Textile Dyehouse Research Articles

Impact of Powdered Activated Carbon and Anion Exchange Resin on Photocatalytic Treatment of Textile Wastewater

In order to clarify the impact of activated carbon and anion exchange resin on photocatalytic oxidation (PCO) of textile industry wastewater, TiO2-based PCO was investigated with aqueous solutions containing the reactive dye Reactive Blue 4 (RB4) and with a textile dye house effluent in the absence and in the presence of powdered activated carbon (PAC) and the anion exchange resin Lewatit MP 500. Addition of Lewatit improved RB4 removal to a larger extent than PAC addition. Contrasting to chloride and sulfate, hydrogen carbonate clearly inhibited PCO of RB4. However, the depression of dye removal by hydrogen carbonate was minute in the presence of Lewatit although the hydrogen carbonate concentration was not markedly decreased. Unfortunately, the beneficial effect of Lewatit addition on PCO nearly disappeared when the Lewatit/TiO2 mixture was reused three times. This was probably caused by oxidative damage of the resin. Color removal from the real dye house effluent during PCO was improved by Lewatit, but not by PAC. Contrastingly, PAC addition increased TOC removal by PCO from the real wastewater to some extent, while Lewatit had no impact. Sorbent addition does not lead to an acceptable area demand for solar PCO of the dye house effluent.

Keratin hydrolysate as an exhausting agent in textile reactive dyeing process

Salt is an essential exhausting agent for the dyeing of cotton fabric with reactive dyes. The usage of salt leads to an increased effluent load in terms of total dissolved solids and also limits the opportunities for recycling textile dye house effluents. These effluents are difficult to degrade and their disposal leads to environmental pollution. In the present work, we have prepared keratin hydrolysate (KH) from waste of wool processing industries to reduce the usage of salt in dyeing. The KH was fixed to the cotton fabric at five different add on percentage, and the presence of the KH on the fabric was confirmed by FTIR, TGA and SEM-EDX Studies. The KH-fixed fabrics were further dyed with reactive dyes without addition of salt. The colour strength of the fabric increased up to 91 % to that of the control sample. The studies reveal that the tone of the fabric was not altered and KH usage can significantly reduce salt consumption in reactive dyeing process.

Photocatalytic treatment of textile dyehouse effluents with simulated and natural solar light

In the present study, the photocatalytic treatment of two synthetic textile dyehouse effluents was investigated. The first synthetic effluent (SE1) is a Remazol Black B aqueous solution, while the second one (SE2) is an aqueous mixture of sixteen dyes and auxiliary chemicals that are usually employed in the textile industry. Various illumination sources were studied, while emphasis was given on the use of simulated and natural solar light. Results indicated that the use of solar irradiation can constitute an advantageous treatment strategy, due to its energy efficient and environmentally friendly operation, for textile dyehouse effluents. Specifically, it was observed that total decolorization and mineralization of SE1 occurred after about 120 min and 300 min, respectively, in the presence of at least 2 g L-1 TiO2, under natural sunlight. On the other hand, total decolorization of SE2 was achieved only after 300 min of photocatalytic treatment, while COD removal practically remained unchanged, at about 20%, regardless the applied operating parameters, due to the presence of other organic and inorganic substances. Furthermore, it was found that process efficiency was significantly affected by the catalyst loading.

Anodic oxidation of textile dyehouse effluents on boron-doped diamond electrode

The electrochemical oxidation of textile effluents over a boron-doped diamond anode was investigated in the present study. Experiments were conducted with a multi-component synthetic solution containing seventeen dyes and other auxiliary inorganics, as well as an actual effluent from a textile dyeing process. The effect of varying operating parameters, such as current density (4–50mA/cm2), electrolyte concentration (0.1–0.5M HClO4), initial solution pH (1–12.3) and temperature (22–43°C), on process efficiency was investigated following changes in total organic carbon (TOC), chemical oxygen demand (COD) and color. Complete decolorization accompanied by significant mineralization (up to 85% depending on the conditions) could be achieved after 180min of treatment. Performance was improved at higher electrolyte concentrations and lower pH values, while the effect of temperature was marginal. Energy consumption per unit mass of COD removed was favored at lower current densities, since energy was unnecessarily wasted to side reactions at higher densities.

The treatment of wastewaters by supercritical water oxidation

In this study, the treatment performance of SCWO process is evaluated on various industrial wastewaters such as textile dyehouse effluent; pesticide containing model wastewater; olive mill wastewater and cheese whey. These wastewaters have significant pollution potentials due to their high organic loads. The experiments were made under sub- and supercritical conditions in a continuous flow reactor, using H2O2 as the oxygen source. The removal efficiencies are evaluated in terms of total organic carbon concentrations (TOC). The results demonstrate that at various experimental conditions, SCWO provides high organic conversion yields up to 100% in very short reaction times within 30 s for each wastewater sample.

Application of membrane processes in closing of water cycle in a textile dye-house

In this study, investigations were made to close water cycle in dye-houses. At the first stage, optimum operation conditions of a membrane nanofiltration were determined. Experiments were carried out for DL membranes (Osmonics, USA). The effect of temperature, pressure and pH was investigated. Investigations were performed for different types of real wastewater produced in a laboratory-scale Pyrotec S dyeing apparatus (Roaches) for various types of reactive dyes. An over 90% dye hold-up was obtained for all dye baths. At the final stage of the experiments, dyeing processes were carried out with the use of a filtrate from nanofiltration as water applied for dyeing, rinsing and washing after dyeing. In cooperation with the Technical University of Lodz, we have managed to apply biological degradation of the concentrate, carried out in two different reactor systems.

Natural dyes for textile dyeing: A comparison of methods to assess the quality of Canadian golden rod plant material

The introduction of natural dyes into modern textile dyehouses requires the classification of products of standardised quality with regard to colour depth and shade of the dyeings. Canadian golden rod was chosen as a representative example to test the methods that are available to assess the quality of different crops of plant material which had been collected over a period of five years. Aqueous solutions containing the extracted flavonoid dyes were characterised by means of direct photometry, measurement of absorbance after addition of FeCl 2, analysis of total phenolics (TPH) in the extract and dyeings on wool yarn. TPH calculated as gallic acid varied from 62 g/kg to 97 g/kg of plant material; only one sample exceeded this range with a value for TPH of 142 g/kg. Correlation among TPH, photometry in the presence of FeCl 2 and lightness of the dyeings can be used to characterise samples. However, correlation between the photometric results and colour depth of dyeings is not sufficient to permit characterisation of the plant material with regard to the final dyeing. At present, a combination of laboratory dyeings and CIELab coordinates was found to be suitable to establish an experimental basis for standardisation of plant material.

Treatment of textile dyehouse wastewater by TiO 2 photocatalysis

The oxidative degradation of an actual textile dyehouse wastewater was investigated by means of photocatalysis in the presence of TiO 2. The UV-A-induced photocatalytic oxidation over TiO 2 suspensions was capable of decolorizing the effluent completely, as well as reducing chemical oxygen demand (COD) sufficiently (COD reduction generally varied between about 40% and 90% depending on the operating conditions) after 4 h of treatment. Two crystalline forms of TiO 2, viz. anatase and rutile, were tested for their photocatalytic activity and anatase was found to be more active than rutile. The extent of photocatalytic degradation was found to increase with increasing TiO 2 concentration up to 0.5 g/L TiO 2, above which degradation remained practically constant, reaching a plateau. Furthermore, textile effluent degradation was enhanced at acidic conditions (i.e. pH=3) and in the presence of hydrogen peroxide. To assess catalyst activity on repeated use, experiments were performed where the catalyst was recovered and reused; after three successive uses, TiO 2 had sufficiently retained its photocatalytic activity. Finally, the luminescent marine bacteria Vibrio fischeri was used to assess the acute ecotoxicity of samples prior to and after the photocatalytic treatment and it was found that ecotoxicity was fully eliminated following photocatalytic oxidation.

Advanced treatment of textile wastewater for reuse using electrochemical oxidation and membrane filtration

The treatment of textile wastewater for reuse using an electrochemical oxidation step combined with a membrane filtration step is reported in this paper. The electrolytical process is a traditional one, which is easy to scale up and to apply in practice. This paper proposes a modification of the transfer-flow membrane (TFM) module with fibres welded in an arc-shape to enhance the mechanical properties of the fibres and to increase the specific membrane surface of TFM modules. The goal of this research was to study the performance of the arc-shaped TFM module to demonstrate these sequences of electrochemical oxidation coupled with membrane filtration processes and to develop a potential dyehouse wastewater treatment system for reuse. Two testing sequences of electrochemical oxidation and membrane filtration were studied in a sequential batch order. The results show clearly that fibres welded in an arc-shape can enhance the mechanical properties of the fibres effectively and that electrochemical oxidation and membrane filtration as sequential processes are feasible. Electrochemical oxidation has a high removal (89.8% efficiency) of the chemical oxygen demand (COD) of the wastewater while the membrane filter can almost totally remove the total suspended solids (TSS) (nearly 100% reduction) and turbidity (98.3% elimination) in it. Coincidentally, their advantages make up for their disadvantages. After these two steps, all the wastewater indices decrease to low levels; in particular, COD levels are reduced to 18.2 mg•l-1. The treated water can be reused in many production areas of the textile dyehouse factory. To take best advantage of this disposal system, the two processes should run in a rational sequence, with membrane filtration following the electrochemical oxidation process. With widely studied electrodes, this research offers a promising way for recycling textile wastewater. Key words: electrolysis, oxidation, membrane, dye, wastewater treatment Water SA Vol.31(1) 2005: 127-132

Treatment of a textile effluent: application of a combination method involving adsorption and nanofiltration

A combination of adsorption and nanofiltration (NF) was adopted for the treatment of a textile dyehouse effluent containing a mixture of two reactive dyes. The effluent stream was first treated in a batch adsorption process with sawdust as an adsorbent to reduce the dye concentration of the effluent by about 83% for Dye 1 and 93% for Dye 2. The effluent from the adsorption unit was passed through an NF unit for the removal of the remaining small amount of dyes and to recover the associated chemicals (mainly salt) in the effluent stream. The dyes remaining after this step were less than 1 ppm. The percentage removal of COD was greater than 99%, and the salt recovery was on the order of 90%. Equilibrium studies were carried out with synthetic solutions of the dyes (both single component as well as two-component systems) at room temperature. The adsorption rates were studied in detail using varying amounts of the adsorbent. NF of the effluent was performed in a cross-flow system using a 400 molecular weight cut-off membrane. A detailed study was carried out to observe the effect of the process parameters, namely applied pressure and bulk velocity on the process outputs such as dye rejection, COD removal, permeate flux and salt recovery. Finally, direct NF of the effluent (with the original high concentration) was undertaken, and the performance of the process was compared with the combination method. The permeate flux for the proposed combined method was found to be about twice that for the direct NF method. The dye rejection improved significantly compared to adsorption.

Natural dyes in modern textile dyehouses — how to combine experiences of two centuries to meet the demands of the future?

Plant materials which are available from farming regions in the moderate Austrian climate were investigated to serve as sources for natural dyes in textile dyeing operations. The extraction of the dye components from the plant materials was performed with boiling water without addition of chemicals or solvents. Based upon a rigorous selection of possible plant sources, a selection of natural dyestuffs applicable in a one-bath dyeing step was established. A broad variation in shade and color depth can be achieved by applying mixtures of natural dyestuffs in various combinations of iron- and alum-mordants. More than 60% of tested dyeings achieved acceptable fastness properties. On the basis of the developed natural dyestuff-based dyeing procedures, a comparison was made between the effluents from processes based upon them and those based upon the current ‘state-of-the-art’ techniques utilizing synthetic dyes. The comparison revealed that a lowering of the chemical load released with waste water can be expected by shifting to the plant-based dyes.

Algal Treatment of Textile Dyehouse Wastewater

Algal Treatment of Textile Dyehouse Wastewater

Membrane filtration of textile dyehouse wastewater for technological water reuse

Polish textile industry demands big amounts of water and produces wastewater having high load of contaminants. The continued increase in the costs of chemicals, energy and water makes their recovery more important today than it was years ago when separation techniques by membrane filtration were first introduced to the textile industry. The aim of introducing membrane filtration is not only to reduce water consumption and wastewater streams. Membrane filtration also reduces the consumption of energy as the warm water can be recovered. While the filtration techniques applied for textile wastewater treatment and water recovery have been used at only few installations, these installations have been reported as successful and have been able to save enough to repay the recovery process in one to two years [1]. The paper describes the results of research works and implementation project concerning cleaner technology and water reuse in textile dyehouse. The goal of the research was application of membrane filtration to reuse water after dyeing of cotton and polyester fabrics. The Textile Research Institute in Lodz, Poland, together with the Danish partners, the Technical University of Denmark, the Institute for Product Development and RINSE has carried out this research. The research was sponsored by Danish Environmental Protection Agency DEPA. Membrane filtration has been tested in lab and pilot scale. The experiments were done with selected two membranes for nanofiltration and one for reverse osmosis. All membranes were manufactured by Desalination Systems and made of proprietary polysulphone. The lab tests investigated membrane performance using chemicals selected from real process wastewater. The pilot scale tests were done to prove membrane performance in industrial use and determine dimensioning parameters for full-scale system. The results of lab and pilot scale tests have shown that membranes can be used with the rinsing water from dyeing of cotton and polyester fabrics. As the result of the pilot scale tests two full scale systems were proposed: nanofiltration system producing permeate which can be used in limited technological processes and reverse osmosis system producing permeate of the same quality as technological water.

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.

Recovery of water and auxiliary chemicals from effluents of textile dye houses

A process to recover at least 80% of water, auxiliary chemicals and energy from effluents of textile dye-houses has been developed. The water and the auxiliary chemicals can be reused by the textile industry to dye either light or dark shades. Energy is recovered in the form of hot water. The pay-back time for the process is between 18 and 30 months, depending upon the degree of automation. Moreover, this technology minimizes the discharge of pullutants contributing greatly to the solution of many environmental problems. Spiral wound membrane modules specifically designed for this application are used. Pretreatment to the membrane system is done by physico-chemical and/or biological units and sand filters.

Recent Advances in Water Reuse Research in South Africa

Due to limited water resources, water reuse is pursued as a major component of an overall strategy to optimise water use in South Africa. Progress in South African water reuse research, mainly since 1985, is reviewed. In the field of potable reuse research, the topics addressed are epidemiological studies, activated carbon, the microbiology of reclaimed water, bioassaying, and reverse osmosis. Information is provided on the scale of direct agricultural and industrial reuse of purified sewage effluents. Indirect reuse is steadily increasing and research which traditionally addressed direct potable reuse is becoming of equal relevance to indirect reuse. In addition, research becomes necessary on problems which relate specifically to indirect reuse, such as : treatment of algal waters, variation of raw water quality, upgrading of sewage effluent quality, organohalogens, and salination problems. Recent advances in research on internal water reuse by industry focused in particular on membranes and salt removal technology. Cases mentioned are textile dyehouse, scouring, bleaching and mercerising processes; bottle washing; wool scouring; water works wash water; and power station cooling.

New mineral-carbon sorbent: Mechanism and effectiveness of sorption

The mechanism and effectiveness of a new mineral-carbon sorbent, produced from spent fuller's earth after lubricating oil rafination, were examined. The sorbent was produced by carbonization of organic compounds at 623 K in the presence of sulphuric acid. The surface area of the sorbent is 133 m 2/g and its structure contains numerous mesopores. Acidic and basic groups are present on the sorbent surface. The influence of the sorbent characterization of the sorbent surface, contact time, temperature, initial sorbate concentration and sorbate chemical properties has been determined on the basis of investigations of sorption of selected compounds. Functional groups on the surface of the sorbent affected sorption of compounds occurring in the ionic form. Intraparticle diffusion was the sorption rate-controlling step. Increase in the initial concentration of the sorbate affected the rate and capacity of the sorption; sorbate functional group analysis indicated a negative effect of hydroxyl groups. Sorbate molecular mass had a significant effect on the sorption, while its solubility and polarity were insignificant. The results were confirmed with industrial and municipal waste. The best effects were obtained with wastewaters containing large molecules having electrostatic charge from a textile dyehouse.

Search for benzidine and its metabolites in urine of workers weighing benzidine-derived dyes.

Urinary benzidine and conjugates have been used to assess the extent of occupational exposure to benzidine-based azo dyes. The aim of the present study was to investigate the presence of benzidine and its conjugates in the urine of workers exposed to benzidine-derived dyes. Urine samples were collected from 29 workers in three textile dyehouses, two tanneries, and two dyestuff quality control laboratories in West Yorkshire and Lancashire. In 200 samples, obtained over a period of 15 months and analysed by gas chromatography/mass spectrometry, no free benzidine or monoacetylbenzidine was detected. Nevertheless, after strong acid hydrolysis of urine samples taken on two separate occasions from textile dye weighers where the standard of hygiene appeared below average, trace amounts of benzidine were detected suggesting the excretion of a benzidine derived dye or a metabolite thereof.