Egyptian Journal of Aquatic Research (2014) 40, 301–308

HO ST E D BYNational Institute of Oceanography and Fisheries

Egyptian Journal of Aquatic Research

http://ees.elsevier.com/ejarwww.sciencedirect.com

FULL LENGTH ARTICLE

Bioremediation of the textile waste effluent

by Chlorella vulgaris

* Corresponding author.

E-mail address: halayassin12@yahoo.com (H.Y. El-Kassas).

Peer review under responsibility of National Institute of Oceanography

and Fisheries.

http://dx.doi.org/10.1016/j.ejar.2014.08.003

1687-4285 ª 2014 Hosting by Elsevier B.V. on behalf of National Institute of Oceanography and Fisheries.

Open access under CC BY-NC-ND license.

Hala Yassin El-Kassas a,*, Laila Abdelfattah Mohamed b

a Hydrobiology Department, Marine Environment Division, National Institute of Oceanography and Fisheries, Kayet Bay,El-Anfoushy, Alexandria, Egyptb Marine Chemistry Department, Marine Environment Division, National Institute of Oceanography and Fisheries,Kayet Bay, El-Anfoushy, Alexandria, Egypt

Received 10 March 2014; revised 24 August 2014; accepted 24 August 2014Available online 2 October 2014

KEYWORDS

Chlorella vulgaris;

COD;

Colour removal;

Microalgae;

Textile waste effluent

Abstract The microalgae biomass production from textile waste effluent is a possible solution for

the environmental impact generated by the effluent discharge into water sources. The potential

application of Chlorella vulgaris for bioremediation of textile waste effluent (WE) was investigated

using 22 Central Composite Design (CCD). This work addresses the adaptation of the microalgae

C. vulgaris in textile waste effluent (WE) and the study of the best dilution of the WE for maximum

biomass production and for the removal of colour and Chemical Oxygen Demand (COD) by this

microalga. The cultivation of C. vulgaris, presented maximum cellular concentrations Cmax and

maximum specific growth rates lmax in the wastewater concentration of 5.0% and 17.5%, respec-

tively. The highest colour and COD removals occurred with 17.5% of textile waste effluent. The

results of C. vulgaris culture in the textile waste effluent demonstrated the possibility of using this

microalga for the colour and COD removal and for biomass production. There was a significant

negative relationship between textile waste effluent concentration and Cmax at 0.05 level of signifi-

cance. However, sodium bicarbonate concentration did not significantly influence the responses of

Cmax and the removal of colour and COD.ª 2014 Hosting by Elsevier B.V. on behalf of National Institute of Oceanography and Fisheries.

Open access under CC BY-NC-ND license.

Introduction

Theworld is facing a number of environmental challenges. Con-sequently, Egypt has directed significant concern to resolve the

pressing environmental problems by taking several measures

including ratifying various international environmental con-ventions and treaties that are to be harmonized into the nationallegislative framework. The textile industry and its waste waters

have been increasing proportionally, making it one of the mainsources of severe pollution problems worldwide (IPPC 2003).

Synthetic dye usage has increased in the textile and dyeingindustries because of their ease and cost-effectiveness in syn-

thesis, firmness, high stability to light, temperature, detergentand microbial attack and variety in colour compared with nat-ural dyes (Nawar and Doma, 1989; Couto, 2009). The major

302 H.Y. El-Kassas, L.A. Mohamed

environmental problem associated with the use of dyes is theirlose during dyeing process since the fixation efficiency rangesfrom 60 to 90% (Sugiura et al., 1999).

Fifteen percent of the total world production of dyes is lostduring dyeing process and is released in the textile effluents.The release of coloured wastewaters in the ecosystem is a dra-

matic source of esthetic pollution, eutrophication, and pertur-bations including decrease in the photosynthetic activity anddissolved oxygen (DO) as well as alteration of the pH, increase

in the biochemical oxygen demand (BOD) and chemical oxy-gen demand (COD), in aquatic life (Amin et al., 2008). There-fore, treatment of these industrial effluents is necessary prior totheir final discharge to the environment. Various physical/

chemical methods have been used for the removal of dyes fromwastewaters (dos Santos et al., 2007; Saratale et al., 2011).These methods have some drawbacks, such as not all dyes, cur-

rently used can be degraded or removed with physical andchemical processes and sometimes the degradation productsare more toxic (Abadulla et al., 2000; Nerud et al., 2001;

Sharma et al., 2002). So that treatment methods must be tai-lored to the chemistry of the dyes (ICABRU, 2009).

Biological techniques which are cheaper and easier to oper-

ate have become the focus in recent studies of dye degradationand decolorization. Microbial and enzymatic decolorizationand degradation of azo dyes have significant potential toaddress this problem due to their environmentally-friendly,

inexpensive nature, and also they do not produce large quanti-ties of sludge (Saratale et al., 2011).

Micro algae are known to remove dyes by bioadsorption,

biodegradation and bioconversion. Microalgae degrade dyesfor nitrogen source, by removing nitrogen, phosphorus, andcarbon from water, it can help reduce eutrophication in the

aquatic environment (Olguın, 2003; Ruiz et al., 2011) and,are unique in sequestering carbon dioxide, one of the maincontributors to the greenhouse effect (Mata et al., 2011).

Moreover, microalgae can grow at a rapid pace and, in inhos-pitable conditions, using water unfit for human consumption(Mata et al., 2010, 2011).

In this study, statistical experimental design was employed.

These designs have many advantages and were used in manysuccessful degradative studies (Saravanan et al., 2008). Com-pared to conventional one factor at a time experiments, statisti-

cal based factorial design of experiments gave more meaningfulinformation on the effects, main and interaction, of the factorinvolved in the given study. Furthermore, the added advantage

of reduction in the number of experiments to be performed.Employing such techniques proves more attractive for system-atic investigations without compromising the accuracy of repre-sentation of the environmental system (Montgomery, 2004). On

the other hand, single variable optimization methods are notonly tedious, but also can lead to miss interpretation of results,especially because the interaction effects between different fac-

tors are over looked (Wenster-Botz, 2000).Therefore, this research article aims to phytoremediate a

textile waste effluent generated from Kafr Eldwar Dyeing Tex-

tile Industry, local textile dyeing industry, near Alexandria-Egypt. The present study was designed to identify microalgaestrains present in the waste effluent. In addition, the ability

of the dominant algal strain, Chlorella vulgaris was evaluatedas an efficient phytoremediator to decolorize, detoxify anddegrade this effluent. This work addresses the adaptation ofthe microalgae C. vulgaris in a textile waste effluent and studies

the ideal wastewater dilution as well as sodium bicarbonateconcentration for the maximum reduction of colour andChemical Oxygen Demand (COD).

Materials and methods

Textile effluent characterization

The textile waste effluent (WE) was collected from the region

of waste discharge at the water body as it reaches Abu-Qirbay in Alexandria, Egypt and stored under cooling to 4 �C.Physio-chemical analyses of the water sample were carried

out following the methods described by APHA (2000).The microalgal flora in the effluent was identified following

the Utermohl’s (1958) method. The samples were immediately

fixed with 4% formaldehyde for laboratory analysis and mic-roalgae were counted and identified using 2 ml settling cham-bers with a Nikon TS 100 inverted microscope at 400xmagnification. The dominant algal strain, Chlorella vulgaris

was used throughout the study work.

The alga strain and growth conditions

The alga strain C. vulgaris was isolated and purified in axeniccultures and used throughout this study. It was cultivated asbatch cultures in 1 l Erlenmeyer flasks with Bold’s Basal Med-

ium (BBM) (Nichols, 1973) at an initial count of 4 · 103

cells ml�1. For the production of biomass, exponentially grow-ing algae culture was transferred into fresh sterile medium

[10% (v/v) of inoculums]; Cultures were illuminated by tubularfluorescent lamps (PHILIPS Master TL-D 85 W/840). Thelight intensity at the surface of the culturing vessels was100 l mol photons m�2 s�1 with a photoperiod of 16:8 h light:

dark at 25 ± 1 �C.The culture medium for the runs was the final textile effluent

itself, which was used after dilution according to a Factorial

Design. Algal cells were inoculated at a concentration of 20%(Vinoculation/Vmedia) in 500 ml Erlenmeyer flasks incubated at athermo-statically controlled environmental chamber at

25 ± 1 �C with a luminance of 3.000 lux and with a 12 hourslight/dark photoperiod (Tanticharoen et al., 1994) for 15 days.The experiment was carried out in triplicate and average valueswere recorded.

Factorial design

A 22 Central Composite Design (CCD) was used to study the

influence of the wastewater concentration and sodium bicar-bonate concentration on the C. vulgaris growth and theremoval of wastewater pollutants. The maximum wastewater

concentration for the Factorial Run Design was stipulatedfrom the preliminary cultivation tests of the microalgae inthe textile waste effluent, using as standard. Table 1 shows

the real and coded values of the variables used in the 22 CentralComposite Design (CCD). Distilled water was used for thedilutions of the waste effluent.

Monitoring of algal growth

Data of the cell density using a haemocytometer slide versusculture times were plotted and submitted to polynomial

Table 1 Physicochemical characteristics of the textile indus-

trial effluent WE.

Parameter Unit Value

Colour intensity Absorbance at 660 nm 0.114

pH – 8.05

Conductivity mS 10.23

TS mg l�1 735

TDS mg l�1 506

TSS mg l�1 229

COD mgO2 l�1 51.2

CL% 0.26

SO4 mg l�1 88.67

TP mg l�1 1.51

P lg l�1 0.96

TN % 0.105

NO2 lg l�1 0.55

NO3 lg l�1 1.95

Ca mg l�1 140.28

Mg mg l�1 159.72

Heavy metals

Cu mg l�1 7.05

Zn mg l�1 8.61

Cr mg l�1 6.33

Mn mg l�1 10.5

Fe mg l�1 380.4

Table 2 Taxonomic composition and proportional represen-

tation of the microalgae groups at the WE during January,

2013.

Group Genus Species Cells l�1 %

Chlorophyta 7 9 156,763,9 44.65

Bacillariophyta 3 6 137,102,4 39.05

Cyanophyta 6 9 456,423 12.3

Euglenophyta 2 2 140,438 4.00

Total 18 26 353,552,4 100

Bioremediation 303

adjusts. The polynomial equations obtained were used to cal-culate the maximum cellular concentration (Cmax, cells ml�1),

for each run of the 22 Central Composite Design (CCD).The maximum specific growth rate (lmax, d

�1) was obtainedthrough exponential adjustment in the logarithmic phase of

growth. The results of Cmax and lmax of the runs were analyzedstatistically through the analysis of variance and response sur-face methodology. Similarly, pH, electric conductivity (EC),

and dry weight (DW) were measured at zero-time and at theend of the experimental period.

Analysis of pollutants removal

The determinations of pollution parameters including colourand COD were accomplished at the beginning and at the endof each run, in agreement with the methodology described

by APHA (2000). The percent reductions of these parameterswere calculated by the equation:

Parameter reduction ð%Þ ¼ xi � xf=xf � 100 being :

xi = Parameter before the biomass growth and xf = Parame-

ter after the biomass growth. The results of colour and CODremoval of the CCD runs were analyzed statistically throughthe analysis of variance (ANOVAs) at 95% confidence interval

and response surface methodology.

Determination of total dye

Eight commercially textile azo dyes are used in this textile

dying industry. They are Metanil yellow, Fast Orange, FastRed, Direct Blue, Acid Fast Red, Direct Fast Scarlet, CongoRed and Acid Fast N Blue. The final textile sample effluents

just before discharging were taken and their light absorbancewas measured at wavelengths of 660 nm. UV–Vis spectra were

determined using a spectrophotometer Spekol 1300, AnalytikaJena, Spain.

Results

Physicochemical characteristics of the WE

The results presented in Table 1 revealed that the values of pH,conductivity, TS, TDS and TP obtained for the WE used in

this study were 8.05, 10.23 mS, 735 mg l�1, 506 mg l�1, and1.51 mg l�1, respectively. However, COD (51.2 mgO2 l

�1).The heavy metal contents of the WE range from 6.33 mg l�1

for Cr to 380.4 mg l�1 for Fe.

Microalgae flora present in the WE

Algal flora that occurred in the WE were identified. The resultsrevealed that the species belonging to 4 families were identifiedduring January, 2013 (Table 2, Fig. 1). The mean total phyto-plankton cell abundance was 353, 552, 4 cells l�1. The tempo-

ral pattern showed the presence of 26 taxons recorded thatChlorophyta made up the highest number (44.65%) and arerepresented by (8 genera, 14 species) Chlorella vulgaris Beyer-

inck, Ankistrodesmus falcatus (Corda) Ralfs, Ankistrodesmussetigerus (Schroder) G.S.West., Coelastrum microporum Nageli,Crucigenia rectangularis (Nageli) Gay, Crucigenia tetrapedia

(Kirchner) Kuntze, Crucigenia quadrata Morren, Kirchneriellacontorta (Schmidle) Bohlin, Pediastrum simplex Meyen, Pedia-strum tetras (Ehrenberg) Ralfs, Scenedesmus bijugatus Kut-

zing, Scenedesmus dimorphus (Turpin) Kutzing, Scenedesmusquadricauda Chodat, and Tetraedron trigonum (Nageli) Hans-girg, Followed by Bacillariophyta (39.05%), 7 genera and 10species, including Amphora ovalis (Kutzing) Kutzing, Bacillar-

ia paradoxa J.F.Gmelin, Cyclotella meneghiniana Kutzing,Cyclotella glomerata H.Bachmann, Aulacoseira granulata(Ehrenberg) Simonsen, Navicula gracilis Lauby, Nitzschia apicu-

lata (W.Gregory) Grunow, Nitzschia obtusa W.Smith, Nitzschiapalea (Kutzing) W.Smith, Nitzschia sigma (Kutzing) W.Smithand Synedra ulna (Nitzsch) Ehrenberg , then Cyanophyta

(12.3%); (6 genera, 9 species), Aphanocapsa delicatissima West& G.S.West , Chroococcus dispersus (Keissler) Lemmermann,Chroococcus minutus (Kutzing) Nageli, Dactylococcopsisacicularis Lemmermann, Merismopedia punctata Meyen,

Microcystis aeruginosa (Kutzing) Kutzing, Oscillatorialimnetica Lemmermann, Oscillatoria irrigua Kutzing exGomont and Oscillatoria tenuis C.Agardh but there was a

remarkably low number of Euglinophyta (4.00%) were repre-sented by 2 genera and 3 species that are Euglena caudataHubner, Phacus curvicauda Svirenko and Phacus pyrum

0

50

100

150

200

250

0 2 4 6 8 10 12 14C

ell n

umbe

r (x

103

ml-1

)

Incubation period (days)

5 6 7 8

Figure 3 Time course of C. vulgaris cell numbers (cells ml�1) for

5–8 runs of the CCD. The 5th run (WC= 5.0%;

SBC= 10.0 g l�1); the 6th run (WC = 30.0%; SBC= 10.0 g l�1);

the 7th (WC= 17.5%; SBC = 5.0 g l�1) and the 8th run

(WC= 17.5%; SBC = 15.0 g l�1). WC: wastewater concentra-

tion; SBC: sodium bicarbonate concentration.

50

100

150

200

250

Cel

l num

ber

(x 1

03m

l-1)

9 10

Figure 1 Percentage abundance of the microalgae groups in the WE.

304 H.Y. El-Kassas, L.A. Mohamed

(Ehrenberg) W.Archer. Chlorella vulgaris is the most dominantspecies of Chlorophyta.

Cultivation of the microalga C. vulgaris and pollutants removal

alga growth

The results presented graphically in Figs. 2–4 show the growthcurves of C. vulgaris obtained for each run of factorialdesign. The results recorded in Table 3 represents the maxi-

mum specific growth rate (lmax) and Cmax of the 1st to 10th

runs of the factorial design for evaluating the influence ofthe concentrations of both wastewater and sodium bicarbon-ate on the growth of the microalga C. vulgaris, as well as the

reduction of colour and COD. The largest SBC in 3rd run(13.5%), compared to 1st run (6.5%), caused no increasingof the values of lmax and Cmax. The 5

th run, which was accom-

plished with the smallest WC (5.0%), SBC of 10.0 g l�1,obtained the largest Cmax of 270,009 cells ml�1.

The 2nd run (WC = 26.5%; SBC= 6.5 g l�1), 4th run

(WC= 26.5%; SBC = 13.5 g l�1) and 6th run (WC= 30.0%;SBC = 10.0 g l�1) presented cellular death of culture and con-sequently the smallest values of Cmax was 211,070 cells ml�1.The comparison of 7th run (WC = 17.5%; SBC = 5.0 g l�1)

and 8th run (WC= 17.5%; SBC = 15.0 g l�1), revealed thatthe addition of sodium bicarbonate in the superior level resultedin obtaining higher values of lmax and Cmax of 0.52 d�1 and

0 0 2 4 6 8 10 12 14

Incubation period (days)

Figure 4 Time course of C. vulgaris cell numbers (cells ml�1) for

the 9th and 10th runs of the CCD. The 9th run (WC= 17.5%;

SBC= 10.0 g l�1) and 10th run (WC= 17.5%; SBC =

10.0 g l�1). WC: wastewater concentration; SBC: sodium bicar-

bonate concentration.

0

50

100

150

200

250

300

0 2 4 6 8 10 12 14

Cel

l num

ber

(x10

3m

l-1)

Incubation period (days)

1 2 3 4

Figure 2 Time course of C. vulgaris cell numbers (cells ml�1) for

1–4 runs of the CCD. 1st run (WC = 8.5%; SBC = 6.5 g l�1); the

2nd run (WC= 26.5%; SBC = 6.5 g l�1); the 3rd run

(WC= 8.5%; SBC = 13.5 g l�1) and 4th run (WC= 26.5%;

SBC = 13.5 g l�1). WC: wastewater concentration; SBC: sodium

bicarbonate concentration.

218,080 cells ml�1for 8th run, in comparison to 0.26 d�1 and210,090 cells ml�1 for 7th run.

The 9th and 10th runs, which are replicates (WC= 17.5%;

SBC= 10.0 g l�1), wherever the result of lmax was found inrun 10 (0.52 d�1) and of Cmax in run 9 (224,030 cells ml�1).The growth curves of the 9th and 10th runs presented a similar

behavior and log phase. Beside dyes, the WE contains otherpollutants such as COD. Growth of C. vulgaris reduces boththe colour and other pollutants, resulting in the bioremediation

Table 3 Coded and real values of wastewater concentration (WC, %) and sodium bicarbonate concentration (SBC, g l�1) and results

of maximum specific growth rate (lmax, d1), maximum cellular concentration (Cmax, cells ml�1) and removal of colour (%), COD (%),

in the CCD runs.

Run (WC, %) SBC, g l�1 Colour removal % COD removal % Cmax (cells ml�1) lmax Dry wt (g l�1)

1 8.5 (�1) 6.5 (�1) 74.6 69.25 260,000 0.89 1.74

2 26.5 (+1) 6.5 (�1) 73.7 65.60 211,070 0.42 1.88

3 8.5 (�1) 13.5 (+1) 72.8 67.50 252,090 0.87 1.68

4 26.5 (+1) 13.5 (+1) 71.16 51.25 220,002 0.47 0.90

5 5.0 (�a) 10 (0) 72.07 53.75 270,009 0.53 0.77

6 30.0 (+a) 10 (0) 74.66 63.13 220,123 0.56 0.88

7 17.5 (0) 5 (�a) 71.28 63.50 210,090 0.26 0.86

8 17.5 (0) 15 (+a) 76.32 49.10 218,080 0.53 1.55

9 17.5 (0) 10 (0) 75.40 63.75 224,030 0.52 1.50

10 17.5 (0) 10 (0) 75.68 69.90 208,011 0.52 1.49

Bioremediation 305

of the WE. The concentrations of COD recorded at the end ofall runs were smaller than the initial ones, evidencing the CODremoval during the time of this research study.

The results presented in Fig. 5a, b and c show the surfaceresponses of Cmax, colour and COD removal due to WC andSBC. The results indicates that the SBC concentration didnot influence significantly the responses of Cmax and the

removal of colour and COD. However, the linear effects ofWE concentration evidenced significant influences in theanswers of Cmax (p> 0.05). Largest lmax, Cmax were obtained

in the small WE concentration added, in the order of 8.5%,while highest colour and COD removals were obtained inthe other level of WC (17.5%). Parallel to the largest lmax

and Cmax, the maximal algal dry weight records were observed.

Discussion

The characteristics of the WE were highly variable but compa-rable to those reported by a previous study (Rahman, 1993).The physicochemical characteristics of the WE were within

the range of the values recorded by Lim et al. (2010) during theirstudy on bioremediation of Malaysian textile wastewater. Cop-per and chromium compounds have known uses in textile man-ufacturing, particularly for dyeing processes (IPPC, 2003)

Copper has also been previously reported in some dye planteffluents (Sharma et al., 2007). However, the constituents ofthe textile waste effluents differ according to the raw materials

used in this industry.The largest SBC in 3rd run, compared to 1st run containing

the lowest SBC, caused the increase of the values of lmax and

Cmax. The addition of sodium bicarbonate in the superior levelduring 7th run leads to obtaining higher values of lmax andduring 8th runs resulted in obtaining higher values ofCmax. However, 5th run, which was accomplished with the

smallest waste concentration and moderate SBC, obtainedthe maximum Cmax. Using larger WE concentrations, observedin 7th run and 8th runs, the control of the pH through the

sodium bicarbonate buffer is necessary due to the fact thatthe wastewater causes a decrease of the pH in the medium,making the micro alga growth unfeasible. It can be predicted

that the low WE concentration does not cause pH variationsthat limit the growth of the micro alga, thus the buffer effectof the bicarbonate is necessary. However, the statistical analy-

sis revealed that the concentrations of bicarbonate did not sig-nificantly affect the variables lmax and Cmax.

The cellular deaths observed in 2nd, 4th and 6th runs may beattributed to the high WE concentration. Lim et al. (2010)studied the cultivation of C. vulgaris, from textile waste efflu-

ent; they stated that the dilution of the textile waste effluentsis an important factor affecting the algal growth and biomassproductivity. Moreover C. vulgaris grew in 100% waste efflu-ent; although the final biomass attained was significantly lower

(p< 0.05) than that grown in 20–80% textile waste concentra-tion. However, Phang and Chu (2004) reported that C. vulgarisUMACC 001 was shown to be a versatile alga that is able to

grow under various harsh conditions.In this study C. vulgaris succeeded in decolorizing the WE

during all the studied runs. In this respect, Acuner and Dilek

(2004) reported that several species of Chlorella were capableof degrading azo dyes to their aromatic amines and to furthermetabolize the aromatic amines to simpler organic compoundsor CO2 and thereby detoxifying them. Furthermore, El-Sheekh

et al. (2009) reported the ability of C. vulgaris to decolorize avariety of azo dyes via algal azo dye reductase enzyme.

Gupta et al. (2006) and Ozer et al. (2006) suggested that the

dye removal may be attributed to the accumulation of dye ionson the surface of algal biopolymers and further to the diffusionof the dye molecules from aqueous phase onto solid phase of

the biopolymer. Moreover, Daneshvar et al. (2007) stated thatcolour removal by algae was due to three intrinsically differentmechanisms of assimilative utilization of chromophores for the

production of algal biomass, CO2 and H2O transformation ofcoloured molecules to non-coloured molecules, and adsorptionof chromophores on algal biomass. Mohan et al. (2002) attri-bute the decolorization to biosorption followed by bioconver-

sion and biocoagulation.The final COD concentrations recorded at the end of all runs

were smaller than the control value, confirming the COD

removal during the time of this research study. However, itwas observed that the COD removal occurred in runs, in addi-tion to those that presented cellular death. This can be explained

by the fact that Photosynthetic organisms and microalgae pro-duce oxygen that enhances the biological degradation of theorganic matter in the wastewaters (Aslan and Kapdan, 2006;Brito et al., 2007; Hodaifa et al., 2010a,b). COD removal might

not have been accomplished exclusively by C. vulgaris; but alsoby other factors including the chemical oxidation caused by theaeration of the culture as well as microorganisms in the waste-

water, which can promote the COD reduction of the mediumaccording to Metcalf and Eddy (1993).

6.50 7.50

8.50 9.50

10.50 11.50

12.50 13.50

8.50 11.50

14.50 17.50

20.50 23.50

26.50

200.000

210.000

220.000

230.000

240.000

250.000

260.000

Cm

ax (c

ells

ml–

1)

WCSBC

6.507.50

8.509.50

10.50 11.50

12.50 13.50

8.50 11.50

14.50 17.50

20.50 23.50

26.50

71.00

72.00

73.00

74.00

75.00

76.00

Col

our r

emov

al (

%)

WCSBC

6.507.50

8.509.50

10.50 11.50

12.5013.50

8.50

11.50

14.50

17.50

20.50

23.50

26.50

50.00

55.00

60.00

65.00

70.00

CO

D re

mov

al (

%)

WCSBC

(a)

(b)

(c)

Figure 5 Interaction effect between wastewater concentration (WC) and sodium bicarbonate concentration (SBC) on Cmax (a); colour

removal % (b); and COD removal % (c).

306 H.Y. El-Kassas, L.A. Mohamed

The phytoremediation of the textile industrial WE may beaccomplished by phosphorous removal which could havestarted by two different mechanisms: by the biological

assimilation during the biomass growth and by the chemicalprecipitation that occurred predominantly when the biomassconcentration decreases, as during the decline phase or cellular

death (Laliberte et al., 1997).During the different treatments, reduced Electric Conduc-

tivity (EC) values (uS) were observed in the 1st run which are

parallel to the maximum reductions in COD, colour, and thehighest recorded values of Cmax, lmax and this may be due tothe ability of algal species to consume the nutrients during

the algal growth. In this respect, Oswald (1988) stated that

total dissolved salts is one of the important factors that definethe relationship of culture medium species in the cultivation ofmicroalgae during nutrient and xenobiotic compound removal

with the aid of algae-based biosorbents. This agrees with otherstudies using algae such as Synechocystis and Phormidium forremoving colour from reactive dyes (Karacakaya et al., 2009).

The waste grown algal biomass may not be suitable for useas animal feed. However, there has been increased interest inusing algae for biodiesel production (Huang et al., 2010).

Moreover the amount of lipids in chlorophyta may be raisedup to 45% of dry weight by stress or nutrient starvation (Huet al., 2008). Using the current treatment design employed by

the factory, the coloured wastewater is not suitable for final

Bioremediation 307

discharge. The treatment system employing this algal designwill be useful to decolorize and detoxify the textile industrialWE before discharge and algal biomass can be analyzed for

lipid contents for further use in biofuel production.

Conclusions and future directions

The microalga C. vulgaris, grown on the WE showed Cmax

(270,009 cells ml�1), lmax (0.53 d�1) in the smaller wastewater

concentration added to the cultivation medium (5.0 and

8.5%), while larger COD removals (69.25 and 69.90%) andthe largest colour removals (75.68%) were obtained using themoderate waste water concentration in the cultivation medium.

Thus the cultivation of C. vulgaris in WE demonstrated thecapability of biomass production, colour and COD removal;therefore this microalga can be an alternative to assist in the

textile culture effluent treatment, reducing the environmentalimpact caused by their pollutants. The algal biomassgenerated may be useful as feedstock, fertilizers or for biofuelproduction.

Acknowledgments

The authors would like to extend their sincere thanks to Prof.Dr. Sawsan Aboulezz for revision of the manuscript. Noamount of words can adequately express the debt we owe to

our Guide Prof. Dr. Samiha Mahmoud Gharib for her kindassistance during the identification of the algal flora presentin the waste effluent.

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