Wednesday, 21 November 2007
Water scarcity in future: recycled water the answer
Published in The Asian Age/Deccan Chronicle - November 2007
By Syed Akbar
It is 2020. Within a space station a group of men and women have just finished their daily workout. They sip water from specially made bottles.
There is nothing very unearthly about all this, except that the water has been "reclaimed" from sweat, urine and even their exhalations. The space tourists do not grimace while gulping the water. They don’t have any yucky feeling since they have already been drinking such water down below on Earth.
This is no scenario from a futuristic sci-fi movie. Scientists predict that drinking water reclaimed from urine, sewage and sweat may become the norm in the next two decades. Over-exploitation of groundwater is already causing shortage of water and climate change will only add to it. This will leave people with no option but to reuse "grey water" as urine is called.
The National Aeronautics and Space Administration of the United States is conducting a major study with 50 volunteers on the psychological, chemical and biological reactions to consumption of water reclaimed from sewage including toilets. The European Space Agency is asking scientists on an Antarctica expedition to utilise recycled sewage water for drinking at its Concordia research station. This will give the ESA enough inputs for its proposed Mars mission by 2030. Nasa volunteers even "borrow" urine from others and drink it after putting it through a state-of-the-art treatment process.
Countries such as Singapore, Australia and the USA have also started experimenting with recycling of sewage and toilet water and are also supplying it in limited quantities to the population. Singapore mixes one per cent of treated sewage water with 99 per cent of natural water to reduce the yucky feeling among its citizens and Australian cities have taken up massive advertisement campaigns to sensitise people on the issue.
Many nations in water-scarce and drought-hit Africa have taken up similar projects with the assistance of the World Health Organisation and the United States. And in India, people have been even drinking "untreated" sewage water from polluted rivers and other water bodies. They might consider any sort of purification a blessing.
Crores of people living downstream of cities like New Delhi, Patna, Allahabad, Nashik, Rajahmundry, Hyderabad and Vijayawada drink treated sewage water without a second thought.
The Musi River empties into the Krishna River near Suryapet in Nalgonda carrying the treated sewage from Hyderabad. The Vijayawada Municipal Corporation has set up half a dozen such treatment plants to treat and let out sewage into the three irrigation canals that serve as drinking water sources for lakhs of people downstream. Vijayawada discharges 66 millions litres of sewage every day from 31 outlets into water bodies while Hyderabad pumps more than 300 million litres per day into the Musi river through 18 outlets.
Though reclaimed sewage water has not yet been "officially" used for drinking in India, several civic bodies and industrial houses are utilising it for watering lawns and for other purposes.
The Greater Hyderabad Municipal Corporation, for instance, utilises the waste water for watering its avenue plantation on important roads and gardens.
Big industrial houses such as Madras Fertilisers and Chennai Petroleum purchase waste water from Chennai Metro, recycle it and use the "purified" water in their cooling plants. Arvind Mills, Rashtriya Chemicals and Fertilisers, Kanoria Chemicals and Maruti Udyog are also known to use the recycled water for industrial purposes.
ALL THOSE RIVERS
Naturally, a question will arise as to why people should drink treated urine and sewage water when rivers and lakes seem to be positively rippling with water. The simple answer is that there is not enough water to meet the future needs of the ever-growing population. Scientists point out that the quantum of water on earth is constant and this means that water cannot be created afresh. The only option is to recycle the available water to meet the increased demand.
As of now, civic bodies in many countries are supplying reclaimed water at subsidised rates to make people go for it. The Singapore government, in fact, takes tourists to many of its recycling plants to in a bid to create awareness on the importance of water conservation. "Soon water availability may be what will differentiate the haves from the have-nots," says H. Subramaniam, water management expert and vice-president of EverythingAboutWater. According to him, India will become a "water-stressed" country by 2025, with water availability declining to between 1000 and 1,700 cubic metres per person per year.
"The possibility of future wars over water is not science fiction," he says. "It is very real. Increasingly, water is seen a strategic resource to be used with caution and managed with care." Statistics support Subrahmaniam’s argument. The total precipitation including snowfall over India is 4,000 billion cubic metres and fresh water available for use is 1,869 billion cubic metres. This includes replenishable groundwater.
However, the actual amount of water available is just 1,122 billion cubic metres, including 690 billion cubic metres of surface water. Of this, 80 per cent goes into farming leaving just 20 per cent to quench the thirst of 1.02 billion people. India’s projected population by 2025 is 1.39 billion. The per capita availability of water in the country has come down from 5,277 cubic metres per person per year in 1955 to 1,970 cubic metres in 2007. By 2025, this will further go down further. India will face an acute shortage of water and there will be no option but to use recycled sewage water.
THAT YUCKY FEELING
The very thought of drinking treated sewage water or urine might make you want to throw up, but the fact remains that water reclaimed from sewage and toilets is as pure as treated potable water. In some cases, it is even purer.
Several studies by the World Health Organisation and scientific agencies in the US, Japan, the UK and Australia have proved beyond doubt that treated sewage water is perfectly fit for drinking. Volunteers who participated in several "taste and tell" surveys were not able to tell the difference between tap water, bottled water and recycled water. Scientists say that recycled water can even be used for kidney dialysis. Scientists of the University of New South Wales used reverse osmosis system to treat water contaminated with pharmaceutical residues and found that it did not have even nominal traces of the chemicals.
However, some experts fear that some harmful traces might remain even efter strict filtration. "When we use recycled water, we must ensure that micro organisms such as E coli and others should be within limits," said Dr B. Ravishankar, senior medical gastroenterologist at Yashoda Hospital, Secunderabad. "Otherwise, it will open the door for infectious diseases." There is also another factor — Indian toilets are dirtier than those of Singapore, Australia, the UK and the US.
"Most Indians are ignorant of the fact that more than 80 species of dangerous micro-organisms have been found lurking in toilets," said Dr Vijay Punjabi, president of the Indian Medical Association. "There’s a likelihood of these germs making way into the recycled water."
PRESTO, IT IS PURE
What exactly happens to urine, sweat, perspiration and sewage water that are treated?
Scientists are simply aping Nature when they go in for recycling of waste water. In Nature, water from sweat, perspiration, faeces and urine go up into the sky through evaporation and later come down as rain. Many of us consider rain water as pure and do not hesitate to drink it.
In the future, scientists will be using membrane bioreactor process for recycling. It will combine clarification, aeration and filtration in a single stage to ensure pure water.
The low-cost and simple methods involve letting out the treated water into rivers, streams, lakes and tanks allowing it to get mixed with natural water. Later this water is purified and supplied to citizens. This indirect potable reuse is already being undertaken in Singapore. There are also other proven methods such as distillation, freezing, reverse-osmosis, electro-dialysis and ion exchange. Nasa plans to utilise its space technology to supply fresh water to countries that are hit by perennial droughts. "Sewage water can be recycled and reused for a dozen times," said senior physicist B. Raja Rao.
"After that, the water quality becomes quite bad." Health experts such as Dr G.R. Srinivas Rao, however, argue that a country such as India which is endowed with natural sources of water need not use recycled water for drinking.
"It may not be healthy since even a small loophole somewhere in the process can lead to an epidemic," he says.
But if things go on like this, we may not have a choice.
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