Dye Bath Effluent Research Articles

Comparative Evaluation of the Results for the Synthetic and Actual Reactive Dye Bath Effluent Treatment by Nanofiltration Membranes

In this study, the results of nanofiltration experiments carried out on reactive dye house wastewaters are presented. The experiments were performed using lab-scale membrane system. Permeate quality was appropriate to reuse permeate in dyeing process again. Pretreatment and neutralization were the parameters which are very important for the recovery of high amounts of salt and water at the permeate stream. In addition, use of HCl instead of H2SO4 for neutralization increased the NaCl recovery.

Combinative dyebath treatment with activated carbon and UV/H2O2: a case study on Everzol Black-GSP®

Treatability of textile dyebath effluents by two simultaneously operated processes comprising adsorption and advanced oxidation was investigated using a reactive dyestuff, Everzol Black-GSP (EBG). The method was comprised of contacting aqueous solutions of the dye with hydrogen peroxide and granules of activated carbon (GAC) during irradiation of the reactor with ultraviolet light (UV). Control experiments were run separately with each individual process (advanced oxidation with UV/H2O2 and adsorption on GAC) to select the operating parameters on the basis of maximum color removal. The effectiveness of the combined scheme was tested by monitoring the rate of decolorization and the degree of carbon mineralization in effluent samples. It was found that in a combined medium of advanced oxidation and adsorption, color was principally removed by oxidative degradation, while adsorption contributed to the longer process of dye mineralization. Economic evaluation of the system based on total color removal and 50% mineralization showed that in the case of Everzol Black-GSP, which adsorbs relatively poorly on GAC, the proposed combination provides 25% and 35% reduction in hydrogen peroxide and energy consumption relative to the UV/H2O2 system. Higher cost reductions are expected in cases with well adsorbing dyes and/or with less costly adsorbents.

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

In this study, DS5 DK type nanofiltration membranes were tested to recycle the reactive dye bath effluents. Reactive black 5 (RB5), reactive orange 16 (RO16), reactive blue 19 (RB19) and NaCl were used in the experiments to prepare the synthetic dye and salt mixtures. Effects of feed concentration, pressure and cross flow velocity on the permeate flux and color removal were investigated. Permeate flux increased with increasing pressure for all NaCl solutions. Dye concentration had a significant effect on flux values. Under the fixed NaCl concentrations the flux decreased with increasing dye concentrations. Dye rejections greater than 99% were achieved. Permeate was almost colorless. A gel layer formed by the rejected dye on membrane surface operates as a resistance to the permeation of dyes due to complete rejection of high molecule weight dyes, especially for the low salt concentrations. The presence of salt concentration has an interesting effect on color removal. Color removal decreased with increasing salt concentration. Cross flow velocities had also a significant effect on flux values. The dye formed agglomerates at high NaCl concentrations. High cross flow velocities decreased this effect.

Decolorization of textile wastewater by ozonation and Fenton's process

The aim of this study is to investigate the effect of some operational parameters on the efficiency of ozonation and Fenton's process for decolorization and COD removal. Acid Red 337 and Reactive Orange 16 dye solutions and the effluents of acid and reactive dye-bath effluents were used in the experiments. The influence of ozone dose and pH for color and COD removal from the wastewater were studied. Increasing the ozone dose increased the rate constants, and color and COD removal efficiencies. Ozone consumption ratio per unit color and COD removal at any time was found to be almost the same while the applied ozone dose was different. pH did not significantly affect color and COD removal from the wastewater by ozonation. In spite of having high color removal efficiencies (60-91%), limited COD removal efficiencies between 9-17% at 30 minutes ozonation time were obtained. In the Fenton oxidation experiments, the effects of pH, temperature, dosage of ferrous sulfate and hydrogen peroxide, and the proper ratio of Fe(II)/H2O2 were studied. The result indicates that up to 99% color removal and 82% COD removal can be obtained by Fenton's oxidation. While Fenton's oxidation was greatly affected by the pH value, temperature of wastewater did not significantly affect the Fenton process for color removal. Increasing the dose of both hydrogen peroxide and ferrous sulfate enhanced the removal efficiencies of color and COD. Suitable ratios of Fe(II)/H2O2 were found to be between 0.5 and 0.83.

Advanced oxidation of a reactive dyebath effluent: comparison of O3, H2O2/UV-C and TiO2/UV-A processes

In the present study the treatment efficiency of different AOPs (O3/OH−, H2O2/UV-C and TiO2/UV-A) were compared for the oxidation of simulated reactive dyebath effluent containing a mixture of monochlorotriazine type reactive dyes and various dye auxiliary chemicals at typical concentrations encountered in exhausted reactive dyebath liquors. A525 (color), UV280 (aromaticity) and TOC removal rates were assessed to screen the most appropriate oxidative process in terms of reactive dyebath effluent treatment. Special emphasis was laid on the effect of reaction pH and applied oxidant (O3, H2O2) dose on the observed reaction kinetics. It was established that the investigated AOPs were negatively affected by the Na2CO3 content (=867mg/L) which is always present at high concentrations in dyehouse effluents since it is applied as a pH buffer and dye fixation agent during the reactive dyeing process. The ozonation reaction exhibited almost instantaneous decolorization kinetics and a reasonable TOC reduction rate. It appeared to be stable under the investigated advanced oxidation conditions and outranked the other studied AOPs based on the above mentioned criteria. Besides, the electrical energy requirements based on the EE/O parameter (the electrical energy required per order of pollutant removal in 1m3 wastewater) was calculated for the homogenous AOPs in terms of decolorization kinetics. In view of the electrical energy efficiency, ozonation and H2O2/UV-C oxidation at the selected treatment conditions appear to be promising candidates for full-scale dyehouse effluent decolorization.

Photochemical treatment of simulated dyehouse effluents by novel TiO2 photocatalysts: experience with the thin film fixed bed (TFFB) and double skin sheet (DSS) reactor

This study has been undertaken to provide a rather practical assessment of the heterogeneous photocatalytic treatment of two simulated reactive dye-bath effluents via three commercial TiO2 types (Degussa P25, Millennium PC 500 and Sachtleben Mikroanatas), which were employed in fixed film and suspended photochemical reactor configurations. The obtained results have clearly revealed that the inherent advantage of eliminating a proceeding photocatalyst separation step did not justify the significantly lower treatment performance of the thin film fixed bed (TFFB) reactor, which is directly reflected in the values obtained for percent photonic efficiencies (% zeta), first-order decolourisation rate constants (kd) and the collector area requirements per unit of mineralisation rate (CA/M), as compared to the more recently developed suspended double skin sheet (DSS) photoreactor. Generally speaking, Degussa P25 was found to be most efficient among the investigated TiO2 photocatalyst types.

Treatability of a simulated disperse dye-bath by ferrous iron coagulation, ozonation, and ferrous iron-catalyzed ozonation

Dyeing and finishing of textile yarns and fabrics are extremely important processes in terms of both quality and environmental concerns. Among the commercial textile dyes, particularly disperse dyestuffs are of environmental interest because of their widespread use, their potential for formation of toxic aromatic amines and their low removal rate during aerobic waste treatment as well as advanced chemical oxidation. Thus, in the present paper ferrous iron coagulation, ozonation and ferrous iron-catalyzed ozonation were employed at varying pH (3–13) and Fe(II)-ion doses (0.09–18 mM) for the treatment of a simulated disperse dye-bath (average initial apparent color as absorbance at 566 nm=815.4 m −1; COD 0=3784 mg l −1; TOC 0=670 mg l −1; BOD 5,0=58 mg l −1) that more closely resembled an actual dyehouse effluent than an aqueous disperse dye solution. Coagulation with 5000 mg l −1 FeSO 4·7H 2O (18 mM Fe 2+) at pH 11 removed up to 97% color and 54% COD, whereas oxidation via ozonation alone (applied ozone dose=2300 mg l −1) was only effective at pH 3, resulting in 77% color and 11% COD removal. Fe(II)-ion-catalyzed ozonation (3.6 mM Fe 2+ at pH 3; Fe 2+:O 3 molar ratio 1:14) eliminated 95% color and 48% COD and appeared to be the most attractive option among the investigated chemical treatment methods as for its applicability at the natural acidic pH of the disperse dye-bath effluent and at relatively low Fe 2+-ion doses as compared to ferrous sulfate coagulation. However, no TOC reduction was observable for ozonation and catalytic ozonation at the investigated reaction conditions (14 g l −1 O 3 at pH 3). An average six-fold enhancement in the biodegradability parameter of the synthetic dye wastewater expressed in terms of the BOD 5/COD ratio could be achieved by the investigated chemical treatment methods.

Degradation of Remazol Black B dye and its simulated dyebath wastewater by advanced oxidation processes in heterogeneous and homogeneous media

This study focused on the degradation of hydrolysed Remazol Black B (CI Reactive Black 5), a common diazo reactive dye, in aqueous solution. In the presence of various dye auxiliary chemicals a typical Remazol Black exhausted dyebath liquor simulated, which was then treated with homogeneous [ozonation with hydroxy ions, and Fe(II) or Fe(III) with hydrogen peroxide] and heterogeneous (titanium dioxide with UV‐A irradiation) advanced oxidation processes. Treatment performance of the investigated advanced oxidation systems was comparatively assessed in terms of the environmental sum parameters total organic carbon, biochemical oxygen demand and spectrophotometric measurements. The results obtained clearly reveal that the investigated advanced oxidation processes are capable of completely decolourising and partially mineralising the dye solution and its simulated dyebath effluent under predetermined reaction conditions. During the application of alkaline ozonation at an ozone dose of 2340 mg/ml, a three‐fold biodegradability enhancement was observed.

H 2 O 2 /UV-C and Fe 2+ /H 2 O 2 /UV-C versus TiO 2 /UV-A Treatment for Reactive Dye Wastewater

This study investigated the advanced oxidation of commonly used reactive dyestuffs in exhausted dye-bath effluents in homogeneous (H2O2/UV-C and photo-Fenton) and heterogeneous (TiO2/UV-A) media. Photocatalytic treatment efficiencies of two different TiO2 powders (PC 500 and Mikroanatas) and the platinized Degussa P25 were compared with that of the more well-known Degussa P25 in varying pH media. Treatment performance was strongly affected by the initial H2O2 concentration for H2O2/UV-C and photo-Fenton oxidation systems, whereas for the TiO2/UV-A process only PC 500 TiO2 powder, an anatase crystal phase of the semiconductor, exhibited a significantly pH-dependent reaction efficiency. The decolorization rate followed the order of Fenton/UV-C > Pt-P25/UV-A > Mikroanatas/UV-A > P25/UV-A > PC 500/UV-A > H2O2/UV-C, whereas the decreasing order for total organic carbon reduction was Fenton/UV-C > H2O2/UV-C > Mikroanatas/UV-A > Pt-P25/UV-A > P25/UV-A > PC 500/UV-A for the studied reaction conditions. Removal of optical density at 254-nm wavelength ranged between 75 and 96%.

Anaerobic decolorization of reactive dyebath effluents by a two-stage UASB system with tapioca as a co-substrate

This study investigates the anaerobic treatability of the reactive dyebath effluents in three different colors, namely, black, red and blue, by using a pilot scale two-phase UASB system which consisted of an acidification tank and a UASB reactor with a hydraulic retention time of about 12 h for each phase. In the first three experiments, the feed wastewater was prepared from real wastewaters to have a constant coloration of approximately 150 SU (space units) with three different concentrations of tapioca starch as a supplemental carbon source or a co-substrate. The fourth was an experiment on synthetic blue wastewater and the fifth was to study the effect of an initial coloration of 0, 50 or 100 SU with a constant tapioca concentration of 500 mg/l. In the black-dye experiment, using the tapioca concentrations of 500, 1000 and 1500 mg/l, the decolorization efficiencies were not much different, i.e., 67, 71 and 69%, respectively. Subsequently, concentrations of 0, 200 and 500 mg/l tapioca were used for the red-dye and the blue-dye experiments. The decolorization efficiencies of the red-dye experiment were 36, 57 and 56% and those of the blue-dye experiment were 48, 52 and 56%, respectively. In the synthetic wastewater, the decolorization efficiencies were 36, 54 and 57% for 0, 200 and 500 mg/l tapioca, respectively, and in the last experiment, also with the synthetic wastewater, the efficiencies of decolorization of 63% and 56% were found for the initial colorations of 50 and 100 SU, respectively. The supplement of tapioca starch as a co-substrate apparently gave a better color removal performance but the excessively high concentration of tapioca did not enhance the process capability in terms of color removal efficiency. Moreover, experimental results disclosed that sulfate reducing bacteria could increase the organic carbon comsumption of the system but they did not play an important role in color reduction. The acid forming bacteria could have some role in the decolorization process, and the strictly anaerobic methane producing bacteria were not the main and only microorganisms responsible for the color reduction.

Treatability of textile dye-bath effluents by advanced oxidation: preparation for reuse

Treatability of textile dye-bath effluents by advanced oxidation with Fenton and Fenton-like reagents (FeII/H2O2 and FeIII/H2O2), in the presence and absence of UV light was investigated, using a reactive azo-dye (Procion Red HE7B), and typical dye bath constituents. Under the experimental conditions employed, it was found that with 20 min UV irradiation, complete color removal and 79% total organic carbon degradation is possible, when the system is operated at pH=3, and with a H2O2/Fe(II) molar ratio of 20:1. The increased dissolved solids content of the treated solution implies the necessity of an appropriate membrane system to make the effluent reusable in the dye/wash processes.

Treatability of textile dye-bath effluents by advanced oxidation: preparation for reuse

Treatability of textile dye-bath effluents by advanced oxidation with Fenton and Fenton-like reagents (FeII/H 2 O 2 and FeIII/H 2 O 2 ), in the presence and absence of UV light was investigated, using a reactive azo-dye (Procion Red HE7B), and typical dye bath constituents. Under the experimental conditions employed, it was found that with 20 min UV irradiation, complete color removal and 79% total organic carbon degradation is possible, when the system is operated at pH=3, and with a H 2 O 2 /Fe(II) molar ratio of 20:1. The increased dissolved solids content of the treated solution implies the necessity of an appropriate membrane system to make the effluent reusable in the dye/wash processes.

Review: Treatment and reuse of wastewater from the textile wet‐processing industry: Review of emerging technologies

New ecolabels for textile products and tighter restrictions on waste- water discharges are forcing textile wet processors to reuse process water and chemicals. This challenge has prompted intensive research in new advanced treatment technologies, some of which currently making their way to full-scale installations. These comprise polishing treatments such as -ltration, chemical oxidation and specialized Nocculation techniques and pre-treatment steps includ- ing anaerobic digestion, -xed--lm bioreactors, FentonIs reagent oxidation, elec- trolysis, or foam Notation. Though several of these new technologies are promising in terms of cost and performance, they all su†er limitations which require further research and/or need broader validation. A segment of the research deals with the separate handling of speci-c sub-streams such as dyebath effluents to which membrane -ltration is sometimes applied. The main limitation of this approach is the treatment of the concentrate stream. The spectrum of available technologies may, in the future, be further broadened to include oxidation, specialized bio-sorptive processes, solvent extrac- fungi/H 2 O 2 -driven tion, or photocatalysis. 1998 SCI ( J. Chem. T echnol. Biotechnol. 72, 289E302 (1998)

Review: Treatment and reuse of wastewater from the textile wet‐processing industry: review of emerging technologies

New ecolabels for textile products and tighter restrictions on wastewater discharges are forcing textile wet processors to reuse process water and chemicals. This challenge has prompted intensive research in new advanced treatment technologies, some of which currently making their way to full-scale installations. These comprise polishing treatments such as filtration, chemical oxidation and specialized flocculation techniques and pre-treatment steps including anaerobic digestion, fixed-film bioreactors, Fenton's reagent oxidation, electrolysis, or foam flotation. Though several of these new technologies are promising in terms of cost and performance, they all suffer limitations which require further research and/or need broader validation. A segment of the research deals with the separate handling of specific sub-streams such as dyebath effluents to which membrane filtration is sometimes applied. The main limitation of this approach is the treatment of the concentrate stream. The spectrum of available technologies may, in the future, be further broadened to include fungi/H2O2-driven oxidation, specialized bio-sorptive processes, solvent extraction, or photocatalysis. © 1998 SCI

Capillary zone electrophoresis analysis of chlorotriazinyl reactive dyes in dyebath effluent

In order to determine the feasibility of reusing/recycling monochlorotriazinyl reactive dyes in the dyeing of cellulosic fibres, methodologies were established for the identification and quantification of residual organic species derived from monochlorotriazinyl dyes using capillary zone electrophoresis. This enabled information to be secured concerning the level of hydrolysis occurring in the dyebath as well as the relative amounts of coloured species present at the end of both dyeing and subsequent rinsing.

The use of membranes for the recycling of water and chemicals from dyehouse effluents: an economic assessment

The practical and economic feasibility of using membrance technology to recycle/reuse dyes and their associated proces waters and auxiliary chemicals from dyebath effluent in and textile plants is assessed. Factors affecting the practicality of recycling dyes include: the type of process used to dye the fabric, classes of the dye used, the effluent volume, the frequency with which the dye is used and the auxiliary chemicals added to the dyebath during the dyeing process. These considerations also apply to the suitability of recycling the process water associated with the dye. Other factors to consider include the water quality required for recycling and the stage of the process to which this water can be reintroduced. To assess the economics of dyebath effluent reuse, water company treatment and supply charges, and dye and chemical costs must be considered. Data from five textile dyehouses are presented.

Low‐chrome dyeing.

The effect of a rare earth chloride mixture on the reduction of chromium residues in chrome dyebath effluents has been investigated. Chelation between the rare earth cations and chrome dyes took place and level chroming results were obtained even when reduced quantities of dichromate were used in the afterchroming stage. An explanation of these effects is given based on an ion exchange between the trivalent chromium and the rare earth cations during the afterchroming stage. A significant reduction in chromium residues in the dyebath was observed due primarily to the reduction in dichromate addition. The colour of the ‘rare earth’ dyed wool was similar to that of conventionally afterchrome dyed wool. The colour fastness properties of the ‘rare earth’ dyeings were not adversely affected and wool damage was slightly reduced.

Low chrome dyeing. Part 1 — the role of sulphamic acid in the afterchrome dyeing of wool

The role of sulphamic acid in the afterchrome dyeing of wool has been investigated. It was found that chromium residues in the dyebath effluent were significantly reduced when the commonly used formic acid was either partly or wholly replaced with sulphamic acid. The wash fastness properties of the wool fabric dyed in the presence of sulphamic acid were the same as those of wool fabric dyed by the conventional afterchrome process. There was no significant difference in the wool damage caused during the sulphamic acid‐assisted dyeing process and the conventional formic acid dyeing process.

Treatment of Dyebath Effluents by Polymeric Resin Adsorbents and Ion-Exchange Resins

Abstract Exhausted dyebath effluents were collected from various textile mills. The samples were characterized by high levels of TOC, COD, colour and various heavy metals, most notably copper, zinc and chromium. Contacting these wastewater samples with polymeric adsorbent and ion-exchange resins indicated that very of ten excellent treatment results can be obtained. Removal of TOC by the adsorbent resins varied from about 15 to 65%, while COD removals ranged from 15 to 85%. The ion-exchange resins seldom provided significant TOC or COD removal. Zinc was not only present in the highest concentrations, but was also the most difficult to remove. Most importantly, for virtually every effluent there was at least one adsorbent or ion-exchange resin which was capable of attaining almost 100% decolourization.

Heavy metal concentration of exhausted dye bath effluents.

Heavy metal concentration of exhausted dye bath effluents.