Water fleas, most of which average less than five millimetres in length, could play a new role as chemical pollutant vacuum cleaners for wastewater, says a University of Birmingham study in the U.K.
Scientists say the Daphniid species can remain dormant for centuries, allowing scientists to “revive dormant populations that endured varying historical pollution pressures,” the study states. Researchers could then source strains from water flea embryos with “diverse tolerances to chemical pollutants,” and incorporate the tiny crustaceans into scalable, low-cost, low-carbon, and retrofittable nature-inspired tertiary treatment technology for municipal wastewater.
Researchers utilized four Daphnia strains of different ages, spanning a century, to target the removal of four particularly problematic pollutants: the pharmaceutical compound diclofenac; the pesticide atrazine; the heavy metal arsenic; and the industrial chemical perfluorooctane sulfonate, better known as PFOS.
While the water fleas’ lab removal rates for diclofenac hit 90%, the other pollutants were removed in the range of 50-60%. The removal efficiency of PFOS and diclofenac in individual chemical exposures varied significantly by Daphnia genotype, the study found, and chemicals removed were not excreted back into the water.
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“Our profound understanding of water flea biology enabled us to pioneer a nature-inspired tertiary wastewater treatment technology,” announced senior study author and professor, Luisa Orsini, from the University of Birmingham, in a statement. “This refines municipal wastewater effluent and safeguards the ecological health of our rivers,” she added.
Study co-author and University of Birmingham School of Engineering professor, Karl Dean, says their team installed carefully selected water fleas into custom containment devices to refine effluent before its final release. The vessels consisted of a solid frame and a porous mesh that allowed for the movement of water, while retaining the live water flea population and allowing for the collection of dead fleas at the base of the vessel.
“Once in place, our technology largely maintains itself, attributed to the water fleas’ clonal reproduction capability,” Dean said in a statement.
Published in the journal Science of the Total Environment, the study suggests the low-carbon footprint of the water flea technology, combined with prevention of pollution of surface water, “provides a practical solution to meet increasingly stringent regulations.”
The study’s primary authors, Dean and Orsini, are also part of a start-up company which aims to commercialize the Daphnia-based technology.