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Dutch scientist Dr Gatze Lettinga has developed a wastewater treatment that uses less water and produces biogas. The freely-available process has received worldwide recognition.

Dr Lettinga has pioneered wastewater treatment and water purification for the last 40 years, developing and implementing a range of innovative processes for industrial and domestic wastewater. His concepts have been exported around the globe and are being implemented in Brazil, Colombia, India and Singapore.

His upflow anaerobic sludge blanket reactor (UASB) process purifies industrial wastewater cost effectively while producing renewable energy, fertilisers and soil conditioners. UASB uses 40% less water to purify wastewater than other methods.

This ground-breaking high rate anaerobic process won the Lee Kuan Yew Water Prize in Singapore in March 2009 – see BOX. Dr Lettinga is no stranger to accolades, having been awarded the prestigious Tyler Prize for Environmental Achievement from the University of South Carolina in 2007.

How does the USAB water purification process work?

UASB is a single-tank process that treats industrial and domestic wastewater. Wastewater enters the reactor from the bottom, and flows upward. A suspended sludge blanket, comprising microbial granules, filters and treats the wastewater as it flows through. The micro-organisms in the sludge degrade organic compounds from which gases – methane and CO2 – are released. The collected gases can be used as biogas.

The concept was original tested in the mid 1970s and we built our first demonstration unit in Cali, Colombia in the 1980s. Although we initially intended primarily to treat industrial wastewater, we quickly found that it was also particularly effective at processing domestic sewage. For this reason, we constructed our first full-scale UASB plant on the banks of the Ganges in India to process such wastewater.

The process has also been adopted in Brazil. Since the late 1990s, between 100 and 200 UASB installations have been set-up there. The process now forms a main-treatment step in a large proportion of domestic-water treatment systems.

Why did you decide not to patent this method and instead make it an ‘open-source’?

I’m of the opinion that general concepts of benefit to the environment and people as a whole should not be monopolised. This concept should benefit everyone. This is why we have allowed innovative entrepreneurs to take the concept and develop their own specific systems.

Are you in favour of small-scale water purification as opposed to large centralised systems?

Not small-scale purification, but rather appropriate scale. In particular, I feel that it is essential that clean water is not misused through the collection of wastewater. The right treatment systems in terms of industrial and environmental impacts must be put in place.

Above all, it is vitally important that water-treatment systems prevent environmental pollution problems, rather than create or exasperate them.

In my opinion, authorities need to adopt decentralised systems that optimise water consumption.

What can be done to aid technology transfer to developing countries?

We need to show developing countries that concepts such as UASB are not ‘black box’ technologies. People need to understand that they are well-designed systems, which will simply lead to a cleaner environment.

We can improve technology transfer by making people realise that these new concepts will enable people to become self-sufficient. In many cases, the equipment needed to implement new concepts is already available in these countries.

Some countries have been extremely receptive to these innovative concepts. Brazil for example has taken our water-treatment process and developed it further. It has put public funds into encouraging the emergence of such technology, and has embraced the idea of moving towards a sustainable society.

I believe that there isn’t a problem in getting private industries to buy into the idea of these technologies as they have proven to be profitable. Rather the challenge is to make public bodies embrace such technologies and processes.

What can the EU do to ensure energy-efficient and environmentally-friendly approaches to water treatment are adopted in its Member States?

The EU can do enormous things, particularly in water conservation. At present 80% of water use is in agriculture but, in many Member States, wastewater is still not being used. States must be encouraged to harness wastewater for agricultural use.

UASB pioneer wins Singapore water prize

Dr Lettinga received the 2009 Lee Kuan Yew Water Prize for his upflow anaerobic sludge blanket reactor (UASB) technology. This innovative concept overcame competition from 38 other nominees from 19 countries to scoop the top prize worth €154,000. The award was presented to Dr Lettinga on 24 June 2009, during the second Singapore International Water Week. Named after Singapore’s first prime minister, the Lee Kuan Yew Water Prize recognises outstanding contributions in the field of water from an individual or organisation.

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