Cleaning up our wastewater with freshwater algae

Photo by Juan Manuel Valero Rodriguez

Wastewater from treated sewage and urban and industrial run-off has a significant environmental impact on the biological integrity of our coastal marine ecosystems. The best way to manage wastewater is before it enters marine ecosystems, by reducing both contaminant and nutrient inputs. Algal bioremediation can significantly improve the quality of wastewater by removing nutrients. However, before algal bioremediation can be applied to Melbourne’s wastewater, it’s important to identifying suitable algae based on their biomass productivity and ability to outcompete less desirable algae. As part of his PhD, Juan Manuel Valero Rodriguez compared the productivity and competitive ability of three taxa of filamentous macroalgae (Oedogonium, Stigeoclonium and Hyalotheca) under the seasonal light and temperature conditions experienced in temperate environments, including extreme heat and cold. He found that different taxa thrived under different seasonal and competitive conditions and suggests that rather than finding an optimal taxon for all four seasons, in order to maximise stable biomass production, we should either have a seasonal rotation of algae, or bi-cultures of the most dominant ones.

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