Cyanobacteria are photosynthetic microorganisms found in a variety of environments, including marine water bodies. Some species are able to perform biomineralization, producing minerals such as calcium carbonate (CaCO3) that may act as biocement. The biomineralization capability of cyanobacteria has already been explored in the development of Living Building Materials (LBMs), composed of an inert scaffold of sand and hydrogel, that contributes to CO2 capture.

The offshore industry is a significant user of concrete, contributing to 11% of the global CO2 emissions. Therefore, the application of cyanobacteria biomineralized materials is envisioned as a way to reduce CO2 emissions in this sector.

The cyanobacteria biomineralized material has been studied in the fields of construction and is applied in 3D printing, but its potential for offshore applications still needs to be explored.

This study aims to explores the proprieties of cyanobacteria biomineralized materials to catter some requirements of offshore applications, thereby contributing to a more sustainable practice. This was done by first recreating the material from other studies, assessing its mechanical proprieties and testing it in underwater conditions. This was followed by a tinkering process where material qualities (e.g., cyanobacteria optical density (OD), biomineralization/curing time, type of hydrogel, aditional coating) were adjusted to fullfill its purposes.

The impact of these changes were measured through submerging the material in seawater and assessing its mechanical proprieties.

The use of cyanobacteria at an OD of 2.4, resulted in the strongest material. Using agar as an hydrogel binder, countered the dissolvability of the material with a gelatine binder. On the other hand mechanical tests showed that the agar bonded material was significantly weaker than the gelatine bonded material. Adding a silicone rubber coating to the gelatine bonded material did not make the material resistant to seawater. A prolonged biomineralization time improved the strength of the material significantly but more exploration is required to determine if the biomineralization time is the result of this strength or the adjusted sand/medium ratio.

Overall, this study demonstrated that cyanobacteria biomineralized materials can be applied in offshore applications since the right cyanobacteria OD, binder, coating and biomineralization time are employed.

Namibia has been home to some of the world’s oldest ethnic groups since the dawn of civilization. One of these cultures is the Himba, often referred to as ‘the last true pastoral nomads’ of Africa. They are known for inhabiting the water scarce desert region of Kunene in Namibia for centuries. Now, various factors, including climate change and the absence of governmental support, are forcing the Himba population to decide which aspects of ‘modern’ culture to incorporate into their everyday lives.

After decades of declining rainfall and rising temperatures, drought and omakururukiro yokuti (over-utilized land and vegetation) are the reality. The Himba is therefore forced to rely on their nomadic origins for survival, and to travel southwards, ‘following the water’, to Windhoek which is the capital of Namibia. On arrival, they are confronted with inequality apparent in the African urban built environment and take part in the rapid urbanization of Windhoek. They settle in townships, in shacks, located on the outskirts of the city, where access to water and sanitation is limited. Due to landscape topology, climate change and other factors, the high possibility of flooding poses a new risk. Indeed a life-threatening choice: surviving drought in Kunene or surviving floods in Windhoek.