Determination of anionic surfactants in wastewater treatment plant in Algiers City

Abstract

A spectrophotometric method was adapted for the determination of anionic surfactants (AnS) using the Crystal Violet. Anionic surfactant gives an ion pair with the dye, which is extracted with an organic solvent. The developed method has been studied and optimized for various parameters, such as the effect of the buffer solution on the extraction of the ion pair (pH 8.1) and the volume of solvent extraction (15 mL). Determination of AnS in distilled water gives good precision and a significant detection limit up to 2.5 × 10−6 M. Interferences have been eliminated by determining AnS in seawater. An application part for this method was carried out in the determination of AnS in an estuary treatment plant in Algiers city. Many results have been obtained and some interesting observations are made. For this, the optimized method for anionic surfactant determination gives significant and reproducible results.

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Determination of anionic surfactants in
wastewater treatment plant in Algiers City
A. Ferradj & M. Idouhar
To cite this article: A. Ferradj & M. Idouhar (2016) Determination of anionic surfactants
in wastewater treatment plant in Algiers City, Desalination and Water Treatment, 57:53,
25677-25685, DOI: 10.1080/19443994.2016.1157038
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Determination of anionic surfactants in wastewater treatment plant in Algiers
City
A. Ferradj*, M. Idouhar
Lab. Organic Chemistry Applied, Faculty of Chemistry, University of Sciences and Technology Houari Boumediene, USTHB, BP 32
El Alia, Bab Ezzouar, Algiers, Algeria, emails: Ferradj.abdelhak@gmail.com (A. Ferradj), hocineanis@gmail.com (M. Idouhar)
Received 16 February 2014; Accepted 16 February 2016
ABSTRACT
A spectrophotometric method was adapted for the determination of anionic surfactants
(AnS) using the Crystal Violet. Anionic surfactant gives an ion pair with the dye, which is
extracted with an organic solvent. The developed method has been studied and optimized
for various parameters, such as the effect of the buffer solution on the extraction of the ion
pair (pH 8.1) and the volume of solvent extraction (15 mL). Determination of AnS in dis-
tilled water gives good precision and a significant detection limit up to 2.5 ×10
−6
M. Inter-
ferences have been eliminated by determining AnS in seawater. An application part for this
method was carried out in the determination of AnS in an estuary treatment plant in
Algiers city. Many results have been obtained and some interesting observations are made.
For this, the optimized method for anionic surfactant determination gives significant and
reproducible results.
Keywords: Anionic surfactant; Spectrophotometry; Wastewater treatment plant
1. Introduction
The importance of water pollution has increased
significantly since the early 60s worldwide. In indus-
trialized countries, large programs have slowed the
progression of contamination of fresh- and seawater.
This contamination is due to the discharge of domestic
and industrial effluents containing organic materials.
Among these organic compounds, AnS are used in
daily life through commercial detergents, cosmetics,
and many industrial applications. It should be noted
that their high consumption or use has unfortunately
negative consequences on the environment [1,2].
Indeed, direct impacts on different areas are proven as
the pollution from various industrial and urban waste
draining large amounts of these compounds to marine
and freshwaters [3,4].
Several techniques have been developed [5–11]in
order to analyze anionic surfactants (AnS) in indus-
trial and urban waste [12–20]. Generally, different
levels of AnS are determined by UV–visible spec-
trophotometry, based on the principle of extracting
AnS as an ion pair in a suitable organic solvent using
a cationic organic dye [21–24]. AnS concentration is
deduced by measuring the absorbance of the organic
phase to the maximum wavelength of absorption of
the dye.
The ethyl violet offers a wide opportunity for AnS
extraction with different organic solvent, such as ben-
zene and toluene. It is one among the dyes that gives a
steady ion pair extracted in a single step, and it has
been used for the determination of AnS levels in marine
*Corresponding author.
1944-3994/1944-3986 Ó2016 Balaban Desalination Publications. All rights reserved.
Desalination and Water Treatment 57 (2016) 25677–25685
November
www.deswater.com
doi: 10.1080/19443994.2016.1157038

waters [25]. Introduction of Methyl Violet in this
technique proves that this dye [26,27] offers a wide
possibility of determining AnS in marine waters.
Methyl Violet (Crystal Violet (CV)) was used with
toluene as a solvent for the determination of AnS in
Algiers Bay with a very low detection limit and less
interferences [28].
Giving importance to the research carried out in
our laboratory [28] and literature reports on the extrac-
tion of AnS with CV [29], we were interested to
develop and use methods for the determination of AnS
in industrial and urban wastes. The technique was
applied to determine different levels of AnS and follow
their evolution before, during, and after treatment of
wastewater in a treatment plant in Algiers city.
2. Materials and methods
2.1. Materials
(1) UV–visible spectrophotometer: for the study,
we used a UV–visible spectrophotometer JAS-
CO.V Type 530 with quartz cells of 1 cm opti-
cal path.
(2) pH-meter: A TACUSSEL pH meter with calo-
mel electrode was used for pH adjustment.
2.1.1. Chemicals
CV (C
25
H
37
N
3
Cl) is the cationic dye used for this
study.
Sodium Dioctyl sulfosuccinate “Manoxol OT”
(C
20
H
37
NaO
7
S).
Buffer solution: Ammoniacal buffer (NH
4
Cl/NH
3
)
was used, this was prepared by dissolving 26.75 g of
NH
4
Cl in one liter of distilled water and adding 3.6
ml of aqueous NH
3
to adjusted pH between 8 and 8.2.
Sodium Sulfate solution: In order to accelerate
phase separation, 0.5 M of sodium sulfate solution is
added to the extraction system.
Toluene is used as solvent extraction.
2.2. Analytical procedure
Transfer 100 mL of a sample solution containing
anionic surfactant into an Erlenmeyer flask; add 5 mL
of the sodium sulfate solution, 5 mL of ammoniacal
buffer, and 2.5 mL of CV solution. Shake for 15 min
with 10 mL of toluene. After phase separation in a
separator funnel, recover the organic layer and wash
with 10 mL of distilled water. Measure the absorbance
of the organic phase at the maximum wavelength
absorbance of CV against Toluene as reference.
3. Results and discussion
3.1. Validation/optimization of the method
3.1.1 The cationic dye
The absorption spectra of cationic dye present a
characteristic absorption band at 589 nm (Fig. 1).
3.1.2. Standard anionic surfactant
Sodium Dioctyl Sulfosuccinate “Manoxol OT”
(C
20
H
37
NaO
7
S) was used as standard anionic surfac-
tant reference, for its significant response compared to
other commonly used AnS, such as sodium dodecyl
sulfate (SDS). Fig. 2shows the absorption spectra of
the ion pair obtained with both Manoxol OT and SDS.
3.1.3. Extraction of the ion pair
The ion pair formed between the anionic surfactant
(Manoxol OT) and the cationic dye (CV) shows
absorption spectra in Fig. 3. Maximum absorption of
the ion pair appears in toluene at 589 nm. It should be
noted that the initial amount of CV decreases because
of its association with the anionic surfactant in a molar
ratio of 1/1 with a different absorption band for the
ion pair.
3.1.4. Influence of buffer media
The ion pair [(AnS) (CV)] is extracted in the pres-
ence of a basic buffer to prevent the formation of
degradation products of CV, and the elimination of
some interferences. As shown in Fig. 4, the maximum
absorbance is obtained for pH 8.1. For this, the extrac-
tion of AnS with CV will be performed at this pH
(using ammoniacal buffer).
500 600 700
0,0
0,4
0,8
1,2
absorbance
λ nm
589 nm
Fig. 1. Absorption spectra of a solution of Crystal Violet
(5 ×10
−4
M; ε
max
= 2.99 ×10
3
m
2
mol
−1
).
25678 A. Ferradj and M. Idouhar / Desalination and Water Treatment 57 (2016) 25677–25685

3.1.5. The volume of solvent extraction
All extraction steps were carried out with Toluene.
The volume of Toluene was varied according to the
initial conditions ([Manoxol OT] = 5 ×10
−4
M, [CV]
=10
−3
M). As shown in Fig. 5, we note that the maxi-
mum extraction is obtained for 15 mL of Toluene.
3.1.6. Calibration curve in distilled water, precision and
limit of detection
The calibration curve (Fig. 6) obtained for a series
of AnS standard solutions is linear in the range
0–10
−6
M of Manoxol OT with a following linear
regression equation:
A¼2:042 103Cþ0:999;
with a coefficient of correlation r¼0:0997:
The precision is obtained by determining the relative
standard deviation (RSD %). The results obtained
show that the RSD is less than 14.37% for 5 ×10
−4
M
and about 5.64% for 10
−3
M of Manoxol OT. The limit
of detection obtained for 10 replicate of the blank
reagent is found to be 2.5 ×10
−6
M.
The effects of the presence of various species pre-
sent in a sample of seawater, which may interfere
with the extraction of the ion pair [AnS-CV], was
examined using the optimized procedure, taking into
account that a maximum error of ± 5% is tolerable.
The results obtained show that species like Ca
2+
(0.003 M), Mg
2+
(0.014 M), SO2
4(0.02 M) and chlo-
rides from a level of 0.5 M causes real interferences. In
order to remove interferences, we have established a
calibration curve with seawater aqueous standard
solutions of Manoxol OT; samples of seawater were
collected in Algiers bay.
3.1.7. Calibration curve in seawater, precision
The procedure was rigorously applied to get a
calibration curve in seawater. The curve is also linear
in the range 0–10
−5
M of Manoxol OT (Fig. 7), the
500 600 700
0,0
0,4
0,8
1,2
1,6
2,0
Absorbance
λ nm
1
2
3
Fig. 2. UV–visible absorption spectra of: (1) Aqueous
solution of CV ([CV] = 10
−3
M; ε
max
= 1.8 ×10
3
m
2
mol
−1
),
(2) Ion pair (CV) (SDS) ([CV] = 10
−3
M, [SDS] = 8 ×10
−4
M;
ε
max
= 2.1 ×10
3
m
2
mol
−1
), and (3) Ion pair (CV) (Manoxol
OT) [CV] = 10
−3
M, [Manoxol OT] = 8 ×10
−4
M; ε
max
= 2.1
×10
3
m
2
×mol
−1
).
500 600 700
0,0
0,4
0,8
1,2
1,6
2,0
Absorbance
nm
1
2
Fig. 3. Absorption spectra of: (1) Aqueous solution of
Crystal Violet (10
−3
M; ε
max
= 1.8 ×10
3
m
2
mol
−1
) and (2)
Ion pair in Toluene ([Manoxol OT] = 5 ×10
−4
M, [CV]
=10
−3
M; ε
max
= 2.29 ×10
3
m
2
mol
−1
).
56789
1,45
1,40
1,50
1,55
1,60
1,65
1,70
1,75
Absorbance
pH
Fig. 4. Effect of pH on the extraction of the ion pair ([CV]
=10
−3
M, [Manoxol OT] = 5 ×10
−4
M).
A. Ferradj and M. Idouhar / Desalination and Water Treatment 57 (2016) 25677–25685 25679

regression equation is: A= 2.39 ×10
3
C+ 0.123, with a
coefficient of correlation r= 0.996. The results obtained
show that the RSD is less than 17.42% for 2 ×10
−5
M
and about 5.44% for 8 ×10
−4
M of Manoxol OT.
Finally, all optimization parameters lead us to get
a significant and complete method compared to those
used in the same way [2,27].
3.2. Applications to wastewater
Once the method was optimized with different
parameters, we carried out real applications. In order
to complete the establishment of pollution maps of
Algiers bay, the application concerns a treatment plant
of wastewaters in Algiers city. The choice is comforted
by a significant amount of wastewater drained to the
treatment plant and its specific location (Algiers city
center).
A lot of interest is made to follow the changes in
AnS levels in wastewater before, during, and after
treatment in the sewage treatment plant, and later to
be discharged in Oued El Harrach estuary. Most
detergents used (domestic or industrial) are dis-
charged directly through the sewers to the station.
A sampling methodology was adopted in order to
determine different amounts of AnS in all samples col-
lected.
Treatment plant description: The wastewater treat-
ment plant (WWTP) of BARAKI was conducted under
the general scheme of reorganization of Algiers city,
which provided for the creation of the main collectors
along Oued El Harrach estuary.
The catchment of Oued El Harrach estuary with
1,126,000 inhabitants is represented by 20 municipali-
ties. It includes:
(1) Industrial area of Oued Smar (210 industrial
units).
(2) Industrial area of El Harrach (53 industrial
units).
(3) Industrial area of Gue
´de Constantine.
(4) Industrial areas of Dar el Beida, Eucalyptus,
Birtouta, Ouled Chebel.
(5) In total, nearly 300 industrial units discharge
effluents in the estuary without any treatment.
The WWTP sized to receive a quantity of wastewa-
ter estimated at 114,000 m
3
/d [30].
Fig. 8shows the location of the treatment plant of
BARAKI in Algiers city.
3.2.1. Sampling
A systematic sampling was conducted with three
(3) sampling points, chosen in order to follow the vari-
ation of the concentration of AnS before, during, and
after treatment of wastewater in the treatment plant.
The samples collected must be filtered through a
5 1015202530
1,2
1,3
1,4
1,5
1,6
Absorbance
Volume of Toluen mL
Fig. 5. Variation of the volume of solvent extraction ([CV]
=10
−3
M, [Manoxol OT] = 5 ×10
−4
M).
Fig. 6. Calibration curve in distilled water.
Fig. 7. Calibration curve in seawater.
25680 A. Ferradj and M. Idouhar / Desalination and Water Treatment 57 (2016) 25677–25685

membrane (0.45 μm) to eliminate suspender matters
and treated with a hydrogen peroxide solution H
2
O
2
(30%), in order to eliminate organic matters and pro-
teins. The recommended procedure was rigorously
applied without modification for all samples, which
lead us to determine all AnS amounts with three (3)
replicate for all samples. Deduced levels are deter-
mined by using calibration curve in distilled water.
Before the treatment of the results, we first verified the
presence of AnS in the combined form with the dye in
collected samples. The absorption spectra (Fig. 9) show
the same characteristic band of the ion pair.
3.2.2. Results
All results obtained in this campaign lead us to
establish some interesting variations of the AnS con-
centrations vs. some parameters such as: the sampling
time, the day of sampling, and the kind of sampling
point and the period of sampling.
The first interesting variation considered was the
variation of [AnS] vs. the sampling time during the
same day. To give sense to this variation, the graph
has been divided into three curves for each time sam-
pling point (Figs. 10–12).
We noticed that the amounts of AnS gradually
increased throughout the day (8 am–12 pm). For all
the contents, the lowest level deduced during this
sampling campaign was found to be 6.02 ×10
−4
Mat
the tenth day.
Fig. 12 shows that the lowest concentrations are
deduced at point C both at 8 am and at 12 pm, with
the same trend observed on all days, with an increase
Fig. 8. Location of the WWTP in Algiers city. (1) The wastewater treatment plant (WWTP) of BARAKI, (2) Oued
El-Harrach, (3) Industrial areas of Dar el Beida, (4) Industrial area of Oued Smar, (5) Industrial area of El Harrach, and
(6) Industrial area of Gue
´de Constantine.
500 600 700
0,0
0,1
0,2
0,3
Absorbance
λ (nm)
Fig. 9. Absorption spectra of the pair of ions extracted
from a sample.
A. Ferradj and M. Idouhar / Desalination and Water Treatment 57 (2016) 25677–25685 25681

in the content of AnS from 8 am to 12 pm. We also
noticed that different levels of AnS decreases from A
to B and C during all the campaign.
The second considered variation concerns the vari-
ation of [AnS] vs. the day of sampling (Figs. 13 and
14). We have noticed a particular day (the sixth day)
corresponding to the maximal level of AnS deduced at
point A (1.52 ×10
−3
M); this is due to fact that the
sixth day corresponds to a week end day, where great
amounts of sewage from industrial discharges are
carried to the treatment plant. The lowest [AnS] was
deduced at the 10th day (3.25 ×10
−4
M), correspond-
ing to a national holiday, industrial units did not
generate wastewater.
The third variation of [AnS] with the kind of sam-
pling point shows a significant decrease of anionic
surfactant concentration from point A–C for all days,
from 10
−3
to 10
−4
M corresponding to the removal of
about 10% AnS (Fig. 15). The biological treatment of
the sewage (in point B) is carried to ensure AnS
degradation.
The different amounts of AnS deduced in this
campaign lead us to confirm the sensitivity of the
method. Predictable low values of AnS concentrations
Fig. 10. Variation of [AnS] with the time of sampling at point A.
Fig. 11. Variation of [AnS] with the time of sampling at point B.
25682 A. Ferradj and M. Idouhar / Desalination and Water Treatment 57 (2016) 25677–25685

are present after treatment, which can be routed to
marine waters.
In comparison with the different results also
obtained in previous sampling campaigns, we can
confirm that the adopted method gives more satisfac-
tion for its application [28]. Also, in comparison with
most research done in the same field in literature
reports [2,27], we can also confirm the strength and
the sensitivity of our technique.
Used techniques for the determination of AnS
reported in the literature [26–28] did not show more
applications or few [21,22]. Therefore, this permits us
to conclude that the present work shows more
applications in a large concentration range.
Fig. 12. Variation of [AnS] with the time of sampling at point C.
Fig. 13. Variation of [AnS] with the day of sampling at 8 am.
A. Ferradj and M. Idouhar / Desalination and Water Treatment 57 (2016) 25677–25685 25683

4. Conclusion
According to the purpose on the use of the spec-
trophotometric determination of anionic surfactants,
the optimized technique leads us to a direct applica-
tion on real samples from a sampling done in a treat-
ment plant located in Algiers center city. The results
obtained on real samples lead us to make some inter-
esting observations.
Before treatment (point A), high concentrations of
about 10
−3
M are deduced on the sampling period;
this is due to the high daily sewage flow (about
149,040 m
3
/d), divided in 2/3 of urban wastewater
and 1/3 from industrial wastewater and with the high
consumption of detergent.
After treatment (point C), low levels are deduced
for about 10
−4
M, this is due to the biological treat-
ment efficiency suffered by the surfactant molecules
falling on the treatment phase (B).
Final amounts of AnS present in the treatment pro-
cess effective will be carried to be discharged in Oued
Fig. 14. Variation of [AnS] with the day of sampling at 12 pm.
Fig. 15. Variation of [AnS] with the kind of sampling point.
25684 A. Ferradj and M. Idouhar / Desalination and Water Treatment 57 (2016) 25677–25685

El Harrach estuary and in last flows into marine
waters with concentration of 10
−6
M[7].
From the results, we can conclude that the method
gives great satisfaction in the determination of differ-
ent amounts of anionic surfactants.
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