Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 1, Pages: 497-503  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: http://www.jett.dormaj.com  
H S Removal from Sour Water in a Trickling  
2
Biofilter  
Mojtaba Fasihi , Mohammad Hassan Fazaelipoor  
1
1, 2*  
1
Department of Chemical Engineering, Faculty of Engineering, Shahid Bahonar University of Kerman, Iran  
Department of Polymer and Chemical Engineering, Faculty of Engineering, Yazd University, Yazd, Iran  
2
Received: 26/08/2019  
Accepted: 29/01/2020  
Published: 20/02/2020  
Abstract  
Long term desulfurization of sour water was studied in a co-current trickling biofilter (BTF) to find out an alternative to the  
traditional methods (stripping in a packed or try columns) being used in the gas and oil refineries. Microorganisms from an  
-3  
2 2  
operating trickling biofilter, treating low levels of H S (up to 5 g S-H S m ) and organic pollutants, were taken, enriched  
-3 -1  
immobilized on the packing materials. A critical elimination capacity (EC) of 151g S-H  
2
S m h was achieved during stepwise  
S measurement along the bed showed that the most significant  
sulfide removal occurred at the top section of the BTF. Besides the H S concentration, the effect of liquid velocity and aeration  
-3  
2 2  
increase of sulfide concentration from 10 to 50 g S-H S m . H  
2
rate was investigated during two independent experiment. Results showed that aeration rate did not increase sulfate production and  
sulfate selectivity should be improved by regulating of the liquid velocity. It was concluded that biological treatment can be used  
as a viable alternative to traditional methods for H  
2
S removal from sour water.  
Keywords: Sour water, Hydrogen sulfide, Biological removal, Trickling biofilter  
Introduction1  
Sour water is defined as any wastewater that contains  
ꢇ푟ꢀꢈꢊ−−푃ꢋ  
퐻 푆+ꢅ푂 →  
1
ꢉ
2ꢄ  
ꢆ
ꢁ푆푂 +ꢅ퐻 ꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃ(3)  
4
2
2
malodorous materials, usually sulfur compounds such as  
S, dimethyl sulfide, dimethyl disulfide, and methanethiol,  
etc. Sour gas processing, oil refining, Claus tail gas units,  
gasification and other thermal processes are some major  
H
2
The bacteria of sulfur cycle and their applications were  
discussed by Tang et al. [2] in a review paper. A wide variety  
of sulfur oxidizing bacteria (SOB) have been frequently  
assessed based on their growth conditions, carbon and  
electron sources, the sulfide-oxidizing pathway, and the  
location of bio-sulfur storage. Most studies, however, have  
been focused on biogas streams [3-5], and polluted air [6-8].  
2
sources of sour water. H S constitutes the main pollutant in  
sour water and needs to be controlled for its adverse health  
and environmental effects. It is a colorless, flammable, and  
corrosive gas, being extremely toxic to living organisms. In  
petroleum and gas refineries, H S is typically removed from  
2
sour water by steam stripping in packed or tray columns.  
These systems are expensive due to their high energy  
2
Chemotrophic biooxidation of H S from sour water in a  
trickling biofilter (BTF) is still lacking in literature. The  
removal efficiency (RE) of a BTF is influenced by various  
parameters such as packing materials, gas contact time, pH,  
gas-liquid flow pattern, nutrient availability, and substrate  
inhibition. Besides the elimination capacity (EC), the sulfate  
selectivity (produced sulfate/degraded sulfide) is also  
important in BTFs design. Sulfur accumulation inside the  
biofilm due to the partial oxidation can clog the bed and  
significantly reduce the RE of the BTFs. Therefore, a well-  
designed BTF should have a high EC as well as high sulfate  
selectivity for a long term operation. The aim of this work  
2
demand, and operating costs. Biooxidation of H S can be  
used to overcome the difficulties related to conventional  
methods of H S removal. In aerobic biooxidation, dissolved  
S is oxidized to elemental sulfur as an intermediate  
2
H
2
product and/or sulfate as a final product depending on the  
availability of dissolved oxygen (DO) and substrate [1]  
(equations 1-3).  
(
푟ꢀ−푃  
)
ꢂ
퐻 푆+0.5푂 → ꢁ푆 +퐻 푂ꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃ(1)  
2
2
2
was to investigate the H  
2
S removal from sour water in an  
aerobic BTF and to assess the influence of the operating  
(
푟 )  
ꢀ
ꢂ
2ꢄ  
4
ꢆ
푆 +1.5푂 +퐻 푂→ꢁ푆푂 +ꢅ퐻 ꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃꢃ(ꢅ)  
2
2
Corresponging author: Mohammad Hassan Fazaelipoor, (a) Department of Chemical Engineering, Faculty of Engineering,  
Shahid Bahonar University of Kerman, Iran and (b) Department of Polymer and Chemical Engineering, Faculty of Engineering,  
Yazd University, Yazd, Iran., E-mail: fazaelipoor@yazd.ac.ir. Tel: +98 35 31232558.  
4
97  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 1, Pages: 497-503  
parameters such as sulfide loading rate (LR) and empty bed  
residence time (EBRT) on the BTF performance.  
pollutants, were taken and enriched by transferring to the  
Thiobacillus medium which contained 2.0g KNO  
NH Cl, 2.0g KH PO , 2.0g NaHCO , 0.8 g MgSO  
.0 g Na .5H O and 1.0 mL trace element in 1000 mL  
distilled water and the pH was adjusted to 6.5 with  
MNaOH. The trace element solution contained 50g Na  
EDTA, 7.34g CaCl .2H O, 5.0g FeSO .7H O, 2.5g  
MnCl .4H O, 2.2g ZnSO .7H O, 0.5g (NH Mo O,  
.2g CaSO .5H O and 11.0g NaOH in 1000 mL of distilled  
3
, 1.0g  
4
2
4
3
4
.7H O,  
2
5
2
S
2
O
3
2
2
Materials and Methods  
2
.1 Experimental set-up  
4
2
-
The laboratory scale system for sour water treatment is  
shown in Figure 1. The BTF (1) is a Plexiglas column of 90  
mm diameter and 600 mm height. It consists of 3 sampling  
2
2
4
2
2
2
4
2
4
)
6
7 2  
O24.4H  
0
4
2
2
ports (2) to measure H S concentration and sample  
water. To enrich the culture, 5 mL of the mixed culture  
sample was inoculated into 100mL of the Thiobacillus  
medium and incubated at 35 °C for 14 days. The increase in  
turbidity of the medium was interpreted as microbial growth.  
After then 10 mL of the medium was inoculated into 100 mL  
of fresh medium and incubated for 14 days once again.  
Samples were streaked on solid medium, incubated at 35 °C,  
and single colonies of the dominant species were assessed  
for morphological and physiological properties as details in  
Table 1.  
The immobilization process of bacterial cells was  
initiated by transferring the packing materials into  
Thiobacillus mineral salts medium (MSM) containing the  
microorganisms, and then the column were packed with cell  
laden packing materials. For one week, the BTF was fed with  
thiosulfate and thereafter sour water was sent to the filter. To  
avoid cells washout from the bed, the liquid flow was fully  
recycled to the BTF during two weeks.  
microorganisms. Sour water (3) and stripped sour water (4)  
from a gas plant were mixed to provide sour water with  
desired concentrations (5). An air blower (6) was used to  
supply air and a diaphragm pump (7) trickled the sour water  
over the BTF. Two rotameters were used to measure the flow  
rates of liquid (8) and gas phases (9). Air flow was firstly  
passed through a stripped sour water container to increase  
the DO concentration in the liquid phase. The outlet air from  
the stripped sour water container was passed through the  
BTF under a co-current flow pattern. After passing through  
the BTF, the treated sour water was collected in a separate  
container (10) and exhaust air was sent to a caustic column  
2
(11) to ensure that H S was not released to the environment.  
2
.2 Materials  
Microorganisms from an operating trickling biofilter,  
-3  
2 2  
treating low levels of H S (up to 5 g S-H S m ) and organic  
Sampling port  
NaOH  
(11)  
BTF  
1)  
Sampling ports (2)  
FI  
Flow meter (9)  
(
Flow meter (8)  
Stripped sour  
water (4)  
5
Treated sour  
water (10)  
Air blower (6)  
Diaphragm pump (7)  
Sour water  
(
3)  
Fig. 1: Schematic of the experimental setup: 1. The BTF; 2. Sampling ports; 3. Sour water container; 4. Stripped sour water  
container; 5. Mixed sour water; 6. Air blower; 7. Diaphragm pump; 8. Liquid flow meter; 9. Gas flow meter; 10. Treated sour  
water container; 11. Caustic column.  
4
98  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 1, Pages: 497-503  
Table 1: Properties of Thiobacillus sp. enriched from operating BTF  
Irregular, grey  
Colony  
Morphology  
Size (μm)  
Gram-staining  
Short rod  
0.5×1.5-2  
Negative  
2
.3 Methods  
3
Results and discussion  
2
H S concentration in the gas phase was determined using  
3
.1 Effect of the inlet concentration  
gas tube sensors (Gastec Co.). Total dissolved sulfide (TDS)  
was analyzed using silver/sulfide ion electrodes (Metler, Cat.  
No. SC-DMI141). Sulfate concentration was measured by a  
turbidimetric method.  
The RE during experiment E1 decreased from 96-99%  
-3 -1  
2
at the lowest LR (78 g S-H S m h ) to 79-82% at the highest  
-3 -1  
2
LR tested (393g S-H S m h ). During this test, the critical  
-3 -1  
and maximum ECs were 151 and 321 g S-H  
2
S m h ,  
respectively as depicted in Fig.2. The critical EC is  
2
.4 Experimental conditions  
Reference operation conditions was defined as the  
comparable to the values reported by Montebello et al. [9]  
-3 -1  
2
160 g S-H S m h ) for biogas treatment of 2000 to 10000  
ppm of H  
160 g S-H  
(
-3  
2 2  
treatment of real sour water containing 20g S-H S m of H S  
-3 -1  
v
2
S in a randomly packed BTF and Lee et al. [10]  
-3 -1  
-
1
at a TLV of 4.72 m h (LR=157 g S-H  
2
S m h ) and an  
(
2 v 2  
S m h ) for removal of 200 to 2200 ppm of H S  
EBRT of 457 s. Experimental conditions for co-current  
systems are summarized in Table 2. After 20 days of steady  
operation at reference conditions, 3 experiments were  
in a BTF packed with porous ceramic materials. However,  
the maximum EC of the BTF is considerably higher than the  
-3 -1  
value obtained by Montebello et al. [9] (223 g S-H S m h )  
(
2
carried out and the effects of H  
liquid flow rates were studied. During experiment E1, H  
inlet concentration was progressively increased from 10 to  
2
S inlet concentration, gas and  
-3 -1  
2
223 g S-H S m h ) since the EBRT in their study (120 s)  
2
S
is significantly lower than the value of the present work at  
the reference conditions (458 s). Besides the elimination  
capacity, the sulfate selectivity also is a determinative  
parameter affecting the BTFs performance treating sulfides.  
Sulfur accumulation inside the biofilm due to the partial  
oxidation of sulfides can clog the bed and significantly  
reduce the EC of the biofilters. Sulfate selectivity for a  
specific microorganism mainly depends on substrate and  
-3  
2
0 g S-H S m at constant liquid and gas flow rates (sulfide  
-3 -1  
LRs from 78 to 393 g S-H  
During experiment E2, at constant H  
5
2
S m h ) for period of 5 days.  
S inlet concentration of  
2
S m , the liquid flow rate was increased stepwise  
2
-
3
2
0 g S-H  
-
3
-1  
from0.015 to 0.075 m h (sulfide LRs from 78 to 393 g S-  
H
concentration and liquid flow rate (constant LR), the air flow  
rate was increased stepwise from 0.01 to 0.04 m  
-
3 -1  
2
S m h ). During experiment E3, at constant H S inlet  
2
2-  
oxygen availability (ratio DO/S ). Theoretically, higher  
-
3
-1  
h to  
2-  
DO/S is more desirable for sulfate production because  
evaluate the effect of the gas contact time on elimination  
capacity of the BTF. Steady state conditions in the BTF was  
ensured at the end of each step by measuring a constant EC  
at the end of each experiment.  
formation of one mole sulfate needs two moles oxygen,  
while one mole sulfur only needs half mole oxygen.  
Table 2: Experimental conditions  
퐶퐿,ꢌꢊꢍ  
Q
L
3
LR  
(g S-H  
Q
G
Duration  
-
3
-1  
S m-3 h ) (m h ) (days)  
-1  
3
-1  
(m h )  
2
Experiment  
E1  
(g S-H  
2
S m )  
1
2
30  
4
5
0
0
78  
157  
235  
314  
393  
78  
157  
235  
314  
393  
0.03  
0.03  
0.03  
5
0
0
0
0
.015  
.030  
E2  
E3  
20  
20  
0.045  
5
4
0
0
.060  
.075  
0
0
0
0
.03  
.04  
.05  
.06  
0.02  
157  
4
99  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 1, Pages: 497-503  
The ratio DO/S2- depends on sulfide and oxygen  
solubility in the liquid phase, and external mass transfer  
coefficients. Solubility is directly linked to Henry's law  
constants which depends on pressure and temperature.  
External mass transfer coefficients are influenced by the  
fluid flow characteristics in both gas and liquid phases and  
are therefore related to Reynolds number. For a specific  
system with constant operating conditions (pressure and  
3.2 H  
2
S removal along the bed  
S removal efficiency throughout the BTF bed height  
H
2
during E1 is depicted in Fig. 3a. The RE was calculated at  
the three sections (1/3, 2/3, 3/3 of the BTF), corresponding  
to the top, middle and bottom sections of the filter. Results  
2
showed that the most significant H S removal occurred at the  
top section of the filter. This was attributed to high oxygen  
availability at the top section due to the preliminary aeration  
of sour water. This results also indicated that at the reference  
conditions, around 71% and only 9% of RE occurred at the  
top and bottom section, respectively. This means that  
operating the BTF at reference conditions for a long period  
can lead to the starvation conditions for biomass and  
consequently decrease of the microorganisms' colonies in  
the bottom section of the reactor.  
The H S concentration of sour water along the bed is  
2
shown in Fig. 3b. As abovementioned the most part of H  
was degraded at the top section of the BTF which caused H  
concentration dropped significantly in this section. In many  
industrial cases, it is not required to completely removed H  
from sour water. For example, desulfurization of sour water  
2
in the gas plants usually does not require of complete H S  
removal since biomass of the downstream unit (waste water  
2
-
temperature), the ratio DO/S becomes only mass transfer  
depended. At the operating conditions usually occurred in  
the BTFs, the liquid-gas mass transfer for both O and H S  
2 2  
is controlled by the liquid phase which depends on liquid  
velocity. Therefore, the main parameter affect the ratio  
2
-
DO/S in the BTFs is the trickling liquid velocity (TLV).  
During experiment E1, sulfate selectivity of the BTF  
decreased from 99% at the beginning of the E1 to 65% at the  
end of the test. Such sulfate selectivity is higher than the  
values reported by Montebello et al. [9, 11] despite the  
higher TLV used in their study. This can be due to various  
biomass with different sulfur production ability. In fact,  
bacteria can obtain their energy and electron from different  
2
S
S
2
2
S
2
-
oxidation pathways (Eqs 1-3). Besides the ratio DO/S , the  
selection of each path is depended on type of microorganism.  
Some bacteria such as Thiothrix sp. oxidizes sulfide to sulfur  
-
3
treatment) can tolerate H  
a sour water containing 20 g S-H  
BTF with one third size of the BTF used in this study.  
2
S up to 5 g S-H  
2
S m . Therefore,  
2
-
-3  
regardless of the ratio DO/S [12] while a mixed culture  
dominated by Thiobacillus sp. oxidizes a part of sulfide to  
sulfate even at low sulfide concentrations [13].  
2
S m can be treated in a  
4
3
3
2
2
1
1
00  
50  
00  
50  
00  
50  
00  
120  
1
8
00  
0
60  
EC  
4
0
RE  
Sulfate Selectivity  
20  
0
5
0
0
0
50  
100  
150  
200  
250  
300  
350  
400  
450  
500  
-3  
-1  
LR EC g S-H S m h  
2
2
Fig. 2: Elimination capacity and removal efficiency versus H S LR during E1  
5
00  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 1, Pages: 497-503  
1
00  
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
(a)  
CL,H2S=10 g m-3  
CL,H2S=30 g m-3  
CL,H2S=50 g m-3  
CL,H2S=20 g m-3  
CL,H2S=40 g m-3  
1
0
20  
30  
40  
50  
60  
70  
Bed Height (cm)  
50  
45  
40  
35  
30  
25  
20  
15  
10  
5
0
(b)  
0
10  
20  
30  
40  
50  
60  
Bed Height (cm)  
Fig. 3: H  
2
2
S removal along the bed height during E1, (a) RE, (b) H S concentration in the sour water  
1
, by increasing the liquid flow rate from 0.015 to 0.075 m3h-  
. As depicted in Fig 4, during this experiment, RE decreased  
3
.3 Effect of TLV  
The effect of TLV on the reactor performance has been  
studied in biofilters for H S removal from gas streams. In gas  
1
2
from 95-98% at the beginning of the test to 84-87% at the  
highest LR tested. During this experiment, the critical EC  
was similar to the obtained during E1, however the  
streams desulfurization, TLV does not affect the LR and the  
aim of its regulating is mainly to increase gas-liquid mass  
transfer coefficient and to avoid sulfur accumulation due to  
oxygen limitation [13]. In sour water treatment, however the  
LR is influenced by the liquid velocity as well as inlet  
concentration. The effect of TLV on the BTF performance  
in this study was assessed during E2. Like experiment E1,  
3 -  
S m h  
-
3 -  
maximum EC was improved by 7% (343.87 g S-H  
2
S m h  
1
). The sulfate selectivity during E2, decreased from 91% to  
73%. The sulfate selectivity at the highest loading rate tested  
during E2 is 9% higher than the value obtained at the same  
loading rate during E1. This result showed that at the high  
sulfide loading rates, where BTFs are usually oxygen mass  
-
the LR was increased stepwise from 78 to 393 g S-H  
2
5
01  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 1, Pages: 497-503  
transfer limited, decrease of gas-liquid external mass transfer  
resistance by increase of the TLV can be an effective method  
to increase both elimination capacity and sulfate selectivity.  
LR is controlled by liquid stream, and gas phase (aeration) is  
just used to provide oxygen as an electron acceptor in aerobic  
systems. The influence of the EBRT on the BTF  
performance in this study was assessed during E3 in which  
EBRT decreased from 458 s to 229 s. As depicted in Fig. 5,  
during this test the BTF removal efficiency was decreased  
from 95-97% to 88-90%. Similar trend was found by  
Chaiprapat et al. [15] who reported a decrease of sulfide RE  
from 80–90% to 30–40% when the EBRT decreased from  
313 to 78 s.  
3
.4 Effect of gas contact time  
The effect of EBRT on the biofilter performance has  
been repeatedly studied for H S removal from energy-rich  
2
gas streams and various EC and critical EBRT have been  
reported [9, 14, 15]. In gas streams treatment, reduction of  
EBRT increases the LR, while in sour water desulfurization,  
4
3
3
2
2
1
1
00  
50  
00  
50  
00  
50  
00  
120  
1
00  
0
8
60  
EC  
4
2
0
0
RE  
0
5
0
Sulfate Selectivity  
0
0
50  
100  
150  
200  
-1  
LR EC g S-H S m h  
250  
300  
350  
400  
450  
500  
-
3
2
2
Fig. 4: Elimination capacity and removal efficiency versus H S LR during E2  
100  
95  
90  
85  
80  
75  
70  
65  
60  
55  
50  
RE  
Sulfate selectivity  
0
.02  
0.025  
0.03  
0.035  
0.04  
Qg (m h )  
0.045  
-1  
0.05  
0.055  
0.06  
0.065  
3
Fig. 5: Removal efficiency and sulfate selectivity versus gas flow rate  
5
02  
Journal of Environmental Treatment Techniques  
2020, Volume 8, Issue 1, Pages: 497-503  
Reduction of removal efficiency due to decrease of  
EBRT was related to mass transfer limitation due to low  
solubility of both H S and O . The sulfate selectivity during  
2 2  
E3 was almost constant (79%) reflecting that aeration rate  
does not affect the sulfate selectivity. This results indicated  
that in sour water treating, the aeration rate should be kept as  
low as possible and oxygen mass transfer should be  
improved by TLV regulating.  
desulfurization through a multi-step oxidation mechanism.  
Chemical Engineering Journal. 2016;294:447-57  
Vikromvarasiri N, Champreda V, Boonyawanich S, Pisutpaisal  
N, Hydrogen sulfide removal from biogas by biotrickling filter  
inoculated with Halothiobacillus neapolitanus. International  
journal of hydrogen energy. 2017;42, 18425-33  
Kanjanarong J, Giri B S, Jaisi D P, Oliveira F R, Boonsawang  
P, Chaiprapat S, Sing R S, Balakrishna A, Khanal S K.  
Removal of hydrogen sulfide generated during anaerobic  
treatment of sulfate-laden wastewater using biochar: Evaluation  
of efficiency and mechanisms. Bioresource Technol0gy. 2017;  
4
5
2
Conclusion  
Biofilters were demonstrated to be an effective  
2
34:115-121  
2
Liang M S, Liang Y. Biologcal removal of H S from the  
livestock manure using biofilter. Biotechnology  
6
7
alternative to the traditional methods for removing H  
energy-rich gas streams and polluted air. In this study, a BTF  
was used to remove H S from sour water and the effects of  
2
S from  
a
Bioprocessing Engineering. 2013;18:1008-15  
Jaber M.B, Couvert A, Amrane A, Rouxel F, Cloirec P L,  
2
2
Dumont E. Biofiltration of high concentration of H S in waste  
air under extreme acidic conditions. New Biotechnology.  
016;33:136-143  
inlet concentration, TLV and gas contact time on the  
performance of the BTF were investigated. The sulfate  
selectivity during all tests was also assessed. Results showed  
that biological treatment can be used as a viable alternative  
to traditional methods (stripping in a packed or try columns)  
2
8
9
Chen Y, Wang X, He S, Zhu, S. Shen S. The performance of a  
two-layer biotrickling filter filled with new mixed packing  
materials for the removal of  
2
H S from air, Journal of  
for H  
sulfate selectivity compared to previous studies which was  
referred to tendency of microorganism to fully oxidized H  
to sulfate. Results also indicated that the most significant  
S removal occurred at the top section of the BTF which  
2
S removal from sour water. The BTF showed a high  
Environmental Management. 2016;165: 11-16  
Montebello A M, Moraa M, Lópeza L R, Bezerraa T,  
Gamisansb X, Lafuentea J, Baezac M, Gabriela D. Aerobic  
desulfurization of biogas by acidic biotrickling filtration in a  
randomly packed reactor, Journal of Hazardous Material.  
2
S
H
2
2
014;280:200-208  
was attributed to the high oxygen availability at the top  
section due to the preliminary aeration of sour water.  
1
0
Lee E Y, Lee N Y, Cho K S, Ryu H W. Removal of hydrogen  
sulfide by sulfate-resistant Acidithiobacillus thiooxidans AZ11,  
Journal of Bioscience and Bioengineering. 2006;101:309-314  
Aknowledgment  
11 Montebello A M, Baezac M, Lafuentea J, Gabriela D.  
Monitoring and performance of a desulfurizing biotrickling  
filter with an integrated continuous gas/liquid flow analyzer,  
Chemical Engineering Journal. 2010;165:500-507  
The authors would like to thank the laboratory staff of  
4th Gas Plant of “South Pars Gas Complex” (SPGC) for their  
technical support.  
1
2
Mora M, López L R, Lafuente J, Pérez J, Kleerebezem R, Van  
Loosdrecht M, Gamisans X, Gabriel D. Respirometric  
characterization of aerobic sulfide, thiosulfate and elemental  
sulfur oxidation by S-oxidizing biomass. Water Research.  
Ethical issue  
Authors are aware of, and comply with, best practice in  
publication ethics specifically with regard to authorship  
2
016;89:282-292  
1
3
López L R, Bezerra T, Mora M, Lafuente J, Gabriel D.  
Influence of trickling liquid velocity and flow pattern in the  
improvement of oxygen transport in aerobic biotrickling filters  
for biogas desulfurization. Journal of Chemical Technology and  
Biotechnology. 2016;91:1031-39  
(avoidance of guest authorship), dual submission,  
manipulation of figures, competing interests and compliance  
with policies on research ethics. Authors adhere to  
publication requirements that submitted work is original and  
has not been published elsewhere in any language.  
14 Fortuny M, Gamisans X, Deshusses M A, Lafuente J, Casas C,  
Gabriel D. Operational aspects of the desulfurization process of  
energy gases mimics in biotrickling filters. Water Research.  
Competing interests  
The authors declare that there is no conflict of interest  
that would prejudice the impartiality of this scientific work.  
2
011;45:5665-74.  
1
5
Chaiprapat S, Mardthing R, Kantachote D, Karnchanawong S.  
Removal of hydrogen sulfide by complete aerobic oxidation in  
acidic biofiltration. Process Biochem. 2011;46(1):344-52.  
Authors’ contribution  
All authors of this study have a complete contribution  
for data collection, data analyses and manuscript writing  
References  
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