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Advances in Biotreatment of Acid Mine Drainage and
Biorecovery of Metals
Henry H. Tabak, USEPA, Cincinnati, OH
Field
Demonstration and Numerical Evaluation of In-Situ
Bioremediation of Paper Metals-Contaminated
Groundwater
Ming-Kuo Lee, Auburn University, Auburn, AL
Heavy Metal
Toxicity to Sulfate Reducing Bacteria
Brent M. Peyton, Washington State
University, Pullman, WA
Metal
Removal Efficiency and Speciation in Anaerobic Bioreactors
Dr.
Eric D. Van Hullebusch, Wageningen
University, Wageningen, The Netherlands
Ir. Marcel H. Zandvoort, Wageningen
University, Wageningen, The Netherlands
Piet Lens, Wageningen
University, Wageningen, The Netherlands
Kinetic
Parameter Determination in Dynamically Operated
CST-reactors: Paper Ferrous Iron Oxidation by Leptospirillum
ferrooxidans
Robbert Kleerebesem, Technical University of Delft, Delft,
The Netherlands
Design
Challenges for Large-Scale Sulfate Reducing Bioreactors
James J. Gusek, Golder Associates, Inc., Lakewood, CO
Using
Respirometry to Measure Hydrogen Utilization by Sulfate
Reducing Bacteria in the Presence of Copper and Zinc
Edith L. Holder, University of Cincinnati, Cincinnati, OH
Henry
H. Tabak, U.S.
EPA, Environmental Research Center, ORD, National Risk
Management Research Laboratory, 26 West Martin Luther King
Drive, Cincinnati, OH 45268, Tel: 513/569-7681, Fax:
513-569-7105
Rakesh Govind,
University of Cincinnati, Department of Chemical
Engineering, Cincinnati, OH 45221 Tel: 513-556-2666, Fax:
513-556-0217
Acid
mine drainage (AMD) is a severe pollution problem
attributed to past mining activities. AMD is an acidic,
metal-bearing wastewater generated by the oxidation of
metal sulfides to sulfates by Thiobacillus bacteria in
bothe active and abandoned mining operations. The
wastewaters contain substantial quantities of dissolved
solids with the particular pollutants (metal sulfates)
dependent upon the mineralization occurring at the mined
rock surfaces. The exposure of post-mining residuals to
water and air results in a series of chemical and
biological oxidation reactions that produce an effluent
which is highly acidic and contains high concentrations of
various metal sulfates.. The metals (metal sulfates)
usually encountered and considered of concern for
human risk assessment are: arsenic, cadmium, iron, lead,
manganese, zinc and copper. These metals as well as
sulfate are considered serious pollutants of the acid mine
drainage. The pollution generated by abandoned mining
activities in the area of Butte, Montana has resulted in
the designation of the Silver Bow Creek-Butte area known
as Berkeley Pit, as
the largest superfund (National Protection List) site in
U.S.. This paper reports on bench-scale studies conducted
to develop a resource recovery based remediation process
for the cleanup of the Berkeley Pit acid
mine water
The
process utilizes selective, sequential precipitation (SSP)
of metal hydroxides and sulfides such as copper, zinc,
aluminum, iron and manganese from the Berkeley Pit AMD for
their removal from the acidic water and purification.
With additional processing,
the ferrous sulfide precipitates can be converted
into marketable products (i.e pigments). Unique, four
stage and six
stage processes for metal sequential precipitation/separation and
purification have been developed for the above metals
using biogenic
hydrogen sulfide produced by the sulfate reducing activity
of sulfate reducing bacteria (SRB) in separate bioreactor
systems for the treatment of AMD. The six stage SSP system
based on appropriate optimized operating conditions (pH,
temperature, etc.), was
shown to produce high recoveries of above metals from
Berkeley Pit acid mine water, high purity metal precipitates
and an agriculturally usable water ( for irrigation
purposes) that meets USEPA’s Gold Standard criterion.
Information will be provided on the % recovery and purity
of metals fom the four stage and six stage metal
precipitator-settler reactors and on the quality of the
water effluent. This metal SSP process is unique in that
is not only intended for
treatment of the Berkeley Pit acid mine water as
well as other acidic mine waters ( from other acid
mine water pits and effluents from acid mines) but
it is also a remediation process based on metal resource
and recycle.
Several
biotreatment techniques for the treatment of
sulfate utilizing SRB have been proposed in the past,
however few of them have been practically applied to treat
sulfate containing AMD. This research deals with
development of an innovative polypropylene hollow fiber
membrane bioreactor
system for the treatment of acid mine water from the
Berkeley Pit using
hydrogen consuming SRB biofilms. The advantages of using
the membrane bioreactor over the conventional tall liquid
phase sparged gas bioreator systems are: large microporous
membrane surface to the liquid phase; formation of
hydrogen sulfide outside the memrane
preventing mixing
with pressurized hydroge gas inside the membrane;
no requirement of gas recycle compressor; membrane surface is suitable for immobilization of active SRB,
resulting in
formation of biofilms,
thus preventing
washout problems associated with suspended culture
reactors; and lower operating costs
in membrane bioreactors, eliminating gas
recompression an gas recycle costs. Information will br
provided on sulfate reduction rate studies and on
biokinetic tests with suspended SRB
in master culture reactors and with SRB biofilms in
bench-scale SRB membrane reactors. Data will be presented
also on the effect of sulfate loading rates in scale-up
membrane units, under varied pHs and temperatures, to
determine and optimize sulfate conversions for an
effective AMD biotreatment. Pilot-scale studies have generated data which indicate
that SRB membrane bioreactor systems
can be applied toward field-scale biotreatment of
AMD and for a recovery
of high
purity metals and a usable water.
Field
Demonstration and Numerical Evaluation of In Situ
Bioremediation of Metals-Contaminated Groundwater
Ming-Kuo Lee, Department of Geology &
Geography, Auburn University, Auburn, AL, 36849, Tel:
334-844-4898, Fax: 334-844-4486
James A. Saunders, Department of Geology & Geography,
Auburn University, Auburn, AL, 36849, Tel: 334-844-4884, Fax: 334-844-4486
An unconfined aquifer below a car-battery recycling
plant in Troy, Alabama, is heavily contaminated with
sulfuric acids and metals including Pb, Cd, Zn, Cu, and
Fe. This
industrial site is analogous to natural acid mine drainage
sites containing acidic, metals-laden groundwaters that
are toxic to natural life and humans. Field experiments
were conducted to demonstrate that indigenous bacteria can
be stimulated to remove metals by injection of
water-soluble nutrients into a shallow contaminated
aquifer. Our
field data demonstrate that the indigenous sulfate
reducing bacteria (SRB) were capable of anaerobically
catalyzing sulfate reduction to form insoluble metal
sulfide solids.
Genetic sequencing data indicate that injected
nutrients initiated bacterial sulfate reduction by one
principal species (Desulfosporosinus
orientis) under highly acidic conditions. A reaction
path model of sulfate reduction shows the Eh effects on
mineral precipitation and pH controls on the sorption of
different metals. Our
modeling results show that lead strongly adsorbs to
hydrous ferric oxides (HFO) present in the aquifer over a
wide pH range. Both
sorption and solid sulfide formation are important for
removing lead. Although
modeling shows that the sorption of most metals is
promoted as pH increases, HFO can only scavenge Zn, Cd,
Co, and Ni at relatively neutral pH conditions. Thus concentrations of our primary contaminants Zn and Cd
attenuate in acidic conditions primarily via precipitation
or co-precipitation of solid sulfide phase as Eh drops.
The modeling result explains why the Pb plume is
retarded in migration with respect to the Cd plume under
the acidic conditions at the site. Modeling results have
implications for remediating other sites where
anthropogenic or natural
geochemical processes release heavy metals and contaminate
water supplies.
Heavy
Metal Toxicity to Sulfate Reducing Bacteria
Brent M. Peyton, Center for Multiphase Environmental
Research, Washington State University, PO Box 642710,
Pullman, WA 99164-2710, Tel: 509-335-4002, Fax:
509-335-4806
Rajesh K. Sani, Center for Multiphase Environmental
Research, Washington State University, PO Box 642710,
Pullman, WA 99164-2710, Tel: 509-335-6433, Fax:
509-335-4806
Sulfate-reducing bacteria (SRB) play an important role in
precipitation of heavy metals in natural waters and some
wastewaters. Under
anaerobic conditions, SRB utilize the sulfate ion during
the oxidation of organic material, forming hydrogen
sulfide that forms insoluble complexes with many heavy
metals. For efficient treatment of waters containing heavy
metals by SRB either in
situ or ex situ, there must be sufficient knowledge of the toxicity of
various heavy metals to SRB populations. In the present
study, an SRB metal toxicity medium (MTM) that eliminates
the formation of metal precipitates and minimizes metal
complexation was developed to better understand the role
of metal concentrations in SRB toxicity. At pH values from
6 to 8, with an increase in Pb(II) concentration, specific
growth rates decreased and lag times increased. The
minimum inhibiting concentration (MIC) of Pb(II) causing a
complete inhibition in growth at pH 6 was 10 mM, as compared to 15 mM at pH 7.2 and 8. Using MTM, measured MIC values are 40
times lower than previously reported. Live/dead staining,
based on membrane integrity, indicated that while Pb(II)
and Cu(II) inhibited growth, these metals did not cause a
loss of D.
desulfuricans membrane integrity. In the presence of
Cu(II), growth yields of D. desulfuricans G20
decreased significantly with increasing Cu(II)
concentrations from 0 to 18 mM
and no measurable growth was observed at 30 mM Cu(II). Using MTM, the Cu(II)
concentration causing 50% inhibition in final cell protein
(IC50) was evaluated to be 16 mM
which is 100 times lower than previously reported. The results show that D.
desulfuricans in the presence of Cu(II) follow a
clearly different growth pattern than in the presence of
Pb(II). It is
therefore likely that Cu(II) toxicity proceeds by a
different mechanism than Pb(II) toxicity.
Metal
Removal Efficiency and Speciation in Anaerobic Bioreactors
Dr.
Eric D. Van Hullebusch, Sub-Department of Environmental
Technology, Wageningen University, ``Biotechnion``-
Bomenweg, 2, P.O. Box 8129, 6700 EV Wageningen, The
Netherlands, Tel: + (31) (0) 317 483228, Fax: + (31) (0)
317 482108, Email: Eric.vanHullebusch@wur.nl
Ir. Marcel H. Zandvoort, Sub-Department of Environmental
Technology, Wageningen University, ``Biotechnion``-
Bomenweg, 2, P.O. Box 8129, 6700 EV Wageningen, The
Netherlands
Dr. Piet N. L. Lens, Sub-Department of Environmental
Technology, Wageningen University, ``Biotechnion``-
Bomenweg, 2, P.O. Box 8129, 6700 EV Wageningen, The
Netherlands
Mine
waters and industrial effluents may contain high sulfate
and metal concentrations and pose significant
disposal problems that require urgent solution to
avoid serious environmental contamination. In mine waters,
sulfate and heavy metals such copper, nickel, cobalt, zinc
and iron originate from the chemical or biological
oxidation of exposed sulfide minerals. This presentation
describes the cobalt and nickel removal capacity of
anaerobic granular sludge at different pH conditions and
iron (II) concentrations.
Experimental equilibrium data obtained for nickel and
cobalt have been analyzed by the Langmiur, Freundlich and
Redlich-Peterson isotherm equations in order to determine
which of them can better represent metal biosorption on
sludge (van Hullebusch et al., 2003). Metal
speciation techniques were used to determine which phases
are involved in the binding of these metals. In the last
few decades, several sequential extraction procedures have
been developed, making it difficult to compare the results
obtained by the different methods. Three extraction
techniques (Tessier, Stover and the Bureau Communautaire
de Reference (BCR)) were applied to two different
anaerobic granular sludges. The objective of
this study was to determine whether the sequential
extraction methods can provide useful
information on the distribution of trace (Co, Ni,
Zn and Cu) and major elements (Mn and Fe) in anaerobic
granular sludges. It was found that the distribution of
heavy metals is strongly influenced by certain solid
phases, although it was difficult to identify properly the
different chemical forms of heavy metals. Sulphides
fraction appears to be important scavenging phases of
trace metals in anaerobic granular sludge. Moreover, under
anaerobic conditions, sulphate reducing bacteria (SRB)
oxidise simple organic compounds by utilising sulphate as
an electron and generate sulphide (S 2-
). This
biogenically produced sulphide can react with dissolved
metals to form metal sulphide precipitates characterised
by low solubility’s products. Metal removal efficiency
was shown to be enhanced in sulphidogenic conditions.
Van
HULLEBUSCH E., ZANDVOORT M.H. and P.N.L. LENS, (2003),
Nickel and Cobalt sorption on
anaerobic granular sludges: kinetic and equilibrium
studies, submitted to Journal of Chemical
Technology
and Biotechnology.
Kinetic
Parameter Determination in Dynamically Operated
CST-reactors: Ferrous Iron Oxidation by Leptospirillum
ferrooxidans
R.
Kleerebezem, J.G. Kuenen, and M.C.M. van Loosdrecht,
Kluyver Laboratory for Biotechnology, TU Delft, 2628 BC
Delft, The Netherlands, Email: R.Kleerebezem@tnw.tudelft.nl
In
order to investigate the interaction between the
biological iron and sulfur cycle in acidic environments,
we have conducted kinetic experiments in continuously
stirred tank reactors (CSTR). Model organisms utilized are
Leptospirillum
ferrooxidans and Acidithiobacillus
ferrooxidans. Contrary to A.
ferrooxidans, L.
ferrooxidans is not capable of oxidation of reduced
sulfur compounds.
The
FeII oxidation kinetics by L.
ferrooxidans and A.
ferrooxidans have been investigated in dynamic CSTR
experiments that allow for rapid and accurate
determination of kinetic parameter values. By on-line
measurement of oxygen and carbon dioxide in the off gas of
the reactor, and the FeII:FeIII concentration ratio in the
medium, mass balances for electron donor, acceptor and
biomass can be established. As opposed to steady state
measurements, we conducted experiments in CSTR’s that
are operated at a variable dilution rate. This dynamic
approach allows for kinetic parameter determination within
a few day period. It furthermore enables quantitative
measurement and subsequent modeling of the response of the
system on short-term perturbations.
The
specific objective of the work presented here was to
investigate the coupling between catabolism and anabolism
in FeII-oxidizing cultures of L.
ferrooxidans. Bioenergetic analysis of dynamic CSTR-data
demonstrated that catabolism and anabolism are strictly
stoichiometrically coupled, and therefor the process
operates at a variable bioenergetic efficiency. The actual
free energy dissipated per mole biomass formed is between
1800 and 3000 kJ C-mol-1 biomass depending on
the actual concentrations FeII and FeIII in the medium. L. ferrooxidans, however, does have the capacity to uncouple
catabolism and anabolism upon carbon dioxide limitation,
or dosage of a membrane potential dissipating weak acid (propionic
acid). This suggests that the organism is capable of
uncoupling FeII respiration and biomass production, but is
not able to optimize its bioenergetic efficiency of
growth.
The
experimental methodology developed allowed for rapid
kinetic characterization of L.
ferrooxidans. It is significantly less laborious than
steady state measurements in chemostat reactors, but lacks
the disadvantages of rapidly changing conditions as
obtained in batch experiments. It furthermore allows for
direct identification of the response of the system on
changes imposed to the system. In the near future we will
use a comparable approach for measurement of mixed
substrate (FeII and S) degradation in acidic environments.
Design Challenges for Large Scale Sulfate Reducing
Bioreactors
James J. Gusek, P.E., Golder Associates, Inc.,
44 Union Blvd #300, Lakewood, CO 80228, Tel: 720-920-4581, Email: jgusek@golder.com
The
first large scale, 1,200 gpm capacity, sulfate reducing
bioreactor (SRBR) was constructed in 1996 at an
underground lead mine in Missouri. Other large scale SRBR systems have been built elsewhere
since then. This
technology holds much promise for economically treating
heavy metals and has progressed steadily from the
laboratory to industrial applications.
Scale-up challenges include designing for: seasonal
temperature variations, minimizing short circuits, changes
in metal loading rates, storm water impacts, and
resistance to vandalism.
However, the biggest challenge may be designing for
the progressive biological degradation of the organic
substrate and its effects on the hydraulics of the SRBR
cells.
Due
to the wide variability of the organic materials that may
be locally available at economical costs, the design of
organic substrate SRBR systems is not and may never become
a “cookbook” approach.
Balancing geochemical requirements with intuitive
physical resistance to organic decay currently plays a
large role in the large scale system design process.
Additional
Keywords: passive
treatment, acid rock drainage, heavy metals, sulfate
reducing bacteria
Using
Respirometry to Measure Hydrogen Utilization in Sulfate
Reducing Bacteria in the Presence of Copper and Zinc
Edith
L. Holder, University of Cincinnati, Department of Civil
and Environmental Engineering, Cincinnati, OH 45221-0071,
Tel: 513-569-7178, Fax: 513-569-7105
Margaret J. Kupferle, University of Cincinnati, Department
of Civil and Environmental Engineering, Cincinnati, OH
45221-0071, Tel: 513-569-7548, Fax: 513-569-7105
Henry H. Tabak, U.S. Environmental Protection Agency,
National Risk Management Research Laboratory, Cincinnati,
OH 45268, Tel: 513-569-7681, Fax: 513-569-7105
John R. Haines, U.S. Environmental Protection Agency,
National Risk Management Research Laboratory, Cincinnati,
OH 45268, Tel: 513-569-7446, Fax: 513-569-7105
A
respirometric method has been developed to measure
hydrogen utilization by sulfate reducing bacteria (SRB).
One application of this method has been to test
inhibitory metals effects on the SRB culture used in a
novel acid mine drainage treatment technology.
As a control parameter for that technology, it is
necessary to know the metal concentration that has either
an inhibitory or toxic effect on the bacteria both alone
and in the acid mine waste matrix.
An
enrichment culture of SRB was developed that is
mixotrophic, utilizing carbon dioxide (CO2) and
acetate as the carbon sources and hydrogen (H2)
as the electron donor for the conversion of sulfate to
hydrogen sulfide (H2S).
Respirometers (NCON Systems Inc.) were adapted to
measure H2 uptake.
Hydrogen uptake by SRB is similar to the uptake of
oxygen in aerobic cultures in that it causes the
production of another gas, H2S in the former
case and CO2 in the latter.
Produced biogenic H2S is removed with a
zinc acetate trap, analogous to an alkaline trap for CO2
in aerobic respirometry.
In the case of H2 respirometry,
CO2 is retained in the headspace.
Respirometry can differentiate between either a
toxic effect (suppression of hydrogen uptake) or an
inhibitory effect (evidenced by an
increased lag time relative to a control.)
Metal
complexation can be a problem in testing inhibition
effects because most bacteriological media contain
components which can form metal complexes, thereby
reducing the metal bioavailability.
The culture media formulated by Sani et al. (Advances
in Environmental Research 5 (2001) 269-276) was
modified for use with this culture.
Metal complexation was reduced by replacing
orthophosphate with tryptone and PIPES for pH control.
Respirometric
data; metal, sulfate, and sulfide concentrations; and
biomass measurements show that soluble zinc has an
inhibitory effect between 10 and 25 ppm and soluble copper
is inhibitory between 1 and 17 ppm.
The toxic level for zinc is 50 ppm and for copper
is 27 ppm.
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