Cyanide dynamics in catchment areas affected by artisanal gold mining in Burkina Faso

Abstract

Free cyanide (FCN), a carcinogenic product, is a chemical compound that is widely used without any control in artisanal small-scale gold mining (ASGM) for gold processing. Cyanide-containing leachate is released into the environment without any treatment. The dynamics of released FCN in water and soil in two ASGM-affected catchments were primarily investigated during the dry and wet seasons. Secondly, Cyanide Degrading-Bacteria (CDB) collected from the same areas were tested under various environmental conditions in liquid medium to evaluate their efficiency to biodegrade FCN. Once cyanide is released into the environment, it was transported by water run-off and infiltration and created diffuse soil and water pollution that covers almost the entire catchment areas. Highest FCN values are detected in the cyanidation areas and in the catchments outlets during the dry and wet season respectively. FCN dynamics was controlled by climate conditions, land cover and soil characteristics and composition. Besides, CDB could support wide ranges of pH value and nutrients types to degrade FCN with a highest efficiency rate 99 % during 24 hours. These potentialities make them to easily adapt into the environment for controlling the FCN diffusion. The use of CDB could be a good option for the remediation of sites contaminated with cyanide.

Full text

ASM Conference 2018
Johannesburg, 10–11 September 2018
The Southern African Institute of Mining and Metallurgy
143
Cyanide dynamics in catchment areas affected by artisanal
gold mining in Burkina Faso
L.C. Razanamahandry1,2,3, H.A. Andrianisa1, H. Karoui1, H. Yacouba1, E. Manikandan2,3,4
and M. Maaza2,3
1International Institute for Water and Environmental Engineering, Burkina Faso
2University of South Africa (UNISA)
3Nanosciences African network (NANOAFNET), South Africa
4Thiruvalluvar University, India
Free cyanide (FCN), a carcinogenic product, is a chemical compound that is widely used
without any control in artisanal small-scale gold mining (ASGM) for gold processing.
Cyanide-containing leachate is released into the environment without any treatment. The
dynamics of released FCN in water and soil in two ASGM-affected catchments were
primarily investigated during the dry and wet seasons. Secondly, Cyanide Degrading-
Bacteria (CDB) collected from the same areas were tested under various environmental
conditions in liquid medium to evaluate their efficiency to biodegrade FCN. Once cyanide
is released into the environment, it was transported by water run-off and infiltration and
created diffuse soil and water pollution that covers almost the entire catchment areas.
Highest FCN values are detected in the cyanidation areas and in the catchments outlets
during the dry and wet season respectively. FCN dynamics was controlled by climate
conditions, land cover and soil characteristics and composition. Besides, CDB could
support wide ranges of pH value and nutrients types to degrade FCN with a highest
efficiency rate 99 % during 24 hours. These potentialities make them to easily adapt into
the environment for controlling the FCN diffusion. The use of CDB could be a good option
for the remediation of sites contaminated with cyanide.
Keywords: Soil and water contamination, cyanide mobility, decontamination, Burkina
Faso.
INTRODUCTION
The use of cyanide in artisanal small-scale gold mining (ASGM) is widespread in West-Africa,
particularly in Burkina Faso (Luning, 2006). The cyanidation process is an efficient and inexpensive
method used to recover residual gold in the ore after amalgamation ; the residual complex product
containing cyanide is often leached into the environment without any treatment (Velásquez-lópez et.
al., 2011), and liberate free cyanide (FCN) ions that are highly toxic to most living organisms (Hijosa-
Valsero et al., 2013; Luque-Almagro et. al., 2016).
FCN released into the environment can diffuse throughout the catchment areas depending on the
environmental conditions (Razanamahandry et. al., 2018).

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Cyanides are present in water, essentially in the form of HCN (Razanamahandry et. al., 2017). They can
also be in the form of cyanide salts, KCN, NaCN, CaCN or in the form of metallo-cyanide complexes of
variable stability(Dzombak et. al., 2015). Free cyanides are in equilibrium with pH and temperature
(Brignon, 2011). At pH <8, the free cyanide HCN form is found at more than 93%(Brignon, 2011). The
complex alkaline metallo-cyanide forms are very soluble in water and their dissociation is very fast
(Dzombak et al., 2015). The work conducted by (Guimaraes et al., 2011), on the mobility of cyanide in
the dry season and the wet season in the Equator region show that cyanide levels in surface water vary
very little at these two seasons of the year. Indeed, these studies reveal that when the dilution of the
mining effluents is reduced and the activities are intense in the dry season, the cyanide concentration of
surface water downstream of the Puyango river remains high up to 280μgL-1 then in the wet season, the
strong turbulence of the water is not sufficient enough to oxidize all the free water cyanide that reaches
48μgL-1 downstream and that it can spread further than 100 km.
Soil characteristics and compositions were demonstrated as among the factors that control the pollutant
dynamics (Razanamahandry et. al., 2018). The mobility of cyanide compounds in soil depends on the
stability and dissociation characteristics of the compound, soil type, soil permeability, soil chemistry,
and the presence of aerobic and anaerobic microorganisms (Fuller, 1984; Razanamahandry et.al., 2018).A
study of the mobility of complex iron cyanide in soil layers of humus-rich soils under varying pH and
redox potential conditions, conducted by Razanamahandry et. al.( 2017) ; Rennert and Mansfeldt (2009),
showed that organic matter plays a very important role in the fate of iron cyanide in the soil. Organic
matter promotes the sorption of complex cyanides, especially in fluvisols. The destruction of organic
matter reduces the sorption by 99% (Mansfeldt and Biernath, 2001).
Several methods were reported for the efficient removal of FCN , including physical and chemical
methods (Botz et. al., 2015; Mekuto et.al., 2018). Biological methods are highly appreciated due to its
passive and environmental eco-friendly treatment (Baxter and Cummings, 2006; Botz et al., 2005;
Chaptawala et. al., 1998). Micro-organisms have shown their efficiency to remove FCN under various
environmental conditions such as pH value, temperature and nutrients types (Kumar et. al., 2013). The
removal efficiency rates depend solely on these environmental conditions (Kumar et. al., 2013).
Mirizadeh et. al. (2014) have reported a FCN removal rate of 85 % by using glucose as nutrient with an
initial FCN concentration of 200 mg L-1. A FCN removal rate of 99 % was obtained by the following
micro-organisms: Pseudomonas Fluorescens, Serretia marcescens RL2b and Burkholderia cepacia under acidic,
neutral and basic conditions respectively (Adjei and Ohta, 2000; Dursun et. al., 1999; Kumar et. al., 2013).
There are several bacteria that are capable of growing in a medium containing only cyanide that is used
as both carbon and nitrogen source. But others such as Pseudomonas fluorescens P70 and Burkholderia
cepacia strain C3 cannot grow in a medium containing only cyanide as a nutrient. In these cases, it is
necessary to add an external source of carbon such as glucose (Dursun e.t al., 1999), arabinose, fructose,
galactose, mannose and xylose. It seems that hexose (fructose and glucose) promotes the use of cyanide,
with pentose (arabinose and xylose) and there is a slight degradation of cyanide by B. Cepacia (Adjei &
Ohta, 2000).
In the present study, we investigated how FCN behave once released into the environment in order to
know if illegal cyanidation could affect soil and water quality at catchment level. Then, we have
conducted laboratory tests to check if by using locally available bacterial species, it was possible to
degrade released FCN efficiently, under various environmental conditions. The study was focused on
free cyanide (FCN) because it is the most toxic form of cyanide (Botz et al., 2015).
MATERIALS AND METHOD
Sites studies
Figure 1 shows the two ASGM sites in Burkina Faso that were selected based on their different climate
conditions: Sahelian or arid climate for the Zougnazagmiline site in the North and Soudanese or humid
climate for the Galgouli site in the South.

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The Galgouli site is located at longitude -3,479 ° and latitude 10,021 ° near the Ivory Coast border. It is
located in the department of Kampti around 450 km far from Ouagadougou in the province of Poni,
and in the south-western region of Burkina Faso.
The Zougnazagmiline site is geographically located at the longitude of 0.717 ° and at latitude 13.633 °.
It is located in the department of Bouroum which is about 250 km from Ouagadougou. It is in the
province of Namentenga in the North Central region of Burkina Faso.
Figure 1. Study areas locations
Data collection
Soil and water samples were collected during the dry season and the wet season in 2015. Soil sampling
was done by core sampling at each horizon from 20 cm to 1 m deep. The top layer of soil was chosen
because it is an area that comes in direct contact with cyanide. Sampling was done by coring using a
hand auger. The auger is graduated with a step of 10 cm up to 100 cm and half is hollow. It is driven
into the ground using manual force exerted on a hammer.
The soil enters the hollow part during the hammering moment. As the auger enters the soil, a rotational
movement is applied to ensure that it is does not get blocked in the ground. The maximum depth
reached by the auger is noted before removing it .
This depth defines the number of samples available at each sampling point. In the absence of obstacles,
five (05) samples (0cm -20 cm horizon, 20 cm-40 cm, 40 cm-60 cm, 60 cm-80 cm and 80 cm-100 cm) should
be obtained at each sampling point. The availability of the 05 samples is not always obvious at all
sampling points. The presence of obstacles in a rocky area, reduces this number. The deepest horizon is
at the end of the auger. The samples were packed in a plastic bag bearing the number of the sampling

146
point. These are black plastic bags that have been used for all samples to avoid photo degradation of
cyanide against solar light (Kjeldsen, 1999).
In total, about a hundred samples spread over some thirty points were collected at each study site per
season. These samples were stored in a cooler at 4 °C to maintain their physicochemical properties.
Water samples were taken from labelled 500 ml borosilicate glass vials previously oven sterilized at
160 °C for 15 minutes. The number of samples varied according to the season. Groundwater (13 samples
at Zougnazagmiline and 4 at Galgouli), surface water and water in an abandoned cyanidation basin
(7 samples at Zougnazagmiline and 24 at Galgouli) were collected. Physico-chemical parameters such
as pH, redox potential, electrical conductivity and temperature were directly measured in the field to
ensure the reliability of the data obtained. The pH meter (WTW 3310, Germany) was used to measure
both pH and redox potential. Electrical conductivity and temperature were measured using a
conductivity meter (WTW 3308, Germany). After analysing these parameters, a few NaOH pellets were
added to each sample to prevent volatilization of the HCN, according to standard method SM-4500-
CN-F (American Public Health Association, 1998). During the dry season, often only about ten samples
become available, mainly from drilling; on the other hand, during the wet season, about twenty samples
were taken. Then the samples were stored at 4 °C in coolers to keep the microbial flora intact. The
analysis of these samples was carried out 48 hours after the day of sampling.
Biodegradation tests
CDB origin
Indigenous CDB was isolated from the contaminated soil and water samples in the mining catchment
areas. CDB Isolation procedure have been reported in Razanamahandry et. al.(2016).
pH influence on the FCN biodegradation
Four liquid media of 250 ml, and containing FCN concentrations of 60 mg / l were prepared in
Erlenmeyer flasks. Then, a 1ml solution containing CDB, whose initial bacterial density is known, was
added to each flask. The pH of each solution was adjusted to 5, 7, 9.5 and 10.5, respectively. The
concentration of 60 mg/l was chosen according to the biodegradation test results in Razanamahandry
et.al.( 2016). It is the concentration which had the greatest efficiency for cyanide degradation. These
media were stirred with a magnetic stirrer at 200 rpm; the tests were conducted at room temperature
in a ventilated hood.
The pH adjustment was made by adding a few drops of 10 N hydrochloric acid and sodium hydroxide
with a Pasteur pipette according to whether we wanted to either lower or raise the pH value.
Nutrient influence on the FCN biodegradation
This test aims to determine the influence of the presence of nutrients in the environment on the
effectiveness of biodegradation and possibly identify the type of nutrient that allows the best
degradation of cyanide. Bacteria degrade cyanide as a source of carbon and nitrogen. Two categories of
nutrients were chosen, namely carbon sources and nitrogen sources, in order to discover whether the
bacteria were heterotrophs, bacteria capable of oxidizing all compounds containing the carbon atom or
lithotrophs, bacteria capable of oxidizing only inorganic compounds.
For the carbon sources glucose, sucrose and glycerol were chosen and for the nitrogen sources meat
extract, yeast extract, ammonium sulphate and peptone were used.
Nutrients were selected based on the Kumar et.al. (2013) studies of cyanide degradation using Serretia
marcescens RL2b as bacteria source and many others investigating the effect of one or more of these
nutrients (Mirizadeh et. al., 2014). Our choice was justified by the fact that some of these nutrients can
be identified at the site by their chemical composition. For example, peptones come from the enzymatic
digestion of meat, fructose, sucrose; and glucose can be found in foods such as fruits and sugars, hence
the possibility of their presence at the site.

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Seven liquid medias were prepared, being cyanide solutions of a concentration of C = 60 mg l-1 and a
volume of V = 250 ml, all contained in Erlenmeyer flasks. The same quantity of 1 ml of solution of CDB,
of which the initial bacterial density was known, was added to the seven backgrounds. To each of the
media, the nutrients mentioned above were added individually at a concentration of 20 mg l-1. These
media were stirred with a magnetic stirrer at 200 rpm and the test conducted under a ventilated hood.
During this experiment, monitoring of cyanide degradation is performed by sampling each sample for
free cyanide assay every hour for 24 hours, as well as for .ammonium assay and bacterial growth. The
pH of all the media was monitored throughout the duration of the experiment.
Analytical methods
FCN concentrations, bacterial growth and ammonium concentration were respectively measured
according to the pyridine pyrazolone method, the optical density measurement and the Nessler reagent
application (Razanamahandry et.al., 2016b).
A vertical profile of the FCN concentrations, depending on soil depth, from the top layer to a depth of
100 cm was plotted using ORIGIN software.
RESULTS AND DISCUSSION
Figure 2 shows the concentrations of FCN in water samples collected from the two catchment areas
during the dry season (DS) and during the wet season (WS). The highest concentrations of FCN was
found around the cyanidation areas and the catchment outlets at both sites. In Galgouli, lower
concentrations of FCN were generally found in the WS as mining activities t only take place during the
DS, and water dilution has to be considered during the WS. In Zougnazagmiline, however, higher
concentration of FCN was found at the catchment outlet in the WS because in this area, the riverbeds
are completely dry during the DS. Therefore, there was no FCN transport in the DS. FCN accumulated
in the cyanidation zones and was transported only in the WS.

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Figure 2. FCN in water samples at (a) Galgouli and (b) Zougnazagmiline in dry (DS) and wet (WS) seasons.
FCN evolution by profile at each layer from a 20 cm soil depth to a depth of 1 m was studied at each
site. The results of these studies are shown in Figure 3.
The general trend shows a high concentration of FCN at the soil surface at both sites. The concentration
of FCN is high at the level of the layers from 0 cm to 40 cm. However, it tends to decrease from 40 cm
to a depth of 100 cm. The same trend is observed for both seasons of study. Nevertheless, the FCN
concentration from 80 cm to a depth of 100 cm is higher during the WS compared to the DS at two sites,
except at Galgouli in 2016 where FCN values for both seasons were similar.

149
Figure 3. FCN vertical distribution in soil at (A) Galgouli and (B) Zougnazagmiline site during the dry (left)
and wet (right) seasons for different soil layer depths [0-20 cm]; [20-40 cm]; [40-60 com]; [60-80 cm] and [80-
100 cm].
FCN infiltration is greater in Zougnazagmiline than in Galgouli at the soil layer 80 cm -100 cm.
Theoretically, plant cover promotes soil infiltration capacity (FAO,1996). Vegetation is more abundantly
at the Galgouli site than at the Zougnazagmiline site. Therefore, FCN concentrations on soil layer 60 cm
to 1 m depth would be higher in Galgouli than in Zougnazagmiline. However, results show the inverse
during the WS at the two sites. Several reasons such as microbial activities, vegetation type and soil
characteristics and compositions have been suggested by way of explaining these results.
Specific micro-organism degrade FCN during the infiltration process by using it as a source of nitrogen
and carbon to produce less toxic products such as ammonium and carbon dioxide (Alesii, 1976; Kumar
et.al., 2013) Some vegetation could also be able to bioaccumulate the FCN (Akinbile and Yusoff, 2012).
Finally, soil compositions as the presence of iron could be influenced the FCN mobility (Dzombak et.
al., 2015).
pH effect on FCN biodegradation
The acidity or alkalinity of the biodegradation medium may affect the physiological and biochemical
characteristics of the purifying microorganisms (Kumar et.al., 2013) and as a result may affect the

150
biodegradation of cyanide. Because of this, it is important to study biodegradation under different
conditions (acidity, alkalinity, neutrality).
Figure 4 shows cyanide degradation rates for different pH values: 5; 7; 9.5; 10.5 at different times, the
CNL biodegradation curves and NH4 + production associated with these pH tests.
Figure 1. FCN removal rate efficiency (A) and bacterial growth (B) under various pH; [CN-] initial=60 mg L-1;
without nutrients.
Figure 4 (A) shows the biodegradation of cyanide which is effective for all pH values studied with a
minimum degradation rate of 99.2%. Because several species of bacteria were isolated, each species with
its own physiological and biochemical characteristics, one could hypothesize that for a given pH value
we have at least one species that could develop. This would explain why biodegradation of cyanide is
effective for all pH values. A pH value of 9.5 is the optimum pH, followed by pH = 7, pH = 5 and pH
10.5. The degradation rate increases with pH up to a value of 10.5. These results could be explained by
the difficulty bacteria have to resist very basic environments.
In Figure 4 (B), the decreasing curves represent the evolution of the cyanide concentration for the
different pH values while the increasing curves are representative of the evolution of the bacterial
population. Two phases were observed during the bacteria growth: the lag phase and the exponential
phase. The latency time of a bacterium is the time it takes to get acclimated to its new environment,
especially resources, and to use these resources optimally (Mekuto et.al., 2013). During the exponential
phase, microorganisms grow and divide at maximum speed because they are accustomed to the
medium and have secreted the enzymes necessary to use the available cyanide (Prescott et. al., 2002).
The increase in the bacterial population at the same time as the decrease in cyanide, proves that bacteria
consume cyanide as a source of nutrients (Potivichay, anon and Kitleartpornpairoat, 2010).
Nutrients effect on the FCN biodegradation
Figure 5 shows the cyanide removal rates, associated with bacterial population growth when different
carbon and nitrogen source were used, and with different . Although all the nutrients studied allow a
good biodegradation of cyanide as shown in Figure 5.
 

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Figure 5. FCN removal rate efficiency under various nutrients: (A) Carbon source and (B) Nitrogen source;
pH=9,5; [CN-] initial =60 mg L-1 and CDB growth: (C) under carbon source and (D) under nitrogen source.
Regardless of the type of nutrient used, the minimum removal rate was 94.21%. These results are similar
to those obtained by Kumar et.al. (2013).
Glucose makes it possible to have the highest yield of cyanide degradation with a 100% removal rate. It
is therefore the optimal nutrient followed by ammonium sulphate with 99.8%, while yeast extract has
the lowest yield at 94.21%.
Similarly, in several studies on the biodegradation of cyanide, glucose has been shown to be an optimal
external carbon source. This is the case also in studies by (Mirizadeh et. al., 2014) on the biodegradation
of cyanide under basic conditions. The study found a cyanide reduction rate of 85% with glucose for
an initial cyanide concentration of 200 mg /l. (Dursun et.al., 1999) have also shown that glucose
promotes the degradation of cyanide by bacteria.
Moreover, it is found that among all the nutrients used, it is the ammonium sulphate which makes it
possible to obtain the strongest bacterial growth. This is because bacteria are found among the different
families used, and which prefer ammonium. The ammonium sulphate (NH4 2SO4) dissociates in water
in the form of ammonium ion NH
4 + and sulphate ion SO42- so the bacteria start by consuming this
ammonium which makes them grow before consuming cyanide. Simultaneously the other families of
bacteria attack cyanide directly, also making them grow ; while the ammonium resulting from the
degradation of the cyanide will also be consumed by t bacteria that prefers it.

 


152
The large number of bacteria that results justifies the high rate of cyanide degradation of 99.8% in the
presence of ammonium sulphate.
Kumar et.al. (2013) also obtained a 100% cyanide degradation fort with ammonium sulphate. Glycerol
and sucrose also obtain a strong reduction of cyanide, in the order of 98%, which is consistent with the
results obtained by Kumar et.al. (2013).
According to their composition sheets, the peptone contains 14% to 15% of total nitrogen, the yeast
extract 10% to 11.8% and the meat extract 11.5% to 12.5%. Their nitrogen contents are close, which could
explain the fact that we achieved similar rates of degradation by using them as nitrogen sources for the
biodegradation of cyanide. These results agree with those of Kumar et. al. (2013) who found almost the
same rate of degradations for peptone, yeast extract and meat extract at the end of their experiment.
Logically, therefore, ammonium sulphate allows a better abatement of cyanide than the last mentioned
nutrients because it contains a percentage of total nitrogen of 21%, which is superior to theirs.
CONCLUSIONS
FCN into the mining catchment areas of Galgouli and Zougnazagmiline sites was very mobile during
the two different seasons. During the DS when gold mining reaches its optimal phase, FCN was detected
mostly at the cyanidation areas. FCN was transported by run-off and rainwater infiltration to the
catchment outlet during the WS. FCN dynamics into these sites studies were closely controlled by
climate conditions, the soil characteristics and compositions and the ground cover. Indigenous CDB
isolated could efficiently degrade up to 99% of FCN under a wide range of the pH from acidic to basic
conditions. Glucose and ammonium sulphate produce the greatest degradations of cyanide (100% and
99.8%) among the nutrients, but all nutrients used did not inhibit FCN degradation. Future work should
focus on the analysis of the physico-chemical properties and microbial compositions of the soil. The
results of such a study will be a significant asset in the study of cyanide dynamics when there are
cyanide-mineral or cyanide-clay interactions in the soil.
ACKNOWLEDGEMENTS
This work was supported by the Swiss Agency for Development and Cooperation [Grant No
81016359/1]. The authors acknowledge the funding agency and also thank the laboratory technicians
who provided full assistance with laboratory analyses.
REFERENCES
Adjei, M., Ohta, Y., (2000). Factors affecting the biodegradation of cyanide by Burkholderia cepacia
strain C-3. J. Biosci. Bioeng. 89, 274–277.
Akinbile, C.O., Yusoff, M.S., (2012). Assessing water hyacinth (Eichhornia crassopes) and lettuce
(Pistia stratiotes) effectiveness in aquaculture wastewater treatment. Int. J. Phytoremediation 14,
201–11. https://doi.org/10.1080/15226514.2011.587482.
Alesii, B.A. et W.H.F., (1976). The mobility of three cyanide forms in soils, dans Residual management
by land disposalNo Title, in: EPA-600/9-76-015. U.S. Environmental Protection Agency,
Cincinnati, O. (Ed.), Proceedings of the Hazardous Waste Research Symposium. Tucson,
Arizona, W.H.
American Public Health Association, .(1998). Standard Methods SM-4500-CN-F. . American Water
Works Association, and Water Environment Federation, Washington, D.C.

153
Baxter, J., Cummings, S.P., (2006.) The current and future applications of microorganism in the
bioremediation of cyanide contamination. Antonie Van Leeuwenhoek 90, 1–17.
https://doi.org/10.1007/s10482-006-9057-y.
Botz, M., Mudder, T., Akcil, A., (2015). Cyanide treatment: physical, chemical and biological processes,
in: Adams, M.. E.L. (Ed.), Advances in Gold Ore Processing. Amsterdam, pp. 1 – 28.
Botz, M., Mudder, T., Akcil, A., (2005). Cyanide treatment: physical, chemical and biological processes,
Adams, M. ed.
Brignon, J.M., (2011). Données technico-économiques sur les substances chimiques en France :
Cyanures. INERIS France. https://doi.org/DRC-11-118962-11076A.
Chaptawala, K.D.., Babu, G.., Vijaya, O.., Kumar, K.., Wolfram, J.., (1998.) Biodegradation of cyanides,
cyanates and thiocyanates to ammonia and carbon dioxide by immobilized cells of pseudomonas
putida. J. Ind. Microbiol. Biotechnol. 20, 28 – 33.
Clarke, C., Morna, B.A., (2009.) Cyanide Usage In The Gold Mining Industry Under Wet Tropical
Conditions. Helensvale, Australia.
Dey, U., Chatterjee, S., Mondal, N.K., 2(016.) Isolation and characterization of arsenic-resistant bacteria
and possible application in bioremediation. Biotechnol. Reports 10, 1–7.
https://doi.org/10.1016/j.btre.2016.02.002.
Dursun, A.Y. ; Alık, A. C.; Aksu, Z., (1999). « Degradation of ferrous(II) cyanide complex ions by
Pseudomonas fluorescens ». Process Biochem. 34, 901–908.
Dzombak, A., Rajat, S., Wong Chong, M., (2015). Cyanide in water and soil.
Fuller, W.H., (1984). Cyanides in the environment with particular attention to soil, in: Cyanide and the
Environment. Geochemical Engineering Program Vol 1. Colorado State University, Fort Collins,
pp. 19 – 46.
Guimaraes, J.R.D., Betancourt, O., Rodrigues, M., Barriga, R., Cueva, E., Betancourt, S., 2011. Long-
range effect of cyanide on mercury methylation in a gold mining area in southern Ecuador. Sci.
Total Environ. 409, 5026–5033. https://doi.org/10.1016/j.scitotenv.2011.08.021.
Hijosa-Valsero, M., Molina, R., Schikora, H., Müller, M., Bayona, J.M., (2013). Removal of cyanide from
water by means of plasma discharge technology. Water Res. 47, 1701–1707.
https://doi.org/10.1016/j.watres.2013.01.001.
Kjeldsen, P., (1999). Behaviour of cyanides in soil and groundwater: a review 279–307.
Kumar, V., Kumar, V., Bhalla, T.C., (2013). In vitro cyanide degradation by Serretia marcescens RL2b.
Int. J. Environ. Sci. 3, 1969–1979. https://doi.org/10.6088/ijes.2013030600018.
Luque-Almagro, V.M., Moreno-Vivián, C., Roldán, M.D., (2016). Biodegradation of cyanide wastes
from mining and jewellery industries. Curr. Opin. Biotechnol. 38, 9–13.
https://doi.org/10.1016/j.copbio.2015.12.004.
Mansfeldt, T., Biernath, H., (2001). Method comparison for the determination of total cyanide in
deposited blast furnace sludge 435, 377–384.

154
Mekuto, L., Jackson, V.A., Ntwampe, K.S., Obed., (2013). Biodegradation of Free Cyanide Using
Bacillus Sp . Consortium Dominated by Bacillus Safensis , Lichenformis and Tequilensis Strains :
A Bioprocess Supported Solely with Whey. Bioremediation Biodegrad. 1 –7.
https://doi.org/10.4172/2155-6199.S18-004.
Mekuto, L., Ntwampe, S.K.O., Mudumbi, J.B.N., (2018). Microbial communities associated with the co-
metabolism of free cyanide and thiocyanate under alkaline conditions. 3 Biotech 8,
https://doi.org/10.1007/s13205–018–1124–3. https://doi.org/10.1007/s13205-018-1124-3.
Mirizadeh, S., Yaghmaei, S., Ghobadi Nejad, Z., (2014). Biodegradation of cyanide by a new isolated
strain under alkaline conditions and optimization by response surface methodology (RSM). J.
Environ. Heal. Sci. Eng. 12, 85. https://doi.org/10.1186/2052-336X-12-85.
Potivichayanon, S., Kitleartpornpairoat, R., (2010). Biodegradation of Cyanide by a Novel Cyanide-
degrading Bacterium. World Acad. Sci. Eng. Technol. 4, 1093–1096.
Prescott., L.M., Harley, J.P., Klein, D.A., (2002). Microbiologie. 2ème édition française, Traduction de la
5ème édition américaine par Claire Michelle Bacq Calberg et Jean Dusart (Université de Liège).
Razanamahandry, L.C., Andrianisa, H.A., Karoui, H., Kouakou, K.M., Yacouba, H., (2016).
Biodegradation of free cyanide by bacterial species isolated from cyanide-contaminated artisanal gold
mining catchment area in Burkina Faso. Chemosphere 157, 71–78.
https://doi.org/10.1016/j.chemosphere.2016.05.020.
Razanamahandry, L.C., Andrianisa, H.A., Karoui, H., Kouakou, K.M., Yacouba, H., (2016).
Biodegradation of free cyanide by bacterial species isolated from cyanide-contaminated artisanal
gold mining catchment area in Burkina Faso. Chemosphere 157, 71–78.
https://doi.org/10.1016/j.chemosphere.2016.05.020.
Razanamahandry, L.C., Andrianisa, H.A., Karoui, H., Podgorski, J., Yacouba, H., (2018.) Prediction
model for cyanide soil pollution in artisanal gold mining area by using logistic regression.
Catena 162, 40–50. https://doi.org/10.1016/j.catena.2017.11.018.
Razanamahandry, L.C., Karoui, H., Andrianisa, H.A., Yacouba, H., (2017). Bioremediation of soil and
water polluted by cyanide: A review. African J. Environ. Sci. Technol. 11, 272–291.
https://doi.org/10.5897/AJEST2016.2264.
Rennert, T., Mansfeldt, T., (2009). Mobility of Iron-Cyanide Complexes in a Humic Topsoil under
Varying Redox Conditions 2009. https://doi.org/10.1155/2009/857640.
Velásquez-lópez, P.C., Veiga, M.M., Klein, B., Shandro, J.A., Hall, K., (2011). Cyanidation of mercury-
rich tailings in artisanal and small-scale gold mining : identifying strategies to manage
environmental risks in Southern Ecuador. J. Clean. Prod. 19, 1125–1133.
https://doi.org/10.1016/j.jclepro.2010.09.008.

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Dr Harinaivo Anderson Andrianisa
Head of Water and Sanitary Engineering Department
International Institute for Water and Environmental Engineering
Dr Andrianisa has a PhD in Production and Development Science and a Master of Engineering Degree
in Civil and Environmental Engineering from Japan, and a degree of Engineer in Hydraulics from
Madagascar. He has been joining the 2iE Institute in Burkina Faso in 2012. During the last six years, he
has conducted extensive research works on cyanide issues in artisanal mining in Burkina Faso. Besides,
Dr Andrianisa is also interested in water and sanitation issues in developing countries, focusing his
researches on low-cost sanitation technologies and on the integration of the informal recycling sector
into formal waste management systems. Before that, Dr Andrianisa was a consulting-engineer in
Madagascar, specialising in environmental impact assessment and environmental and social
management of small to middle-scale mining projects.

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