Sustainable clean drinking water solution

'There are still two billion people in the world without access to clean drinking water,' says Olivier Gr?ninger, a postdoc in Professor Wendelin Stark¡¯s group at ETH Zurich. These are the people whom the chemical engineer wants to help. Over the past five years, he has developed an inexpensive and efficient water filter that is easy to manufacture and use. In a field study conducted in Colombia, Gr?ninger taught small entrepreneurs how to make the filter. There are now 100 of these filters being used in Colombia and neighbouring Ecuador by families living in rural areas. Four hundred people are benefiting from this ETH project. Thanks to the filters, people can purify river water or water from polluted groundwater wells and drink it safely.

Praised by expert juries

Gr?ninger¡¯s project is based on the extensive know-how of filter membranes accumulated by the group working under Professor Stark, in which Gr?ninger spent recent years working on his doctoral thesis. The goal of his thesis was to find an application for water filter membranes that would be practicable for developing countries.

His project, called Openversum, has already attracted a lot of attention and has received awards from expert juries. It was among the six finalists for this year¡¯s Hult Prize, a prestigious and highly endowed international prize awarded by the Clinton Global Initiative and the United Nations Foundation, among others. In spring, the project also won the Community Award, part of the Swiss Youth and Future Prize launched by the Swiss Agency for Development and Cooperation (SDC) and the State Secretariat for Economic Affairs (SECO).

Gr?ninger remains modest, however: 'The filter design itself really isn¡¯t rocket science.' The big challenge, he says, lies in finding a sustainable solution that will keep these families supplied with drinking water for many years to come.

Gr?ninger recounts regrettable past cases of NGOs supplying households with free water filters and then withdrawing from the market. This meant that no experts were available to change or repair the filters one year later.

That is why Gr?ninger and his team at Openversum are taking a different approach. They work with local small entrepreneurs and train them to build the filters from scratch. Setting up a functioning supply chain for sourcing the individual components is also part of the process. These local entrepreneurs then sell the filters to families and take care of their long-term maintenance. ¡°From the outset, we knew we didn¡¯t want to just develop a product and then export it. We were looking to export the knowledge,¡± Gr?ninger says.

Another challenge was to gain the trust of the locals. He says it helped that they were working with an NGO based locally in Ecuador that people were familiar with. This organisation issued vouchers to the families so they could obtain the water filters at a reduced price.

Gr?ninger might downplay the engineering challenges, but in fact the ETH water filters have various merits. 'What¡¯s special about our system is that it filters lots of different substances out of the water, while being very cheap,' he says.

The filter system consists of three layers. The first is a layer of activated carbon that traps unwanted compounds and any pesticides present in the water. The water then passes through a membrane with micropores that filter out bacteria and other microbiological contaminants. Finally, a layer of ferric hydroxide powder binds heavy metals and phosphate.

For the field trials in Colombia and Ecuador, Gr?ninger and his team used a commercially available membrane. In future, however, he plans to use a membrane he developed at ETH Zurich. Unlike conventional products, this membrane is manufactured without organic solvents, is extremely cheap and robust, and can easily be disposed of after use because it is biodegradable.

ETH Zurich has already patented such a membrane, and Gr?ninger would like to have it certified for use in the treatment of drinking water. To this end, he plans to establish Openversum as an official ETH spin-off.

Climate-friendly technology

Gr?ninger aims to continue his work in Colombia and Ecuador. He is also looking to expand the project to the African continent as soon as possible, because that is where the need is greatest. The project¡¯s initial focus in Africa is set to be on Uganda and Somalia, where Gr?ninger has already found partners.

Openversum¡¯s approach helps to create local jobs by providing an income for the local entrepreneurs who are trained to maintain the filters. And, ultimately, it¡¯s good for the climate too as such water filters help to reduce carbon emissions. Without them, the water would have to be boiled before being used, meaning that they help to save fossil fuels.