361
Indonesian Journal of Science & Technology 6 (2) (2021) 361-370

Indonesian Journal of Science & Technology
Journal homepage: http://ejournal.upi.edu/index.php/ijost/

Physico-chemical investigation of wastewater from the
Sebdou-Tlemcen textile complex North-West Algeria
Asma Khelassi-Sefaoui1*, Abderrahmane Khechekhouche2, Manel Zaoui-Djelloul Daouadji3,4, Hamza Idrici 3
1

Department of Hydraulic, Institute of Sciences and Technology, University Center of Maghnia, Algeria
2
Technology faculty, University of El Oued, Algeria
3
Department of Chemistry, Faculty of Mathematics & Matter Sciences, University of Kasdi Merbah, Algeria
4
Pollution and waste Treatment Laboratory, University of Kasdi Merbah, Algeria
Correspondence: Email : khelassi_asma@yahoo.fr

ABSTRACT
Wastewater treatment is a process used in several
countries, particularly in Algeria. A study on Earth for
one month was carried out at the sewage plant of the
Sebdou textile complex, Tlemcen, north-west of
Algeria. Regular samples gave average values at the
outlet such that the water temperature is 22 ° C, the ph
7.43, the biochemical oxygen demand BOD5 is 36.5 mg
/ l, the chemical oxygen demand COD vary between 100
and 200 mg / l at the exit of the WWTP mg / l and finally
suspended solids SS is of the order of 36.2 mg / l. All
these values conform with the standards and therefore
the treatment plant operates within Algerian
standards.
© 2021 Tim Pengembang Jurnal UPI

ARTICLE INFO
Article History:
Submitted/Received 06 Dec 2020
First revised 30 Mar 2021
Accepted 23 May 2021
First available online 28 May 2021
Publication
date 01 Sep 2021
____________________
Keywords:
BOD5,
COD,
pH,
SS,
Temperature,
Textile,
Wastewater.

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1. INTRODUCTION
Water is an essential element for the life
and the real and sustainable socioeconomic development of a country
(Westall & Brack, 2018). Water treatment
in general directly affects human life and of
course their environment. This treatment
can be presented in several forms, the
least known is solar treatment and the
more well-known is the treatment of
physicochemical
and
biological
wastewater (Khechekhouche et al., 2020
A, 2020 B, 2020 C; Kishor Kumar et al.,
2020; Yahiaoui et al., 2020; Kim et al.,
2019). One of the sources of wastewater is
the industry. The textile industry
specifically is one of the industries that
consume large amounts of water and have
reported that this amount is in the order of
200 liters of water per kilogram of finished
textile product (Nguyen & Juang, 2013).
This textile sector, therefore, generates
effluents characterized by a significant
load of organic matter which requires
treatment before their discharge into the
receiving environment (Belbahloul, et al.,
2014).
Nowadays, protecting the environment
is a major problem for mankind. Textile mill
effluents are complex mixtures of
chemicals, the composition of which
differs over time and depending on the
facility. They can have high concentrations
of suspended solids and metals, as well as
dyes and surface-active molecules (Heba &
Eman, 2020). The textile industry uses
around 10,000 types of dyes, the majority
are recalcitrant organic molecules
generally presenting problems of color,
high concentrations of BOD5, COD,
suspended solids MES, as well as high
toxicity
and
conductivity.
Several
purification processes have been tested,

for example, the biological processes and
the most used being the activated sludge
treatment due to its simplicity and its
economy and which allows obtaining
significant purification results (Imane
Bencheikh et al., 2021). Chlorine is
considered to be the most widely used
chemical agent in the world for disinfecting
water, which has saved millions of lives
from water-borne diseases (Weinberg et
al., 2006). However, water chlorination
may result in the generation of byproducts which may be toxic to humans
(Shammas et al., 2005).
The objective of this work is to evaluate
the purifying power of a physicochemical
treatment plant of the discharges of an
industrial textile unit E.A.T.I.T Sebdou,
North-West Algeria.
2. MATERIALS AND METHODS
The sewage treatment plant of the
Sebdou textile complex depends on the
textile industries company DENIM (the
technical word for blue jeans) and is
located in Sebdou (western Algeria), 37 km
south of Tlemcen. This economic and
public SPA company with the legal form of
a"joint-stock company" aims to produce
and market fabrics (denim blue, gabardine
and military fabrics). The date of the start
of construction was in 1976 and the date of
commissioning of the complex was in
1979.
2.1 Presentation of the wastewater
treatment plant
The treatment in this station goes
through
several
phases
shown
schematically in Figure 1.

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Figure 1. Schematic diagram of the physicochemical treatment process in the station of the
textile industrial unit.
2.2. Wastewater and industrial water
purification processes in the station
 Screening: Placed in the lifting stations,
these baskets are suspended in front of
the downstream end of the inlet pipe.
This material often equips small
installations (<5000 eH). However, they
can be found in the largest factories as a
backup for automatic screening devices.
 Sandblasting: Its function is the removal
of sand and heavy materials. This is to
ensure removal by sedimentation of
sands and heavy materials to prevent
abrasion of mechanical equipment and
deposits in the pipes and the bottom of
the basins (clogging, reduction of useful
volumes).
2.3. Mixing and equalization basin n° 1

This basin as shown in Figure 2, is used for
equalization and mixing of textile
wastewater, steam production, rinsing
filters,
regeneration
wastewater).
Remembering coarse materials (fibers,
pieces of fabric), it was placed in the basin of
a special screen (moisturize) (Q = 200 m3/h).
04 immersible aerators mix the water and
supply oxygen before this water is
introduced into the neutralization tank (1) by
the immersible pumps (of the same Q and
same H). Aeration (or oxygen supply) is
intended to mix and prevent anaerobic
putrefaction, in the case of longer residence
times or less wastewater.
The level is adjusted via the contacts. The
switch should be adjusted so that at least 1 m
of water covers the submersible aerators. In
normal operation, only one pump is running.
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At maximum load, a second pump is started
at the highest level.
2.4. Rapid mixing and neutralization basin
(physicochemical treatment)
The neutralization basin as shown in
Figure 3, is used to adjust the pH value and
keep this selected value (control center
setting), sulfuric acid (H2SO4) or lime hydrate
(Ca (OH)) a solution inert has a pH value = 7.
Acid solutions have a pH value of less than 7.
To neutralize such a solution, a detergent is
dosed in this case with a bed of 5% lime. Basic
solutions have a pH value greater than 7. And
are neutralized with an acid (10% sulfuric
acid). In the neutralization tank, a pH value
measurement continuously measures the pH
value.
2.5. Flocculator-clarifier (separation of
sludge and clear water)

All heavy metal ions present are reduced
to insoluble hydroxide and removed with the
ferric oxide hydrate flakes. By the two
preceding methods, practically complete
elimination of these toxic elements is
obtained.
2.6. Biological treatment basin
Figure 5 shows the biological treatment
basin. During the activated sludge treatment
process, chemically treated and clarified
wastewater is aerated and thoroughly mixed,
and then recycled to the activated sludge
basin. Floating sludge flakes (biozones)
remove organic pollutants from wastewater
and deposit them in post-clarification ponds.
Biologically formed flocculated sludge
develops many small organisms, including
bacteria, hence its name activated sludge.
2.7. Final clarification basin

Figure 4 shows the flocculator-clarifier.
The chemical flocculation taking place in the
clarifying flocculator largely eliminates the
dye content of the wastewater, in addition to
a large part of other pollution. Fine
suspended particles and colloidal particles
are deposited. At the same time, any toxic
sulphite ions present react with the iron ions
of the ferric chloride to form insoluble iron
sulphide which simultaneously settles in the
flakes.

For the final clarification process, we use
the law of gravity according to which
materials heavier than water, in this case, the
mud flakes fall in that direction. This
mechanical process takes place in 2 circular
clarification basin as shown in Figure 6a.
Figure 6b shows the post-chlorination
basin where water inoculated with chlorine
(Cl2) is added to the clarified water flowing in
free fall out of the final clarification basin.
There everything is mixed using a stirrer.

Figure 2. Photo of mixing and equalization
basin N ° 1.

Figure 3. Mixing and neutralization basin
N °2.

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Figure 4. Clarifying flocculator.

Figure 6a. Final clarification basin.
3.RESULTS AND DISCUSSION
3.1. Temperature
Temperature is an important ecological
factor in aqueous media. Its rise can strongly
disrupt aquatic life (thermal pollution). It
plays an important role in nitrification and
biological denitrification. Nitrification is
optimal for temperatures ranging from 28 to
32 ° C on the other hand, it is greatly reduced
for temperatures of 12 to 15 ° C and it stops
for temperatures below 5 ° C (Behera et al.,
2020). According to the results obtained in
Figure 7, we note that the water temperature
varies between 20 ° C and 25 ° C at the
entrance to the WWTP with an average of
22.5 ° C while at the exit it oscillates between
15 ° C and 18 ° C with an average of 16.5 ° C.
It can be seen that the water temperature
values at the outlet of the WWTP do not

Figure 5. Biological basin (aeration basin).

Figure 6b. Post chlorination basin.
exceed the authorized standard of 30 ° C
(Tom et al., 2020).
3.2. Water pH
In nature, bacteria can grow over a wide
pH range of approximately 5 to 8. However,
their optimal growth and activity are around
a pH of 7.5 to 8.50, that is, is the case with
our operating conditions in the basins. The
pH values of the treated water, which vary
between 7 and 7.5 with an average of 7.17,
so they are lower than those of the raw water
which varies between 10.5 and 14 with an
average value of 12.1 as shown in Figure 8.
The pH values at the outlet are very close to
neutrality and they are relatively constant
and do not exceed the authorized standard
for industrial discharges (pH 6.5 to 8.5).

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3.3. Suspended matter (SS)
Figure 9 shows the variation in the (SS) of
raw and treated water at the entry and exit
of the WWTP. The passage of the effluent in
a purification station makes it possible to
reduce the SS of the treated effluent from
380 mg / l to an average value of 36.2 mg / l
satisfactory compared to the value of the
Algerian discharge standards which is 30 at
40mg / l. The reduction rate reaches a yield
of 88.15%.
3.4. Biological oxygen demand (BOD5)
Figure 10 shows the variation of the BOD5
of the treated raw water at the outlet of the
WWTP. The textile industry discharges water

with a BOD5 value of 150 mg / l. The BOD5
values at the outlet of the WWTP range from
28 mg / l to 44 mg / l with an average of 30 to
40 mg / l of 36.5 mg / l. It can be seen that
this value does not exceed the authorized
standard of 30 to 40 mg / l.
3.5. Chemical oxygen demand (COD)
The textile industry rejects aux with a COD
value of 250 mg / l. We observe in the figure,
a significant decrease in COD during the
treatment of the effluent in a WWTP. The
concentration is reduced from 828.4 mg / l to
154.4 mg / l. This COD value does not exceed
the authorized Algerian standard which is
250 mg / l, as shown in Figure 11.

Figure 7. Water temperature variation in the treatment plant.

Figure 8. Change in the hydrogen potential (pH) of the water in the treatment plant.
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Figure 9. Variation in the (SS) of raw and treated water from the WWTP.

Figure 10. Change in BOD5 of treated water from the WWTP.

Figure 11. Change in COD of raw and treated water from the WWTP.
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The value of the COD / BOD ratio indicates
the coefficient of biodegradability of an
effluent, it also makes it possible to define its
origin (Suschka & Ferreira, 1986). Usually, the
COD value is:
COD = 1.5 to 2 times BOD for urban
wastewater;
COD = 1 to 10 times BOD for all of the
wastewater;
COD> 2.5 times BOD for industrial
wastewater. (The results are shown in Table.
I).
3.6. Sedimentation at the outlet of the
flocculator

Figure 12 shows the daily variation in
sedimentation at the outlet of the
clarification basin and the inlet of the
biological treatment basin of the WWTP. It
should be noted that the results obtained
and presented in the figure vary between
82% and 99%. This result indicates the good
role of the flocculator. There is a wide
variation in the sedimentation of the sludge
at the entrance to the biological basin,
varying between 32 and 90%. This refers to
emptying the tub now and then as the basin
drain has been designed to keep around 30%
of the mud in that basin.

Table 1. The COD and BOD values for the last week of the month (final clarification output).
FINAL CLARIFICATION OUTPUT
Day N°1

Day N°2

COD
mg/
130

COD
mg/
162

COD
mg/
36

Day N°3
COD
mg/
44

COD
mg/
153

COD
mg/
28

Day N°4

Day N°5

COD
mg/
160

COD
mg/
167

COD
mg/
32

COD
mg/
39

Figure 12. Daily variation in the sedimentation of the sludge at the outlet of the WWTP
flocculator.

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4.CONCLUSION
The monitoring of the pollution
parameters carried out on the purified
wastewater of the Sebdou textile complex
showed significant variations in certain
parameters. However, others show only
small fluctuations.
 The average value of the temperature of
the wastewater is of the order of 25 ° C
with an average of 22 ° C at the outlet, so
it complies with Algerian standards.
 The pH values of the purified water are
between 7 and 7.5 with an average of
7.43, so it complies with the Algerian
discharge standards (pH 6.5 to 8.5).
 BOD5, its values are between 28 and 44
mg / l in treated water, with an average
of 36.5 mg / l. So it is not in accordance
with the Algerian discharge standards (30
- 40 mg / l).
 The COD values vary between 100 and
200 mg / l at the outlet of the WWTP,
showing the efficiency of the latter in

terms of water pollution control in
accordance with Algerian discharge
standards (250 mg / l).
 The mean value of the SS is 36.2 mg / l
and it is satisfactory compared to the
value of the Algerian discharge standards
which is 30 to 40 mg / l.
In addition, according to the analyzed
parameters of the treated water of the
sewage treatment plant of the Sebdou textile
complex, it should be noted that they all
comply with the discharge standards and
according to the results obtained we confirm
the proper functioning of this station.
purification, which will undoubtedly help to
preserve the receiving environment (Oued
Tafna) from the pollution generated by this
plant.
5. AUTHORS’ NOTE
The authors declare that there is no conflict
of interest regarding the publication of this
article. Authors confirmed that the data and
the paper are free from plagiarism.

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