Award-winning floating islands help treat wetlands

First prototypes developed in 2014

Wetlands are miracles of nature. They provide us with so much more than just cleaner water. They provide ecosystem services, habitat for fish and other organisms, and a suite of edible resources to the human and animal communities that surround them. Importantly, wetlands also control floods, act as sponges to recharge natural underground water, and provide a purification function to enhance water quality.

Yet anthropogenic developments and impacts continue to degrade these vital aquatic ecosystems. Many wetlands are stressed, lifeless and polluted, with detrimental consequences for ecosystem and human health. It is these water security related challenges that motivated me to investigate innovative ecological engineering ways of addressing aquatic ecosystem degradation in a “mobile” way.

My research work around ecological engineering has led to the development of an innovative floating treatment wetland called the AqueouSphere which won the Eco-Innovation prize at the prestigious South African Eco-Logic awards 2015/2016 and came third in the City of Johannesburg’s Green Challenge Fund 2015. The AqueouSphere development forms part of my MPhil studies at Monash South Africa and is linked to the work of the International Water Security Network.

First prototypes developed in 2014

It all began in 2014 when I developed the first prototype of the AqueouSphere which was introduced into the Silverlakes Golf Estate in Pretoria, South Africa. At the time, this floating treatment wetland island was only 1m2 in size, but large enough to test the mechanics behind the technology. A second prototype, also 1m2, was later introduced with different vegetation and material. Various plant types are used, depending on the ultimate purpose.

The first prototype of the AqueouSphere has proved to be extremely adaptable. It can be used in both wet and dry applications. Not only can the AqueouSpheres be used for waste and storm water treatment, but it can also be used for fish spawning, various conservation practices, shoreline remediation, living walkways, erosion control, aesthetic water-scaping, community projects, and carbon sequestration. The AqueouSpheres can also contribute to sustainable businesses, particularly for local agricultural communities, and inspire other downstream businesses.

Aqueousphere floating treatment island one year after installation

The AqueouSphere prototypes have since been deployed in various riverine habitats in the Johannesburg area. The study has so far revealed that two plant species – Cyperus and Typh – are able to absorb significant levels of manganese, iron, aluminium and other contaminants through their roots and foliage, while promoting a reduction in algae and improved overall ecosystem function and health.

Parallel to the development of the AqueouSphere, I have also instituted phytotechnological trials in a laboratory in Bapsfontein, Gauteng. These trials involve four different water sources as growth media, with three types of water plants suspended in 10 litre pots. Preliminary results from the trials are showing that elevated levels of manganese, iron, aluminium and other contaminants can be removed by the wetland plants from the aquatic environment in which the trials are taking place. The trials are proving that various forms of contaminants can be effectively absorbed into the roots and foliage of these wetland plants.

Phytotechnological trials conducted in a laboratory on contaminant
uptake from wetland plants

The phytotechnological trials have confirmed that by using the appropriate plants, both non-metallic and metallic contaminants can be sustainably removed from an aquatic environment by means of floating treatment wetland islands, while at the same time promoting ecosystem rehabilitation and creating micro-habitats.

These results have led to the upscaling of the project to introduce larger islands in excess of 20m2 which have since been installed in the City of Johannesburg. In the long term, it is envisaged that this project will significantly contribute to the wider application of ecological engineering solutions that support wetland rehabilitation.

Yolandi is an MPhil (Integrated Water Management) student at Monash South Africa. Professionally, she works for Baoberry, a multi award winning and multi-disciplinary environmental, social and ecological services company specialising in ecological engineering innovations and services.