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Wastewater efuent characteristics from Moroccan textile industry Y. Mountassir, A. Benyaich, M. Rezrazi, P. Berçot and L. Gebrati ABSTRACT The objectives of this work were to carry out a complete characterization of textile wastewater, resulting from a textile unit located in the Marrakesh region. A physico-chemical characterization has been performed, focused on organic and toxicological aspects. The cladoceran Daphnia magna was used as the sensor organism and lethal concentration as a criterion to measure the toxicity of textile wastewater. The physico-chemical and toxicological status of a local textile efuent showed considerable values limitation, when compared to the European Union standard limit and Moroccan guide level and other studies. In view of those characteristics, the wastewater efuent from the textile industry should be considered to be treated before discharge to the environment. Y. Mountassir A. Benyaich Laboratory of Physical Chemistry of Materials and Environment, Department of Chemistry, University Cadi Ayyad, Faculty of Science Semlalia, BP 2390, Marrakesh, Morocco Y. Mountassir M. Rezrazi P. Berçot (corresponding author) Institut UTINAM, CNRS UMR 6213, Université de Franche-Comté, 16 route de Gray 25030 Besançon Cedex, France E-mail: [email protected] L. Gebrati Ecotoxicology Laboratory, Department of Biology, University Cadi Ayyad, Faculty of Science Semlalia, BP 2390, Marrakesh, Morocco Key words | Daphnia magna, dyeing, Morocco, textile wastewater, toxicity, wastewater INTRODUCTION Textiles is one of the important sectors in Morocco and the leading sector which produces excessive wastewater (Choukr-Allah ). In that branch of industry, there are different production processes. Textile wastewater contains high concentrations of inor- ganic and organic chemicals and is highly colored from the residual dyestuffs. The efuents contain a wide range of con- taminants such as salts, enzymes, surfactants, oxidizing and reducing agents (Badani et al. ; Jo et al. ). The major pollutants of textile wastewater include high suspended solids (SS), chemical oxygen demand (COD), biological oxygen demand (BOD), heat, strong color, extreme pH and other inorganic pollutants and nutrients (Al-kdasi et al. ; Gebrati et al. ). The variety of raw materials, chemicals, processes and technological variations applied to the processes affect the type and quantity of wastewater and the applied purication technologies. Consequently, characterization of textile efu- ents is of great importance for the treatment of efuents (Bisccops et al. ) and to assess their ecological impact. The main methods of textile wastewater treatment are divided between three techniques: chemical, physical and biological. Currently the main methods of textile dye treat- ment are by physical and chemical treatment. The methods include electrochemical (Arslan-Alaton et al. ; Mountassir et al. ), biological treatment (Sarayu & Sandhya ), photochemical processing (Gebrati et al. ), ion-exchange, and a variety of membrane techniques (Badani et al. ; Alcaina-Miranda et al. ). To highlight the danger that can be generated by the textile efuents in receiving waters, we are interested in identifying and assessing the characteristics of these efu- ents. This study describes the physico-chemical and toxicological characterization of wastewater obtained during several sampling campaigns from a textile factory in Morocco. EXPERIMENTAL The experiment was conducted using wastewater from a large textile industrial Tenmarlocated in the industrial 2791 © IWA Publishing 2013 Water Science & Technology | 67.12 | 2013 doi: 10.2166/wst.2013.205

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Page 1: Wastewater effluent characteristics from Moroccan textile industry

2791 © IWA Publishing 2013 Water Science & Technology | 67.12 | 2013

Wastewater effluent characteristics from Moroccan

textile industry

Y. Mountassir, A. Benyaich, M. Rezrazi, P. Berçot and L. Gebrati

ABSTRACT

The objectives of this work were to carry out a complete characterization of textile wastewater,

resulting from a textile unit located in the Marrakesh region. A physico-chemical characterization has

been performed, focused on organic and toxicological aspects. The cladoceran Daphnia magna was

used as the sensor organism and lethal concentration as a criterion to measure the toxicity of textile

wastewater. The physico-chemical and toxicological status of a local textile effluent showed

considerable values limitation, when compared to the European Union standard limit and Moroccan

guide level and other studies. In view of those characteristics, the wastewater effluent from the

textile industry should be considered to be treated before discharge to the environment.

doi: 10.2166/wst.2013.205

Y. MountassirA. BenyaichLaboratory of Physical Chemistry of Materials and

Environment,Department of Chemistry,University Cadi Ayyad,Faculty of Science Semlalia,BP 2390, Marrakesh,Morocco

Y. MountassirM. RezraziP. Berçot (corresponding author)Institut UTINAM, CNRS UMR 6213,Université de Franche-Comté,16 route de Gray 25030 Besançon Cedex,FranceE-mail: [email protected]

L. GebratiEcotoxicology Laboratory,Department of Biology,University Cadi Ayyad,Faculty of Science Semlalia,BP 2390, Marrakesh,Morocco

Key words | Daphnia magna, dyeing, Morocco, textile wastewater, toxicity, wastewater

INTRODUCTION

Textiles is one of the important sectors in Morocco and the

leading sector which produces excessive wastewater(Choukr-Allah ). In that branch of industry, there aredifferent production processes.

Textile wastewater contains high concentrations of inor-ganic and organic chemicals and is highly colored from theresidual dyestuffs. The effluents contain a wide range of con-taminants such as salts, enzymes, surfactants, oxidizing and

reducing agents (Badani et al. ; Jo et al. ). The majorpollutants of textile wastewater include high suspendedsolids (SS), chemical oxygen demand (COD), biological

oxygen demand (BOD), heat, strong color, extreme pHand other inorganic pollutants and nutrients (Al-kdasiet al. ; Gebrati et al. ).

The variety of raw materials, chemicals, processes andtechnological variations applied to the processes affect thetype and quantity of wastewater and the applied purification

technologies. Consequently, characterization of textile efflu-ents is of great importance for the treatment of effluents(Bisccops et al. ) and to assess their ecological impact.The main methods of textile wastewater treatment are

divided between three techniques: chemical, physical and

biological. Currently the main methods of textile dye treat-ment are by physical and chemical treatment. Themethods include electrochemical (Arslan-Alaton et al.; Mountassir et al. ), biological treatment (Sarayu& Sandhya ), photochemical processing (Gebrati et al.), ion-exchange, and a variety of membrane techniques(Badani et al. ; Alcaina-Miranda et al. ).

To highlight the danger that can be generated by thetextile effluents in receiving waters, we are interested inidentifying and assessing the characteristics of these efflu-

ents. This study describes the physico-chemical andtoxicological characterization of wastewater obtainedduring several sampling campaigns from a textile factory

in Morocco.

EXPERIMENTAL

The experiment was conducted using wastewater from alarge textile industrial ‘Tenmar’ located in the industrial

Page 2: Wastewater effluent characteristics from Moroccan textile industry

2792 Y. Mountassir et al. | Wastewater effluent characteristics from textile industry Water Science & Technology | 67.12 | 2013

zone of Marrakesh city (Morocco). The main activity of this

company is the transformation of the wire of cotton, by knit-ting, tinting and bleaching, with capacity reaching morethan 30 tons per week.

The factories consist of various departments, whichcarry out different operations from knitting until thedyeing and finishing processes. All these activities consumea large amount of water and use a huge number of chemi-

cals, salts, dyes and chemical additives (Figure 1). Themedium flow of the textile stream is around 150 m3 per day.

Sample collection and analysis

In order to evaluate the complexity and variability of the tex-tile wastewaters, several samplings were taken directly at the

outlet of the machines and from the global effluent contain-ing wastewater from the dyeing, bleaching and washingprocesses. The dyes used in industry are reactive dyes Dri-

marene (Clariant, Mutenz, Switzerland).The samples were preserved in a refrigerator maintained

at 4 WC without chemical addition for all the parametersmeasured except for the metals, and nitric acid was used

to lower pH to a value of less than 2 before refrigeration.The samples were taken during the period of heaviestactivity, corresponding to the highest volume discharge.

Sampling protocol was followed carefully to inhibit theintrusion of any foreign particles, which may affect theresults. The color of the samples was measured by UV-

Figure 1 | Cotton fabric production and associated water pollutants.

visible spectrophotometer (Model 7800 UV/VIS). Tempera-

ture was measured at the time of sample collection bymercury thermometer graduated 0–100 WC. pH and conduc-tivity were measured using respectively a PHM220 pHmeter

and a CDM210 conductimeter (Radiometer Analytical SAS,Villeurbanne, France). A quantitative analysis for the deter-mination of total suspended solids (TSS) was carried out bygravimetric method. The total nitrogen (TN) was measured

after mineralization of the samples and transformation innitrates. The nitrate (NO3

�-N) was determined according toAFNOR (Association Française de Normalisation) method

T90–01. The total phosphorus (TP) was determined aftermineralization of samples in the autoclave in the presenceof sodium persulfate. COD was determined by the dichro-

mate digestion method. The 5-day biochemical oxygendemand (BOD5) was determined by the sodium azide modi-fication of the Winkler method (AFNOR ). Metalmeasurement (Al, Fe, Mn, Cu, Zn, Pb and Cd) was carried

out by a flame Atomic Absorption Spectrophotometer(UNICAM 929).

Toxicity test

The toxicity test was conducted in accordance with themethod adopted by AFNOR (AFNOR ), bringing

together in test tubes the Daphnia selected with differentdilutions of the effluent tested. In each test tube, five Daph-nia in a volume of 10 mL were introduced. For each dilution

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2793 Y. Mountassir et al. | Wastewater effluent characteristics from textile industry Water Science & Technology | 67.12 | 2013

four repetitions were performed. The tubes were then placed

in the dark in thermostated aquaria at 20 WC. For each test, apreliminary test before the final test was carried out in orderto determine the LC50 value of 24 h (lethal concentration).

Specimens ofDaphnia magna used in the test were obtainedfrom a farm where animals are fed with algae (Chlorella-vulgaris). In parallel, a control test in the dilution waterwas conducted in four replicates.

The test is to control the mobility of Daphnia after 24,48, 72 and 96 h of incubation, by counting the immobileDaphnia in each tube within 15 seconds after moderate agi-

tation of the test tube. The results were processed by thestatistical test ‘Probit EPA’ to determine the LC50 at 24 hand LC50 48 h. The term toxic unit (TU) was introduced to

compare the relative toxicity (Equation (A.1)).

Toxic unit: TU ¼ 100%LC50

ðA:1Þ

RESULTS AND DISCUSSION

Characteristics of textile wastewater

Characterization of textile process effluent streams is veryimportant to develop strategies for water treatment and

reuse. Therefore, to evaluate the pollution content, severalsamples were analyzed and the results were comparedwith Moroccan and European Union (EU) Wastewater Dis-charge Standards. The variation of parameters according to

the EU standard was analyzed (Figures 2–5).In the effluent samples, temperature varies between 26.6

and 40 WC (Figure 2(a)) the average temperature is 35.23 WC.

This does not reflect the reality that the temperature mayreach 60 WC in finishing programs. This was noticed during afew sampling campaigns directly at the outlet of the machines.

Thus, this increase results in an acceleration of chemical andbiochemical reactions leading to a deficiency of oxygen, nui-sance odors and inhibiting activity of most microorganisms.

The use of sodium carbonate and salt in the dyeing pro-cess and electrolytes (sodium sulfate) in the bleachingprocess causes an increase in electrical conductivity (EC)of the wastewater. The mean value of EC for all analyzed

samples is 3.4 ms/cm, which is above the permissiblelimits fixed by Moroccan standards for indirect wastewaterdischarge into receiving water bodies (sewer) (2.7 ms/cm)

(Figure 2(b)). The pH of different effluent samples appearedto be, between 8 and 10 (Figure 2(c)). The average value over

the sampling period is about 9.3, which exceeds EU limits of

6–9 regarding from all industrial wastewater discharged.Generally, an alkaline pH of textile effluent is associatedwith the process of bleaching and it is extremely undesirable

in water.The washing wastewater has a pH of 6 and 7 while other

samples have higher pH levels, especially the finishing pro-cess. These results are in accordance with the results of

Arslan Alaton et al. () who reported that the textilewastes were highly alkaline.

Effluent pH affects the physico-chemical properties of

water, which in turn adversely affects aquatic life, plantsand humans. This also changes soil permeability, whichresults in polluting underground resources of water

(Prasad & Rao ). pH levels of 11.0 and 10.5 weremeasured in the wastewater of textile industries in France(Allègre et al. ) and in India (Prasad et al. ). Clearly,the discharge of such effluents raises the pH of river water

and increases the salt content of soils (release to soil). Inaddition, high salt content played a part in making arableland partially or totally infertile.

TSS values fell within the range 127–600 mg/L (Figure2(d)). TSS values of a majority of the samples are muchhigher than the permissible threshold values of discharge

of wastewater into the public sewer, which predicts the pres-ence of excess of materials in textile effluents. High TSS isone of the most important sources of sediments, which

can reduce the light penetration into water and ultimatelydecrease the photosynthesis. The decrease in photosyntheticrate reduces the dissolved oxygen level of wastewater, whichresults in decreased purification of wastewater by micro-

organisms (Tyagi & Mehra ).The variability of textile wastewater based on the change

in the UV-visible absorption spectra was represented

(Figure 3(a)). Each spectrum is based on the nature of thesubstances present in wastewater, absorbing the light in aspecific wavelength range. It is difficult to determine the

principal dye used in dyeing baths from UV-visible absorp-tion data, because of the complexity of the wastewater.This complexity is partly due to the mixture of the dyes and

additives used, and also due to the parallel operation of sev-eral dyeing, bleaching and washing machines (Figure 3(b)).

The COD values of textile effluents were found to be inthe range of 1 and 2 g/L, increasing to 2.8 g/L, which

exceeds the limits authorized by Moroccan guide levels(500 mg/L) (Figure 4(a)). These values are influenced bythe presence of oxidizable organic and/or inorganic com-

pounds. We note that the COD of the different finishingprocesses is generally above 1 g/L. The COD value of the

Page 4: Wastewater effluent characteristics from Moroccan textile industry

Figure 2 | Averages of: temperature (a), electrical conductivity (EC) (b), pH (c) and total suspended solids (TSS) (d) of the effluent.

2794 Y. Mountassir et al. | Wastewater effluent characteristics from textile industry Water Science & Technology | 67.12 | 2013

washing process was 1.16 g/L, mainly due to the release of a

considerable amount of color from textiles (Figure 4(b)).The BOD was found to be in the range of 300–550 mg/L

(Figure 4(c)), resulting in the wastewater being hardly

biodegradable (Figure 4(d)), because the BOD to COD

ratio of the wastewater is between 0.11 and 0.34. Theseresults agree with previous research (Gebrati et al. ).Some studies have shown that in general the products

Page 5: Wastewater effluent characteristics from Moroccan textile industry

Figure 3 | Wavelength scanning of some sampling campaigns on textile wastewater (a) and of wastewater from finishing programs (b).

2795 Y. Mountassir et al. | Wastewater effluent characteristics from textile industry Water Science & Technology | 67.12 | 2013

used for textiles and dyes are especially toxic and non-biode-gradable or very little biodegradable (Meriç et al. ;Gebrati et al. ).

The mean values were measured for the forms of TN, TP,

chloride and hydrogen peroxide in the textile effluent(Figure 5(a)). TN means the sum of total Kjeldahl nitrogen(TKN), nitrate-nitrogen (N-NO3) and nitrite-nitrogen

(N-NO2). Analysis of these values shows that the content ofnitrogen compounds and phosphates in textile mill effluentsis rather high. TheN-NO3 concentration is in the range of 20–

67 mg/L. The N-NO2 concentration is above 2 mg/L and themean TKN levels of 56 mg/L exceeded the Moroccan guide-line of 30 mg/L. Therefore, its TN is 127 mg/L, which comes

from dyes and raw materials. The mean total phosphoruslevel of 78 mg/L was higher than the EU and Moroccanlimit of 10 mg/L for the discharge of wastewater in thepublic sewer.

This richness of nutrients can constitute an advantage inthe event of establishment of a biological treatment. In mostcases, activated sludge systems (aerobic treatment) are

applied. However, the low biodegradability of most of thedyes and chemicals used in the textile industry means theirbiological treatment by the activated sludge process does

not always achieve great success. It is remarkable that most

of these dyes resist aerobic biological treatment, so adsor-bents, such as bentonite clay or activated carbon, are addedto biological treatment systems in order to eliminate non-biodegradable or microorganism-toxic organic substances

produced by the textile industry (Pala & Tokat ).This effluent contributes then to enrichment of nitrates

in receiving mediums. As for the high concentrations of

chloride and hydrogen peroxide, they are due to the use ofalkaline and peroxide in the bleaching stages and in thedifferent finishing processes respectively. However, sodium

hypochlorite (Naþ, ClO�) was detected during a fewsampling campaigns taken directly at the outlet of thebleaching stage. High concentration of chloride ions con-

tributed greatly to enhance the EC and can constitute anadvantage in the vent of applications of electrochemicaltechnologies in water and wastewater treatment.

The metals are often used as oxidizing agents, as metal

complex dyes, dye stripping agents, and finishers (Zeineret al. ). The level in the global effluent is quite high;metals even at very low concentrations are toxic to living

organisms, including humans as well as the microbial popu-lation present in the effluent (Figure 5(b)). For example,copper is toxic to aquatic plants at concentrations below

1 mg/L, whereas a concentration close to this level can be

Page 6: Wastewater effluent characteristics from Moroccan textile industry

Figure 4 | Average effluent chemical oxygen demand (COD) (a), average values of COD and BOD5 of finishing processes (b), average effluent 5-day biochemical oxygen demand (BOD5) (c)

and evaluation of biodegradability (BOD5/COD ratio) for some sampling campaigns (d).

2796 Y. Mountassir et al. | Wastewater effluent characteristics from textile industry Water Science & Technology | 67.12 | 2013

toxic to some fish. In addition, metals may limit the use ofthe effluent for irrigation in agriculture due to its toxicity

(Tuzen et al. ).

As seen in the Figure 5(b), aluminum showed relativelyhigh concentrations; the average value was greater than

0.2 mg/L. The iron concentration was 2.5 mg/L. Table 1

Page 7: Wastewater effluent characteristics from Moroccan textile industry

Figure 5 | Mean values measured for the forms of nitrogen and phosphorus, chloride and hydrogen peroxide in the textile effluent (a) and average effluent of metal concentrations:

aluminum, iron, manganese, copper, zinc, lead and cadmium (b).

Table 1 | Literature values of heavy metals concentration (mg/L) in textile samples

ElementsData fromPrasad & Rao (2010)

Data fromAli et al. (2009)

Data fromOhioma et al. (2009) Present study EU Limita

Moroccanguide levela

Al – – – 0.32 – –

Fe 6.78 6 27.21 2.5 1 2

Mn 5.1 4.34 3.8 0.6 1 1

Cu 3.98 6.36 2.2 1.4 1 1

Zn 1.1 3.23 8.7 0.66 2 2

Pb 0.33 0.28 1.92 1.4 1 0.5

Cd 0.6 0.51 – 0.05 0.3 0.2

aIndirect discharge limits (discharge in sewer).

EU: European Union.

Table 2 | Toxicity test

Cl50–24 h UT-24 ha Cl50–48 h UT-48 h

Global effluent 4.462 22.41 1.592 62.81

Dyeing 2.354 42.480 1.435 69.68

Bleaching 6.683 14.96 4.3 23.5

Washing 20.7 ≈4.9 16.87 5.927

Chi-square experimental 7.652 5.413

Theoretical chi-square 12.592 12.592

aToxic units.

2797 Y. Mountassir et al. | Wastewater effluent characteristics from textile industry Water Science & Technology | 67.12 | 2013

shows the comparison of metal concentration in thisresearch with various industrial wastewaters.

Generally, metal concentrations in this study werefound to be important, and all analyzed samples arebeyond the limit established by the EU and the Moroccanguide level the indirect discharge and greater than the

values proposed by Metcalf & Eddy () for domesticwastewater. Based on its overall characteristics, the effluentwas considered not to be suitable for discharge into munici-

pality sewers without pretreatment. Thus, a pretreatment

Page 8: Wastewater effluent characteristics from Moroccan textile industry

Table 3 | Classification of industrial effluents in order of their toxicity

CL50 (%) >100 10<CL50< 100 1<CL50< 10 CL50< 1

UTa (%) <1 1<UT< 10 10<UT< 100 UT> 100

Degree of toxicity No toxicity A little toxic toxic Very toxic

aToxic units.

2798 Y. Mountassir et al. | Wastewater effluent characteristics from textile industry Water Science & Technology | 67.12 | 2013

step involving coagulation and flocculation coupled withcarbon adsorption was recommended.

Toxicity evaluation

The purpose of the toxicity test was to determine the textile

wastewater LC50 of the global, effluent and effluent from adifferent finishing process (bleaching, washing and dyeing).The test was performed with cladoceran Daphnia magnaaccording to AFNOR. The response established for theacute toxicity test with D. magna was the average lethalconcentration (LC50) at which 50% of the species were

killed during 24 h of exposure to the effluent. Immobiliz-ation toxicity of wastewater for D. magna is summarizedin Table 2.

The results show that all water samples showed impor-tant toxicity as classified by Vasseur et al. () (Table 3)with a CL50 value of 24 h of 4.462, 2.354, 6.683 and 20.7for global effluent, dyeing, bleaching and washing processes

respectively (Table 2).Generally, the toxicities are the result of combined and

synergetic effects of the organic and mineral compounds

and toxic metals (Ademoroti et al. ; Sponza & Demir-den ), but it is difficult to correlate the values of LC50

for 24 h with those of the physico-chemical parameters,

given that the tested effluents are very complex matrices.In the study performed by Villegas-Navarro et al. () itwas shown that textile effluents, have a relatively high tox-icity on D. magna, with acute toxicity unit (ATU) levels

between 2.2 and 960. All samples affected the mortality ofD. magna due to their toxicity. However, dyeing and bleach-ing stages (presence of ClO� and H2O2 used in the textile

industry as bleaching agents) were the most toxic (Ville-gas-Navarro et al. ).

CONCLUSIONS

The results showed the effluent from the local textile unitwas alkaline and presented a high salt concentration. The

amount of nitrogen, phosphorus and metals presented inthe effluent were significantly higher. The concentrationsof solids and the oxygen demands were quite high. The ana-

lyzed samples demonstrate that 100% of them support theconclusion that textile discharges are serious potential pol-lution sources and are very important sources of toxic

discharges. The treatment of all effluents generated bythe textile factories in Morocco before their discharge isrecommended.

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First received 29 November 2012; accepted in revised form 18 February 2013