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International Journal of Phytoremediation
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/bijp20
The evaluation of bacterial-augmented floating
treatment wetlands for concomitant removal of
phenol and chromium from contaminated water
Iffat Rashid, Syed Najaf Hasan Naqvi, Hareem Mohsin, Kaneez Fatima,
Muhammad Afzal, Fahad Al-Misned, Irshad Bibi, Fawad Ali & Nabeel Khan
Niazi
To cite this article: Iffat Rashid, Syed Najaf Hasan Naqvi, Hareem Mohsin, Kaneez Fatima,
Muhammad Afzal, Fahad Al-Misned, Irshad Bibi, Fawad Ali & Nabeel Khan Niazi (2023): The
evaluation of bacterial-augmented floating treatment wetlands for concomitant removal of
phenol and chromium from contaminated water, International Journal of Phytoremediation,
DOI: 10.1080/15226514.2023.2240428
To link to this article: https://doi.org/10.1080/15226514.2023.2240428
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The evaluation of bacterial-augmented floating treatment wetlands for
concomitant removal of phenol and chromium from contaminated water
Iffat Rashid
a
, Syed Najaf Hasan Naqvi
b
, Hareem Mohsin
a
, Kaneez Fatima
a
, Muhammad Afzal
b
,
Fahad Al-Misned
c
, Irshad Bibi
d
, Fawad Ali
e,f
, and Nabeel Khan Niazi
d
a
Department of Life Sciences, School of Science, University of Management and Technology, Lahore, Pakistan;
b
Soil and Environmental
Biotechnology Division, National Institute for Biotechnology and Genetic Engineering, Faisalabad, Pakistan;
c
Department of Zoology, College
of Science, King Saud University, Riyadh, Saudi Arabia;
d
Institute of Soil and Environmental Sciences, University of Agriculture Faisalabad,
Faisalabad 38040, Pakistan;
e
Centre of Planetary Health and Food Security, Griffith University, Nathan Campus (4111), Brisbane, QLD,
Australia;
f
Department of Agriculture and Fisheries (QDAF), Mareeba (4880), QLD, Australia
ABSTRACT
Contamination of aquatic ecosystems with organic and inorganic contaminants is a global threat
due to their hazardous effects on the environment and human health. Floating treatment wetland
(FTW) technology is a cost-effective and sustainable alternative to existing treatment approaches.
It consists of a buoyant mat in which wetland plants can grow and develop their roots in a sus-
pended manner and can be implemented to treat stormwater, municipal wastewater, and indus-
trial effluents. Here we explored the potential of bacterial-augmented FTWs for the concurrent
remediation of phenol and hexavalent chromium (Cr
6þ
) contaminated water and evaluated treated
water toxicity using Triticum aestivum L. (wheat) as a test plant. The FTWs carrying Phragmites aus-
tralis L. (common reed) were inoculated with a consortium of four bacterial strains (Burkholderia
phytofirmans PsJN, Acinetobacter lwofii ACRH76, Pseudomonas aeruginosa PJRS20, Bacillus sp.
PJRS25) and evaluated for their potential to simultaneously remove phenol and chromium (Cr)
from contaminated water. Results revealed that the FTWs efficiently improved water quality by
removing phenol (86%) and Cr (80%), with combined use of P. australis and bacterial consortium
after 50 days. The phytotoxicity assay demonstrated that the germination of wheat seed (96%)
was significantly higher where bacterial-augmented FTWs treated water was used compared to
untreated water. This pilot-scale study highlights that the combined application of wetland plants
and bacterial consortium in FTWs is a promising approach for concomitant abatement of phenol
and Cr from contaminated water, especially for developing countries like Pakistan where the appli-
cation of advanced and expensive technologies is limited.
NOVELTY STATEMENT
This pilot-scale research provides new interventions and information required for establishing a
large-scale remediation framework for the effective, sustainable and eco-friendly remediation of
phenol and Cr co-contaminated aquatic ecosystems, using bacterial augmented floating wetlands
technology (FTWs).
KEYWORDS
Bioremediation; health;
organic and inorganic co-
contamination; sustainable
remediation; water
treatment
Introduction
Industrialization and urbanization led to the over-exploit-
ation of natural water and soil resources globally, and espe-
cially in developing countries. Despite getting advantages
from these rapid advancements, the planet, Earth, is getting
harmed to an irreversible extent (Ali et al.2023; Gayathiri
et al. 2022). Untreated wastewater containing various mixed
contaminants is released into the aquatic and terrestrial
environments and causes potential risks to the food chain
(Batra et al. 2022; Younas et al.2023). A huge percentage of
industrial wastewater is dumped into the water bodies and
land, which makes them the most contaminated and dam-
aged component of the biosphere. Industrial effluents typic-
ally consist of organic (e.g., crude oil, phenols, aromatic
compounds) and inorganic (such as heavy metals) contami-
nants. Among the mixed toxic substances, chromium (Cr)
and phenol are reported to be simultaneously present in
industrial wastewater (Bhattacharya et al. 2015), which are
discharged directly into the water without prior treatment
(Guo et al. 2021; Shah et al. 2022).
Chromium is a toxic metal existing in trivalent (Cr
3þ
)
and hexavalent (Cr
6þ
) forms (Younas et al. 2022). It is
widely used in the tanning industry (Tripathi et al. 2022).
CONTACT Kaneez Fatima kaneezfatima77@yahoo.com Department of Life Sciences, School of Science, University of Management and Technology, Lahore,
Pakistan; Nabeel Khan Niazi nabeelkniazi@gmail.com,nabeel.niazi@uaf.edu.pk Institute of Soil and Environmental Sciences, University of Agriculture
Faisalabad, Faisalabad 38040, Pakistan.
Supplemental data for this article can be accessed online at https://doi.org/10.1080/15226514.2023.2240428.
ß2023 Taylor & Francis Group, LLC
INTERNATIONAL JOURNAL OF PHYTOREMEDIATION
https://doi.org/10.1080/15226514.2023.2240428
The toxicity of both forms of Cr is related to their oxidation
state, solubility, and bioavailability (Nowicka 2022). Cr
6þ
is
more toxic, mutagenic, and carcinogenic than Cr
3þ
; the for-
mer is reported to cause shortness of breath, skin burns,
neurological and gastrointestinal effects, abdominal pain,
vomiting and hemorrhage when ingested in high quantities
by humans or animals (Yasir et al. 2021). The recommended
limits for Cr concentration in well water/groundwater is
0.5 mg/L (Ullah et al. 2022). Under natural conditions,
plant’s Cr content is <1lg/g. Toxicity of Cr has been
reported in plant nutrient solution 0.5–5 mg/L and in soil 5–
100 mg/g (Kapoor et al. 2022). Above this concentration, Cr
inhibits plant growth, creates nutrient imbalance and affects
biochemically important processes in plants. Further to the
above, Cr is responsible for interfering with DNA replication
in microbes, which leads to mutation and altering the
enzyme structures (Hossini et al. 2022). In the case of phe-
nol (an organic contaminant), it is a toxic aromatic com-
pound that is used in the production of phenolic resins,
nylon, and other synthetic fibers (Supreeth 2022). Like Cr, it
can cause serious health hazards to humans, such as skin
irritation, reproductive, and developmental damage in
humans (Garg et al. 2022). Hence, the US Environmental
Protection Agency (USEPA) has set a safe concentration of
phenol in wastewater at 0.1 mg/L (United States
Environmental Protection Agency) (EPA 2023).
Various chemical and mechanical techniques such as pre-
cipitation, coagulation/flocculation, and screening are com-
monly employed in wastewater treatment, but they have
certain limitations. Such as, these physico-chemical
approaches require significant energy inputs, which lead to
increased operational costs (Kumar et al. 2022). The floating
treatment wetlands (FTWs) turned out to be the most
promising solution for remediation of both organic and
inorganic contaminants remediation (Singh et al. 2022).
Floating treatment wetlands technology has gained much
attention because it is a cost-effective, environmentally
friendly, esthetically pleasing, and effective water treatment
approach (Rehman et al. 2019). The setup allows maximum
root contact with wastewater for effective Cr and phenol
removal through various mechanisms such as phytoextrac-
tion, phytotransformation, phytostabilization, rhizofiltration
and phytovolatilization (Sinha et al. 2009; Sharma et al.
2021). Moreover, plant roots in floating mats provide a
habitat for the microorganisms to survive either aerobically
or anaerobically, resulting in biofilm (Shahid et al. 2020).
Several remediation strategies are employed using bacteria
such as, biosorption, bioaccumulation, biotransformation,
and bioleaching to convert Cr
6þ
to Cr
3þ
; the later being less
toxic and immobile (Shahid et al. 2020). To detoxify phenol,
bacteria may possess phenol hydroxylase enzymes which
breaks down the phenol to catechol followed by further deg-
radation to intermediates such as muconic acid and fumar-
ate, thus entering central metabolic pathways for energy
generation. Thus, beneficial association between plants
and microbes facilitates the efficient removal of toxic
chemicals/substances and contributes to the overall purifica-
tion of wastewater in FTWs (Shahid et al. 2020).
While remediation of complex Cr and phenol co-contami-
nated water has not been explored previously, this study investi-
gated the potential of FTWs planted with Phragmites australis
L. (common reed) along with bacterial co-cultures for the con-
comitant elimination of phenol and Cr from contaminated
water. Equally important, the efficiency of FTWs for wastewater
treatment was also evaluated through a phytotoxicity bioassay of
the treated wastewater, using Triticum aesativum as a test plant.
Materials and methods
Bacterial strains and wetland plant
To assess removal of phenol and Cr from contaminated
water, four bacterial strains were used for phenol degrad-
ation namely: Burkholderia phytofirmans Ps.JN,
Acinetobacter sp. CYRH21, Acinetobacter lwofii ACRH76,
Bacillus pumilus A1 (Saleem et al. 2019), and five bacterial
strains (Staphylococcus saprophyticus PJSl1, Pseudomonas
aeruginosa PJRS20, Bacillus sp. PJRS25, Microbacterium
arborescens HU33, Enterobacter sp. HU38) (Khan et al.
2015) were used for Cr removal from wastewater.
Phragmites australis L. (Common reed), a halophytic grass,
was chosen to develop FTWs because of its well-known ability
to survive in the presence of various contaminants (Shi et al.
2018; Saleem et al. 2019;Younaset al. 2022).
Determination of minimal inhibitory concentrations
(MICs)
Resistance against phenol and chromate (Cr
6þ
) was examined
separately (Panneerselvam et al. 2013;Poiet al. 2017). Bacterial
strains were aseptically inoculated on minimal salt medium
(MSM) agar plates containing 10 to 100 mg/L of Cr
6þ
and incu-
bated at 37 C for 72 h. While plates of MSM comprising 100
to 1,500 mg/L phenol were spot-inoculated with selected bacter-
ial strains and incubated at 37Cfor72h(Darmaet al. 2020).
In vitro compatibility among selected bacterial strains
The compatibility of selected bacterial strains was studied by
co-culturing them on MSM agar medium. Co-inoculated
strains were streaked perpendicularly and plates were sub-
jected to incubation at 37 C for 24 h and observed for zone
of inhibition. After compatibility test, bacterial strains were
cultivated separately in MSM broth at 37 C for 24 h fol-
lowed by culture standardization with 0.5 McFarland
standard. Bacterial cells were harvested by centrifugation
and re-suspended in sterile 0.9% NaCl solution. After re-sus-
pension, bacterial strains were equally mixed in 1:1:1:1 ratio
to formulate bacterial consortium (Fatima et al. 2018).
Simultaneous removal of phenol and chromium by
bacterial consortium
For the concomitant removal of phenol and Cr, selected
bacterial consortium (1%) was inoculated in 250 mL
Erlenmeyer flasks containing 100 mL MSM broth with
2 I. RASHID ET AL.
phenol or Cr concentrations (phenol/Cr: 100/5, 300/15,
500/25, 700/35, 900/45 and 1,100/55 mg/L) (Chandrasekaran
et al. 2018). All the flasks along with control were incubated
in a shaking incubator for 7 days at 37 C and 120 rpm. The
FTW experiment was performed in triplicate and percentage
removal of Cr and phenol was calculated as follows:
Removal %
ðÞ
¼
Initial concentration final concentration
initial
concentration
2
43
5100
Development of FTWs
Fifteen FTWs microcosms were developed using a polystyr-
ene sheet as a mat. The sheet was cut in a circular shape;
each mat was bored to create a hole to insert five healthy
seedlings of P. australis. The mats with seedlings were
placed over the water tanks having 20 L tap water. The
plants were allowed to develop their roots in the tap water
for one month, the tap water was replaced with phenol
(500 mg/L) and Cr (25 mg/L) co-contaminated water. Each
treatment was run in triplicate in natural environmental
conditions at the National Institute for Biotechnology and
Genetic Engineering (NIBGE) in Faisalabad, Pakistan.
Control (C1): fresh water (without phenol and Cr) hav-
ing FTWs
Control (C2): water contaminated with phenol
(500 mg/L) and Cr (25 mg/L) without FTWs
Treatment 1 (T1): water contaminated with phenol
(500 mg/L) and Cr (25 mg/L) and FTWs
Treatment 2 (T2): water contaminated with phenol
(500 mg/L), Cr (25 mg/L), FTWs and bacterial
consortium
Treatment 3 (T3): water contaminated with phenol
(500 mg/L), Cr (25 mg/L) and bacterial consortium
Analysis of residual concentration of phenol and Cr in
water
Treated water samples were collected for 50 days at 10 days
intervals as reported earlier (Afzal et al. 2014). The residual
concentration of phenol in treated water was detected spec-
trophotometrically. Water samples (25 mL) were taken and
ammonium hydroxide (NH
4
OH; 0.5 mL) solution was added
to it before analysis. The pH was adjusted immediately to
7.9 ± 0.1 with phosphate buffer; 0.5 mL 4-amino antipyrine
(APP) solution and one mL potassium ferricyanide (K
3
Fe
(CN) 6) solution were added into it and mixed well. After
15 min, absorbance was recorded at 500 nm using an UV-Vs
Spectrophotometer (Shimadzu, Japan, CECIL CE7200) and
readings were compared with standard phenol.
Water samples were collected to analyze Cr
6þ
removal by
1,5-diphenylcarbazide (DPC) method as previously described
by (Lace et al. 2019). Briefly, 10 mL sample was added in
test tubes, followed by a few drops of 3 M H
2
SO
4
and
0.5 mL DPC. The absorbance of the mixture was taken at
540 nm using an UV-Vis Spectrophotometer.
Plant growth
Plants were harvested after 50 days of growth in FTWs.
Plant roots were washed carefully with tap water, followed
by rinsing in deionized water. Roots and shoots were cut
and their length and biomass were recorded for each treat-
ment. The plant samples were oven-dried at 65 C for three
days and dry biomass was recorded as well (Hwang et al.
2020).
Evaluation of toxicity of treated water
Phytotoxicity bioassay was performed to asses the efficacy of
bacterial augmented FTWs treated wastewater using
Triticum aestivum L. (wheat) seeds. Firstly, all seeds were
surface sterilized with 0.01% sodium hypochlorite for 1 to
2 min, then rinsed two or three times in distilled water. The
seeds (30) were placed in 80 mm diameter petri plates con-
taining agricultural uncontaminated soil (300 g). For 7 days,
3 mL tap water, phenol and Cr contaminated water and bac-
terial augmented FTWs treated water were sprinkled on
seeds. The percentage of seed germination was recorded
after 7 days (L
opez-Luna et al. 2009).
Statistical analysis
Data were analyzed using the SPSS software package (SPSS
Inc., Chicago, IL, USA) and analysis of variance was applied
following Duncan’s multiple range test (MRT) to estimate
significant variances between treatments.
Results
Determination of phenol and chromium resistance
Two strains, Ps.JN and ACRH76, exhibited maximum
growth in the presence of phenol at 1,100 mg/L. The A1 and
CYRH21 showed resistance against phenol upto 500 mg/L
(Table S1). Moreover, PJRS20 and PJRS25 were capable to
grow in the presence of Cr upto 60 mg/L, while PJS11,
HU33 and HU38 showed maximum resistance up to 40 mg/
L(Table S2).
The bacterial strains exhibiting maximum resistance were
checked for their compatibility to formulate bacterial con-
sortium. Bacterial strains, namely Ps.JN, ACRH76, PJRS20
and PJRS25, were able to grow on MSM agar plates as no
clearing zone was observed.
Microbial growth and simultaneous removal of phenol
and chromium
Bacterial consortium was able to grow at 500 and 25 mg/L
phenol and Cr concentrations, respectively. The maximum
Cr decrease at 25 mg/L concentration was 36% while for
phenol it was 51% at 500 mg/L (Figure 1). Phenol and Cr
reduction was not observed in sterile MSM controls.
INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 3
Plant growth monitoring study
The effect of bacterial inoculation on roots, shoots and bio-
mass of P. australis was recorded at the end of the experi-
ment (Table 1). In phenol-Cr co-contaminated water,
bacterial inoculation significantly increased root length
(14%) and shoot length (9%) of P. australis. It produced
lower amount of biomass compared to the plants in polluted
water (Table 2), although inoculation of bacterial consor-
tium enhanced plant growth and hence biomass.
Removal of phenol and Cr by FTWs
The elimination of phenol and Cr in different FTWs is pre-
sented in Figure 2. The initial concentration of phenol in
contaminated water was 500 mg/L and for Cr it was
25 mg/L. A minimal reduction in the concentrations of phe-
nol and Cr was detected in the treatments, where bacterial
consortium was inoculated without vegetation (T3). In T3,
61% phenol and 44% Cr concentration were reduced com-
pared to control. For vegetated reactors, removal percentage
(67% phenol and 60% Cr) was slightly high (T1), albeit
maximum removal (86% phenol and 80% Cr) was found in
the vegetated reactors with bacterial consortia (T2).
Phytotoxicity bioassay
Phytotoxicity bioassay was performed to determine the
detoxification level of treated water. Results showed that
there was more germination of seeds (96%) exposed to
the water treated in FTWs augmented with the bacterial
consortium (T2). Minimum seed germination (30%) was
observed by the seeds exposed to untreated phenol- and
Cr-contaminated water.
Discussion
Environmental contaminants, either organic or inorganic,
present a grave challenge to the development of a sustain-
able ecosystem. Industries tend to produce tons of pollu-
tants, thus releasing them to the water and soil
environments, which not only damage the ecosystem, but
also pose a serious long lasting threat due to their persistent
nature (Singh et al. 2021). In this study, combined applica-
tion of selected bacterial consortium (Ps.JN, ACRH76,
PJRS20 and PJRS25) and P. australis were chosen to assess
simultaneous removal of Cr and phenol from polluted water
because of their reported resistance and growth in the pres-
ence of these environmental pollutants.
For the selection of phenol resistant bacterial strains,
MIC was performed for PsJN, ACRH76, A1, and CYRH21.
The results showed that PsJN and ACRH76, resisted phenol
up to a concentration of 1,300 mg/L while A1 and CYRH21
showed growth till 1,100 mg/L (Table S1). Several studies
have focused on the catabolic genes of gram-negative bac-
teria such as Pseudomonas, Burkholderia, Acinetobacter, and
Sphingomonas (Gao et al. 2017; Tian et al. 2017). They carry
dioxygenase and catechol 2, 3-dioxygenase genes which are
essential for the removal of a variety of toxicants in polluted
sites (Murphy et al. 2023).
In the case of Cr
þ6
resistant bacterial strains, MIC was
performed for PJRS20, PJRS25, HU33 and HU38. The
results revealed that PJRS20 and PJRS25 resisted Cr
6þ
up to
100 mg/L while HU33 and HU38, showed growth up to
80 mg/L (Table S2). Resistance to Cr could be due to the
efflux pumps taking up Cr
6þ
and reducing it to less toxic
form (Cr
3þ
) in the presence of Cr reductase enzyme. Hence,
on the basis of MIC, PsJN, ACRH76, PJRS20, and PJRS25
were chosen for a compatibility test, formulation of bacterial
consortium and simultaneous removal of phenol and Cr.
In MSMs, bacterial consortium simultaneously reduced
the phenol and Cr concentrations by 51% and 36% respect-
ively compared with values of controls (Figure 1).
Bhattacharya et al. (2014) reported efficient concomitant
removal of phenol and Cr using Acinetobacter sp. B9.
Initially, the water was contaminated with phenol (47 mg/L)
and Cr
6þ
(16 mg/L). The complete elimination of phenol
and 87% reduction of Cr
6þ
were observed, displaying the
proficiency of the bacterial strain for probable application in
Figure 1. Representaion of simultaneous removal of Phenol and Cr by selected
bacterial consortium (PsJN, ACRH76, PJRS20 and PJRS25) showing a maximum
51% of phenol and 36% of Cr removal.
Table 1. Effect of bacterial consortium on the growth of Phragmites australis.
Treatment
Initial day Final day (50)
Root length (cm) Shoot length (cm) Root length (cm) Shoot length (cm)
Control 1 19
a
(1.2) 27
a
(2.5) 34
b
(3.1) 58
b
(3.6)
T1 18
a
(1.1) 26
a
(2.4) 29
a
(2.6) 40
a
(3.6)
T2 16
a
(1.0) 28
a
(2.6) 40
c
(3.5) 65
c
(3.9)
Control 1: Treatment containing fresh water (without phenol and Cr) and vegetated with P. australis; T1: Treatment contain-
ing phenol and Cr contaminated water and vegetated with P. australis; T2: Treatment containing phenol and Cr contami-
nated water, selected bacterial consortium and vegetated with P. australis Each value is the mean of three replicates;
means in the same column followed by different letters are statastically different at a 5% level of significance; standard
deviations are presented in parentheses.
4 I. RASHID ET AL.
industrial contamination control. The strain ACRH76 is also
an identified bacterium from genus Acinetobacter and results
in phenol and Cr removal from the water. Yasir et al.
(2021) observed that the use of Burkholderia sp. led to sim-
ultaneous elimination of chlorinated biphenyls and Cr
þ6
which complies with our results, as PsJN was identified as
Burkholderia phytofirmans.
Plants and microbes are well known to reduce, detoxify,
and degrade environmental pollutants. But, the main disad-
vantage is their slow removal process (Priyadarshanee and
Das 2021). However, the combined usage of microbes and
plants have been proven as cost-effective and efficient
method (Ancona et al. 2022; Raklami et al. 2022; Yaashikaa
et al. 2022). In pilot-scale study, the treatment T1 (water
contaminated with phenol (500 mg/L) and Cr (25 mg/L) and
FTWs) led to reduce 67% phenol and 60% Cr, while treat-
ment T3 (water contaminated with phenol (500 mg/L), Cr
(25 mg/L) and bacterial consortium) was successful in
removing 61% phenol and 44% Cr. The Treatment T2
(water contaminated with phenol (500 mg/L), Cr (25 mg/L)
FTW and bacterial consortium) exhibited 86% and 80%
removal of phenol and Cr, respectively. Saleem et al. (2019)
reported that the removal rate of phenol (96%) was signifi-
cantly high in the treatment where vegetation and bacterial
consortium was used as compared with the individual part-
ners, i.e., plants (66%) and bacteria (61%) separately.
Sharma et al. (2021) reported that FTWs vegetated with
Eichhornia crassipes (water hyacinth) can remove 98.83% of
Cr from the tannery effluent. When the plants and bacteria
are used in combination, plants release chemicals and
nutrients resulting in chemotaxis while bacteria produce
essential enzymes and metabolites like dioxygenases, 1-ami-
nocyclopropane-1-carboxylate (ACC) deaminase, Indole 3-
acetic acid (IAA) etc. enabling plants to survive in pollutant
rich environment (Danish et al. 2019; Del Carmen et al.
2020).
The controlled application of pretreated wastewater in
horticulture or main water bodies is a common practice in
many countries (Chojnacka et al. 2020; Kumar and Goyal,
2020). Seed germination of wheat was assessed to determine
the efficiency of FTWs treated wastewater. The results
revealed that maximum seed germinations were recorded in
T2 (vegetation þbacteria) as compared to T1 (vegetation
only) and T3 (bacteria only) treated wastewater. This is
because of the maximum removal of phenol and Cr from
water by the combined application of bacterial consortium
and FTWs. These results are in compliance with the study
conducted by Phoungthong et al. (2016).
Hence, the selected bacterial consortium along with con-
structed FTW in our study proved to be an effective strategy
to treat co-contaminated water, which also allows the use of
treated wastewater for agricultural purposes (Magwaza et al.
2020; Oliveira et al. 2021). The study also paves the way to
conduct similar field experiments and evaluate the real-time
success in long-term processes.
Conclusions
The findings from this study reveal that bacterial augmented
Phragmites australis in FTWs represents a potent solution
for simultaneous removal of phenol and Cr from contami-
nated water and can be an alternative approach for conven-
tional wastewater treatment. Inoculated bacteria (PsJN,
ACRH76, PJRS20 and PJRS25) helped P. australis in the
removal of phenol (86%) and Cr (80%) from water with
improved plant biomass compared to plants grown in unin-
oculated treatments. Hence, we suggest that bacterial aug-
mented FTWs is a promising, environmentally-friendly and
cost-effective solution for effective treatment of organic and
inorganic contaminants. As this is a pilot-scale study, further
research is required to assess the impact of selected bacterial
consortium, wetland plant and optimum conditions to
implement this set-up at a large-scale where co-contamin-
ation of organic and inorganic pollutants prevails in real-
world scenario.
Acknowledgments
We are thankful to Soil and Environmental Biotechnology Division,
National Institute for Biotechnology and Genetic Engineering,
Faisalabad for providing necessary facilities. Thanks are extended by
Dr. Nabeel Khan Niazi to the Higher Education Commission of
Pakistan. The authors are grateful to the Researchers Supporting
Project No. RSP-2023/24, King Saud University, Riyadh, Saudi Arabia.
Table 2. Effect of bacterial consortium on the biomass of Phragmites australis.
Trearment
Fresh biomass (g/FTW unit) Dry biomass (g/FTW unit)
Root Shoot Root Shoot
Control 1 19
b
(2.9) 68
b
(5.3) 10
b
(2.4) 41
b
(3.5
T1 13
a
(1.7) 57
a
(5.8) 6
a
(1.9) 34
a
(3.8)
T2 28
c
(3.0) 81
c
(6.5) 19
c
(3.2) 58
c
(4.5)
Control 1: Treatment containing fresh water (without phenol and Cr) and
vegetated with P. australis; T1: Treatment containing phenol and Cr contami-
nated water and vegetated with P. australis; T2: Treatment containing phe-
nol and Cr contaminated water, bacterial consortium and vegetated with P.
australis. Each value is the mean of three replicates; means in the same col-
umn followed by different letters are statastically different at a 5% level of
significance; standard deviations are presented in parentheses.
Figure 2. Simultaneous removal of phenol and Cr by selected bacterial consor-
tium (PsJN, ACRH76, PJRS20, and PJRS25) and FTWs in pilot-scale study. C: phe-
nol and Cr contaminated water, T1: phenol and Cr-contaminated water þFTW,
T2: phenol and Cr contaminated water þFTW and bacteria, T3: phenol and Cr
contaminated water þbacteria. The error bars represent the standard errors.
INTERNATIONAL JOURNAL OF PHYTOREMEDIATION 5
Disclosure statement
No potential conflict of interest was reported by the author(s).
Funding
This work was supported by Higher Education Commission (HEC)
Pakistan.
ORCID
Muhammad Afzal http://orcid.org/0000-0003-1511-816X
Nabeel Khan Niazi http://orcid.org/0000-0003-4459-1124
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