Pilot-scale Enzymatic Decolorization of Industrial Dyeing Process Wastewater

A novel process for the biotechnical decolourisation of textile wet-processing wastewaters is described. An ST-type reactor prototype was designed and installed at a Portuguese textile dyeing and printing company. The choice of location of the bioreactor was critical. A cocktail of oxidoreductases made up of both commercially available enzymes as well as from crude fungal preparations were used to efficiently decolourise the azo dyes used in the industrial dyeing process. The bioreactor had temperature and pH control systems to ensure optimal enzymatic decolourisation, this being 50ºC and pH 6. 4. The recycled bio-treated wastewater was tested for washing of dyed fabrics. No difference was seen in the washing fastness between dyed cotton fabrics that were washed with treated water as compared with fresh water. Also the difference in colour was negligible (ΔE<0.5 CIELB Units), thereby validating the re-use of the bio-treated waters.

Journal of Textile Engineering & Fashion Technology, 2018

Increasing social awareness and social cognition about environment are challenging the textile industry, which has highly coloured waste water. For this reason, in this study, enzymatic decolorizations of three different coloured reactive dyeing baths containing soda, salt and reactive dyes with laccase were studied. The maximum absorbance of the red coloured bath showed hypsochromic shift after enzymatic decolorization, i.e. shifted towards the blue region. The percentage of colour removal was the highest in the red and the lowest in the orange due to their tinctorial strengths. The highest colour removal among three colours were observed at 0.5 and 2% dyestuff concentrations, which indicated that laccase could be used successfully in decolorization of textile waste water.

Chemical Engineering Journal, 2008

The anaerobic decolourisation of azo dye Acid Orange 7 (AO7) was studied in a continuous upflow stirred packed-bed reactor (USPBR) filled with biological activated carbon (BAC). Special stirring of BAC and different biodegradation models were investigated. The application of appropriate stirring in the carbon bed resulted in an increase of azo dye bioconversion up to 96% in 0.5 min, compared to unstirred reactor system with ensuring high dye degradation rates at very short space times. In addition, USPBR provided much more reproducible data to make kinetic modeling of AO7 biodegradation. First-order, autocatalytic and Michaelis–Menten models were found to describe the decolourisation process rather well at lower initial dye concentration. AO7 showed significant inhibition effect to biomass beyond inlet dye concentrations of 300 mg L−1. Expanding Michaelis–Menten kinetics by a substrate inhibition factor resulted in a model giving good fitting to experimental points, independently on the initial colourant concentration. Processing at very low hydraulic residence time together with higher initial dye concentration resulted in toxicity to bacteria.

Journal of Environmental Science and Health Part A-toxic/hazardous Substances & Environmental Engineering, 2004

Batch anaerobic and sequential anaerobic upflow anaerobic sludge blanket (UASB)/aerobic continuous stirred tank reactor (CSTR) were used to determine the color and COD removals under anaerobic/aerobic conditions. Two azo dyes namely ''Reactive Black 5 (RB 5),'' ''Congo Red (CR),'' and glucose as a carbon source were used for synthetic wastewater. The course of the decolorization process approximates to first order and zero order kinetics with respect to dye concentration for RB 5 and Congo Red azo dyes, respectively, in batch conditions. The decolorization kinetic constant (K 0 ) values increased from 3.6 to 11.8 mg (L h) À1 as increases in dye concentrations from 200 to 3200 mg L À1 for CR. Increases in dye concentrations from 0 to 3200 mg L À1 reduce the decolorization rate constant (k 1 ) values from 0.0141 to 0.0019 h À1 in batch studies performed with RB 5. Decolorization was achieved effectively under test conditions but ultimate decolorization of azo dyes was not observed at all dye concentrations in batch assay conditions. Dye concentrations of 100 mg L À1 and 3000 mg L À1 of glucose-COD containing basal medium were used for continuous studies. The effect of organic loadings and HRT, on the color removal efficiencies and methane gas productions were monitored. 94.1-45.4% COD and 79-73% ORDER REPRINTS color removal efficiencies were obtained at an organic system during decolorization of Reactive Black 5. 92.3-77.0% COD and 95.3-92.2% decolorization efficiencies were achieved at a organic loading rate of 1.03-6.65 kg (m 3 day) À1 and a HRT of 3.54-0.49 for Congo Red treatment. The results of this study showed that, although decolorization continued, COD removal efficiencies and methane gas production were depressed at high organic loadings under anaerobic conditions. Furthermore, VFA accumulation, alkalinity consumption, and methane gas percentage were monitored at organic loading as high as 2.49-4.74 kg (m 3 day) À1 and 24.60-30.62 kg (m 3 day) À1 , respectively, through the decolorization of RB 5 and CR dyes in the UASB reactor.

1997

In this study, the ability of anaerobic system to decolorize different reactive azo dyes were investigated Three reactive azo dyes were used in this study including CI-198 (Remazol Red RB), CI-141 (Reactive Red) and CI-5 (Remazol Black B). Most of the study on reactive azo dyes degradation used parent dyes (commercial dyes without any teatrrent), but it was known that mostly of the dyes ended up in the waste stream as a hydrolyzed form. Thus, the decolorization of parent and hydrolyzed fomt dyes were also compared in this study. The standard assay conditions for measurement of dye decolorization were adopted from Carliell et al. (1995). Experimen8 were performed in senrm bottles with the temperature was maintained at37"C and an initial dye concentration of 100 mg/L. This study shows that the Earent and hydrolyzed form dyes had the same decolorization behavior. It also shows that the decolorization of CI-198 and CI-141 in anaerobic system was found to be fust order with respect to dye concentration. However, decolorization of CI-5 was much more complex.

Bioresource Technology, 2009

Biocatalytic treatment of a synthetic dye house effluent, simulating a textile wastewater containing various reactive dyestuffs (Reactive Yellow 15, Reactive Red 239 and Reactive Black 5) and auxiliary chemicals, was investigated in a batch reactor using a commercial laccase. A high decolourisation (above 86%) was achieved at the maximum wavelength of Reactive Black 5. The decolourisation at the other dyes wavelengths (above 63% for RY15 and around 41% for RR239) and the total decolourisation based on all the visible spectrum (around 55%) were not so good, being somewhat lower than in the case of a mixture of the dyes (above 89% for RB5, 77% for RY15, 68% for RR239 and above 84% for total decolourisation). Even so, these results suggest the applicability of this method to treat textile dyeing wastewaters. Kinetic models were developed to simulate the synthetic effluent decolourisation by commercial laccase. The kinetic constants of the models were estimated by minimizing the difference between the predicted and the experimental time courses. The close correlation between the experimental data and the simulated values seems to demonstrate that the models are able to describe with remarkable accuracy the simulated effluent degradation. Water quality parameters such as TOC, COD, BOD 5 and toxicity were found to be under the maximum permissible discharge limits for textile industries wastewaters.

Dyestuff sector is one of the core chemical industries in India. Maharashtra and Gujarat account for 90% of dyestuff production in India due to the availability of raw materials and dominance of textile industry in these regions. During industrial processing up to 40 % of the used dyestuffs are released in to the process water. The untreated effluents released from the dyeing units cause a major threat to the environment. Direct discharge of dye effluents causes formation of toxic aromatic amines in receiving media. The majority of colour removal techniques work either by concentrating the colour into the sludge or by partial or complete breakdown of the coloured molecules. Although a variety of effective physical and chemical treatment methods are commercially available, most of them are either expensive, not adaptable to a wide range of dyes, or do not completely solve the problem of complete decolourization of dye containing industrial effluents. Biodegradation have been explored...

Biotechnology and Bioprocess Engineering, 2011

Reactive dyes are extensively used in textile industry in the last years due to their superior performance, but they are environmentally hazardous and difficult to treat effectively by classical methods. In the present work, the decolorization and degradation of four commercial reactive azo dyes, namely Remazol Red RR, Remazol Yellow RR, Procion Crimson H-exl and Procion Yellow H-exl, were studied using photocatalytic processes (TiO 2 /UV and TiO 2 /UV/H 2 O 2 ). Decolorization and degradation were found to strongly depend on the system parameters (TiO 2 loading, dye and H 2 O 2 initial concentrations, and pH). Decolorization efficiency (%) sharply increases with increasing the TiO 2 loading, especially up to 1 g/L, as well as with decreasing the initial dye concentration from 250 down to 50 mg/L. At pH = 3, a > 90% decolorization of all dyes can be achieved in only 15 min. Addition of H 2 O 2 increases the decolorization rates up to an optimum value (97.9% Remazol Red RR decolorization at 12 min irradiation, with a 0.5%w/w initial H 2 O 2 concentration and pH = 3). Among the four dyes examined, significant differences in decolorization and degradation rates were revealed, but decolorization and degradation efficiencies up to 100% (in 25 min and 4 h respectively) are possible with proper combinations of the system parameters.

DergiPark (Istanbul University), 2007

Anaerobic treatment system was used for determination of colour removal under batch conditions. Azo-dye (Reactive Black 5, RB 5) with glucose as a carbon source was used as a synthetic wastewater. The decolourization process follows first order kinetics with respect to RB 5 azo-dye concentration in batch conditions. Decolourization rate constant (k 1) value for dye concentration of 150 mgL-1 was 0.1751 h-1 in the batch experimental study performed with RB 5. Maximum Reactive Black 5 removal efficiency was obtained after 24 hour (99%) under batch experimental condition.

Applied Microbiology and Biotechnology, 2012

The effects of different components of real dyeing bath formulations, such as the equalizing and fixing additives-acids, salts, and surfactants-on the decolorization catalyzed by Funalia trogii enzymatic extracts, were investigated to understand their influence on the recalcitrance to biodegradation of this type of wastewater. The decolorization of selected dyes and dye mixtures after tissue dyeing was performed in the presence/absence of auxiliary compounds. All spent dyeing baths were enzymatically decolorized to different extents, by the addition of extracts containing laccase only or laccase plus cellobiose dehydrogenase. Whereas surfactant auxiliaries, in some instances, inhibit the decolorization of spent dyeing baths, in several occurrences the acid/salt additives favor the enzymatic process. In general, the complete spent dyeing formulations are better degraded than those containing the dyes only. The comparison of extracellular extracts obtained from spent straws from the commercial growth of Pleurotus sp. mushrooms with those from F. trogii reveals similar decolorization extents thus allowing to further reduce the costs of bioremediation.