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Algae Turf Scrubber

Production of fertilizers for food gardens

The pilot project was a joint project of eThekwini Water and Sanitation (EWS) and the Free Hanseatic City of Bremen. The test phase ran from mid-March 2013 to mid-2014.

It is known that algae absorb nutrients which can be used to enrich soil. When algae grow on a body of water, they consume nutrients and sequester carbon. It is difficult to filter the algae and take them out of the water. The proposed algae filter provides optimal conditions for algae to grow on a medium placed in water. The medium can then be removed from the body of water to collect the algae and test their use as a fertilizer. This may serve as a free source of nutrients for the local population. They can use the algae as fertilizer in their flower and vegetable gardens which are also known as food gardens. With the help of solar energy, the filter has the added benefit of improving water quality and binding the carbon as well as unwanted dissolved nutrients in the water.

In the project period it was examined whether:

  • algae grow in the river uMhlangane and can be harvested in situ,
  • if the algae substrate is harmless for the environment,
  • if the algae substrate can be used as fertilizer.

The following activities were carried out:

  • the development of a suitable filter system on which the algae can grow,
  • observation of the growth of algae,
  • analyzing the algae for contaminants,
  • analysis of various nutrient concentrations.

The following steps could not be carried out:

  • development of a method for harvesting and drying the algae,
  • training of local population to use algae.

Before the end of the project the metal trays, which were used for the growth of algae, were stolen from the river. Theft of metal parts for other use is a serious problem in South Africa and has also been a problem in several projects which Bremen and Durban carry out together and which can endanger the success of a project. Currently, the project cannot be continued.