RESUMEN
Decolorization of textile dyes and study of their intermediate compounds is necessary to comprehend the mechanism of dye degradation. In the present study, different fungal mediated solutions were explored to provide an alternative to treat the reactive dyes. Growing biomass of Pleurotus sajor caju showed 83% decolorization (249.99 mg L-1 removal) of Reactive Blue 13 (RB 13) and 63% decolorization (188.83 mg L-1) of Reactive Black 5 (RB 5) at 300 mg L-1 initial concentration on 8 d. Higher laccase activity was positively correlated with increase in decolorization. However, increasing dye concentration has inhibitory effect on fungal biomass due to increase in toxicity. In laccase mediated decolorization, laccase produced from P. sajor caju using carbon rich waste material as substrate showed 89% decolorization (276.36 mg L-1 removal) of RB 13 and 33% decolorization (105.37 mg L-1 removal) of RB 5 at 300 mg L-1 initial dye concentration in 100 min at 30 °C and pH 3.0'. Comparing the two methods, laccase-mediated decolorization shows better decolorization in less time and does not produce sludge. Further, the present work also attempted to study the dye degradation pathway for Reactive blue 13 via laccase mediated process. Fourier-transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography-mass spectrometry (GC-MS) were utilized to identify the degraded products. The GC-MS analysis showed the formation of naphthalene, naphthalene 2-ol, benzene,1-2, dicarboxylic acid, 4, amino, 6,chloro, 1-3-5, triazin-2-ol as the final degraded products after enzymatic degradation of RB 13. These findings provide in-depth study of laccase-mediated textile dye degradation mechanism.
Asunto(s)
Biodegradación Ambiental , Colorantes , Hongos , Textiles , Colorantes/química , Colorantes/toxicidad , Hongos/metabolismo , Cromatografía de Gases y Espectrometría de Masas , Lacasa/metabolismoRESUMEN
Understanding the role of oxido-reductase enzymes followed by deciphering the functional genes and their corresponding proteins are crucial for the speculation of molecular mechanism for azo dye degradation. In the present study, decolourization efficiency of developed microbial consortium was tested using 100 mgL-1 reactive blue 13 (RB13) and the results showed â¼92.67% decolourization of RB13 at 48 h of incubation. The fourier-transform infrared spectroscopy (FTIR), high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) analysis were performed to identify the metabolites formed during RB13 degradation, followed by hypothesizing the metabolic pathway. The GC-MS analysis showed formation of 1,4-dihydronaphthalen-1-ol and 1,3,5-triazin-2-amine as the final degraded compounds after enzymatic breakdown of RB13 dye. The activity of different oxido-reductase enzymes was determined, and the results showed that NADH DCIP reductase and azo reductase had higher activity than other enzymes. It clearly indicated the degradation was initiated with the enzymatic cleavage of azo bond of RB13. Further, the functional genes were annotated against the database of clusters of orthologous groups (COGs) and kyoto encyclopedia of genes and genomes (KEGG). It provided valuable information about the role of crucial functional genes and their corresponding proteins correlated with dominant bacterial species in degradation of RB13. Hence, the present research is the first systematic study that correlated the formation of degradation compounds with the functional genes/enzymes and their corresponding bacterial species responsible for RB13 degradation.
Asunto(s)
Colorantes , Consorcios Microbianos , Colorantes/química , Biodegradación Ambiental , Compuestos Azo/química , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
Enzymatic (laccase mediated) decolorization of dyes remains inefficient for recalcitrant dyes, which can be better handled by electrocoagulation (EC). However, EC is energy intensive and produce large amount of sludge. In light of the same, present study offers a promising solution for the treatment of textile effluent meeting surface discharge norms, using hybridization of enzymatic and electrocoagulation treatment. The findings revealed best color removal (90%) of undiluted (raw) textile effluent (4592 hazen) is achievable by employing EC using zinc-coated iron electrode at current density 25 mA cm-2 followed by partially purified laccase (LT) treatment, and activated carbon (AC) polishing at ambient conditions. Overall, the decolorization performance of Hybrid EC-LT integrated AC approach was 1.95 times better than only laccase treatment. Also, the sludge generation from Hybrid EC-LT integrated AC (0.7 g L-1) was 3.3 times lesser than EC alone (2.1 g L-1). Therefore, the present study recommends Hybrid EC-LT integrated AC could be potential approach to treat complex textile effluent sustainably with lower energy input and waste sludge generation.
Asunto(s)
Lacasa , Aguas del Alcantarillado , Industria Textil , Electrocoagulación , Colorantes , Carbón Orgánico , Residuos Industriales/análisisRESUMEN
Desizing process in textile industry produces large volume of starch effluent. This carbon-rich waste can be used for resource recovery, such as the production of industrially useful enzymes. The present work assesses the usability of starch effluent from textile industry as an additional carbon source for enhanced production of α-amylase during solid-state fermentation (SSF) of agro-wastes by Trichoderma reesei. A significant increase (p ≤ 0.05) in α-amylase activity (25.48 ± 1.12 U mL-1) was observed with supplementation of starch effluent in SSF. Partial purification of α-amylase by 80% ammonium sulphate precipitation produced a yield of 58.39% enzyme with purification fold of 1.89. The enzyme was thermally stable at 40 °C with 90% residual activity after 5 h and 70% residual activity at 50 °C after 3 h. Using Michaelis-Menten kinetics analysis, the estimated Km and Vmax values for the partially purified α-amylase were found to be 2.55 mg mL-1 and 53.47 U mg-1, respectively. For the rapid assessment of the industrial application, desizing of the fabric was attempted. The cotton fabric was efficiently desized using α-amylase (at a concentration of 1% on the weight of fabric basis) at 80 °C. The present work demonstrates starch effluent from desizing process as a resource for the production of amylase. The amylase can further be used in the desizing process. With in-depth research, the work may lead to the development of a closed-loop, waste-recycling process for the textile industry.