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

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.