Hundreds of students from around the world took part in the Cambridge Upper Secondary Science Competition to find sustainable solutions to real-life problems. The team from Willow International School in the capital, Maputo, found a way of removing methylene blue dye from water. Methylene blue is a synthetic dye which when released from factories into lakes and rivers, kills aquatic life and poses a threat to public health. According to the students, the conventional technologies that are used to treat such wastewater are expensive and complex. Over nine months they tested the effectiveness of using the shrub-like plant pyracantha coccinea to remove the dye. One of the students said they were extremely happy to have come top of Africa in the competition in what was a “fantastic and challenging experience”. The Willow International’s deputy head teacher said the school was very proud of them and thanked the competition’s organisers in the UK for “giving students opportunities to grow in a way where everyone can shine”. The overall world winner of the competition will be announced in December.