An expert in the human factor

If you ask children what they want to be when they grow up, they usually say a pilot, a vet or a professional footballer. Nadja Contzen had other ambitions. “I wanted to work in waste disposal and to use technology to revolutionise the refuse system,” she smiles. Her idea was that nothing should ever be burned or buried again; everything should be reused. Even at the tender age of four or five, she was already spearheading her first mini-revolution. “I introduced a composter at our kindergarten. At the end of the week, I took it away and tipped the contents on the compost heap in our family garden.” Contzen grew up in an environmentally conscious household in a village on Lake Zurich. The family didn’t have a car, her mother was active in the Green Party, and all of the children had to lend a hand in the garden – the concepts of ecology and sustainability were an integral part of their daily lives. The fact that she didn’t embark upon a career in waste disposal wasn’t ultimately because of the boy in her kindergarten class who told her that girls couldn’t be bin men. “It was more that I realised that the sustainable use of natural resources does not only depend on new technologies but also on a better understanding of how people make certain decisions and how behavioural patterns can be changed.”

Contzen, who studied psychology at the University of Zurich, became very aware that the latter is not as easy as one might hope when she was researching for her doctoral thesis at Eawag. In Haiti and Ethiopia, she studied how handwashing can be promoted as a health measure. “Some people in my circle of friends couldn’t understand why we even need research into this area. ‘Surely it’s their own fault if they don’t wash their hands,’ was one comment that occasionally came up.” However, she says that if you travel to such areas and are confronted with the reality of life on the ground, you get a better understanding of why, especially in this context, handwashing is not a matter of course.“ In the rural area of Ethiopia that I visited, a family has just 25 litres of water available to them each day – for drinking, cooking, washing and providing drinking water to young animals. There’s not a lot left over for handwashing.” To complicate matters, there is no handwashing infrastructure whatsoever. The water comes not out of a tap but rather from the 25 litre jerry can that is filled once a day at a water source – often an hour or more’s walk away. “Handwashing means pouring water from the jerry can into a cup so that you can then wet first one hand and then the other with water from the cup. You then lather with soap and repeat the cup routine to rinse the soap off,” says Contzen. “It’s not until you do it yourself that you realise what a complicated, elaborate process handwashing can be. That helps you understand even better why people don’t prioritise it in their everyday lives.”

This example demonstrates the importance of decentralised water treatment systems, such as the "Water Wall" developed by Eawag (see article “Autarky – ultimate convenience in a one-stop solution”). In locations where there is no mains water supply, these systems provide user-friendly infrastructure and allow wastewater to be treated in a self-contained cycle and reused for handwashing, for example. “Innovative technologies play a fundamental role, paving the way for key advances in relation to drinking water, sanitation and hygiene,” says Contzen. But they still don’t guarantee progress. “The key question is whether people accept, use and correctly apply these technologies in the first place.” This is where the environmental health psychologist’s research comes in. Since 2019, she has led the Environmental Health Psychology group at Eawag. “We’re interested in the human component. What behavioural patterns and decisions lead humans to put the environment and their health at risk? Are environmental and health risks even perceived as such? What does it take for people to change their behaviour or to accept and use new technologies?”

In the Indian city of Bengaluru, Contzen and her group studied which aspects of psychology play a decisive role in the success of decentralised water technologies. The city’s rapidly growing outlying districts are not connected to the central sewage system, and so decentralised water treatment at the individual building level is stipulated by law. Here, the costs of installing, operating and maintaining the system must be met by the residents themselves. “The perceived benefits – such as the positive impact on the environment or the positive image associated with using a system of this kind – explain the acceptance of these systems best,” says Contzen, summarising the results of a survey of people with and without a decentralised wastewater treatment system. “If you want to promote a system like this, you should therefore focus on highlighting the benefits, rather than on playing down the cost or potential risks.” In other words, cost needn’t necessarily be a barrier to a system’s acceptance. In fact, the greater obstacle is if a technology requires a change in people’s behaviour, as is the case with chlorination in order to disinfect drinking water at the household level, for example. “People first need to buy the chlorine, measure out the right amount, add it to the water, stir the chlorinated water and then leave it to sit for at least half an hour. In other words, it requires you to plan in advance,” says Contzen. It’s an elaborate routine that people first have to learn.

Collaboration leads to better solutions

Eberhard Morgenroth says that it is a significant challenge to develop technologies and procedures that not only ensure perfect water quality but that are also cheap and easy to use – without turning people’s lives upside down. As an environmental engineer at Eawag, Morgenroth accompanied the project in Bengaluru. “The input of social scientists such as Nadja Contzen is extremely important and valuable to us as engineers,” he says. This appreciation is mutual, with Contzen saying that “the interdisciplinary collaboration at Eawag is hugely rewarding.”

Though Contzen might not have revolutionised waste recycling (yet), her research represents an important contribution to the recycling of water, the sustainable handling of this valuable resource, and the improvement of health in the Global South.