A
technique
of
using
microbially
formed
manganese
oxides
to
takeup
and
immobilise
metal
effluents
is
described.
An
algal
facilitated
bacterial
oxidation
of
manganese
(Mn
2
+),
which
overcomes
slow
rates
of
bacteria-only
manganese
oxidation,
was
used
to
produced
high
yields
of
oxides
using
1.6
g/L
Mn
2+
at
neutral
pH.
Metals
such
as
Cu,
Zn,
Co
and
Ni
can
be
immobilised
in
stable
co-precipitated
manganese
oxides.
This
effect
was
achieved
either
by
the
direct
addition
of
metals
during
oxidation
or
by
pretreating
algal
cells
with
metals
prior
to
oxidation.
Acid
leaching
(pH
2
H2SO
4)
showed
that
the
immobilised
metals
were
tightly
bound
by
the
manganese
oxides.
Transmission
electron
microscopy
and
X-ray
analysis
(TEM/EDAX)
confirmed
that
bioformed
manganese
oxides
had
physically
encapsulated
the
added
metal
ions,
thereby
preventing
their
release.