Treatment and reuse of reactive dyeing effluents

https://doi.org/10.1016/j.memsci.2005.06.014Get rights and content

Abstract

Industrial textile processing comprises the operations of pretreatment, dyeing, printing and finishing. These production processes are not only heavy consumers of energy and water; they also produce a substantial amount of chemical pollution. Of all dyed textile fibres, cotton occupies the number-one position, and more than 50% of its production is dyed with reactive dyes, owing to their technical characteristics. Unfortunately, this class of dyes is also the most unfavorable one from the ecological point of view, as the effluents produced are relatively heavily colored, contain high concentrations of salt and exhibit high BOD/COD values. Dyeing 1 kg of cotton with reactive dyes requires an average of 70–150 L water, 0.6 kg NaCl and 40 g reactive dye. The composition of the dye bath which we propose to treat contains solid particles (cotton fibres), dyeing auxiliaries (organic compounds), hydrolyzed reactive dyes, substantial quantities of alkalis (sodium carbonate and soda ash) and very high concentration of sodium chloride or sodium sulfate. This paper presented the state of the art of the different processes currently used for the treatment of dye house wastewaters and evaluated a four-step process [1] to recover the water and the mineral salts, while leaving the spent dyes in the reject stream. Processes evaluated included (1) cartridge filtration to remove textile fibres, (2) acidification to make the brine recovered, suitable for reuse and further dyeing operations, (3) nanofiltration (NF) to concentrate the hydrolyzed dyes and (4) reverse osmosis (RO) to further concentrate the salts for reuse in the dyeing process. A cut-off of 100 μm is sufficient to trap textile fibres, regardless of the type of effluent and the texture of the textile dyed. The hydrolyzed reactive dyes present in the treated effluents comprise the entire range of possible types of reactive dyes. For this acidification, we studied the influence of the concentration of sodium chloride, the influence of the temperature and we verified that the volume neither depends on the concentrations of reactive hydrolyzed dyes nor sodium chloride. After defining the nanofiltration membrane, we studied the effect of the pH, temperature, pressure and velocity as well as the experimental procedure on the permeate flux, recovery of the salt and removal of the color. An increase of either of the parameters temperature and pressure leads to an increase of the permeate flux. On the other hand, a rise in the pH leads to a decrease of the permeate flux. The retention factor of the sodium chloride is low when the concentration of sodium chloride is high in the retentate. Our aim was to recover 80–90% of the sodium chloride, but our experiments showed that the recovery went as high as 99%. Depending on the dyes used, the experimental procedure can be carried out in one, two or three steps. The dye retention level was always higher than 98%. After studying the operating variables, experiments with the recycled brines in new dyeing operations were carried out with specimen dyeings prepared with usual water using different classes of reactive dyes. There was no difference in the results in terms of depth, shade or fastness properties, whichever type of water was used. These last results therefore validate our process and its special innovative feature: recycling not only the water but also the mineral salts.

Introduction

Even though it appears to be in plentiful supply on the earth's surface, water is a rare and precious commodity, and only an infinitesimal part of the earth's water reserves (approximately 0.03%) constitutes the water resource which is available for human activities. The growth of the world's population and industry has given rise to a constantly growing demand for water in proportion to the supply available, which remains constant. According to the data of the I.F.E.N (Institut Français de l’ENvironnement), the amount of water taken from the natural environment in France was estimated at about 40 billion m3 (1995). On the global level, the question of the supply of fresh water is becoming more acute every day. In the dyeing of textile materials, water is used firstly in the form of steam to heat the treatment baths, and secondly to enable the transfer of dyes to the fibers. Cotton, which is the world's most widely used fiber, is also the substrate that requires the most water in its processing. The dyeing of one kilogram of cotton with reactive dyes demands from 70 to 150 L [2] water, 0.6 to 0.8 kg NaCl and anywhere from 30 to 60 g dyestuff. More than 80,000 tonnes of reactive dyes are produced and consumed each year, making it possible to estimate the total pollution caused by their use. After the dyeing is completed, the various treatment baths are drained out, including the first dye bath, which has a very high salt concentration, is heavily colored and contains a substantial load of organic substances. One solution to this problem consists in mixing together all the different aqueous effluents, then concentrating the pollution and reusing the water either has rinsing water or as processing water, depending on the treatment selected (either nanofiltration or reverse osmosis for the membrane processes). These treatments concern only very dilute dye baths. This is generally not the case of the first dye baths recovered which are the most heavily polluted ones. The wastewater produced by a reactive dyeing contains:

  • -

    Hydrolyzed reactive dyes not fixed on the substrate, representing 20–30% of the reactive dyes applied (on average 2 g L−1). This residual amount is responsible for the coloration of the effluents and cannot be recycled.

  • -

    Dyeing auxiliaries or organic substances, which are non-recyclable and responsible for the high BOD/COD of the effluents.

  • -

    Textile fibres.

  • -

    Sixty to one hundred gram per liter electrolyte, essentially sodium chloride and sodium carbonate, which is responsible for the very high saline content of the wastewater.

In addition, these effluents exhibit a pH of 10–11 and a high temperature (50–70 °C). The legal regulations respecting the limit values for the release of wastewater are changing and are becoming increasingly severe, including the limits with respect to salinity. In France, the activities of installations subjected to authorization are delimited by a decree of 2 February 1998.

The objectives of this study were (a) to removal cotton fibres and to control the carbonate concentration which might strongly influence the nanofiltration, (b) the treatment of dye baths by nanofiltration in order to recover and reuse the sodium chloride and the water, (c) to select the NF membranes that were able to operate at high temperatures (50–70 °C), allowed for passage of monovalent salts, while retaining the hydrolyzed reactive dyes and (d) evaluate a RO process that was robust in terms of operating at elevated temperature (40–50 °C), able to operate at 80 × 105 Pa (80 bar) transmembrane pressure (TMP), and achieve greater than 90% of sodium chloride was reused. The simplified Fig. 1 presents the challenges of this study.

The process proposed by this study [1] has the following simultaneous advantages:

  • -

    compact: the place available in the dye houses is small;

  • -

    progressive: fashions and colors change; treatment must take place at the outlet of the dyeing machine, regardless of the bath, yet be capable of recycling a maximum amount of water and mineral salts;

  • -

    flexible: widely variable volumes must be capable of being treated;

  • -

    feasible: the quality of the water and of the brine must be constant, so as to be reusable for a new dyeing.

This paper presented the different methods currently used for the treatment of dye house effluents and those which are in the course of development. Then, it evaluated a four-step process to recover only the water and salts, while leaving the spent dyes in the reject stream. Processes evaluated included (1) cartridge filtration to remove textile fibres, (2) acidification to make the brine recovered, suitable for reuse and further dyeing operations, (3) nanofiltration (NF) to concentrate the hydrolyzed dyes and (4) reverse osmosis (RO) to further concentrate the salts for reuse in the dyeing process.

Section snippets

Review of current treatment methods of treating dyeing effluents

Owing to their high BOD/COD, their coloration and their salt load, the wastewaters resulting from dyeing cotton with reactive dyes are very polluted. For example, for Drimaren HF, this ratio is constant and around 0.35 for each dyeing step (bleaching step BOD = 1850 mg L−1, COD = 5700 mg L−1; neutralization step BOD = 290 mg L−1, COD = 830 mg L−1; dyeing step BOD = 500 mg L−1, COD = 1440 mg L−1; soaping step BOD = 310 mg L−1, COD = 960 mg L−1). As aquatic organisms need light in order to develop, any deficit in this respect

Solutions

The effluents which constitute the object of this study result from the dyeing of cotton with reactive dyes by the exhaust process. The reactive dyes used are of the following types: vinyl sulfone, monochlorodifluoropyrimidine, monochlorotriazine, trichloropyrimidine and monofluorotriazine. The hydrolyzed reactive dyes present in the treated effluents comprise the entire range of possible types of reactive dyes. Diagrammatically, a reactive dye has the form of a complex molecule which is

Results and discussion

The results are normalized with respect to temperature.

Conclusion

Textile process who dye cotton by the exhaust method with reactive dyes are facing by increasingly restrictive environmental problems. It consists of different steps (pretreatments, nanofiltration and reverse osmosis). The two pretreatments ensured the efficiency and strength of our process and take into account the industrial requirements. After having determined the cut-off of the prefilter on the laboratory-scale, this choice was validated on industrial site. All cotton fibres were stopped.

References (61)

  • S.H. Lin et al.

    Treatment of textile wastewater by chemical methods for reuse

    Water Res.

    (1997)
  • A. Erswell et al.

    The reuse of reactive dye liquors using charged ultrafiltration membrane technology

    Desalination

    (1988)
  • B. Van der Bruggen et al.

    Mechanisms of retention and flux decline for the nanofiltration of dye baths from the textile industry

    Sep. Purif. Technol.

    (2001)
  • C. Tang et al.

    Nanofiltration of textile wastewater for water reuse

    Desalination

    (2002)
  • I. Koyuncu

    Reactive dye removal in dye/salt mixtures by nanofiltration membranes containing vinylsulphone dyes: effects of feed concentration and cross flow velocity

    Desalination

    (2002)
  • R. Jiraratananon et al.

    Performance evaluation of nanofiltration membranes for treatment of effluents containing reactive dye and salt

    Desalination

    (2000)
  • A. Akbari et al.

    Treatment of textile dye effluent using a polyamide-based nanofiltration membrane

    Chem. Eng. Pro.

    (2002)
  • N. Rossignol et al.

    Production of exocellular pigment by the marine diatom Haslea ostrearia Simonsen in a photobioreactor equipped with immersed ultrafiltration membranes

    Bio. Technol.

    (2000)
  • V. Freger et al.

    Separation of concentrated organic/inorganic salt mixtures by nanofiltration

    J. Membr. Sci.

    (2000)
  • G. Ciardelli et al.

    The treatment and reuse of wastewater in the textile industry by means of ozonation and electroflocculation

    Water Res.

    (2001)
  • M. Mignani et al.

    Innovative ultrafiltration for wastewater reuse

    Desalination

    (1999)
  • M.H. Al-Malack et al.

    Use of crossflow microfiltration in wastewater treatment

    Water Res.

    (1997)
  • C. Allègre et al.

    Savings and reuse of salts and water present in dye house effluents

    Desalination

    (2004)
  • G. Hagmeyer et al.

    Modelling the salt rejection of nanofiltration membranes for ternary ion mixtures and for single salts at different pH values

    Desalination

    (1998)
  • R.F. Weiss

    carbon dioxide in water and seawater: the solubility of a non-ideal gaz

    Mar. Chem.

    (1974)
  • A.G. Dickson et al.

    A comparison of the equilibrium constants for the dissociation of carbonic acid in seawater media

    Deep Sea Res. Part A. Oceanogr. Res. Pap.

    (1987)
  • B. Van der Bruggen et al.

    Influence of molecular size, polarity and charge on the retention of organic molecules by nanofiltration

    J. Membr. Sci.

    (1999)
  • C. Martin-Orue et al.

    Nanofiltration of amino acid and peptide solutions: mechanisms of separation

    J. Membr. Sci.

    (1998)
  • Y. Xu et al.

    Investigation of the solute separation by charged nanofiltration membrane: effect of pH, ionic strength and solute type

    J. Membr. Sci.

    (1999)
  • A. Erswell et al.

    The reuse of reactive dye liquors using charged ultrafiltration membrane technology

    Desalination

    (1988)
  • Cited by (438)

    View all citing articles on Scopus
    View full text