Treatment of textile dye effluents using a new photografted nanofiltration membrane (original) (raw)
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This paper reviews the application of polymeric nanofiltration membranes (NF) in the specific waste stream in the textile industry, which typically generates large volumes of wastewater containing complex contaminants from its daily operation. It is necessary that as much of this waste as possible is recycled instead of being disposed of in landfill sites. Most of the conventional technologies seem unable to provide sufficient treatment for the effluents. Therefore, it is generally accepted that NF membranes offer solutions for the problem. Of these NF membranes, the thin-film composite nanofiltration (TFC–NF) membrane is the most widely used by researchers in their studies. The effects of the manufacturing conditions of TFC–NF are discussed to provide valuable information for those who are going to choose NF membranes in textile wastewater treatment. The preliminary performances of commercial NF membranes have been examined in terms of dye rejection, salt rejection, permeate flux and COD rejection. Some of the commercial membranes achieved maximum separation of dye and salts while some achieved higher flux. This is because of the large variability of the parameters of textile wastewater and the NF membranes chosen. Due to the scarcity of published papers covering the transport model that is specifically suitable for textile coloured wastewater, a brief review of transport models of NF membranes with the presence of the dyes and salts is given. Membrane fouling mechanisms and methods to control fouling are also reviewed. Future directions in NF membrane research are also discussed to further expand research and development related to textile wastewater treatment.
A combined treatment approach for dye and sulfate rich textile nanofiltration membrane concentrate
Journal of water process engineering, 2019
Fenton process and Fenton coupled biological treatment were examined for the treatment of the textile nanofiltration (NF) membrane concentrate. Maximum chemical oxygen demand (COD) and total organic carbon (TOC) removal efficiency was found to be 87.1% and 80.8% respectively at molar concentrations of 35 mM Fe 2+ and 175 mM H 2 O 2 and pH 3 for 30 min in the single Fenton process. As a second alternative, sequencing batch reactor (SBR) was operated to carry out biological treatment after Fenton process at a lower chemical dosage (pH: 3, C Fe+2 : 20 mM, C H2O2 : 100 mM, 30 min). The ratio of biological oxygen demand in 5 days (BOD 5)/COD was enhanced to 0.51 at molar concentrations of 20 mM Fe 2+ and 100 mM H 2 O 2. According to respirometric analysis and SBR results, it was stated that the oxidation intermediates formed during the treatment of membrane concentrate with Fenton process had no inhibitory/toxic effects on the hetetrophic biomass. The maximum COD removal efficiency in biological treatment after Fenton process was 75% under equilibrium condition using a SBR operated at 10 days of sludge retention time and 12 h of hydraulic retention time (HRT).
Removal of Reactive Dyes from Dye-house Effluent Using Nanofiltration Membrane
Dye-house industrial processing includes pretreatment, dyeing, printing and finishing. These production processes are not only energy and water intensive but also a major source of heavy chemical pollution. Of all dyed textile fibers, cotton occupies a dominated loading position. As cotton is dyed with reactive dyes in Al-alamia Company for Dyeing and Weaving, the effluent wastewater is heavily polluted with cotton fibers (unfixed dyes >50% of the used dyeing material) owing to their technical properties. These ecologically harmful effluents are relatively heavily colored; contain high concentrations of salt, exhibiting high COD/BOD and TDS values. Dyeing 1 kg of cotton with reactive dyes requires an average of 70-150 L water, 600 g NaCl and 40 g reactive dye. The composition of the usually practiced dye bath contains solid particles, dyeing auxiliaries, hydrolyzed reactive dyes, substantial quantities of alkalis and very high concentration of sodium chloride or sodium sulfate. Convential separation methods failed to achieve satisfactory results for dye removal. Fortunately the application of membrane separation processes proved its technical reliability and feasibility. The main objective of this work is to investigate the performance of low pressure driven membrane separation of nanofiltration as an advanced separation technology for treating effluent dye-house stream in order to recover dyes and recycle treated water. For this purpose removal of C.I. Reactive Black B (RB5) from dye-house effluents was investigated on a bench scale. In these experiments the performance of a Desal HL2521TF nanofiltration membrane element under various operating conditions of pressure, flow rate, and temperature was investigated. Permeate and salt fluxes, system recovery and salt rejections under variable operating conditions were discussed. In fact, experimental test results in terms of color, COD, and TDS were measured routinely. It is noteworthy that in course of the experimental work complete chemical analysis for feed, permeate, and concentrate were conducted. Direct analysis of membrane fouling has been performed using scanning electron microscopy (SEM) on the standard NF membrane element. An IR-technique was used to determine the actual chemical composition of the reactive dye being used.
Different membrane processes were experimented on at pilot scale to verify the possibility of reusing textile wastewater. The pilot plant used sand filtration and ultrafilWation (UF) as pre-treatments for a membrane process of nannfilWation (NF) or reverse osmosis (RO). UF was obtained by the installation of an innovative module designed on fiat membranes operating under vacuum; the configuration of the NF and RO membranes was spiral wound. The efficiency of the various trealments in removing pollutants from textile wastewater from an activated sludge plant was tested on the reduced scale to optimize the industrial plant design. The UF module tested works at low operating pressure (that involves low energy costs) and guarantees a constant permeate (feed of the next membrane process of NF or RO). The RO permeate can be reused in the dyeing processes as demonstrated by many yarn dyeing tests on the industrial scale. NF does not reach the retention behaviour of RO (total hardness removal of 75% and >90% for NF and RO, respectively). Nevertheless, a change in the freshwater trealment (atpresent an ion-exchange resin softening) downstream from the use of process water in the factory would decrease the secondary effluent salinity, so the design of the advanced purification industrial plant could reasonably foresee a NF treamlent instead of RO, allowing a reduction of the costs.
The applicability of nanofiltration for the treatment and reuse of textile reactive dye effluent
Water SA, 2015
The main aim of the study was to test the feasibility of using nanofiltration (NF) processes for the treatment of reactive dyebath effluents from the textile industry, in order to recover the water and chemicals (salts) for reuse purposes. The study of the reusability of nanofiltered water for dyeing has been given little or no attention. About 30% of reactive dyes remain unfixed on fibres; the unfixed dyes are responsible for the colouration in effluents. Membrane processes were employed to treat reactive dye-bath effluents to recover the salts and water. Investigations were conducted firstly with ultrafiltration (UF) used as a pretreatment for NF. Secondly, evaluations were performed for 2 types of NF membranes (SR90 and NF90), in terms of quality of permeate produced and fluxes achieved for 2 different samples of effluent. The effect of cleaning on membrane performance was assessed. A reusability test was carried out on both permeate samples for dyeing light and dark shade recipes. The use of UF as pre-treatment to NF resulted in rejection of colloidal substances > 90% and a 15% flux improvement. Permeate from NF90 had a conductivity of 76 µS/cm and total organic carbon (TOC) of 20 mg/ℓ, as compared to SR90 which had a conductivity of 8.3 mS/cm and a TOC of 58 mg/ℓ. Light shade from NF90 gave satisfactory results on dyeing, with no colour difference. However a variation in colour was noticed when the medium sample was used to dye the light shade. Both NF permeates gave satisfactory results when used to dye the dark shades. Permeate from NF90 was within the accepted range for reuse, while permeate from SR90 had a higher salt recovery. Chemical cleaning resulted in 80% flux recovery. From the reusability test it was concluded that permeate from NF90 met the reuse criteria for feed water to the dye bath.
Nanofiltration process on dye removal from simulated textile wastewater
International Journal of Environmental Science & Technology, 2008
Dyestuffs removal from industrial wastewater requires special advanced technologies, since dyes are usually difficult to remove by biological methods. In this study nanofiltration process was used for removal of different dyestuffs from solutions. The rate of dye removal by spiral wound nanofiltration membrane in film thin composite MWCO=90 Dalton, was evaluated for four classes of dyes acidic, disperse, reactive and direct in red and blue dyes medium. Dye absorbance was measured by spectrophotometric method (2120 Standard Method 1998). Effects of feed concentration, pressure and total dissolved solids concentration were also studied. Results showed that increasing dye concentration lead to higher color removal up to 98 % and at different pressures for acidic and reactive blue were up to 99.7 %. Different types of dyes had no effect on dye removal and permeate flux. During 2 h.of the operation time, permeate flux decline was increased. Permeate fluxes for different types of red dyes were from 16.6 to 12.6 (L/m 2 /h.) and for blue dyes were from 16.6 to 10.45 (L/m 2 /h.). Presence of sodium chloride in dye solutions increased dye rejections nearby 100 %. Chemical oxygen demand removal efficiencies for reactive blue, disperse blue, direct and disperse red dyes were also approximately 100 %.
Efficiency Evaluation of Textile Basic Dye Remova L from Water by Nanofiltration
Nanofiltration, widely developed over the past decade, is a promising technology for the treatment of organic and inorganic pollutants in surface and groundwater resources. The aim of the present research was to study the efficiency of textile dyes removal by a commercial nanofilter NF90 (Dow-Film Tec). Dye rejection was studied using basic dye (Basic Chrysoidine Cryst Yellow Gold 0.4%) with its relevant additive. Experiments were continued until the fouling time of the membrane. Each experiment was repeated after washing to evaluate the efficiency of the washing process. Results showed that the values of color removal were 97.98 % for the simulated textile wastewater containing basic dye. The membrane was sensitive to fouling since most of dyes were used for polyamide textile dyeing. Washing the membrane with a solution including NaOH (pH=12) and HCl (pH=2) showed its efficiency to solve the fouling problem. The filtration process was efficient and promising for reusing wastewater ...
2017
Textile dyeing processes are among the most dangerous and unfriendly industrial processes towards the environment because of the coloured wastewaters they produce and which are heavily polluted with textile auxiliaries and chemicals. The ultra-filtration method was studied as a wastewater treatment technique for the decolourization of residual dye bath effluents. The objective of this work is to study the removal rate of a vat dye used in the textile industry through an indigo solution, by the asymmetric organic membrane optimized polysulfone modified according to different weight percentages of titanium oxide.
Treatment of textile effluents by membrane technologies
The textile industry is a large water consumer. As regulations become stringent and the cost of freshwater increases, reclamation of wastewater becomes more and more attractive. This paper presents the results of the laboratory-scale membrane experiments of textile industry effluents previously biologically treated by activated sludge. Different types of Microfiltration (MF), Ultrafiltration (UF) and Nanofiltration (NF) membranes were evaluated for permeate flux and their suitability in separating COD, colour, conductivity, Total dissolved salts (TDS) and turbidity. Experiments demonstrated that membrane treatment is a very promising advanced treatment option for pollution control for textile industry effluents.
Treatment of effluents from textile-rinsing operations by thermally stable nanofiltration membranes
Desalination, 2004
Thermally stable nanofiltration membranes were used to recover hot water from rinsing effluents from acid and reactive dyeing operations. Two types of flat-sheet membranes, and MPF-36 (MWCO 1000), were tested at 60°C and 10 bar. Experiments carried out with the made-up feeds containing acid dye and acetic acid showed that both membranes were able to retain more than 99% of dye. MPF-36 suffered from substantial flux decline due to the dye and acid in the feeds but still provided higher fluxes than MPF-34. Furthermore, reactive dye rejection of MPF-36 was acceptable, ranging from 97 to 99.5%, while the fluxes, 105-140 l/m 2 .h, were exceptionally high. MPF-36 was then further tested with the wastewater from industrial processes. The membrane could recover hot water by removing more than 98% of acid dye and 90% of reactive dyes. Despite severe fouling by acid dye, the membrane was still able to provide 40-50 l/m 2 .h of permeate fluxes. For the reactive dye rinsing effluents, remarkably high fluxes of 120-150 l/m 2 .h were obtained. Chemical cleaning of the used membrane with 0.2% wt. HNO 3 and subsequently 0.5% wt. NaOH recovered 80-100% of the flux.