higher costs associated with water discharge,” said Nanda.

Factoring in all this, DuPont has come up with a treatment plant, the size of a heavy hauler truck, that can cater to four villages with around 60,000 inhabitants. In contrast, a water treatment plant can be the size of a football stadium, catering to millions of users. “The filtration technique is specific to systems with a small footprint, and the current capacity of 5,000m3 per day can be expanded by up to 25 per cent without requiring further mechanical or electrical work,” added Nanda.

In this method, waste water is recycled using a membrane-based system through Reverse Osmosis (RO). Membrane bio-reactors, that are based on the process of ultrafiltration with a bioreactor, treat the wastewater, which can then be used for irrigation.

Water recycling crucial

Water recycling is no longer a fad and is the need of the hour, S Rajavel, Head of the Water and Effluent Treatment business at L&T told BusinessLine recently.

L&T’s water and effluent treatment business is eyeing a slew of desalination and water treatment projects worth $1 billion in the country.

Chennai generates 550MLD (millions of liters per day) of sewage in a day, which would be treated and re-used. Gujarat has mandated that industry use recycled water, which would be sourced from municipal waste water treatment plants. These plants would need to treat the waste water with UF and RO, to bring the water up to acceptable standards for waste water.

For the end-consumer, DuPont believes that the cost could come down to 35 paise per litre.

However, the RO method of treating water has seen a push-back.

A non-profit, ‘Friends’, has argued in court that RO systems involve a high level of water wastage, of up to 80 per cent. “With RO more water gets wasted and there is a loss of minerals like calcium and magnesium in the process,” said a water expert.

Additionally, an expert committee constituted under the Ministry of Environment and Forests noted that RO technology was not required in places with piped water supply from rivers, lakes and ponds, where the level of total dissolved solids (TDS) is far lower than in ground water sources.

Installation of RO plants is advisable for sources having TDS levels of above 500 mg/litre. Where the TDS levels are below that level-ultrafiltration technology clubbed with ultraviolet radiation would suffice.

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