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Dryad

Harnessing waterfleas for water reclamation: A nature-based tertiary wastewater treatment technology

Abstract

Urbanisation, population growth, and climate change have put unprecedented pressure on water resources, leading to a global water crisis and the need for water reuse. However, water reuse is unsafe unless persistent chemical pollutants are removed from reclaimed water.. State-of-the-art technologies for the reduction of persistent chemical pollutants in wastewater typically involves high operational and energy costs and potentially generates toxic by-products (e.g., bromate from ozonation). Nature-base solutions are preferred to these technologies for their lower environmental impact. However, so far, bio-based tertiary wastewater treatments have been inefficient for industrial-scale applications. Moreover, they often demand significant financial investment and large infrastructure, undermining sustainability objectives. Here, we present a scalable, low-cost, low-carbon, and retrofittable nature-inspired solution that could be retrofitted into current wastewater treatment systems to remove persistent chemical pollutants. The technology uses the water flea Daphnia to non-selectively uptake and retain persistent chemical pollutants (pharmaceutical, pesticides and industrial chemicals). We showed Daphnia’s removal efficiency at laboratory scale ranging between 50% for PFOS and 90% for diclofenac. We validate the removal efficiency of diclofenac at prototype scale showing sustained performance over four weeks in outdoor seminatural conditions. A techno-commercial analysis on the Daphnia-based technology suggests several technical, commercial and sustainability advantages over established and emerging treatments at comparable removal efficiency, benchmarked on available data on individual chemicals. Further testing of the technology is underway in open flow environments holding real wastewater. The technology has the potential to improve the quality of wastewater effluent  meeting requirements to produce water appropriate for reuse in irrigation, industrial application, and household use. By preventing persistent chemicals from entering waterways, this technology has the potential to maximise the shift to clean growth, enabling water reuse, reducing resource depletion and preventing environmental pollution.