Biological removal of methanethiol from gas and water streams by using Thiobacillus...
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Biological removal of methanethiol from gas and water
streams by using Thiobacillus thioparus:investigation of biodegradability and optimization of sulfur production
Journal: Environmental Technology
Manuscript ID: OA-TENT-2013-0577.R3
Manuscript Type: Original Article
Date Submitted by the Author: 20-Dec-2013
Complete List of Authors: Badr, Kiumars; Environmental Research Center in Petroleum and
Petrochemical Industries, Shiraz University, bahmani, mahmoud; Environmental Research Center in Petroleum and Petrochemical Industries, Shiraz University Jahanmiri, Abdolhossein; shiraz university, Mowla, Dariush; shiraz university, ; Environmental Research Center in Petroleum and Petrochemical Industries, Shiraz University
Keywords: Methanethiol removal, Biodegradability, Biological oxidation, Elemental sulfur, Thiobacillus thioparus
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Biological removal of methanethiol from gas and water streams by using
Thiobacillus thioparus:investigation of biodegradability and optimization of
sulfur production
Kiumars Badr a, Mahmoud Bahmani
a, Abdolhossein Jahanmiri
b, Dariush Mowla
a, b, *
a Environmental Research Center in Petroleum and Petrochemical Industrial, School of Chemical Engineering,
Shiraz University, Shiraz, Iran b School of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran
Abstract
The present work mainly deals with biological oxidation which was tested using the bacterium
Thiobacillus thioparus in semi-batch bioreactor systems to evaluate the removal efficiencies and
optimal conditions for the biodegradation of methanethiol (MT) in order to treat the natural gas
and refinery output streams. The efficiency of this method is analyzed by evaluating the
concentration of MT in a bioreactor. The effect of operational parameters such as initial
concentration of MT, pH, temperature, dissolved oxygen, initial concentration of bacteria and
reaction time on the degradation of MT were studied. In this process, MT is converted into
elemental sulfur particles as an intermediate in the oxidation process of MT to sulfate. The
obtained results showed that the highest degradation rate occurred during the first 300 minutes of
reaction time. The optimal conditions of the different initial MT concentration with 0.3 to 0.6
bacteria OD, dissolved oxygen of 0.5 ppm, acidic pH value of 6.2 and temperature of 30°C are
obtained. Acidic pH and oxygen-limiting conditions were applied to obtain 80 to 85 %
selectivity for elemental sulfur formation in products. Under the optimal conditions, and for the
highest (8.51mM) and the lowest (0.53mM) concentration of MT, the biological removal were
about 89% and 94% respectively.
Keywords: Methanethiol removal; Biodegradability; Biological oxidation; Elemental sulfur;
Thiobacillus thioparus.
* Corresponding author. E-mail: [email protected] (Dariush Mowla).
Tel.: +98-711-2303071
Fax: +98-711- 6473180
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1. Introduction
Mercaptans (thiols) are highly reactive sulfur-containing species well known for their
disagreeable odors. The most volatile of thiols is methanethiol (MT, CH3SH), which is one of the
natural sources of sulfur could be emitted into the atmosphere [1-3]. It is a colorless gas with a
smell like rotten cabbage. MT is commonly present in both natural gas and refinery streams.
Examples of various gas and refinery streams containing MT and hydrogen sulfide are given in
Table 1.
They have to be removed mainly for three reasons:
(a) Both MT and hydrogen sulfide are acid compounds and therefore they can cause serious
corrosion problems,
(b) They have an offensive odor and a low odor threshold,
(c) Most of them are highly toxic.
The maximum permissible concentration of gaseous MT in the work place is 5.0 ppm (threshold
limit value-time weighted average concentration, TLV-TWA) and 0.5 ppm as defined by
American Conference of Governmental Industrial Hygienists (ACGIH). In addition,
Occupational Safety and Health Administration (OSHA) defined the MT concentration to 10
ppm as permissible exposure limit time weighted average concentration (PEL TWA) [4, 5]. At a
higher concentrations MT becomes very toxic and may causes harmful health effects.
Table 1.
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Due to high chemical requirements, energy and disposal costs, the chemical and physical
removal processes of mercaptan are expensive. For example, there are two main chemical
processes for removal of MT: Merox processes [13] and Merichem processes [14] which in these
methods, MT is not removed from the fuel, but rather transformed into disulfides which are toxic
and flammable compounds.
Hence after both of the traditional treatments which have mentioned above, the sulfur content in
the fuel is not reduced by only these treatments [15]. To overcome disadvantages of
physiochemical process for mercaptan removal (e.g., high pressure, high temperature, need for
special chemicals and usually generate an additional problem in the disposition of the exhausted
reagents [16]), the use of biological treatment is an interesting alternative because of low costs,
operational simplicity and intrinsically clean technologies [17-19].
Biological treatment uses several species of bacteria to convert MT into a non-toxic form
materials such as sulfate or sulfur particles. There are different types of bioreactors, which could
be used for biological MT removal, the more common types are: bioscrubber, biotrickling filter
and biofilter.
An example of VRSC (Volatile Reduced Sulfur Compounds) gases treatment by biotrickling
filter, is the research of Rukojärvi et al. [20] who is obtained removal capacities of 48, 37 and 3
gS·m-3
·h-1
for H2S, DMS and MT, respectively, using a biotrickling filter inoculated with a
microbial consortium. Hartikainen et al. [21] reached elimination capacities of 6, 7 and 4 gS·m-
3·h
-1 for H2S, DMS and MT, respectively applying a non inoculated fibrous peat as support.
However, it has been reported that biofilters inoculated with pure cultures, mainly bacteria from
the Thiobacillus, Acidithiobacillus and Hyphomicrobium genera, depending on the biofilm
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generation conditions have a lower start-up time and a more stable operation over the time [22,
23].
In the two mentioned processes, the gas containing MT passes through a moist, packed bed of
particles, which are coated by microorganism. Because of direct contact of gas- bacteria in
biotrickling filter and biofilter systems, there is an increment in mass transfer resistance from gas
phase to liquid phase which causes mass transfer limitation and also these are appropriate for low
mercaptan capacity. In these processes, sulfate is produced with no elemental sulfur [24].
In the case of hydrogen sulfide and volatile organic sulfur compounds (VOSCs) removal from
natural gas and refinery streams, bioscrubber is more suitable than two previous processes.
Mesa et al. [25] described a bioscrubber system which could be applied into a system by a
combination of chemical and biological processes for H2S removal from biogas. H2S removal
can be achieved by absorption in a ferric sulfate solution and producing ferrous sulfate and
elemental sulfur. Ferric sulfate could be regenerated by biological oxidation using
Acidithiobacillus ferrooxidans.
Benschop et al. [26] obtained a full scale plant located northeast of Brooks, Alberta, Canada used
Shell-Paques® process for natural gas desulfurization. H2S is removed from a gaseous stream by
absorption into scrubbing liquid. The hydrogen sulfide containing scrubbing liquid is treated in
the bioreactor where it is mostly converted biologically to elemental sulfur.
Roosta et al.[27] investigated biological sulfide removal in a batch bioreactor. In this process,
hydrogen sulfide is converted into elemental sulfur particles as an intermediate in the oxidation
of hydrogen sulfide to sulfate. The main product is elemental sulfur at low dissolved oxygen.
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In the first step the gaseous stream reacts with a concentrated solution of sodium hydroxide (14
wt% NaOH) in which MT are dissolved as the corresponding sodium salts according to:
OHSNaCHNaOHSHCH aqg 2)(3)(3 +→+ (1)
The first step takes place in an extraction column, where MT are washed by a counter current of
caustic stream and the treated gas is passed overhead. The treated gas now free of MT, could be
delivered directly to the customers. The loaded scrubbing liquid or contaminated wastewater
with MT, sends to the bioreactor.
A review on bacteria of the sulfur cycle was discussed by Tang et al. [28]. In their research, for
MT reduction, aerobic microorganisms are used. In the aerobic bioreactor, MT is biologically
oxidized according to the following equations [29]:
−−++→+ OHCOSOSCH 3
25
2
0
23 (2)
+−−++→+ HCOSOOSCH 33 2
2
423 (3)
+−−++→+ HCOOSOSCH 62
272 2
2
3223 (4)
Although the formation of sulfate and thiosulfate consumes more energy than the formation of
elemental sulfur however, it is possible to obtain a selectivity between 80 and 85 percent for the
formation of elemental sulfur by applying oxygen-limiting conditions and decreasing the pH to
the extent of acidic pH [30, 31]. There is a mediated reaction for sulfate production which can
carry out in an appropriate conditions (Eq. (5)):
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+−−+→++ HSOOOHS 2
42
0
23 (5)
In appropriate temperatureand presence of enough oxygen, the non-biological reaction occurs
which is written below (Eq. (6)) [32]:
OHSSCHCHOSHCH 23323 212 +→+ (6)
The previous investigations show clearly that biological removal processes can be applied
effectively to remove MT pollution in gas. However, only a few studies have been done directly
on removal hazardous MT material effectively by low temperature and cost, high speed and
neutral pH and also produces just sulfur selectively instead of other hazardous materials [33].The
previous researches have generally checked degradation of only about 0.2 mM [34] and didn’t
mentioned the type of produced materials and also a few operational parameters have been
studied. Therefore, more detailed experimental investigations are required for better
understanding the removal efficiency of this very harmful component.
In this study, we present the results of bioreactor experiments on MT removal. Biodegradation of
MT is assessed by evaluating the effects of parameters as well as production of elemental sulfur
selectivity in a so called semi-batch bioreactor.
2. Materials and method
2.1. Strain and media
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In this study, Thiobacillus thioparus (DSMZ 5368) is used as sulfur oxidizing bacteria for
producing elemental sulfur and sulfate as the products in the oxidation of MT. The medium for
growth is shown in Table 2 [35]. Each compound was purchased in the highest purity that was
commercially available.
After addition of all compounds, the pH of the medium was 7.1 ± 0.1 at 30 ◦C. Then the strain
(100 cm3 of the medium culture containing bacteria with an OD600 of about 0.5) added to a flask
containing 2000 cm3 of the medium. After that, the medium kept in a shaker incubator with 150
rpm and temperature about 30 ˚C for five days to obtain enough concentration of bacteria.
Table 2.
2.2. Experimental set-up and procedure
A reactor with total volume of 3.8 L operated under semi-batch conditions, as shown in Figure 1
constructed. During each experiment, the temperature, dissolved oxygen, Initial MT
concentration and pH were controlled. The reactor was placed in a water bath to control the
temperature within 0.5 ˚C of the set point (30 ˚C). The pH was controlled using 1N HCl and 1N
NaOH solutions between 5.6 and 8.2. The dissolved oxygen (DO) was changed between 0.5 and
6 ppm and controlled using nitrogen and oxygen injection, it means that when their
concentrations were low or completely finish, system were charged them again through closing
and opening manual valve. The free thiosulfate and bromocresol purple main medium was the
original inoculum of this bioreactor (Table 1). The bioreactor was charged with 2000 cm3 of the
medium and inoculated with centrifuged biomass (bacteria OD = 0.3-0.6). After temperature
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stabilization, feeding of MT to the bioreactor was started. MT solution was prepared by solving
sodium methyl mercaptide (21%w) in deionized water. The concentration of prepared MT
solution was 500 mM. The concentration of this solution was standardized based on mercuric
acetate and N,N-dimethyl- p-phenylenediamine described by Moore using a spectrophotometer
(Zeiss) at 500 nm [36].
The reactor was equipped with sensors for temperature, pH (Metrohm LL-Unitrode Pt 1000),
dissolved oxygen (AZ 8403) and oxidation reduction potential (ORP Ag/AgCl electrode AZ
8501) electrode. ORP electrode is a tool in order to measure the tendency of a chemical species
to acquire electrons and thereby be reduced. Reduction potential is measured in millivolts. A
diffuser was placed in the floor of bioreactor for scattering the circulating gas. The flow rate of
the circulating gas was enough (15 Lmin-1
) for mixing the contents of the close bioreactor. The
gas was circulated by an air pump (ACO-308). Three sampling instruments were prepared on the
head of the bioreactor. The concentrations of dimethyle disulfide (DMDS) were determined
indirectly by spectrophotometry at a wavelength of 285 nm [37]. At this wavelength, MT did not
show any significant absorbance at all concentrations tested compared to the medium solution.
The total concentrations of MT were determined based on mercuric acetate and N,N-dimethyl- p-
phenylenediamine described by Moore using a spectrophotometer at 500 nm [36].The
concentration of sulfate was determined via the turbidimetry method at 420 nm [38]. While the
thiosulfate concentration was determined via methylene blue method at 760 nm [39]. The
concentration of sulfur particles was determined based on toluene described by Roosta et al.
using spectrophotometer at 290 nm [27].
An UV/VIS spectrophotometer (Optima, SP 3000 plus) was used for measurement of all
components.
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The synthetic substrate is made by dissolving MT in the liquid feed and in the ranges applicable
in the oil and gas refineries streams. For identification of sulfides volatilized from liquid feed, a
volume of 3 L of MT (6 mM) was stirred for 12 h, in the bioreactor under experimental
conditions (pH=6, T=30 ˚C). After this time, spectrophotometric analyses confirmed the
negligibility of the MT volatilization amount. Some key parameters have been checked to
determine the optimum conditions for MT removal. In the first section of the experiments, the
optimal conditions in terms of temperature, pH and dissolved oxygen are obtained for removal
the most part of MT as well as production of elemental sulfur. In the second section, in order to
determine the amount of removal efficiency and sulfur production, different initial
concentrations of MT were used and variations of MT concentration were measured versus time
at achieved optimal conditions.
Figure 1.
3. Results and discussion
3.1. Effects of temperature and pH
As it was mentioned before, for bacteria growth, they should be placed at incubator in
temperature about 30 ˚C. But the temperature may vary from the optimum value in industrial
conditions. The temperature was varied from 25˚C to 35˚C whereas other parameters were
almost kept constant.
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Variations of uneliminated MT with temperature is illustrated in Figure 2(a) which reveals that
the best performance for MT removal could be obtained at T=30˚C.
The optimal pH range for Thiobacillus thioparus is between 6 and 8. However, it can grow in
higher and lower range of pH values. The effect of pH on the uneliminated MT concentration or
in fact on bacteria activity is illustrated in Figure 2(b). As it is obvious, as pH increases,
uneliminated MT is increased, because the activity of bacteria has been decreased. This fact is
correct for pH values lower than 6.
At pH higher than 8.2 and lower than 6 the activity was reduced sharply, however in the pH
between 6 and 8.2 change of activity was low. Furthermore, at high and very low pH values, OD
of bacteria is decreased. The reasons for concentration reduction of bacteria could be proved by
two facts: first, the bacteria cannot grow at high or low pH and second, the activity reduction
causes more accumulation of MT in the bioreactor and high concentration of MT is toxic for the
bacteria [40, 41].
Because of oxygen lacking, a large amount of MT was converted to sulfur particles according to
Eq. 2. Thiosulfate is an undesired product in biological MT removal which is produced during
sulfur production according to Eq. 4. The effect of pH on thiosulfate production is demonestrated
in Figure 2(c). The result shows that the production of thiosulfate decreases with the pHs
reduction. Based on reactions 2 and 4 it is found out, OH- is produced along with production of
elemental sulfur which leads to alkaline conditions of reactor (Eq. 2).Beside it, H+ as well as
thiosulfate are produced which cause acidic conditions in reactor (Eq. 4). According to Le
Chatelier's principle, as pH in reactor decreases, reaction 2 is reinforced and reaction 4 is
prevented. Furthermore , since the rate constant of reaction 4 at pH=6 is low in comparison with
that of reactions 2 and 3, production of thiosulfate is negligible [42, 43].
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Figure 2.
In addition, the effect of bacteria concentration on uneliminated MT and the relation between the
absorbency of bacteria at 600 nm and the concentration of bacteria are investigated in Figures. 1
and 2 available in supplementary file. Also, an equation is achieved to relate OD and number of
bacteria in the medium culture.
3.2. Effects of initial MT concentration at different time on MT removal
Time consumption is an important factor for each experimental work in batch or semi-batch
reactors. Figure 3 shows variation of MT concentration with time at specified pH, temperature
and bacteria OD. As it is clear from this figure, after approximately 300 minutes majority of MT
is removed. Another key parameter which influences the efficiency of system is initial
concentration of MT. Therefore experiments are performed to obtain variation of MT
concentration versus time at various initial MT concentration.
Figure 3.
By increasing the initial concentration of MT from 0.53 to 4.25 mM, the removal efficiency in
300 minute (at the lowest concentrations, the sulfur bacteria were substrate limited for a
significant part of the time, therefore efficiency is increased in shorter time ) is increased, but
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after 4.25 mM, by increasing the initial concentration of MT the removal efficiency is decreased,
as a result, more time is required for higher reduction.
3.3. Effect of dissolved oxygen on sulfur production
The only desired product in the biological MT removal is sulfur particle. In addition, the rate of
sulfate production decreases with reduction of DO and oxidation of MT to sulfur particles
increases consequently [45]. Thus, for more production of sulfur, the oxygen concentration
should be limited. The effect of DO values on sulfur production is illustrated in Figure 4. The
result show that, at initial MT concentration about 2.12 mM and DO value of 3.94 ppm only less
than 9% sulfur is produced, while at DO of 0.91 more than 70% of MT load is converted to
sulfur particles.
Figure 4.
3.4. Effect of time and initial concentration of MT on products
The effect of initial MT concentration on sulfur particle production is studied and the results are
shown in Figure 5(a). This fig shows that at low initial MT concentration the most part of MT is
converted to sulfate. Increasing the initial concentration of MT leads to production of more
sulfur particles and less sulfate [46].
The output products contain sulfate, elemental sulfur, thiosulfate, dimethyl disulfide and carbon
dioxide, however CO2 is one of the main products because of its existence in the surrendered gas
phase. Figure 5(b) indicates that at interval of 60-120 minutes, since initial concentration of MT
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is low, the amount of MT converted to sulfate and also elemental sulfur through biological
oxidation is low while, as it is clear from Figure 5(c), at high concentration of MT it doesn’t
observe. Figure 5(c) indicates that in first 120 minutes a bit biological oxidation is done, in fact
in this period of time bacteria adopted themselves by conditions to use available sulfur in
components as nutrients. Figure 5(b) reveals that at interval of 120-200 minutes, the amount of
produced sulfate is higher than elemental sulfur because at the first period of removal process
mediated reaction (Eq.5) improves fastly. But this conditions could be changed by consuming
time and increasing MT concentration as Figure 5(c). DMDS is one of materials which is
produced in first period of 120 minutes. Since more oxidation (non-biological) of DMDS needs
higher temperature and catalyst, after 120 minutes its production rate is decreased which shows
that at this condition, applied bacteria were able to reduce and break DMDS to sulfate and
elemental sulfur.
Figure 5.
4. Conclusion
In this study, biological removal of methanethiol (MT) in a semi-batch bioreactor is investigated.
The efficiency of the treatment process is checked at different operational conditions such as
temperature, pH, bacteria concentration (by Optical Density), dissolved oxygen, reaction time
and initial concentration of MT. Removal efficiency of MT increases by raising the bacteria
concentration to its optimum value for used its initial concentrations. The results show that MT
removal is decreased in pH higher than 8.2 and lower than 6 value. By increasing initial MT
concentration or at low dissolved oxygen, more parts of MT are converted to elemental sulfur,
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thus elemental sulfur selectivity increased and sulfate selectivity decreased. Under the optimal
conditions for the highest (8.51mM) and the lowest (0.53mM) concentration of MT, the
biological removal of MT after approximately 300 minutes reached about 89% and 94%
respectively, which shows that the applied method can be very effective for MT removal in
industrial applications.
References
1. G. Labouri, R. Cadours, A. Barreau, and F. Lecomte, IFPEXOL: an attractive solution
for RSH and COS removal from natural gas, Proceedings of the Laurance Reid gas
conditioning conference, Norman, Oklahoma ,2001.
2. F.A.T. Andersson, A. Karlsson, B.H. Svensson, and J. Ejlertsson, Occurrence and
abatement of volatile sulfur compounds during biogas production, J. Air. Waste. Manage.
Assoc. 54 (2004), pp. 855–861.
3. A.F. Carlsson and J.B. Rajani, New options for mercaptans removal, Hydrocarb. Eng. 10
(2005), pp. 23–26.
4. J.H. Ruth, Odor thresholds and irritation levels of several chemical substances ,a review,
Am. Ind. Hyg. Assoc. J. 47 (1986), pp. 142–151.
5. http://www.osha.gov/dts/chemicalsampling/data/CH_254300.html
6. E. Smet and H.V. Langenhove, Abatement of volatile organic sulfur compounds in
odorous emissions from the bio-industry, J. Chromatogr. 881 (1998), pp. 569–581.
7. R. Iranpour, H.H.J. Cox, S. Fan, V. Abkian, R.J. Kearney, and R.T. Haug, Short-term and
long-term effects of increasing temperatures on the stability and the production of
Page 14 of 27
URL: http:/mc.manuscriptcentral.com/tent
Environmental Technology
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
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nly
15
volatile sulfur compounds in full-scale thermophilic anaerobic digesters, Biotechnol.
Bioeng. 91 (2005), pp. 199–212.
8. G. Börjesson, Inhibition of methane oxidation by volatile sulfur compounds (CH3SH and
CS2) in landfill cover soils, Waste. Manage. Res. 19 (2001), pp. 314–319.
9. K.H. Kim, Y.J. Choi, E.C. Jeon, and Y. Sunwoo, Characterization of malodorous sulfur
compounds in landfill gas, Atmos. Environ. 39 (2005), pp. 1103–1112.
10. M.A. Karnofski, Odor generation in the kraft process, J. Chem. Educ. 52 (1975), pp.
490–492.
11. A.A. Manieh and N. Ghorayeb, How to design a caustic wash, Hydrocarb. Proc. 60
(1981), pp. 143–144.
12. J. Sipma, A. Svitelskaya, B. Van Der Mark, L.W. Hulshoff Pol, G. Lettinga, C.J.N.
Buisman, and A.J.H. Janssen, Potentials of biological oxidation processes for the
treatment of spent sulfidic caustics containing thiols, Water. Res. 38 (2004), pp. 4331–
4340.
13. A. Farshi and Z. Rabiei, Kinetic Study for Oxidation of Existing Mercaptans in Kerosene
Using Impregnated Activated Carbon with MEROX Catalyst in Alkaline Solution,
Petroleum & Coal. 47 (2005), pp. 49–56.
14. A.L. Kohl and R.B. Nielsen, Gas Purification, 5th
edn. Houston, Gulf Publishing Co,
1997.
15. A. de Angelis, Natural gas removal of hydrogen sulphide and mercaptans, Appl. Catal.
B. 113– 114 (2012), pp. 37– 42.
16. A.A. Chan, Attempted biofiltration of reduced sulphur compounds from pulp and paper
mill in Northern Sweden, Environ. Prog. 25 (2006), pp. 152-160.
Page 15 of 27
URL: http:/mc.manuscriptcentral.com/tent
Environmental Technology
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960
For Peer Review O
nly
16
17. J.W. Van Groenestijn and P.G.M. Hesselink, Biotechniques for air pollution control,
Biodegradation. 4 (1993), pp. 283-301.
18. D. McNevin and J. Barford, Biofiltration as an odour abatement strategy, Biochem. Eng.
J. 5 (2000), pp. 231-242.
19. J.E. Lepo, C.R. Cripe, J.L. Kavanaugh, S. Zhang, and G.P. Norton, The effect of amount
of crude oil on extent of its biodegradation in open water‐ and sandy beach‐ laboratory
simulations, Environ. technol. 24 (2003), pp. 1291-1302.
20. dA. Rukojärvi, J. Ruuskanen, and P.J. Martikainen, Oxidation of gas mixtures containing
dimethyl sulfide, hydrogen sulfide, and methanethiol using a two-stage biotrickling filter,
J. Air. Waste. Manage. Assoc. 51 (2001), pp. 11-16.
21. T. Hartikainen, P. Martikainen, M. Olkkonen, and J. Ruuskanen, Peat biofilters in long-
term experiments for removing odorous sulphur compounds, Water. Air. Soil. Pollut. 133
(2002), pp. 335-348.
22. B. Sercu, D. Núñez, G. Aroca, N. Boon, W. Verstraete, and H. Van Langenhove,
Inoculation and start-up of a biotricking filter removing dimethyl sulfide, Chem. Eng. J.
113 (2005), pp. 127-134.
23. G. Aroca, A. Arancibia, K. Guerrero, D. Núñez, P. Oyarzún, and H. Urrutia, Comparison
on the removal of hydrogen sulfide in biotrickling filters inoculated with Thiobacillus
thioparus and Acidithiobacillus thiooxidans, Electron. J. Biotechn. 10 (2007), pp. 1-6.
24. V. Herrygers, H. Van Langenhove, and E. Smet, Environmental technologies to treat
sulfur pollution, Principles and Engineering, P. Lens and L. Hulshoff, eds., IWA
Publishing, London, 2000.
Page 16 of 27
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25. M.M. Mesa, M. Macías, and D. Cantero, Biological iron oxidation by Acidithiobacillus
ferrooxidans, Chem. Biochem. Eng. Q. 16 (2002), pp. 69-73.
26. A. Benschop, A. Janssen , A. Hoksberg , M. Seriwala, R. Abry, and C. Ngai, The shell-
Paques /THIOPAQ gas desulphurization process: Successful start up first commercial
unit, (2002). Available at: http://www.paques.nl (2006/02/15).
27. A. Roosta, A. Jahanmiri, D. Mowla, and A. Niazi, Mathematical modeling of biological
sulfide removal in a fed batch bioreactor, Biochem. Eng. J. 58– 59 (2011), pp. 50– 56.
28. K. Tang, V. Baskaran, and M. Nemati, Bacteria of the sulphur cycle: an overview of
microbiology, biokinetics and their role in petroleum and mining industries. Biochem.
Eng. J. 44 (2009), pp. 73–94.
29. B.P. Lomans, C. Van der Drift, A. Pol, and H.J.M. Op den Camp, Microbial cycling of
volatile organic sulfur compounds, Cell. Mol. Life. Sci. 59 (2002), pp. 575-588.
30. A.J.H. Janssen, R. Sleyster, C. Van der Kaa, A. Jochemsen, J. Bontsema, and G. Lettinga,
Biological sulfide oxidation in a fed-batch reactor, Biotechnol. Bioeng. 47 (1995), pp.
327-333.
31. J.M. Visser, L.A. Robertson, H.W. Van Verseveld, and J.G. Kuenen, Sulfur production
by obligately chemolithoautotrophic Thiobacillus species, Appl. Environ. Microb. 63
(1997), pp. 2300-2305.
32. R.C. Van Leerdam, M. Bonilla-Salinas, F.A.M. de Bok, H. Bruning, P.N.L. Lens, A.J.M.
Stams, and A.J.H. Janssen, Anaerobic methanethiol degradation and methanogenic
community analysis in an alkaline (pH 10) biological process for liquefied petroleum gas
desulfurization, Biotechnol. Bioeng. 101 (2008), pp. 691-701.
Page 17 of 27
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33. F.A.M. De Bok, R.C. Van Leerdam, B.P. Lomans, H. Smidt, P.N.L. Lens, A.J.H.
Janssen, and A.J.M. Stams, Degradation of methanethiol by methylotrophic
methanogenic archaea in a lab-scale upflow anaerobic sludge blanket reactor, Appl.
Environ. Microb. 72 (2006), pp. 7540-7547.
34. M. Cáceres, M., Morales, R., San Martín, H., Urrutia, and G. Aroca, Oxidation of volatile
reduced sulphur compounds in biotrickling filter inoculated with Thiobacillus thioparus,
Electron. J. Biotechn. 13 (2010), pp. 1-9.
35. Leibniz institute DSMZ-German collection of microorganisms and cell cultures, catalogue of
microorganisms, http://www.dsmz.de/catalogues/catalogue-microorganisms.html
36. H. Moore, H.L. Helwig, and R.J. Graul, A Spectrophotometric Method for the
Determination of Mercaptans in Air. Am. Ind. Hyg. Assoc. J. 21 (1960), pp. 466-470.
37. W.E. Kleinjan, A. de Keizer, and A.J.H. Janssen, Kinetics of the reaction between
dissolved sodium sulfide and biologically produced sulfur. Ind. Eng. Chem. Res. 44
(2005), pp. 309-317.
38. M.A.H. Franson, Standard Methods for the Examination of Water and Wastewater,
twenty first edn. Am. Public. Health. Assoc. 2005.
39. T. Urich, Functional and Structure Characterization of a Sulfur Disproportionating
Enzyme, phD thesis, Darmstadt University, Netherlands, 2005.
40. T.J. Beveridge, Role of cellular design in bacterial metal accumulation and
mineralization, Annu. Rev. Microbiol. 43 (1989), pp. 147–171.
41. L.E. Macaskie, The application of biotechnology to the treatment of wastes produced by
the nuclear fuel cycle – biodegradation and bioaccumulation as a means of treating
radionuclide-containing streams, Crit. Rev. Biotechnol. 11 (1991), pp. 41–112.
Page 18 of 27
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19
42. F.P. Van den Ende and H. Van Gemerden, Sulfide oxidation under oxygen limitation by a
thiobacillus thioparus isolated from a marine microbial mat, FEMS Microbiol. Ecol. 13
(1993), pp. 69–77.
43. P.L.F. Van den Bosch, O.C. Van Beusekom, C.J.N. Buisman, and A.J.H. Janssen, Sulfide
oxidation under halo-alkaline conditions in a fed-batch bioreactor, Biotechnol. Bioeng.
97 (2007), pp. 1053-1063.
44. E. Cervantes‐González, N.G. Rojas‐Avelizapa, R. Cruz‐Camarillo, J. García‐Mena, and
L.I. Rojas‐Avelizapa, Oil-removal enhancement in media with keratinous or chitinous
wastes by hydrocarbon-degrading bacteria isolated from oil-polluted soils, Environ.
technol. 29 (2008), pp. 171-182.
45. A.J.H. Janssen, S. Meijer, J. Bontsema, G. Lettinga, Application of the redox potential for
controlling a sulfide oxidizing bioreactor, Biotechnol. Bioeng. 60 (1998), pp. 147–155.
46. W.E. Kleinjan, A. de Keizer, A.J.H. Janssen, Biologically produced sulfur, Top. Curr.
Chem. 230 (2003), pp. 167–188.
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Tables
Table 1. Examples of gas and refinery streams contaminated with MT, hydrogen sulfide and dimethyle disulfide.
Source Sulfur compound Concentration (mM) Reference
Anaerobic wastewater sludge digester MT 3.8-7.6e-3 [6]
H2S 1.8-3.6e-1
Landfill gas MT Up to 7.4e-2 [7, 8]
H2S Up to 4.4
Kraft paper production process MT 1.7e-1 [9, 10]
H2S 3.4e-2
DMDS 0.3e-2
Liquefied petroleum gas(LPG) MT 9 [11]
H2S 1.76
Refinery sulfidic spent caustics MT 0.01-0.42 [12]
H2S 0.91-1.97
Table 2. Medium culture of thiobacillus thioparus [35]
Main medium Vitamin mixture Trace metals
KH2PO4 2.0 g Thiamine-HCl.2H2O 10.0 mg Na2-EDTA 50.0 g
K2HPO4 2.0 g Nicotinic acid 20.0 mg ZnSO4·7H2O 11.0 g
NH4Cl 0.4 g Pyridoxine-HCl 20.0 mg CaCl2·2H2O 7.34 g
Na2CO3 0.4 g p-Aminobenzoic acid 10.0 mg MnCl2·4H2O 2.5 g
MgCl2·6H2O 0.2 g Riboflavin 20.0 mg CoCl2·6H2O 0.5 g
Vitamin solution 3.0 ml Ca-pantothenate 20.0 mg (NH4)6 Mo7O24.4H2O 0.5 g
Trace metals solution 1.0 ml Biotin 1.0 mg FeSO4·7H2O 5.0 g
Bromocresol purple sol 2.0 ml Vitamin B12 1.0 mg CuSO4·5H2O 0.2 g
Na2S2O3·5H2O 5.0 g Distilled water 1000 ml NaOH 11.0
Distilled water 1000 ml Distilled water 1000 ml
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Figure Captions
Figure 1. A schematic diagram of the experimental set-up. 1: nitrogen, 2: oxygen, 3 and 4: needle valve, 5:
bioreactor, 6: thermometer, 7: dissolved oxygen sensor, 8: pH sensor, 9: sampler, 10: ORP sensor, 11: acid tank, 12:
base tank, 13: air circulation compressor, 14: water bath.
Figure 2. Variation of uneliminated MT with temperature (a) and pH (b); Variation of
thiosulfate and sulfur production with pH (T=30˚C, bacteria OD= 0.5±0.04, initial conc. of MT=
2.12 mM, DO= 1ppm, time=300min)(c).
Figure 3. Variation of MT conc. with time at various initial MT conc.
Figure 4. Variation of S0 selectivity with Dissolved oxygen.
Figure 5. Variation of S0
production with initial MT concentration (a); Variation of
concentration with time for different components (b, c).
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Figures
Figure 1.
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Figure 2.
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Figure 3.
Figure 4.
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Figure 5.
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Supplementary file
Effects of bacteria concentration
Variation of uneliminated MT with initial MT concentration at various bacteria OD is shown in
Figure 1. At low MT concentrations, the bacterial oxidation process is slow due to substrate
limitation. At a constant initial MT concentration, higher OD of bacteria led to lower
uneliminated MT.
Figure 1. Variation of uneliminated MT with initial MT conc. at various bacteria OD.
In addition, a relation between the absorbency of bacteria at 600 nm and the concentration of
bacteria is needed. For this purpose, the method of colony forming unit (CFU) is used [44]. For
convenience the results are given as CFU/ml (colony-forming units per milliliter). The theory
behind the technique of CFU is to establish that a single bacterium can grow and become a
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colony, via binary fission. Then the colonies are counted and an equation is obtained to relate
OD and number of bacteria in the medium culture, as shown in Figure 2 and Eq. (1).
Figure 2. Relation between OD and colony forming units of medium with bacteria.
8
600 10)77.02.4(/ −=bacteria
ODmlCFU (1)
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