Treatment of textile wastewater using different processes

Final report

Master of Water Engineering

By Abdalmunem Ammar

211028725

Supervisor: Dr. Jega Jegatheesan

ABSTRACT

The textile wastewater treatment is a big challenge to environmental chemists,

engineers and the water authorities. It produces a great amount of wastewater

that is extremely coloured with substantial loading of inorganic salts. Dead end

and cross flow nanofiltration using thin film composite polyamide membrane

were used to recover the flux and reject the colour. Using a solution mixed of

dye (type of acid green 25) and NaCl, the study focused on the controlling flux,

dye rejection, and salt rejection by varying the main parameter; feed pressure,

dye concentration and salt concentration. Results show that flux was

independent of the method used and the osmotic pressure caused from the

presence of NaCl. Also, dye concentration had significant effect on the flux and

the rejection. Working at pressure 8 bars, the relative average dye rejection was

above 99 %, with an average salt rejection less than 12 % for both methods.

Additionally, high flux on the dead end method was approximately 30 l/m2h and

for the cross flow method was less than 20 l/m2h. Therefore, it can be recovered

a high quality of water for reusing purposes. In cross flow method, the

membrane did not have foul, which ran for long term to recover the same

amount of flux with dye rejection more than 99 %.

Acknowledgements I would like to express the deepest appreciation to my supervisor associate

professor Jage Jegatheesan, for his excellent guidance, caring, patience, and

providing me with an excellent atmosphere for doing research. Without his

guidance and persistent help this project would not have been possible. I would

like to thank, Dr. Li Shu for her invaluable guidance throughout the project.

Thanks to Leanne Farago and other workers in the laboratory.

I would also like to thank my wonderful family. They always supported me and

encouraged me with their best wishes. Also, I would like to thank all my

friends, especially Libyan friends were supporting me in here.

ii

ContentsABSTRACT........................................................................................................................................... i

List of Figures....................................................................................................................................... iv

List of Tables.........................................................................................................................................v

1 Introduction:..................................................................................................................................1

1.1 Background:..........................................................................................................................1

1.1.1. Textile dyeing wastewater risk:......................................................................................2

1.1.2. The textile industry standards for water pollutants:.......................................................3

1.2 Objectives of the study:.........................................................................................................4

1.3 Scope of research:..................................................................................................................5

2 Literature review...........................................................................................................................6

2.1 The physical and physicochemical treatment methods..........................................................6

2.1.1 Adsorption:....................................................................................................................6

2.1.2 Ion Exchange:................................................................................................................7

2.1.3 Coagulation-Flocculation:..............................................................................................7

2.1.4 Membrane Technology:.................................................................................................8

2.1.5 Irradiation:...................................................................................................................11

2.2 The chemical methods for textile wastewater treatment......................................................11

2.3 The biological treatment for textile wastewater treatment:..................................................12

2.3.1 Aerobic Treatment:......................................................................................................12

2.3.2 Anaerobic Treatment:..................................................................................................13

2.3.3 Coupled Anaerobic--Aerobic Treatment:.....................................................................14

3 Materials and Methods:...............................................................................................................17

3.1 Materials:.............................................................................................................................17

3.2 Equipment:..........................................................................................................................17

3.3 Experiment set-up:...............................................................................................................18

3.4 Methods:..............................................................................................................................18

3.4.1 Preparation of dye solutions:........................................................................................18

3.4.2 Standard curve to calculate concentration of effluent dye solutions:............................19

3.4.3 Treatment by Nano-filtration:......................................................................................20

3.4.4 Treatment by forward osmosis:....................................................................................22

3.4.5 Measurement of dye concentration:.............................................................................22

4 Results and discussion.................................................................................................................23

4.1 Dead end method:................................................................................................................23

iii

4.1.1 Experiments with distilled water:.....................................................................................23

4.1.2 Effect of dye concentration:.............................................................................................23

4.1.3 Effect dye concentration on dye removal:........................................................................24

4.1.4 Effect of dye concentration on flux:.................................................................................25

4.1.5 Effect dye concentration on salt removal:........................................................................26

4.1.6 Effect of salt concentration on flux:.................................................................................27

4.2 Run experiment for long term:.............................................................................................28

4.2.1 Effect of time on dye rejection for long term:..................................................................28

4.2.2 Effect of time on salt rejection for long term:..................................................................29

4.2.3 Effect of time on the flux:................................................................................................29

5 Conclusion:..................................................................................................................................31

Reference:........................................................................................................................................32

List of Figures

iv

Figure 1 the schematic diagram of experimental set-up.......................................................................24Figure 2 Structures of acid green 25 dye used in this study.................................................................25Figure 3 Calibration curve of Acid green 25 dye using UV-spectrophotometer..................................26Figure 4 Effect dye concentration on dye removal..............................................................................30Figure 5 Effect of dye concentration on flux.......................................................................................31Figure 6 Effect dye concentration on salt removal...............................................................................32Figure 7 Effect of salt concentration on flux.......................................................................................33Figure 8 Effect of time on dye rejection for long term.........................................................................34Figure 9 Effect of time on salt rejection for long term.........................................................................35Figure 10 Effect of time on flux for long term.....................................................................................35

List of TablesTable 1 the main dyes and chemicals used in synthetic textile mills by Kg/month................................9

v

Table 2 textile industry standards for water pollutants in China..........................................................10Table 3 textile industry standards for water pollutants in Germany.....................................................10Table 4 Comparison between the types of membranes........................................................................15Table 5 effect dye concentration on flux and dye rejection at different pressure and flow rate by using NF........................................................................................................................................................16Table 6 summary of comparison of oxidative methods.......................................................................18Table 7 applications of combined different processes to treat textile wastewater................................21Table 8 Flux of using distilled water...................................................................................................29Table 9 Comparison between Nano filtration experiments for short term runs by using dead end method and for long term by using cross flow method........................................................................36

vi

1 Introduction

1.1 Background

Textile industry is the largest water consumers in the worldwide in its

manufacturing processes (Fu, Zhang & Wang 2011). The textile industry in

Australia has been used more than 12,793 ML of drinking water/year in 2004 –

2005 which is approximately 50% is in Victoria because it has largest industry

(Australian Industry Group 2012). Textile wastewater is containing pollutants

from different stages, such as dyeing, sizing processes, finishing, and multiple

wash cycles washing as well as other processes (Sahinkaya et al. 2008). Textile

industry is one of the world's most complex industries in manufacturing

industry (Arumai Dhas 2008). The textile industry wastewater is evaluated as

the highest polluting among all manufacturing (Şen & Demirer 2003).

According to studies, the most important of pollutants in the textile wastewater

are large amount of suspended solids (SS), pH, colour and salts. Recalcitrant

organics contain dye, sizing agents and dying aids. As well as the “dye is the

most difficult constituent of the textile wastewater to treat” (Şen & Demirer

2003). Also the textile wastewater has high temperature, biochemical oxygen

demand (BOD), acidity, high chemical oxygen demand concentration (COD)

and other soluble substances (Ahn, Chang & Yoon 1999; Kim et al. 2002). All

those contents making the processes of treat textile wastewater more complex.

As in recent years, they have been developed several processes to treat textile

wastewater. However, each process has disadvantage which cannot be used

separately. According to Ahn, Chang and Yoon (1999) when using coagulation

process, will be produce a large quantity of sludge and will become a pollutant

itself which the treatment cost will increase. As well the oxidation process, for

example ozonation effectively decolourises with most dyes. Nevertheless, it is

not effectively with remove COD and the effectiveness of decolourisation will

decrease by impurities which the treatment cost will be increase because the

quantity of ozone will increase also. In addition, Activated carbon adsorption

will be not suitable for any dye such as the insoluble dyes (Ahn, Chang & Yoon

1999).

1.1.1. Textile dyeing wastewater riskAs the textile dyeing and finishing industry has produced a massive pollution

which is the most chemically intensive industries on worldwide (Kant 2012).

According to Kant 2012, “More than 3600 individual textile dyes are being

manufactured by the Industry today. The industry is using more than 8000

chemicals in various processes of textile manufacture including dyeing and

printing”. By this figure if a textile wastewater discharges into the environment

without any treatment, it will has a serious effect on surrounding land and

natural waters (Wang et al. 2011). Next table show the main dyes and chemicals

used in synthetic textile mills by Kg/month:

2

Table 1 the main dyes and chemicals used in synthetic textile mills by Kg/month

No. Chemical Quantity Kg/month

1 Acetic Acid 16112 Ammonium Sulphate 8583 P V Acetate 9544 Wetting Agent 1255 Caustic Soda 62126 Softener 8567 Organic Solvent 2478 Organic Resin 51159 Formic Acid 1227

10 Soap 15411 Hydrosulphites 656312 Hydrochloric Acid 30913 Hydrogen Peroxide 103814 Leveling & Dispersing Agent 547

15 Solvent 1425 32116 Oxalic Acid 47117 Polyesthylene Emulsion 117418 Sulphuric Acid 67819 Disperse Dyes (Polyester) 150020 Vat Dyes (Viscose) 90021 Sulphur Dyes 30022 Reactive Dyes 45

Source: Kant 2012.

1.1.2. The textile industry standards for water pollutantsTextile wastewater has dangerous effect on the people and the environment,

which need to requirements for release of the wastewater. They are using

different raw materials, dyes, technology and equipment, which is required

different standards for wastewater emission depended to local conditions and

environmental protection requirements (Wang et al. 2011). Tables have shown

the standards textile wastewater in china and Germany:

3

Table 2 textile industry standards for water pollutants in China

Serial

numberParameters

The Limits of

Discharged

Concentration

The Limits of

Discharged

Concentration for new

Factory

The Special Limits

of Discharged

Concentration

1 COD 100mg/L 80 mg/L 60 mg/L

2 BOD 25 mg/L 20 mg/L 15 mg/L

3 pH 6~9 6~9 6~9

4 SS 70 mg/L 60 mg/L 20 mg/L

5 Chrominance 80 60 40

6 TN 20 mg/L 15 mg/L 12 mg/L

7 NH3-N 15 mg/L 12 mg/L 10 mg/L

8 TP 1.0 mg/L 0.5 mg/L 0.5 mg/L

9 S 1.0 mg/L Cannot be detected Cannot be detected

10 ClO2 0.5 mg/L 0.5 mg/L 0.5 mg/L

11 Cr6+ 0.5 mg/L Cannot be detected Cannot be detected

12 Aniline 1.0 mg/L Cannot be detected Cannot be detected

Source: Wang et al. 2011.

Table 3 textile industry standards for water pollutants in Germany

Serial number Parameters The Limits of Discharged Concentration

1 COD 160mg/L2 BOD 25 mg/L3 TP 2.0 mg/L4 TN 20 mg/L5 NH3-N 10 mg/L6 Nitrite 1.0 mg/L

Source: Wang et al. 2011.

1.2 Objectives of the study

The objectives of this research are focuses on the treat textile wastewater using

Nano filtration membrane with using dead end method for short term and for

long term using cross flow method, and study the characteristics of textile

wastewater to understanding of the removal of dye and sodium chloride after

treating.

4

1.3 Scope of research

This project is compare the treat the dye solution by mixing dye which I used

acid green 25 for dye with different concentration and sodium chloride in the

water by using Nano filtration proses with different method. The comparison

will by measure the dye, salt rejection and the parameter flux.

5

2 Literature review

Textile industry produced a wastewater has a large amount of dyes and

chemicals. The textile wastewater can be treated by different processes such as

chemical, physical, or biological processes (Valh et al. 2011). However, all

treatment technology has limitation, advantage, and disadvantage. It is very

complex and difficult to treat because the dye contains in textile wastewater can

differ daily or even hourly, also has huge quantity of suspended solids, which is

one of wastewater treatment process is unable to treat the textile wastewater and

provide high efficient treatment and will be effect by cost as well.

2.1 The physical and physicochemical treatment methods

The main goal of these methods is to remove particulate matter and undissolved

chemicals in textile wastewater, which are adsorption, coagulation, flocculation,

ion exchange, membrane technology and irradiation (Valh et al. 2011).

2.1.1 Adsorption

The adsorption is more commonly used method in physicochemical textile

wastewater. For example, by using activated carbon, kaolin and silicon

polymers is the most commonly for treatment textile wastewater to remove

colour. Different adsorbents have selective in depended of adsorption of dyes.

The best adsorbent of dye wastewater by activated carbon (Robinson et al.

2001). It using widely to remove colour and COD which is reduced to 92.17%

and 91.15%, respectively and it is high effective for adsorbing mordant, acid,

6

and cationic dye. However, activated carbon is a less extent, direct, disperse,

pigment, vat, and reactive dyes(Robinson et al. 2001). Additionally, using

activated carbon for adsorbing is expensive, and the carbon must to be

reactivated otherwise removing the concentrates have to be considered.

Consequences of reactivation will be loss 10 ± 15% of the sorbent(Robinson et

al. 2001).

2.1.2 Ion Exchange

Ion exchange was not widely used for treat the dye containing wastewater,

because it cannot absorption a wide range of dyes. “Effluent is passed through

the ion exchange resin until the available exchange sites are saturated”. Ion

exchange can be removed anion and cation dye from dye containing

wastewater. This way for treatment has advantage when use this method for

removal soluble dyes, which can reclamation and regeneration of solvent

without loss of adsorbent, as well as it has disadvantage which has high cost and

it not effective for all dyes(Robinson et al. 2001).

2.1.3 Coagulation-Flocculation

Coagulation-flocculation method has using commonly in textile wastewater

treatment plants worldwide such as France and Germany (Valh et al 2011),

which has been reported that these possesses used for reduces COD remove

colour from textile wastewater. For coagulation and flocculation in textile

wastewater treatment required addition of chemicals such as aluminum sulhate,

7

copper sulfate, calcium chloride, ferric sulfate and different copolymers for

instance, hexamine, and pentaethylene to make flocks with the dye, which are

will separate by sedimentation tank or filtration (Verma, Dash & Bhunia 2012).

Coagulation-flocculation processes are effectively for disperse and sulphur

dyes. On the other hand, coagulation-flocculation has very low capacity to

remove colour when used it with direct, vat, reactive, and acid dyes. In addition,

these methods produce high amounts of polluted sludge, which after that should

be treated (dos Santos, Cervantes & van Lier 2007).

2.1.4 Membrane Technology

A membrane (semi-permeable membrane) can be defined as a thin layer of

material that is capable of separating materials. For this processes using

pressure difference between the feed and perm when driving force is apply to

across the membrane(Ahmad, Harris & Ooi 2012). The selective barrier that

allowed specific of particles and dissolved components to pass through, and

retaining the passage of others, which can be classified the return materials by

several criteria such as the size, shape and charge of the retained molecules, the

pressure applied on the membrane and the pore size of the membrane. The

classifications of membrane are microfiltration, ultrafiltration, Nano filtration,

and reverse osmosis(Van der Bruggen & Vandecasteele 2003).

8

Table 4 Comparison between the types of membranes

Microfiltration (MF)

Ultrafiltration (UF)

Nano filtration (NF)

Reverse osmosis (RO)

Permeability range (L.m-2.h-

1.bar-1)

> 50 10- 50 1.4- 12 0.05- 1.4

Pressure range (bar)

0.1- 2 1- 5 5- 20 10- 100

Typical Retentates

SolidsKaolin, silica, yeast, bacteria,

dextrose‘mud’, granular starch, pigments

Macromoleculesproteins,

polyvinyl alcohol, gelatinized starch, pectin, dispersed

dyes

Salts (small molecules)

sodium nitrate, sugar,

soluble dyes, amino acid

Dissolved ionssodium, chloride, macromolecules

Separation mechanism

Sieving Sieving Sieving- charge effects

Solution- Diffusion

Source: (Van der Bruggen & Vandecasteele 2003).

2.1.4.1 Nano filtration

The history of using Nano filtration (NF) membrane back to the 1970s when

operates OR at low pressures (Hilal et al. 2004). Hence, Membrane with a low

rejection of dissolved components, however by high water permeability, would

be a great improvement in the separation technology. This RO membrane with

low pressure became known as Nano filtration membrane (Van der Bruggen &

Vandecasteele 2003). In the second half of the 1980s, NF established and

became the first applications were reported (Conlon & McClellan 1989) and

(Schaep et al. 1998).

Textile wastewater treatment by using Nano filtration has reported by many

researchers. Study by Tang and Chen (2002) was using textile wastewater high

salt and dye concentration, and tread by using NF, they used pressure 500 kpa,

the flux obtained was high, whereas rejecting the dye was 98% and the NaC1

rejecting was less than 14%. In addition, they studied the effect of dye

9

concentration, which were using different concentration of dye at different flow

rate and pressure, with the stabilization of the concentration of salt (NaCl) at 20

g/L, the results show the dye rejection value was constant and the flux values

also constant, varying between 23.5 L/m2h to 25.07 L/m2h by increasing dye

concentration at pressure 200 kPa and flow rate 3 L/min. also the flux and dye

rejection still stable, by increasing the pressure to 500 kPa and flow rate to 5

L/min. Dye rejecting has been observed to increase only slightly when the dye

concentration increase. Another study by Jakobs and Baumgarten (2002) using

NF can remove up to 90% from the nitric acid.

Table 5 effect dye concentration on flux and dye rejection at different pressure and flow rate by using NF.

Dye concentration (ppm)

Pressure (kPa) Flow rate (L/min)

Flux (L/m2h) Dye rejection (%)

82 200 3 23.85 97.2147 200 3 25.07 97.2398 200 3 23.5 97.1705 200 3 24.27 97.4448 200 5 23.12 97.692 500 5 59.58 97.5188 500 5 62.72 97.8455 500 5 55.75 98.1708 500 5 59.76 98.4

890.8 500 5 59.58 98.51583 500 3 78.4 98.1

Source: (Tang & Chen 2002).

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2.1.5 Irradiation:

This method requires sufficient amounts of dissolved oxygen for organic

substances, in order to effectively broken by radiation. The dissolved oxygen

very fast and needs therefore a constant and adequate supply is required. This

affects the cost. Dye-containing wastewater can be treated in a two-pipe gushing

Rector. Irradiation process showed that some dyes and phenolic molecules are

oxidized effectively on a laboratory scale only

2.2 The chemical methods for textile wastewater treatment

This is the most commonly used method of colour removal by chemical means.

This is mainly due to its simplicity of application. The main oxidising agents are

usually hydrogen peroxide (H2O2) and ozone (O3) (Singh & Arora 2011).

Ozone is the best one of oxidants because it has high reactivity with dyes and

high removal efficiencies (Verma, Dash & Bhunia 2012). This agents needs to

be activated by some means, for example, ultra violet light. Many methods of

chemical decolourisation vary depending on the way in which the H2O2 is

activated (Majcen-Le Marechal, Slokar & Taufer 1997). Study by (Singh &

Arora 2011) in this method, the dye molecules when oxidized will be broken

down to small colourless molecules like water, acide, carbon dioxide, sulfates,

aldehydes, and nitrogen it will be depending on the strength of the oxidant

employed and on the dye structure

11

Table 6 summary of comparison of oxidative methods

Oxidation process Advantages Disadvantages

FentonEffective colour removal of soluble and insoluble dyes.

Required a simple equipment and easy operation. Decrease of

COD (except with reactive dyes). No change in volume

Long reaction times. Sludge formation. Salt creation.

Hazardous waste. Excessively expensive

FSR(Fenton sludge recycling system)

Simple equipment and operation. Decrease of COD (except with reactive dyes).

Formation of gases. Salt formation.

OzoneApply in gaseous state. No

change of volume. No sludge production. Effective for azo

dye removal.

Short half-life (20 min). Not suitable for disperse dyes.

Releases of aromatic amines

Ozone/H 2O2 No salt and sludge formation. Short reaction times and very

short reaction times for reactive dyes

Not appropriate for all dyes. Toxicity, hazard, difficult

treatment. No COD reduction. Extra load of water with ozone.

H 2O 2/UV No sludge and salt formation. Reduction of COD and short

reaction times.

Not appropriate to all types of dyes. Require separation of suspended solid particles.

UltrasoundSimplicity in use. Very

effective in integrated system.Relatively new method and

awaiting full scale application.Source: (Valh et al 2011).

2.3 The biological treatment for textile wastewater treatment:

There are different of the biological methods using, some of them are described

in the below:

2.3.1 Aerobic Treatment:

Activated sludge is the most widely treatment processes using in aerobic

treatment for treat textile dyeing effluent, which this method using to eliminate

the biodegradable constituents of effluent such as waxes and carbohydrates

(Joshi & Purwar 2004). Nonetheless, “Dyes, being resistant to biodegradation,

have a very low rate of removal ratio for BOD to COD (BOD/COD is less than

12

0.1) and thus are difficult to remove through biodegradation in the biological

treatment stage”.

Aerobic treatment can be removing approximately 60-70% of organic matter

from textile waste water (Joshi & Purwar 2004). According to studies by Joshi

and Purwar (2004) the level of toxicity will be difficult to decrease because the

existence of organic matter the toxicity level is hardly reduced due to the

presence of organic matter, which needs to be use tertiary treatments to remove

the toxicity. As well, the main problem when treat the dye wastewater, by using

aerobic biological is difficult the acclimatizing microorganisms to the substrate

as a result of the constant change of waste flow because of changes in wet

processing cycles (Singh & Arora 2011).

2.3.2 Anaerobic Treatment:

In anaerobic process the low level of the redox potential will be (<-50mV) can

be realized, which is effective for colour removal from dyes. In anaerobic

conditions, there are several bacteria can be decrease the extremely electrophilic

azo bond in the dye molecules and bring out colourless aromatic amines.

Anaerobic decolourisation of azo dyes was studied for the first time using

intestinal anaerobic bacteria (Valh et al 2011).

13

2.3.3 Coupled Anaerobic--Aerobic Treatment:

Anaerobic-aerobic treatment more effectively on colour removal (88 vs 28%),

also more reduced on TOC (90 vs 79%) if compared with treat textile

wastewater by using aerobic treatment by itself. Studied by Sponza and Isik

(2002) have shown that the anaerobic-aerobic system removed colour up to

98% in the anaerobic stage, and removed about 85-89% of the remaining COD

in the aerobic stage without any decolourisation happened in this stage.

Another studied by Singh and Arora (2011) has been investigated that can be

removed colour and toxication by anaerobic-aerobic system from textile

wastewater having soluble and insoluble dyes for example disperse, vat reactive

dyes. The results presented that decolourization from all kinds of dyes was

anaerobically. Additionally, by using this system the treated effluent has been

showed no toxicity.

14

Table 7 applications of combined different processes to treat textile wastewater

Treatment processes First stage Second stage Remarks

Physical/membrane treatment (2007) Coagulation UFAchieved significant colloidal particle removal which is remove turbidity more than 97%, irrespective of the kind and dosage of coagulant used. The membrane fouling was dependent on the kind of coagulant used. The inorganic coagulants were more efficient to decrease contamination in comparison to polymer coagulant (Choo, Choi & Hwang 2007).

Membrane treatment (2006) UF NFUltrafiltration was an appropriate pre-treatment of a NR/RO method for textile wastewater reuse. To treat with the waste water with high variability values of COD and conductivity, they observed flux decline at the lowest cross flow velocity was significantly studied because of the solid deposition on the membrane surface (Barredo-Damas et al. 2006).

Physical/membrane treatment (2005) Coagulation/ flocculation

NFStudy stated that the quality of permeate after coagulation/ flocculation did not match the requirement of reuse on the site. On the other hand, this process can act as pre-treatment of NF to limit membrane fouling. By using this integrated method, great quality permeate can be obtained (Suksaroj et al. 2005).

Chemical/membrane treatment (2005)

Electrochemical

oxidation

MembraneStudy shown that treated by using membrane before electrochemical oxidation method will resulted 82.2% of COD removal, 98.3% turbidity removal and 91.1% colour removal compared to electrochemical oxidation before the membrane method ( 86.2%, 95.1%, 85.2%) of COD, turbidity, and colour, respectively. This is because of low colour concentration residual in wastewater after the electrochemical oxidation process (Chen, X et al. 2005).

Chemical/biological treatment (2003) Ozonation AerobicUsing ozonation as pre-treatment was able to increase the bioavailability of the dye before it was treated with the aerobic process. Remove to a higher colour 99.8% and DOC 85% to higher doses of ozone, were needed. This can make it the cost less (Libra & Sosath 2003).

Physical/membrane treatment (2002) Sand filtration

and MF

NFSand filtration and MF in a pilot plant were essential in the decrease of particulate matter and turbidity (100%, 78%) respectively. To completely remove conductivity, colour and COD, Nano filtration was responsible for removal (Marcucci et al. 2002).

15

Physical/chemical treatment (1997) Coagulation and electrochemical

oxidation

Ion exchangeWater produced from this combined treatment was reported good to decrease conductivity, COD and colour; but, Effectiveness of treatments were significantly different with variable reaction times of H2O2 and current of electrochemical treatment (Lin & Chen 1997).

Physical/chemical/ biological treatment

(1996)

Coagulation and electrochemical

oxidation

Activated sludge

Continuous treatment by combined Coagulation, electrochemical oxidation and activated sludge showed that promising quality of permeate water could be achieved in addition to 24% cost savings over conventional processes. However, (as applied wastewater flow rate, current, time in the activated sludge aeration egc.) Operating parameters should be considered in order to optimize the treatment (Lin & Peng 1996).

Physical/chemical treatment (1994) Coagulation OzonationCoagulation of wastewater after ozonation treatment showed less efficient COD and colour decrease compared to Ozonation of wastewater after coagulation method under the similar conditions of wastewater. It was because of additional 20-25% and 90% of decrease of COD and colour, respectively, can be achieved by using ozonation after the coagulation treatment (Tzitzi, Vayenas & Lyberatos 1994).

Source: (Lau & Ismail 2009)

16

3 Materials and Methods:

3.1 Materials:

The chemicals materials were used during the research are sodium chloride

(NaCl). It is one of the most public inorganic salts that have been usually used

in dyeing process for the purpose of enhancing the degree of dye on fabric.

Also, acid green 25 (C28H20N2Na2O8S2) for the dye was provided at Deakin

university laboratory. Distilled water was used to prepare the dye solutions.

Nano-filtration membrane (DOW FILMTEC –NF245) was used for this

research has the following specification:

(YMNF2453001) 12x12’

Polymer: Polyamide

MWCO: 200-400D

Rej-Size: 99 MgSO4

pH@25oC: 2-11

Typical Flux/psi GFD@PSI: 52.0-72.0/130

3.2 Equipment:

The all glassware used in this experiment was washed by distilled water before

using in the experiments such as beakers and funnels. As well as using water

stirrers to mixing the solution; weighing balance connected to the computer and

a stirred cell of 180 mL capacity as shown in appendices was used for the Nano-

17

filtration experiment. A UV visible spectrophotometer 300 was used to measure

the absorbance of dye solution before and after experiments. A conductivity

meter and pH meter were used to measure the conductivity and pH of the

solution

3.3 Experiment set-up:

The experiment was carried out as shown in figure (1). The stirred cell was set

on water stirrer to keep mixing the solution during the run the experiment, its

connected to nitrogen gas to apply pressure to the system and connected to

small beaker to collect the sample of the permeate and it set on weighing

balance connected to computer to measure the permeate flux continuously.

Figure 1 the schematic diagram of experimental set-up

3.4 Methods:

3.4.1 Preparation of dye solutions:

The dye solution was prepared in four groups with different concentration by

dissolving different amounts of acid green 25, in distilled water with equal

18

amount of sodium chloride (NaCl) (15 g) to produce solution with

concentrations 250, 500, 750, and 1000 mg/L. the solution was mixing for 24

hours by using water stirrers.

Figure 2 Structures of acid green 25 dye used in this study

3.4.2 Standard curve to calculate concentration of effluent dye solutions:

In order to draw the standard curve to know the concentration of dye solution

after pass through Nano-filtration; different low masses of acid green 25

dissolving in distilled water to produce different samples with 400, 200, 100,

50, 25, 12.5, 6.125, 3.907, 1.953, 0.977 and 0.488 mg/L concentration, with the

similar amount of sodium chloride (15 g) and mixing for one day. Then the

absorbance was measure for each sample to draw the relationship between the

absorbance and dye solution as shown in following figure:

19

0 50 100 150 200 250 300 350 400 4500

0.5

1

1.5

2

2.5

3

3.5

Dye concentration (mg/L)

Abso

rptio

n

Figure 3 Calibration curve of Acid green 25 dye using UV-spectrophotometer.

3.4.3 Treatment by Nano-filtration:

The operating conditions of the experiments were divided to two phases. The

first phase operating the experiment for short term which was for one hour; dye

solution of 180 ml for each concentration was used in stirred cell, apply 8 bar

(800 KPa) pressure by using nitrogen gas. A water stirrer was adjusted on speed

300 rpm to preventing the dye to precipitate on the membrane. The sample was

collected in the beaker. For the weight of permeate was recorded every 3

minutes by connected the balance to the computer. Samples were collected

every 15 minutes and measured the conductivity, pH and absorbance to

calculate the concentration of the effluent. Second phase, it was operating for

long term which was for 6 hours by selected dye solution of 1000 mg/L

concentration and using the same condition of short experiment. Permeate

20

weight was recorded every 3 minutes as well and samples of permeate were

collected every 30 minutes to do the measurements.

The rejection of dye concentration (R) was calculated by

R (% )=[1−(CPCF )]∗100 %

Where CP and CF are the dye concentrations in permeate and the feed solution,

respectively.

The flux of permeate in membrane filtration process was calculated by

Flux (l /m ²∗h)=(m2−m1)/ ρ

A∗t

Where (m2) the final mass after 3 min running

(m1) the initial mass before 15 min running

(ρ) Solution Density = 1.015 kg/L

(A) Affective membrane area = 0.00216 m2

(t) Running time (3min)

The salt rejection (R) was defined as follows:

R (% )=[1−(CPCF )]∗100 %

21

Where CP is the salt concentration in the permeate solution and CF are the salt

concentrations in the feed solution.

3.4.4 Measurement of dye concentration:

The dye concentration of permeate was measured by measuring the absorbance

directly by using UV visible spectrophotometer 300 because the dye

concentration was low, and the dye concentration determined from the standard

curve. However, for the solution with high dye concentration which was

remaining after running the experiment was diluted before measuring the

absorbance order to measuring the dye concentrations.

22

4 Results and discussion

4.1 Dead end method:

4.1.1 Experiments with distilled water:

In the first the system was operated with the distilled water at different pressure

for 10 minutes. As it can see from the table 8 gives the membrane fluxs were

increasing as a function of pressure.

Table 8 Flux of using distilled water

Pressure (Bar) 2 4 6 8

Flux (L/m2h ) 11.97 24.02 32.87 43.97

4.1.2 Effect of dye concentration:

To examine the effects of dye concentration, experiments were using different

dye concentrations, the pressure and salt concentration were kept constant at 8

bar and 15 g/L, respectively.

23

4.1.3 Effect dye concentration on dye removal:

Figure 4 Effect dye concentration on dye removal

In figure 4 shown compares the dye rejection for the solution with different

concentrations. The expectation with increasing dye concentration, for dye

rejection is decrease which is higher with lower feed concentration and lower

with higher feed concentration. The results are shown clearly with increasing

dye concentration from 250 mg/L to 1000 mg/L (at P = 800 kPa), the

percentage of dye rejection was found to remain reasonably constant, varying

between 99.8% and 99.69%. Therefore, for these conditions of initial dye

concentration does not affect the rejection of dye significantly. However, from

the figure 4 also it can see the dye rejection after half hour for the solution high

concentration was higher than the solution with low concentration. It may due

to increase the dye accumulation on membrane surface for high concentration,

which is the colour rejection became higher than the solution with lower dye

concentration (Koyuncu 2002)

24

200 300 400 500 600 700 800 900 1000 110090.00%91.00%92.00%93.00%94.00%95.00%96.00%97.00%98.00%99.00%

100.00%

After half an hourAfter one hour

Dye concentration (mg/L)

Dye

reje

ction

(%)

4.1.4 Effect of dye concentration on flux:

0 10 20 30 40 50 60 700.005.00

10.0015.0020.0025.0030.0035.0040.0045.0050.00

Relationship between time and flux for different concentrations of dye

500 mg/L750 mg/L1000 mg/L

Time(min)

Flux

(l/m

²*h)

Figure 5 Effect of dye concentration on flux

The figure 5 shows the permeate flux for solutions with different dye

concentrations. It can be clearly seen that the permeate flux decline slightly

when increased the dye concentration from 250 to 1000 mg/L. Which is the dye

concentration has a significant effect on the permeate flux. It may causing by

concentration polarisation, which are defined to be the increase of solutes on the

membrane surface(Chen, H-L, Chen & Juang 2008). Koyuncu (2002) has

reported that the flux values had effected by the dye concentration significantly,

which decreased with increasing the concentration of dye with fixed NaCl

concentration. It may be caused by the adsorption of the dye on the membrane

surface which was observed at the experimental runs, which are shows by the

colour on the membrane surface after filtration. The permeate flux was observed

25

is decreasing for all concentrations of dye, which is not stabilise after operation

the experiments for one hour. It was found that decreasing from 43.22 to 37.02

l/m²h for 500 mg/L dye concentration, and from 39.84 to 28.26 l/m²h for 1000

mg/L. This decreasing may due to the fouling of the membrane(Chen, G et al.

1997).

4.1.5 Effect dye concentration on salt removal

400 500 600 700 800 900 1000 11000%

10%

20%

30%

40%

Salt rejection (%)

Dye concentration (mg/L)

Salt

reje

ction

Figure 6 Effect dye concentration on salt removal

The figure 6 illustrates the effect of dye concentration on salt rejection. It can be

seen that increasing the dye concentration resulted in a slight declining in the

salt rejection. According to Tang and Chen (2001) the lower salt rejection

obtained at lower flux, which has shown in figure 5 decreasing flux when

increasing the dye concentration.

26

4.1.6 Effect of salt concentration on flux

0 10 20 30 40 50 60 700.00

10.00

20.00

30.00

40.00

50.00

60.00

Permeata flux versus time for different salt concentrations

3.25 g/L7.5 g/L15 g/L

Time (min)

Flux

(l/m

²*h)

Figure 7 Effect of salt concentration on flux

The figure 7 shown compares the values of permeate flux for the different salt

concentrations. It clearly can be seen that the permeate flux dropped rapidly by

increasing salt concentration from 3.25 to 15 mg/L. It resulted by increasing

osmatic pressure of salt (Hong, Miller & Bruening 2006; Koyuncu 2002).

The salt concentration of feed solution playing a significant role in treating the

textile wastewater by using Nano filtration membrane separation method. The

salt is considered as an essential component in textile industry to enhance the

degree of dye fixation onto fabric. In general, according to Koyuncu (2002) the

lower the salt concentration, the lower is osmotic pressure and the higher is the

permeate flux.

27

4.2 Run experiment for long term

For the long term experiment where used cross flow method, which the

experiment was running for six hours by using concentration 1000 mg/L of acid

green 25 dye,15 g/L of salt and 8 bars for the pressure.

4.2.1 Effect of time on dye rejection for long term

0 50 100 150 200 250 300 350 40090.00%

91.00%

92.00%

93.00%

94.00%

95.00%

96.00%

97.00%

98.00%

99.00%

100.00%

1000 mg/L

Time (min)

Dye

reje

ction

(%)

Figure 8 Effect of time on dye rejection for long term

The figure 8 shows the relationship between dye rejection and the time for using

dye concentration 1000 mg/L. As it can be clearly shown that the percentage of

dye rejection is constant, which is above than 99 %. It may cause by good mass

transfer through the membrane, which does not allow the dye concentration

polarisation to build layer on the surface of membrane which will prevent the

fouling to occur (Tang and Chen 2001).

28

4.2.2 Effect of time on salt rejection for long term

The salt rejection was obtained for the long term experiment increased by

increasing the time, as shown in figure 9. It cloud be caused by increasing the

salt concentration on the feed solution which will effect on decreasing the salt

rejection (Tang and Chen 2001).

0 50 100 150 200 250 300 350 4000.00%

2.00%

4.00%

6.00%

8.00%

10.00%

12.00%

14.00%

16.00%

18.00%

20.00%

Salt rejection(%)

Time (min)

Salt

reje

ction

(%)

Figure 9 Effect of time on salt rejection for long term

29

4.2.3 Effect of time on the flux

0 50 100 150 200 250 300 350 4000.00

5.00

10.00

15.00

20.00

25.00

Flux (l/m²*h)

Time (min)

Flux

(l/m

²*h)

Figure 10 Effect of time on flux for long term

Figure 10 shows that the relationship between the flux and the time resulted

from Nano filtration long term experiment by using cross flow. The results are

shown in the figure the flux values after six hours (at P = 8 bar, Q = L/ min)

were found to remain reasonably constant, which is varying between 18.53

L/m2h to 22.41 L/m2h. This may cause by the good mass transfer across the

membrane surface which does not allow the dye concentration polarisation

build-up layer for fouling to occur.

Table 9 summarise of the Nano filtration experiments for short term runs by using dead end method and for long term by using cross flow method.

NF / 8 bar Short term Long term (6 hours)Dye concentration (mg/L) 250 500 750 1000 1000NaCl (g/L) 15Average flux (l/m2h) 33.26 37.87 35.23 30.87 20.55Rejection of dye 99.80 % 99.13 % 99.66 % 99.69 % 99.48 %Rejection of salt 16.75 % 21.42 % 15.17 % 11.33 % 11.32 %

30

5 Conclusion

The nanofiltration membrane process has been regarded as one of the promising

methods for treating the textile wastewater, which produce highly coloured

wastewater. Nanofiltration system with different methods; dead end and cross

flow has been setup at the laboratory to suit for the treatment textile wastewater

with high dye concentration. The applied pressure was 8 bars for both methods,

the dye rejection was reached to level more than 99 %; salt rejection was less

than 14 % as well. The flux obtained was high at the dead end than cross flow.

The dye and salt concentration has a significant effect, which increased the flux

by decreasing the dye or salt concentration.

31

Reference

Ahmad, AL, Harris, WA & Ooi, BS 2012, 'Removal of dye from wastewater of textile industry using membrane technology', Jurnal Teknologi, vol. 36, pp. 31–44.

Ahn, DH, Chang, WS & Yoon, TI 1999, 'Dyestuff wastewater treatment using chemical oxidation, physical adsorption and fixed bed biofilm process', Process Biochemistry, vol. 34, no. 5, pp. 429-39.

Arumai Dhas, JP 2008, 'Removal of Cod and Colour from Textile Wastewater Using Limestone and Activated Carbon', Universiti Sains Malaysia.

Australian Industry Group, 2012, ‘Water saving factsheet: Textile Industry’, Australian Industry Group, retrieved 7 Dec 2012, <http://pdf.aigroup.asn.au/environment/7082_WPA_fact_sheet_ TEXTILE.pdf>.

Babu, B. R., et al. (1995). "Textile Technology." Technology.

Barredo-Damas, S, Alcaina-Miranda, M, Iborra-Clar, M, Bes-Pia, A & Mendoza-Roca, J 2006, 'Study of the UF process as pretreatment of NF membranes for textile wastewater reuse', Desalination, vol. 200, no. 1, pp. 745-7.

Chen, G., et al. (1997). "Treatment of textile desizing wastewater by pilot scale nanofiltration membrane separation." Journal of membrane science 127(1): 93-99.

Chen, H.-L., et al. (2008). "Recovery of surfactin from fermentation broths by a hybrid salting-out and membrane filtration process." Separation and Purification Technology 59(3): 244-252.

Chen, X, Shen, Z, Zhu, X, Fan, Y & Wang, W 2005, 'Advanced treatment of textile wastewater for reuse using electrochemical oxidation and membrane filtration', Water SA, vol. 31, no. 1, pp. 127-32.

Choo, K-H, Choi, S-J & Hwang, E-D 2007, 'Effect of coagulant types on textile wastewater reclamation in a combined coagulation/ultrafiltration system', Desalination, vol. 202, no. 1, pp. 262-70.

Conlon, WJ & McClellan, SA 1989, 'Membrane softening: a treatment process comes of age', Journal of the American Water Works Association, vol. 81, no. 11, pp. 47-51.

dos Santos, AB, Cervantes, FJ & van Lier, JB 2007, 'Review paper on current technologies for decolourisation of textile wastewaters: perspectives for anaerobic biotechnology', Bioresource Technology, vol. 98, no. 12, pp. 2369-85.

Edwards, J. C. (2000). Investigation of color removal by chemical oxidation for three reactive textile dyes and spent textile dye wastewater, Virginia Polytechnic Institute and State University.

Fu, Z, Zhang, Y & Wang, X 2011, 'Textiles wastewater treatment using anoxic filter bed and biological wriggle bed-ozone biological aerated filter', Bioresource Technology, vol. 102, no. 4, pp. 3748-53.

Hilal, N, Al-Zoubi, H, Darwish, N, Mohamma, A & Abu Arabi, M 2004, 'A comprehensive review of nanofiltration membranes: Treatment, pretreatment, modelling, and atomic force microscopy', Desalination, vol. 170, no. 3, pp. 281-308.

32

Hong, S. U., et al. (2006). "Removal of dyes, sugars, and amino acids from NaCl solutions using multilayer polyelectrolyte nanofiltration membranes." Industrial & engineering chemistry research 45(18): 6284-6288.

Jakobs, D & Baumgarten, G 2002, 'Nanofiltration of nitric acidic solutions from picture tube production', Desalination, vol. 145, no. 1, pp. 65-8.

Joshi, M & Purwar, R 2004, 'Developments in new processes for colour removal from effluent', Review of Progress in Coloration and Related Topics, vol. 34, no. 1, pp. 58-71.

Kant, R 2012, 'Textile dyeing industry an environmental hazard', Natural Science, vol. 4, no. 1, pp. 22-6.

Kim, T-HTH, Park, C, Lee, J, Shin, E-BEB & Kim, S 2002, 'Pilot scale treatment of textile wastewater by combined process (fluidized biofilm process-chemical coagulation-electrochemical oxidation)', Water Research, vol. 36, no. 16, pp. 3979-88.

Koyuncu, I. (2002). "Reactive dye removal in dye/salt mixtures by nanofiltration membranes containing vinylsulphone dyes: effects of feed concentration and cross flow velocity." Desalination 143(3): 243-253.

Lau, W-J & Ismail, A 2009, 'Polymeric nanofiltration membranes for textile dye wastewater treatment: Preparation, performance evaluation, transport modelling, and fouling control—a review', Desalination, vol. 245, no. 1, pp. 321-48.

Libra, JA & Sosath, F 2003, 'Combination of biological and chemical processes for the treatment of textile wastewater containing reactive dyes', Journal of Chemical Technology and Biotechnology, vol. 78, no. 11, pp. 1149-56.

Lin, SH & Chen, ML 1997, 'Treatment of textile wastewater by chemical methods for reuse', Water Research, vol. 31, no. 4, pp. 868-76.

Lin, SH & Peng, CF 1996, 'Continuous treatment of textile wastewater by combined coagulation, electrochemical oxidation and activated sludge', Water Research, vol. 30, no. 3, pp. 587-92.

Majcen-Le Marechal, A, Slokar, YM & Taufer, T 1997, 'Decoloration of chlorotriazine reactive azo dyes with H< sub> 2</sub> O< sub> 2</sub>/UV', Dyes and Pigments, vol. 33, no. 4, pp. 281-98.

Marcucci, M, Ciardelli, G, Matteucci, A, Ranieri, L & Russo, M 2002, 'Experimental campaigns on textile wastewater for reuse by means of different membrane processes', Desalination, vol. 149, no. 1, pp. 137-43.

Robinson, T, McMullan, G, Marchant, R & Nigam, P 2001, 'Remediation of dyes in textile effluent: a critical review on current treatment technologies with a proposed alternative', Bioresource Technology, vol. 77, no. 3, pp. 247-55.

Sahinkaya, E, Uzal, N, Yetis, U & Dilek, FB 2008, 'Biological treatment and nanofiltration of denim textile wastewater for reuse', Journal of Hazardous Materials, vol. 153, no. 3, pp. 1142-8.

Schaep, J, Van der Bruggen, B, Uytterhoeven, S, Croux, R, Vandecasteele, C, Wilms, D, Van Houtte, E & Vanlerberghe, F 1998, 'Removal of hardness from groundwater by nanofiltration', Desalination, vol. 119, no. 1, pp. 295-301.

33

Şen, S & Demirer, GN 2003, 'Anaerobic treatment of real textile wastewater with a fluidized bed reactor', Water Research, vol. 37, no. 8, p. 1868.

Singh, K & Arora, S 2011, 'Removal of synthetic textile dyes from wastewaters: a critical review on present treatment technologies', Critical Reviews in Environmental Science and Technology, vol. 41, no. 9, pp. 807-78.

Sponza, D & Işik, M 2002, 'Decolorization and azo dye degradation by anaerobic/aerobic sequential process', Enzyme and Microbial Technology, vol. 31, no. 1, pp. 102-10.

Suksaroj, C, Heran, M, Allegre, C & Persin, F 2005, 'Treatment of textile plant effluent by nanofiltration and/or reverse osmosis for water reuse', Desalination, vol. 178, no. 1, pp. 333-41.

Tang, C & Chen, V 2002, 'Nanofiltration of textile wastewater for water reuse', Desalination, vol. 143, no. 1, pp. 11-20.

Tang, C. and V. Chen (2002). "Nanofiltration of textile wastewater for water reuse." Desalination 143(1): 11-20.

Tzitzi, M, Vayenas, D & Lyberatos, G 1994, 'Pretreatment of textile industry wastewaters with ozone', Water Science & Technology, vol. 29, no. 9, pp. 151-60.

Valh, J Marechal, A Vajnhandl, S Jeric, T & Simon, E 2011, ‘Water in the Textile Industry’, University of Maribor Maribor Slovenia.

Van der Bruggen, B & Vandecasteele, C 2003, 'Removal of pollutants from surface water and groundwater by nanofiltration: overview of possible applications in the drinking water industry', Environmental Pollution, vol. 122, no. 3, pp. 435-45.

Verma, AK, Dash, RR & Bhunia, P 2012, 'A review on chemical coagulation/flocculation technologies for removal of colour from textile wastewaters', Journal of environmental management, vol. 93, no. 1, pp. 154-68.

Wang, Z Xue, M Huang, K & Liu, Z 2011, 'Textile Dyeing Wastewater Treatment', Huazhong University of Science and Technology China.

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Appendix

35