Solar-Powered Water Purification

An ETH Zurich Focus Project

The Problem

South Sudan is a landlocked country in Northeast Africa that has been dealing with an ongoing water crisis. A lot of the water the population has access to comes from wells, which can be fraught with microparticles, pathogens and dangerous ions. Infants specifically suffer immensely from the unsafe water intake. Particularly, if parents decide to bottle feed them, the disproportional water intake to body weight ratio poses great health risks. In addition, medical institutions often lack access to safe water for patient treatment. Simultaneously, the Climate Crisis demands a turn toward renewable energy sources.

Our Solution

Apasōn is a solar-powered device, able to purify South Sudanese well-water to infant safety standards. With water of this quality both safe infant formula milk and safe patient treatment can be ensured. Apasōn was designed to fit on the back of a pick-up truck, so that it can easily travel to remote location. It requires no expert knowledge to be operated.


Apasōn is made up of three principle parts: pre-treatment, post-treatment and an electro-dialysis module, which forms the heart of our purification system.
The ED module can remove electrically charged particles from water, using an electric field and semi-permeable anion- and cation-membranes.
The pre-treatment will tackle larger particles like sand and dirt, using an ultrafiltration membrane, while the post-treatment will sterilize the water with the use of UV-light and finally filter out bad flavours with an activated carbon module.
The whole system is self-sufficient, which means that it uses an automated control system and is powered entirely by an off-grid photovoltaic module. A user-friendly GUI allows for easy operation and the device requires little maintenance.

Focus Projects

Focus Projects take place in the third year of the Mechanical and Electrical Engineering Bachelor's degree at ETH Zurich. Over two semesters, a group of eight students works on designing and constructing a sophisticated product, which is then presented at the Focus Roll-Out. The students undergo a thorough application process; getting approved requires extraordinary grades, high motivation, and great performance strength. In addition to knowledge acquisition, the objective is to gain experience in research, product development, organisation, and project management. To find out more about the focus projects and the Roll-Out, click here.

D-MAVT CARES Initiative

The D-MAVT CARES Initiative was founded to promote efforts in sustainability. It offers financial support for focus projects that pursue one or more of the United Nations' sustainable development goals and represents our main sponsor. Out of the 17 sustainable development goals SOWA mainly addresses three, namely Good Health and Well-Being, Clean Water and Sanitation, and Affordable and Clean Energy. Find out more about the D-MAVT CARES Initiative.

SOWA Roll-Out Presentation – 31st May 2022