Aquafarm’s ‘green’ water treatment a first
Floating water fern Azolla filiculoides.
Using plants and animals to purify waste
water while extracting raw materials is the
principle of Aquafarm. In early September
last year, after a year and a half of
research, a trial setup was launched
which should lead to the first biological
water purification within four years.
On an Aquafarm, aquatic plants and
animals remove waste products from the
water, which leads to cleaner water and
complies with the European directive for
natural water. In addition, natural water
purification can be combined with the
production of raw materials such as
proteins and fats.
Making glue from duckweed
The research shows that two organisms
in the Aquafarm work well together:
freshwater worms, which break down
sludge particles and Azolla filiculoides,
a floating water fern that purifies water
by absorbing dissolved nutrients such as
phosphorus. “But in the end, we can add
many more organisms such as mussels,
crustaceans and other aquatic plants,”
says Leon Lamers, professor of Aquatic
Ecology and Environmental Biology at
Radboud University in the Netherlands,
and one of the initiators of Aquafarm.
www.waterafrica.co.za
“The regional water authorities want
to participate in a circular economy
with Aquafarm,” says Lamers. The
researchers are working on creating
an optimised method of reusing waste:
in addition to proteins and fats, it is
conceivable to produce green fertilisers,
fish feed and adhesive coatings. In
a trial at the sewage treatment plant
Dodewaard, 400kg of duckweed has
already been harvested as raw material
for glue production.
Medicine residues and
greenhouse gases
The importance of sustainable water
treatment is increasing. An example
is medicine residue in sewage. This
is now partly being removed by
bacteria in the plants by chance, but to
remove everything requires additional,
expensive techniques. “If we don't gain
more insight into the process soon, there
will be too much medicine residue and
other new contaminants in our drinking
water,” says fellow researcher Tamara
van Bergen.
In addition, water purification
currently emits a lot of greenhouse
gases such as carbon dioxide,
methane and nitrous oxide. Lamers
hopes to reduce those emissions
with Aquafarm. “This can be done by
harvesting biomass and ensuring that
methane and nitrous oxide are broken
down by bacteria from plants.”
In
addition
to
small-scale
experiments at the Radboud University
greenhouse complex, Aquafarm will
work on the installation of a system
at an existing water treatment plant in
years to come. “Large water surfaces
mean new challenges, such as saving
space by stacking and controlling
infections,” says Lamers.
In 2014, Aquafarm was the winning
idea of the Waterwegen Dragon’s Den
in which 100 entrepreneurs, scientists,
regional water authorities and free
thinkers presented opportunities for
reusing the resources of the regional
water authorities. The Aquafarm
project is a collaboration between
Radboud University, Radboud spin-
off Research Centre B-WARE,
Wageningen University, the P2
initiatives factory and three regional
water authorities.
Source: Radboud University
Water Sewage & Effluent May/June 2019
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