Nanofiltration of textile plant effluent for color removal and reduction in COD

Nanofiltration of textile plant effluent for color removal andreduction in COD

S. Chakraborty, M.K. Purkait, S. DasGupta *, S. De, J.K. Basu

Department of Chemical Engineering Indian Institute of Technology, Kharagpur 721 302, India

Received 20 May 2002; received in revised form 30 August 2002; accepted 12 September 2002

Abstract

A membrane based separation process (nanofiltration, NF) is used to treat the effluent from a textile plant. The dye

mixture contains reactive black dye (Cibacron Black B) and reactive red dye (Cibacron Red RB). An organic membrane

with molecular weight cut-off of 400 is used for the experiments. The experiments are conducted in an unstirred batch

and a rectangular cross flow cell. Separations with retentions up to 94 and 92% of the two dyes are achieved respectively

in the cross flow cell where steady state is attained quickly. It is important to note that NF techniques achieve a sharp

reduction in chemical oxygen demand (COD), (up to 94% in cross flow cell), as the dyes are removed from the

permeate. A parametric study of the separation process is undertaken to characterize the effects of the operating

variables, e.g., trans-membrane pressure, dye concentration in the feed and cross flow velocity in case of cross flow NF.

# 2002 Elsevier Science B.V. All rights reserved.

Keywords: Nanofiltration; Cross flow; Textile effluent; Dye; Chemical oxygen demand

1. Introduction

Industrialization and urbanization have resulted

in rapid deterioration of water quality. The

scientific evidences prove that the effluents re-

leased from different industries e.g. textile, leather,

paint etc. comprise of different hazardous and

toxic compounds, some of which are known

carcinogens and others probable carcinogens.

The emergence of industrial centers without a

corresponding growth in civic amenities and

pollution control mechanisms results in a gradual

decay of water quality.

Textile industries, particularly those involved in

finishing processes are major water consumers and

the source of considerable pollution. The environ-

mental challenge for the textile industry is asso-

ciated with liquid waste, which tends to dominate

over air-emissions and solid wastes in terms of the

severity of environmental impacts. A typical textile

unit generates various types of wastewater differ-

ing in magnitude and quality. The wastewater

from printing and dyeing units in a textile plant are

often rich in color, containing residual of reactive

dyes and chemicals, and needs proper treatment

before releasing into the environment.

* Corresponding author. Tel.: �/91-03222-83922; fax: �/91-

03222-75303

E-mail address: [email protected] (S. DasGupta).

Separation and Purification Technology 31 (2003) 141�/151

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1383-5866/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.

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Among the conventional methods for removal

of color from wastewater, viz. chemical coagula-

tion, flotation, chemical oxidation and adsorption

[1], adsorption is the most common technique. But

it is inherently a slow process and its performance

is limited by the equilibrium. Thus there is a

definite need to find alternative treatment pro-

cesses. Membrane techniques hold great promise

in this field, [2] as they have the potential to either

remove the dyestuff and allow reuse of the

auxiliary chemicals used for dyeing or to concen-

trate the dyestuffs and auxiliaries and produce

purified water. Microfiltration is suitable for

removing colloidal dyes from the exhausted dye

bath and the subsequent rinses. Ultrafiltration is

effective as single-step treatment of secondary

textile wastewater. Nanofiltration (NF) allows

the separation of low molecular weight (B/1000)

organic compounds and salts, with an appreciable

softening effect. Reverse osmosis (RO) is suitable

for removing ions and larger species from dye bath

effluents. The permeate produced is usually color-

less and low in total salinity.

Membrane based processes have been used to

treat the textile dye house effluent. The wastewater

from different washing and rinsing steps is treated

by RO [3]. Permeate is reused as washwater and

the retentate is either reused or discarded. Bran-

don et al. [4] and Porter and Goodman [5] used

dynamically formed Zirconium Oxide�/polyacry-

late membrane in tubular form to treat textile dye

house effluent. More than 95% of dye recovery

was observed. Similar results were obtained using

spiral-wound modules [6]. El-Nasher [7] studied

economic feasibility of using RO to treat dye

containing effluent. It was concluded that mem-

brane based separation processes are technically

and economically feasible processes to treat dye-

containing effluent. Nowak et al., [8,9] studied

cross flow ultrafiltration of a textile dye bath in a

tubular membrane and reported up to 97% dye (of

molecular weight �/780) removal and removal of

chemical oxygen demand (COD) and TOC by 75�/

85% and 50�/60%, respectively.

Yazhen et al. [10] had used NF for the treatment

of textile dye plant effluent. Experimental runs

with pure dye solutions as well as an industrial dye

solution confirmed the potential of the process.

Schrig and Widmer [11] undertook NF of a

mixture of dye salt and sodium chloride in a

spiral-wound module. Similarly, Yu et al. [12]

applied NF membrane technology for the desalt-

Nomenclature

C0 feed concentration (ppm)C1,0 concentration of dye 1 in feed (ppm)C2,0 concentration of dye 2 in feed (ppm)Cp permeate concentration (ppm)CFC cross flow cellCOD chemical oxygen demandCP concentration polarizationLp membrane permeability (m3/N s)NF nanofiltrationR0 observed retentionR0,1 observed retention for dye 1 (1�/Cp,1/C1,0)R0,2 observed retention for dye 2 (1�/Cp,2/C2,0)RO reverse osmosisTds total dissolved solidTS total solid contentu0 cross flow velocity (cm/s)UF ultrafiltrationVw permeate flux (m/s)

S. Chakraborty et al. / Separation and Purification Technology 31 (2003) 141�/151142

ing and concentrating of aqueous dye at a dyeproducing plant. The newly developed process

using NF was continuous in operation, was not

labor intensive, and produced a high purity

product of consistent quality.

Recently, Dhale and Mahajani [13] reported a

combined process of NF and wet oxidation to

treat the dye bath waste stream. Rejections up to

99% of color and 97% of COD were reported inNF and retentate was treated by wet oxidation

process. In the work of Van der Bruggen et al. [14]

different samples from the wastewater treatment

sequence of a textile factory were filtrated with

different NF membranes. It had been observed

that flux decline due to adsorption of organic

material on the membrane decreased the mem-

brane capacity by up to 73%, but the process waterflux, which is largely concentration dependent,

reached a stable value in all experiments. It was

concluded that membrane based separation pro-

cesses are technically and economically feasible

processes to treat dye-containing effluent.

However there are certain difficulties in predict-

ing membrane performance as the process is

influenced by several operating parameters. Oneof the most important drawbacks of the membrane

separation processes is the decline in flux due to

concentration polarization (CP) and membrane

fouling during the operation [15,16]. CP refers to

the build up of solute species within a thin

boundary layer adjacent to the membrane surface.

The accumulation of species at the membrane

surface adversely affects the membrane perfor-mance. Due to the limitations imposed by CP and

membrane fouling, there is a need for a detailed

study of the effects of the controlling parameters in

the process.

The present work is a part of a larger work,

which is the combined use of adsorption comple-

mented by NF in the treatment of colored

industrial effluent. It is envisaged that the bulkremoval of the dye will take place in an adsorption

unit, whereas removal of remaining amount (10�/

30 ppm approximately) will be handled in the NF

unit. The present effluent is a mixture of two

reactive dyes namely Cibacron black B and

Cibacron red RB which have been used in dyeing

of 100% cotton knits wear in a winch machine at aTa

ble

1

Ch

ara

cter

izati

on

of

the

effl

uen

tfr

om

the

tex

tile

pla

nt

C1,0

MW

92

3(p

pm

)C

2,0

MW

85

4(p

pm

)p

HC

on

du

ctiv

ity�

/10�

3(m

mh

o/c

m)

TS

(pp

m)

Eq

uiv

ale

nt

salt

con

cen

tra

tio

n(e

qu

iva

len

tN

aC

l)(g

/lit

)C

OD

(mg

/lit

)

17

31

18

6.8

61

16

.31

.05�

/10

55

66

31

2

S. Chakraborty et al. / Separation and Purification Technology 31 (2003) 141�/151 143

hosiery dye house, Singhal Brothers’, located atTangra, Kolkata. In this work, an extensive study

has been carried out to observe the effects of the

process parameters like applied pressure, bulk

velocity and feed concentration in the NF of the

effluent. Two different process configurations,

namely, unstirred batch cell and cross flow cell

have been used. Solution mixture characteristics

e.g., pH, total dissolved solid, conductivity etc. ofthe feed, permeate and retentate streams have been

measured at different operating conditions.

2. Experimental

2.1. Materials

2.1.1. Dyes

The present industrial effluent, which has been

collected from a textile dye house, contains a

mixture of two reactive dyes, namely Cibacron

Black B and Cibacron Red RB, which will be

denoted by dye 1 and 2 respectively in the rest of

the paper. The molecular weights of the two dyes

are 923 and 854, respectively. The characterizationof feed effluent is presented in Table 1.

2.1.2. Membrane

An organic membrane (thin film composite

polyamide) of molecular weight cut-off 400, sup-

plied by M/s Permionics, Baroda was used in the

experiments.

2.2. System configuration

2.2.1. Unstirred batch cell

Fig. 1 represents the flow diagram of the batch

cell operation. The feed solution from the feed

tank is pumped to the batch cell. Inside the cell a

circular membrane is placed over a metallic sup-

port. The diameter of the membrane is 65 mm. The

permeate is collected from the bottom of the cell.

2.2.2. Cross flow cell

Fig. 2 represents the flow diagram of the

continuous cross flow NF unit. From the feed

tank, the feed solution is pumped to the cell, where

it flows through a channel. The membrane on a

metal support forms one side of the channel. The

width of the membrane is 4.5 cm, length is 26 cmand the channel height is 1.65 mm. The retentate

solution is recycled to the feed tank. In the

retentate line of the cell, a rotameter is placed to

measure the flow rate. The pressure inside the cell

is maintained by operating the two valves manu-

ally. Permeate samples are collected from the

bottom of the cell.

2.3. Experimental methods

The experimental process involved the following

steps:

2.3.1. Compaction of membranes

Before using a fresh membrane, it was com-

pacted at a pressure of 690 kPa for 3 h usingdistilled water.

2.3.2. Preparation of feed solution

Required concentrations for NF were prepared

by diluting the feed using distilled water.

2.3.3. Determination of membrane permeability

Membrane permeability was determined using

pure distilled water. Flux values of distilled waterat different operating pressures were measured and

were plotted against pressure difference. The

average value of membrane permeability as mea-

sured was 2.42�/10�11m3/m2 sPa, which remained

almost constant through out the conduction of all

experiments.

Fig. 1. Schematic of unstirred batch NF cell.


2.3.4. Conduction of experiments

Experimental runs were conducted in the two

cells. The operating parameters were the feed

concentration and trans-membrane pressure dif-

ference for unstirred batch system and cross flow

velocity, feed concentration and pressure differ-

ence for cross flow system. During each experi-

ment, cumulative volumes of the permeate were

collected. The permeate flux values were obtained

from the slope of the plot of the cumulativepermeate volume versus time. Permeate samples

were collected at different time and permeate

concentration is measured. Duration of each

experiment was 50�/60 min in batch cell and 45

min in cross flow cell.

2.3.5. Determination of the new permeability

After thoroughly cleaning the system several

times by distilled water, the membrane permeabil-

ity was reevaluated. It was observed that the

membrane permeability remained almost constantbetween successive runs.

2.3.6. Analysis of the samples

2.3.6.1. Measurement of dye concentration. Feed

and permeate samples were analyzed by UV-2100

spectrophotometer, supplied by Shimadzu Cor-poration, Japan (at wavelengths of 599 and 535

nm, for dye 1 and 2, respectively) to measure the

permeate concentration. The standard method by

Vogel [17] was used for the determination of

concentration of each dye in the effluents.

2.3.6.2. Measurement of chemical oxygen demand.

The COD is the measure of oxygen consumed

during the oxidation of the oxidizable organic

matter by a strong oxidizing agent. The sample(feed, permeate and retentate stream at each

operating condition) was refluxed with potassium

dichromate and sulphuric acid in presence of

mercuric sulphate (to neutralize the effect of

chlorides), and silver sulphate (catalyst). The

excess of potassium dichromate was titrated

against ferrous ammonium sulphate using ferroin

as an indicator. The amount of potassium dichro-mate used is proportional to the oxidizable organic

matter present in the sample [18].

b , ml of titrant using blank; a , ml of titrant usingsample.

2.3.6.3. Measurement of conductivity. The conduc-

tivities of all samples (feed, permeate and retentate

streams at each operating conditions) were mea-

sured by an autoranging conductivitymeter Che-

mito 130, manufactured by Toshniwal Instruments

(India) Ltd.

2.3.6.4. Measurement of total solid. Total solid

(TS) of all the samples were measured by taking 10

ml. of each sample in a watch glass and keeping in

a oven till complete drying of the sample.

TS�w

volume (in ml) of sample�1000 mg=lit

Here, w is the weight of the sample after drying.

Fig. 2. Schematic of continuous cross flow NF cell.

COD�(b � a) � (N) of Ferrous Ammonium sulphate � 1000 � 8

Volume (in ml) of samplemg=l


2.3.6.5. Measurement of pH. After each experi-ment, pH of the samples was measured, by a pH-

meter, supplied by Toshniwal Instruments (India)

Ltd.

2.4. Operating conditions

2.4.1. Batch cell

For batch cell, three feed concentrations areused. These are a mixture of (i) 25, 15 ppm (ii) 13,

7 ppm and (iii) 20, 10 ppm of the dye 1 and 2,

respectively. In the subsequent tables and figures

C1,0 and C2,0 refer to the feed concentrations of

dye 1 and 2, respectively. The operating pressures

selected are 276, 484, 550 kPa.

2.4.2. Cross flow cell

Two feed concentrations are chosen for experi-

ments (i) 25, 15 ppm and (ii) 13, 7 ppm of the dye 1

and 2, respectively. Cross flow velocities are 14, 21

and 28 cm/s and applied pressures are 276, 415 and

550 kPa.

3. Results and discussions

3.1. Batch cell

Figs. 3 and 4 represent the variation of observed

retention (R0�/1�/Cp/C0) with time of dye 1 and 2

respectively at different conditions of feed con-

centration and operating pressures. For dye 1 the

expression for the observed retention is R0,1�/1�/

Cp,1/C1,0 and that for dye 2 is R0,2�/1�/Cp,2/C2,0.

It is observed from the figure that initially reten-

tion decreases sharply (specially for higher feed

concentrations) and gradually thereafter, for a

fixed feed concentration. This may be explained

by the phenomena of CP. CP leads to a build up of

the solute particles over the membrane surface,

enhancing the solute permeation by convectionthrough the membrane. Therefore, initially the

permeate concentration increases rapidly, thereby

resulting in a sharp decrease of R0. During

extended operations, the flux due to backward

diffusion from the membrane surface towards the

bulk solution becomes competitive with the con-

vective flux through the membrane and the

decrease in retention becomes gradual. It must be

pointed out here that in the case of a batch cell, the

membrane surface concentration will keep on

increasing and a steady state, as far as the

permeate concentrations are concerned will never

be attained. It may also be observed from the

Fig. 3. Variation of observed retention of dye 1 (MW 924.5) in

a mixture of dyes 1 and 2 with time in the batch cell for different

conditions of DP and C0.

Fig. 4. Variation of observed retention of dye 2 (MW 855.5) in

a mixture of dyes 1 and 2 with time in the batch cell for different

conditions of DP and C0.


figure that at same feed concentration (25:15ppm), R0 is lower for higher operating pressure

(square and triangle symbols in the figure). At

higher operating pressure, permeate concentration

is more due to an enhanced convective flux

through the membrane (because of higher driving

force) and permeate concentration increases with a

decrease in R0.

At a fixed applied pressure difference, permeateconcentration increases with increasing feed con-

centrations (C0). For example, at a pressure of 276

kPa, the permeate concentration values of dye 1

after a time of 1200 s is 2.30 and 1.50 ppm,

respectively for feed concentrations of 25:15 and

13:7 ppm, respectively. But the change in retention

values with feed concentrations is not apparent

here (R0,1 is 0.907 and 0.873, respectively), as theeffect of feed concentration (C0) is normalized.

Fig. 5 represents the percentage removal of

COD with time for the same conditions of feed

concentration and operating pressures as in Figs. 3

and 4. As COD is directly proportional to the

concentration, the profile of the removal of COD

shows the same trend as in Figs. 3 and 4. It is

observed from the figure, that at a feed concentra-tion of 25:15 ppm and operating pressure of 276

kPa, the maximum removal of COD can be upto

90% after a time of 1230 s from the starting of the

experiment.

Fig. 6 shows the variation of flux values with

time for the same conditions of feed concentra-

tions and operating pressures as in Figs. 3 and 4. It

is evident from the figure that the permeate fluxdecreases with time of operation. As explained

earlier, during the experiments, the membrane

surface concentration goes on increasing due to

the CP phenomenon. This leads to an increase in

osmotic pressure near the membrane-solution

interface and thereby, a decrease in the effective

driving force (i.e. trans-membrane pressure). This

leads to a decline in flux. As the operating feedconcentrations are of low range, the decrease in

the permeate flux values are not substantial, and

the curves appear almost flat. From the figure, it is

observed that permeate flux is higher for higher

operating pressure (due to the enhancement in the

driving force) if feed concentration remains same.

With increase in feed concentration permeate flux

decreases. Increase in feed concentration results in

an increase in surface concentration and therefore

osmotic pressure increases and thereby leading to

decrease in driving force and reduction in flux.

3.2. Cross flow cell

A summary of the results of each experiments

conducted in cross flow NF is presented in Table

Fig. 5. Variation of percentage COD removal of effluent

mixture with time in the batch cell for different conditions of

DP and C0.

Fig. 6. Variation of permeate flux of effluent mixture with time

in the batch cell for different conditions of DP and C0.


Table 2

Some properties measured for the textile industrial effluent during conduction of experiments in the cross flow cell

C1,0: C2,0 u0 (cm/s) DP (kPa) Stream Conductivity�/10�3 (mmho/cm) TS (ppm) % COD removal % Color removal

Dye 1 Dye 2

25:15 14 276 Feed 19.9 1.17�/104 90 89.1 92.0

Permeate 13.8 1.02�/104

Retentate 20.5 1.25�/104

25:15 21 276 Feed 19.8 1.18�/104 92.9 90.3

Permeate 13.6 1.02�/104 91.45

Retentate 20.3 1.25�/104

25:15 28 276 Feed 18.9 1.23�/104 94.6 93

Permeate 16.6 1.03�/104 92.63

Retentate 19.1 1.27�/104

25:15 14 415 Feed 14.48 1.23�/104 86.7 84.5

Permeate 13.23 1.06�/104 85.4

Retentate 14.6 1.27�/104

25:15 21 415 Feed 9.41 5.16�/103 89.4 88.7

Permeate 7.96 4.06�/103 89.13

Retentate 9.53 5.97�/103

25:15 28 415 Feed 9.28 4.58�/103 91 89.3

Permeate 7.42 3.85�/103 90.27

Retentate 9.56 4.62�/103

25:15 14 550 Feed 6.91 3.41�/103 79.1 79.7

Permeate 5.55 3.07�/103 80.54

�/ Retentate 6.98 3.57�/103

25:15 21 550 Feed 4.37 2.05�/103 82.7 85

Permeate 3.57 1.42�/103 84.86

Retentate 4.48 1.98�/103

25:15 28 550 Feed 1.49 9.0�/102 87 88.3

Permeate 1.46 6.10�/102 85.4

Retentate 1.12 9.80�/102

13:7 14 276 Feed 1.25 1.47�/103 90.8 87.6

Permeate 1.018 7.60�/102 90.37

Retentate 1.272 1.65�/103

13:7 21 276 Feed 1.18 1.78�/103 92.6 88.2

Permeate 0.942 8.10�/102 91.32

Retentate 1.185 9.70�/102

13:7 28 276 Feed 0.881 3.80�/102 93.9 92.1

Permeate 0.661 1.90�/102 93.77

Retentate 0.872 4.20�/102

13:7 14 415 Feed 0.614 3.10�/102 88.5 84.2

Permeate 0.497 5.0�/101 87.5

Retentate 0.646 3.60�/102

13:7 21 415 Feed 0.455 1.20�/102 90.5 86.8

Permeate 0.342 8.0�/101 89.9

Retentate 0.466 1.15�/102

13:7 28 415 Feed 0.332 1.15�/102 91.4 89.3

Permeate 0.244 7.5�/101 91.3

Retentate 0.342 1.20�/102

13:7 14 550 Feed 0.199 5.40�/102 74.1 67.4

Permeate 0.146 3.40�/102 72.5

Retentate 0.204 6.50�/102

13:7 21 550 Feed 0.252 1.03�/103 79.3 77.1

Permeate 0.179 8.50�/102 81.2


2. Figs. 7 and 8 represent the variation of observed

retention of the two dyes with pressure difference

for two different feed concentrations (25:15 and

13:7 ppm, respectively) and three different cross

flow velocities (14, 21 and 28 cm/s). For the cross

flow cell the retentions mentioned are the steady

state value since the system reaches steady state in

a very short time. In these figures hollow and solid

symbols represent dye 1 and 2, respectively. From

the figure it is observed that R0 decreases with

increase in applied pressure for a particular feed

concentration and cross flow velocity. At higher

pressure permeate concentration is more (as ex-

plained earlier) resulting in lower retention. From

the figure it is also clear that as the cross flow

velocity increases, R0 increases, for same feed

concentration and applied pressure. As cross

flow velocity increases, CP on the membrane

surface decreases, hence membrane surface con-

centration decreases leading to a decrease in

permeate concentration. It may be observed from

Fig. 7 that at a pressure of 276 kPa and bulk

velocity of 28 cm/s, retention can go up to 95 and

93% for the two dyes respectively.

Fig. 9 shows the percentage removal of COD

with pressure at three different cross flow velocities

for effluent feed mixture at two different feed

concentrations. With increase in pressure at con-

stant cross flow velocity, observed retention of dye

decreases and hence COD of permeate increases,

and therefore percentage removal of COD de-

creases. For a feed concentration of 13:7 ppm, a

maximum of 94% of COD has been removed at a

pressure of 276 kPa and cross flow velocity of 28

cm/s.

The variations of permeate flux with operating

pressure for different combinations of feed con-

centrations and cross flow velocities are presented

Table 2 (Continued )

C1,0: C2,0 u0 (cm/s) DP (kPa) Stream Conductivity�/10�3 (mmho/cm) TS (ppm) % COD removal % Color removal

Dye 1 Dye 2

Retentate 0.266 1.15�/103

13:7 28 550 Feed 0.162 5.70�/102 86.1 80

Permeate 0.105 3.60�/102 85.1

Retentate 0.174 6.20�/102

Fig. 7. Variation of observed retention of the two dyes in the

effluent mixture with trans-membrane pressure drop at a same

feed concentration (25:15) and different cross flow velocities.

Fig. 8. Variation of observed retention of the two dyes in the

effluent mixture with trans-membrane pressure drop at a same

feed concentration (13:7) and different cross flow velocities.


in Fig. 10. It is clear from the figure that the flux

profile is higher for higher operating pressure.

With increase in operating pressure (at a fixed feedconcentration), the driving force across the mem-

brane increases leading to an enhancement of

permeate flux. Also, the permeate flux follows

the expected trends with variation in feed concen-

tration at a fixed operating pressure, i.e. flux

decreases with increase in feed concentration (solid

and hollow circle). With increase in feed concen-

tration, the CP is more. This leads to an increase inosmotic pressure near the membrane surface and

the trans-membrane pressure drop decreases. Thus

for higher feed concentration, the permeate flux is

lower. At a fixed feed concentration, flux increases

with cross flow velocity due to reduction in CP,

although the difference is marginal as observed

from the figure (hollow circle and triangle).

4. Conclusion

NF is successfully used to separate two dyes,

Cibacron Black B and Cibacron Red RB from a

hosiery dye house effluent. Two different separa-

tion configurations, namely, unstirred batch cell

and a continuous cross flow cell are used for the

present study. It has been found that substantial

removal of the two dyes (upto 94%) is achieved in

a cross flow cell with a marked reduction in the

chemical oxygen demand of the permeate. A

detailed parametric study is conducted to studythe effect of process variables on the separation

efficiency of the nanofiltration process.

Acknowledgements

This work is partially supported by a grant from

the Ministry of Human Resource and Develop-ment (MHRD), Government of India under the

scheme no. F. 27-6/2000 TS V. Any opinions,

findings and conclusions or recommendations

expressed in this paper are those of the authors

and do not necessarily reflect the views of MHRD.

References

[1] V.K. Gupta, D. Mohan, S. Sharma, M. Sharma, Removal

of basic dyes (Rhodamine B and Methylene blue) from

aqueous solutions using bagasse fly ash, Sep. Sci. Technol.

35 (2000) 2097�/2113.

[2] M. Marcucci, G. Nosenzo, G. Capannelli, I. Ciabatti, D.

Corrieri, G. Ciardelli, Treatment and reuse of textile

Fig. 9. Variation of COD removal with cross flow velocity and

trans-membrane pressure drop during cross flow NF.Fig. 10. Variation of permeate flux of the industrial effluent

with trans-membrane pressure drop at two different feed

concentrations.


effluents based on new ultrafiltration and other membrane

technologies, Desalination 138 (1970) 75�/82.

[3] K. Treffry-Goatley, C. Buckley, G. Groves, Reverse

osmosis treatment and reuse of textile dyehouse effluents,

Desalination 47 (1983) 313�/320.

[4] C. Brandon, D. Jernigan, J. Gaddis, H. Spencer, Closed

cycle textile dyeing: full scale renovation of hot wash water

by hyperfiltration, Desalination 39 (1981) 301�/310.

[5] J. Porter, G. Goodman, Recovery of hotwater, dyes, and

auxiliary chemicals from textile wastewaters, Desalination

49 (1984) 185�/192.

[6] C.K. Buckley, T.reffry Goatley, M. Simpson, A. Bindoff,

G. Groves, Pretreatment, fouling and cleaning in the

membrane processing of industrial effluents, ACS. Symp.

Ser. (1985) 261.

[7] A. El-Nasher, Energy and water conservation through

recycle of dyeing wastewater using dynamic Zr (iv)*/PAA

membranes, Desalination 33 (1980) 21�/47.

[8] K.M. Nowak, T. Winnicki, Decolorization of dye solu-

tions and textile effluents, Desalination 60 (1986) 59�/66.

[9] K.M. Nowak, T. Winnicki, J. Wisniewski, Effect of flow

conditions on ultrafiltration efficiency of dye solutions and

textile effluents, Desalination 71 (1989) 127�/135.

[10] X. Yazhen, R.E. Lebrun, P. Gallo, P. Blond, Treatment of

textile dye plant effluent by nanofiltration membrane, Sep.

Sci. Technol. 34 (1999) 2501�/2519.

[11] P. Schrig, F. Widmer, Characterization of nanofiltration

membranes for the separation of aqueous dye-salt solu-

tions, Desalination 89 (1992) 89�/107.

[12] S. Yu, C. Gao, H. Su, M. Liu, Nanofiltration used for

desalination and concentration in dye production, Desali-

nation 140 (2001) 97�/100.

[13] A.D. Dhale, V.V. Mahajani, Studies on treatment of

disperse dye waste: membrane-wet oxidation process,

Waste Manage. 20 (2000) 85�/92.

[14] B. Van der Bruggen, I. De Vreese, C. Vandecasteele, Water

reclamation in the textile industry: nanofiltration of dye

baths for wool dyeing;, Ind. Eng. Chem. Res. 40 (2001)

3973�/3978.

[15] S.V. Satyanarayana, P.K. Bhattacharya, S. De, Flux

decline during ultrafiltration of kraft black liquor using

different flow modules: a comparative study, Sep. Puri.

Technol. 20 (2000) 155�/167.

[16] B. Van der Bruggen, C. Vandecasteele, Flux decline during

nanofiltration of organic components in aqueous solution,

Environ. Sci. Technol. 35 (2001) 3535�/3540.

[17] A.I. Vogel, Textbook of Practical Organic Chemistry 385

(1970) 818.

[18] R.K. Trivedi, P.K. Goel, Chemical and Biological Meth-

ods for Water Pollution Studies, 2nd ed., Environmental

Publication, Aligarh, 1986, pp. 55�/57.


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Nanofiltration of textile plant effluent for color removal and reduction in COD