Plant based phosphorus recovery from wastewater via algae and macrophytes

At present, resource recovery by irrigation of wastewater to plants is usually driven by the value of the water resource rather than phosphorus recovery. Expanded irrigation for increased phosphorus recovery may be expected as the scarcity and price of phosphorus increases, but providing the necessary treatment, storage and conveyance comes at significant expense. An alternative to taking the wastewater to the plants is instead to take the plants to the wastewater. Algal ponds and macrophyte wetlands are already in widespread use for wastewater treatment and if harvested, would require less than one-tenth of the area to recover phosphorus compared to terrestrial crops/pastures. This area could be further decreased if the phosphorus content of the macrophytes and algae biomass was tripled from 1% to 3% via luxury uptake. While this and many other opportunities for plant based recovery of phosphorus exist, e.g. offshore cultivation, much of this technology development is still in its infancy. Research that enhances our understanding of how to maximise phosphorus uptake and harvest yields; and further add value to the biomass for reuse would see the recovery of phosphorus via plants become an important solution in the future.

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► Algal ponds and macrophyte wetlands in widespread use for wastewater treatment.
► Harvested algae/macrophytes require <1/10 of the area compared to terrestrial crops for phosphorus uptake.
► Luxury uptake could be used to increase the phosphorus content of the biomass.
► Multiple opportunities exist (e.g. offshore cultivation) but are still in their infancy.
► Phosphorus recovery via plants has potential to become an important future solution.