Mycoremediation and toxicity assessment of textile effluent pertaining to its possible correlation with COD

Globally, textile industries are one of the major sectors releasing dye pollutants. This is the first report on the positive correlation between toxicity and chemical oxygen demand (COD) of textile effluent along with the proposed pathway for enzymatic degradation of acid orange 10 using Geotrichum candidum within a very short stretch of time (18 h). Removal efficiency of this mycoremedial approach after 18 h in terms of chemical oxygen demand, biological oxygen demand, total suspended solids, salinity, color and dye concentration in the treated effluent reached to 98.5%, 56.3%,73.2%, 64%, 89% and 87% respectively. Also there was a decrease in pH of the treated effluent. FTIR analysis of the treated effluent confirmed biodegradation. The LCMS analysis showed the degradation of acid orange 10, which was confirmed by the formation of two biodegradation products, 7-oxo-8-iminonapthalene-1,3-disulfonate and nitrosobenzene, which subsequently undergoes stepwise hydrogenation and dehydration to form aniline via phenyl hydroxyl amine as intermediate. The X-ray diffraction studies showed that heavy metal content in the treated effluent has reduced along with decrease in % crystallinity, indicating biodegradation. The connection between toxicity and COD was also inveterated using Pearson’s correlation coefficient. Further the toxicological studies indicated the toxicity of raw textile effluent and relatively lower toxic nature of metabolites generated after biodegradation by G. candidum.

Mycoremediation of Textile Effluent: A Toxicological Evaluation and its Possible Correlation with COD

Globally, textile industries are one of the major sectors releasing dye pollutants. This is the first report on the positive correlation between toxicity and COD of textile effluent along with the proposed pathway for enzymatic degradation of acid orange 10 using Geotrichum candidum within a very short stretch of time (18h). Removal efficiency of this mycoremedial approach after 18 h in terms of color, dye concentration as well as reduction of chemical oxygen demand (COD) and biological oxygen demand (BOD) in the treated effluent reached to 89%, 87%, 98.5% and 96.3% respectively. FT-IR analysis of the treated effluent confirmed biodegradation. The LC-MS analysis showed the degradation of acid orange 10, which was confirmed by the formation of two biodegradation products, 7-oxo-8-iminonapthalene-1,3-disulfonate and nitrosobenzene, which subsequently undergoes stepwise hydrogenation and dehydration to form aniline via phenyl hydroxyl amine as intermediate. The X-ray diffraction (XRD) studies showed that heavy metals content in the treated effluent has reduced along with decrease in % crystallinity, indicating biodegradation. The connection between toxicity and COD was also inveterated using Pearson’s correlation coefficient. Further the toxicological studies indicated the toxicity of raw textile effluent and relatively lower toxic nature of metabolites generated after biodegradation by G. candidum.

Bio-degradation of Azo Dye Acid Orange-10 by a New Isolate of Bacillus subtilis Isolated from Soil Sample around Textile Industry in South Karnataka

Untreated effluents from the textile industry affect aquatic life irreversibly. Synthetic dyes not only change the color of water resources but also make them hazardous.The main objective of the study was to evaluate the decolorizing potential of a new isolate of Bacillus subtilis from soil samples contaminated with industrial effluent in and around textile industrial area in South Karnataka. This isolate of Bacillus subtilis has high decolorizing potential and took only 24 hrs for complete decolorization of acid orange-10 azo dye at 200ppm. Different parameters like temperature, pH, aeration, dye concentration and inoculum size were optimized for complete decolorization of Acid orange-10 azo dye by this isolate of Bacillus subtilis. The dye was completely decolorized at 400C within 24 hrs and it was capable of decolorizing 700 ppm dye in 72 hrs. Optimum pH was found to be 8.5 and maximum decolorization was achieved under static conditions. As the inoculum size increased, the time taken for complete decolorization of Acid orange-10 dye was decreased from 36 hrs at 1% to 16 hrs at 10% of inoculum size. The new isolate decolorizes 100 ppm of dye completely (i.e.100%) within 12hrs of incubation. The time taken for the complete decolorization increased with increase in the concentration of Acid orange-10 azo dye. In conclusion, the new isolate of Bacillus subtilis from soil samples contaminated with textile industrial effluent was found to be a potential candidate for decolorization of Acid orange-10 azo dye in textile effluents.

Tailoring Carbon Nanotubes to Enhance their Efficiency as Electron Shuttle on the Biological Removal of Acid Orange 10 Under Anaerobic Conditions

Anaerobic treatments have been described for the biodegradation of pollutants. However, the reactions proceed slowly due to the recalcitrant nature of these compounds. Carbon nanomaterials (CNM) intermediate in, and favor, the electron transfer, accelerating the anaerobic reduction of pollutants, which act as final electron acceptors. In the present work, different carbon nanotubes (CNT) with modified surface chemistry, namely CNT oxidized with HNO3 (CNT_HNO3) and CNT doped with nitrogen in a ball milling process (CNT_N_MB) were prepared using commercial CNT as a starting material. The new CNM were tested as redox mediators (RM), 0.1 g L−1, in the biological reduction of the azo dye, Acid Orange 10 (AO10), with an anaerobic granular sludge, over 48 h of reaction. Methane production was also assessed to verify the microorganism’s activity and the CNM’s effect on the methanogenic activity. An improvement in the biological removal of AO10 occurred with all CNM (above 90%), when compared with the control without CNM (only 32.4 ± 0.3%). The best results were obtained with CNT_N_MB, which achieved 98.2 ± 0.1% biological AO10 removal, and an 11-fold reduction rate increase. In order to confer magnetic properties to the CNM, tailored CNT were impregnated with 2% of iron-samples: CNT@2%Fe, CNT@2%Fe_N_MB, and CNT@2%Fe_HNO3. The better performance of the CNT doped with nitrogen was confirmed with CNT@2%Fe_N_MB, and the magnetic character facilitated its recovery after treatment, and did not affect its good catalytic properties. No dye removal was observed in the abiotic assays, so the removal was not due to adsorption on the CNM. Furthermore, the microorganism’s viability was maintained during the assay and methane production was not affected by the presence of the CNM. Despite the toxic character of the aromatic amines formed, detoxification was observed after the biological process with thermally treated CNT.