The membrane advantage
Utilities Middle East speaks with Masdar Institute's Dr Nidal Hilal
Utilities Middle East speaks with Masdar Institute’s Dr Nidal Hilal, Professor in Nano-Membranology and Water Technologies, about how membrane research is changing the game in desalination
Speaking to Masdar Institute’s Professor Nidal Hilal, he makes it immediately clear that pressure on the water supply in the Middle East, and the world in general, is a grave and growing problem.
One in eight people around the world drinks water containing pollutants, bacteria and viruses, whilst elsewhere we are consuming too much water from limited resources. Abu Dhabi, for example, consumes 24 times more water than its natural recharge capacity. It is, as Dr Hilal says, an alarming situation.
“Basically we are taking too much water from water resources, and tapping into the sea is the only option available to address such water shortages. Desalination of sea water increasingly proves to be the most practical – and in many cases the only – solution for many countries across the globe, and particularly around the GCC and the Arab world,” he says.
Traditionally, the answer to desalination in this part of the world has been thermal desalination; a high-capital, high-energy solution that is only suitable where fuel is cheap. Whereas high energy costs in much of the world has long since turned attention away from thermal, here in the Middle East there has been far less of a need to seek alternatives.
Now though, with a far greater focus on energy efficient solutions, together with a growing distaste for burning domestic oil for water consumption, the usefulness of membrane technology in desalination has demanded far more attention.
“The importance of membrane technology in the desalination industry is the energy usage. For example, a thermal desalination plant in the region using a muti-stage flash unit is likely to use around 25kwh per cubic metre. This is compared with a unit using a reverse osmosis membrane (RO), which uses between 4 and 5kwh per cubic metre.
Of course energy remains the major cost in the operation of desalination facilities, and this is the attractiveness of RO membranes.”
With significant predicted increases in future energy costs, the need to find energy efficient, sustainable solutions to ensure a secure long-term water supply has grown. Dr Hilal’s research is focused on improving the efficiency of membranes further.
“The disadvantage of membranes is that they become blocked – or fouled – and this impedes the flow and efficiency. When a membrane is blocked, we need more energy to drive the water across the membrane. My research is focused on making new membranes, with different materials, which are called (bio) fouling resistant membranes.”
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Membranes fouling can include calcium carbonate build-up (a particular problem in the region), viruses, bacteria or fungus; all of which can have an immediate impact on the efficiency of a membrane. Dr Hilal’s team is focused on investigating different membrane polymers and the properties of these materials to ensure that fouling materials are kept away from the membrane surface.
“We can do this in a number of ways. You can have the polymer coated in material that prevents fouling, or you can play with the charges of the membrane surface itself. For example, if you have a fouling material with a positive charge, you can create a positive charge on the membrane surface so that it repels this fouling material.
A problem we see in this part of the world is that membrane manufacturers will not always be clear on where the membranes are applicable – wastewater or sea water for example. Therefore what we do here is tailor membranes for specific applications, for particular pollutants, in the application itself,” he says.
Efficiency gains that the team has noted have ranged from 20% to 70% - an especially impressive improvement when you consider the vast amounts of water involved in desalination.
“We have something called a back wash where we put flux from the opposite side of the membrane to kick out all the materials from the pores and shift if from the membrane surface. When we use this anti-fouling material, or an anti-fouling membrane, the time between cleans can increase substantially.”
Dr Hilal’s team are currently working on a membrane distillation project, which involves harnessing the advantages of both membranes and thermal desalination. This process involves having a higher temperature on the face of the membrane, and a lower temperature on the other side, with the resulting difference driving the pure water through the membrane.
“Another project Masdar is looking at is Boron removal from seawater, where we are developing a novel continuous process at a pilot plant to remove Boron from seawater and to meet the World Health Organisations’ limit.”
Dr Hilal has been with Masdar Institute for four months, moving from the UK to establish a centre of excellence in desalination water technologies that undertakes collaborative research of national application.
“Something about Masdar I have to say, and this is what drove me back to this part of the world, is the vision they have for water and for environmental issues and solar energy and so on. It really is amazing in one way or another.”