The increase in heavy metal contamination in
freshwater systems causes serious environmental problems
in most industrialized countries, and the effort to find ecofriendly
techniques for reducing water and sediment contamination
is fundamental for environmental protection.
Permeable barriers made of natural clays can be used as
low-cost and eco-friendly materials for adsorbing heavy
metals from water solution and thus reducing the sediment
contamination. This study discusses the application of
permeable barriers made of vermiculite clay for heavy
metals remediation at the interface between water and
sediments and investigates the possibility to increase their
efficiency by loading the vermiculite surface with a
microbial biofilm of
Pseudomonas putida
, which is well
known to be a heavy metal accumulator. Some batch
assays were performed to verify the uptake capacity of two
systems and their adsorption kinetics, and the results
indicated that the vermiculite bio-barrier system had a
higher removal capacity than the vermiculite barrier
(+34.4 and 22.8 % for Cu and Zn, respectively). Moreover,
the presence of
P. putida biofilm strongly contributed
to fasten the kinetics of metals adsorption onto vermiculite
sheets. In open-system conditions, the presence of a vermiculite
barrier at the interface between water and sediment
could reduce the sediment contamination up to 20 and
23 % for Cu and Zn, respectively, highlighting the efficiency
of these eco-friendly materials for environmental
applications. Nevertheless, the contribution of microbial
biofilm in open-system setup should be optimized, and
some important considerations about biofilm attachment in
a continuous-flow system have been discussed.
