Water processing plant

The stuff of life

The predicted global water shortages are so acute that water has been dubbed 'the petroleum for the next century'. E&T discovers that the problems of water supply and the technologies to improve it are increasingly the same for developed and developing countries.

Last spring Barcelona began receiving emergency supplies of water from a fleet of tankers.

A fatal combination of low rainfall, growing population and booming agriculture has put the city's water supplies under immense strain.

Twenty-three million litres brought in by sea from France and Spain will be used to top up reservoirs until a new pipeline is ready to draw in water from other parts of the country.

Cyprus - similarly to Barcelona - ordered tanker-borne water, this time from Greece, because its reservoirs are at their lowest for a century this year.

Meanwhile, in the south east of America, millions of people are keeping their attention fixed on one particular body of water.

Lake Lanier serves key parts of Georgia, Florida and Alabama, including a nuclear power station. The twin drivers of drought and population expansion have drastically reduced the amount of water available.

The US Army has had to step in and ensure all three states share the meagre resources from Lake Lanier reasonably.

Blogs such as www.atlantawatershortage.com have sprung up to give people daily updates on the drought. Millions of Americans are becoming experts on issues such as reservoir turnover - when cold water heats up and rises to the surface bringing sediment with it and making tap water discoloured and smelly. They might hold their nose, but have little choice but to drink it.

Half-way round the world, Singapore may be a marvel of hi-tech ingenuity but its water security is precarious.

Through a quirk of geology, it has nowhere to store rain water naturally so whatever water it needs mainly comes through pipes from neighbouring Malaysia. This makes the city state very vulnerable should the taps ever be turned off.

Singapore needs around 1.3 billion litres a day, so a few shiploads simply won't do.

When people think about water shortages, the image is of parched African nations, but, increasingly, developed countries too are facing up to problems of water supply and demand.

What has caused planners an extra headache is something we've all seen every time we've filled up the car - the price of oil.

Desalination

Desalination is the traditional method of getting fresh water because you have an unlimited resource - the sea. However, it is an energy-intensive process. Previously this was an acceptable cost, but now getting clean water to people must be energy-efficient, too.

Bruce Horton is the environmental policy adviser for Water UK which represents all UK water and wastewater service suppliers. He is the policy leader on climate change and water resources.

Horton gives an upbeat assessment of the current situation: "Although there are areas in the UK that are more water-stressed than others, unless we do something radical we're not going to run out of water."

The problem is, those water-stressed areas in the south east and Essex are further burdened with creaking infrastructure and a continuously growing demand.

Horton expects a bigger roll out of metering so people can see for themselves what their water usage is.

This highlights one key aspect of water management and that is the need for data. The exact details on flows, leaks, cycles and droughts remain fuzzy. That obviously harms one's ability to provide an efficient service.

A company called Qonnectis has manufactured a device called Leakfrog which can remotely measure all sorts of information about the water flow and transmit it to a central computer. Thames Water has a contract with Qonnectis.

Many water companies in the UK, however, still send out people with sticks and a cup on the end through which they listen for leaks. Sometimes the technology is still that simple.

With water demand on the rise and rainfall coming in deluges rather than steady streams, the UK is looking at adopting technology usually associated with far drier countries.

Desalination is being considered as one way of providing extra resources in the future.

Horton explains: "Some companies have put forward proposals for desalination and they are planning to do it in the most energy efficient way.

"It is quite an attractive option because it is quick, whereas a reservoir can take decades."

The most popular method of getting usable water from the sea is reverse osmosis. This separation process works by forcing water under pressure through a membrane which can filter out the elements you don't want in purified water. The water either flows directly on to the membrane or past it - a so-called transverse flow.

That water will need to be treated once more to make it drinkable.

The process has its drawbacks and one is how to deal with the concentrated salt by-product.

More importantly, and this has only arisen recently, it is another energy intensive process. The cost of the technology means that the search is on to make it more energy efficient.

Surrey solutions

The University of Surrey's Centre for Environmental Health Engineering (CEHE) is currently carrying out pioneering work on fundamental questions about water sanitation and provision.

Much of it has taken place in the field - in developing countries and in partnership with aid agencies. Rwanda after the genocide and Ache in Indonesia after the Asian tsunami benefited from CEHE experts flying in to help to set up local water treatment plants.

Brian Clarke, the centre's jovial deputy director, says that the problems are increasingly the same for all parts of the globe as water-stressed regions are growing in territory.

"It is not going to be a technological fix," he explains. "It will be a bag of clubs and a particular solution for a particular location."

In recent years, CEHE staff have been looking at the potential for extending a range of technologies, including membranes and adjusting them to the developing world and relief agency applications.

The problem is that by leaving a residue of unwanted material on one side of a membrane you are putting on a banquet for bacteria. As they build up, you get fouling of the membrane which means it needs to be treated. That's time and money and possibly the introduction of yet more chemicals into the system. Pre-treatment often only delays the problem.

As Clarke describes it, microbes are "opportunistic", and the process can be complex to predict. It's not a case of one super-membrane being suitable for all occasions. Even similar types of membrane can produce wildly different results.

The CEHE staff looked at ceramic candles that can remove particulates and micro-organisms from raw surface water at the point of use. The effectiveness of numerous types of candles and the reasons for different levels of performance were investigated. Scanning with an electronic microscope showed large variations in the composition of different candles depending on both the manufacturing process and the source of the original ceramic.

Some of the membranes evaluated at Surrey can have extremely fine pores, less than 0.0001nm, for reverse osmosis use. To help track their effectiveness, the team employs bacteriophage (viruses that use bacteria as a host) as tracers.

Also at Surrey is Professor Adel Sharif who leads the Centre for Osmosis Research and Applications (CORA).

Prof Sharif's starting point was to look for the most sustainable source of water - and that was the sea. Then it was a question of how best to turn it into drinking water.

CORA has pioneered Manipulated Osmosis Technology (MOT) which it sees as a successor to reverse osmosis membrane separation. Its patented designs can suck salt water through membranes at low pressure. The specifics are being kept under wraps but the prediction is that it will be more energy efficient and will reduce the amount of fouling that occurs with traditional reverse osmosis methods.

A test plant is being constructed in Gibraltar by the university's spin-off company Aquatechnology which recently merged with Modern Water.

Spotted from space

The team at CEHE also benefits from the work of the university's Surrey Satellite Technology Ltd. Since 1981, it has put some 27 small satellites into orbit.

Some of the dustbin-sized objects form the Disaster Monitoring Constellation (DMC) - a global network of satellites that can image the damage caused by any natural disaster within hours of it happening. These images are made available to affected countries and aid agencies free of charge to help them plan relief efforts.

Each satellite in the DMC is independently owned and operated, providing 5 per cent capacity free for daily imaging of disaster areas. The satellites are spaced around a Sun-synchronous orbit to ensure complete coverage of the globe.

The solutions considered by Surrey's scientists are a lot more sustainable than shipping water to stressed regions. One of the Cypriot tankers, for example, had to dump its 40,000 cubic metres of cargo into the ground this year. The water had lain too long in the hold before it could be pumped to a reservoir and was therefore deemed unfit for consumption.

Dr Joan Rose is the Homer Nowlin Chair in Water Research at Michigan State University.

This November, she will address a conference on sustainable and safe drinking water for developing and developed countries at the University of North Carolina.

She believes we need to completely rethink the way we use water.

"We need a paradigm shift on return flow," she says. "We have to think about saving energy and recycling. No matter whether you are water-rich or water-poor."

Clarke agrees that our perception of water needs to change.

"Every time you go to the toilet and flush, you get rid of nine litres of drinking quality water - just to dispose of something that is actually sterile.

"Most people don't realise that 99.9 per cent of what arrives at a sewage treatment plant is water.

"There is no reason why we cannot go for grey water use from baths and showers that comes back to the roof and is circulated to the toilet."

Singapore schemes

Back in Singapore, the government is already well-advanced on such schemes which will reduce its dependence on water piped from neighbours.

Some of those are obvious, such as huge reservoirs, others involve desalination plants using reverse osmosis to filter sea water, with the resulting liquid made drinkable.

However, a lot of effort is going into using waste water - or, as they like to call it, NEWater - too.

This involves ultrafiltration of 'grey' water, reverse osmosis (again), and blasting it with ultraviolet light - the method that will eventually take care of around a third of Singapore's water needs.

The new technology has been used in conjunction with public information campaigns to educate people about water shortage and to get them thinking differently about what comes out of their tap.

Dr Andrew Benedek, who won this year's prestigious Lee Kuan Yew Water Prize for his contribution to membrane technology, says: "They went ahead and did it the Singapore way. What takes us forever they had done in a year. It took them one year to build a very large plant that would take four or five years to construct in America." Singapore's efforts are being studied worldwide and other countries are reckoned surely to follow in its footsteps.

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