Synthetic dyes are extensively used in several industries including textile, paper, printing, cosmetic and pharmaceutical. Dyes are released in effluent from a wide variety of industries such as textile, tannery, packed food, pulp and... more
Synthetic dyes are extensively used in several industries including textile, paper, printing, cosmetic and pharmaceutical. Dyes are released in effluent from a wide variety of industries such as textile, tannery, packed food, pulp and paper, paint and electroplating thus threatening various forms of life. Non-white rot fungi Aspergillus flavus A6, Aspergillus fumigatus A23, Aspergillus terreus A2 and white rot fungus Phanerochaete chrysosporium were used to decolourize individual dyes, simulated textile effluent (STE) and real textile wastewater (RTW). Fungi could effectively decolourize STE and RTW under optimized conditions of medium (minimal salt medium and potato dextrose agar medium), temperature (40°C for A. flavus A6 and 30°C for P. chrysosporium), pH (4.0 for A. flavus A6 and 5.0 for P. chrysosporium) and agitation (100 rpm for A. flavus A6 and P. chrysosporium). The decolourization of STE by A. flavus A6 and P. chrysosporium was 73 and 62% respectively while the decolourization of RTW by A. flavus A6 and P. chrysosporium was 76 and 68% respectively after 7 d incubation. The mechanism of dye removal by the fungus appeared to be mainly by adsorption and absorption and the biotransformation occurred only after absorption of the dye. Analysis of samples before and after treatment with fungus using TLC indicated the biotransformation of dye.
Up to 50% of the dyes are lost during the dyeing process and about 10–15% of them are discharged in the effluents. Dyes are mutagenic /carcinogenic and also cannot be completely removed by conventional wastewater treatment systems thereby... more
Up to 50% of the dyes are lost during the dyeing process and about 10–15% of them are discharged in the effluents. Dyes are mutagenic /carcinogenic and also cannot be completely removed by conventional wastewater treatment systems thereby causing serious environmental and health concerns. In this study, pre-treated biomass of Aspergillus fumigatus A23 was used as a sorbent for biosorption of a commercial textile azo dye, Acid Black 52 from aqueous solution. A comparison of pre-treatment methods showed that autoclaved biomass could decolorize dye maximally (86%) followed by acid (78%) and alkali (74%) treatment. The batch sorption parameters were optimized with respect to pH, initial dye concentration, adsorbent dose and equilibrium time; biosorption kinetic parameters were also determined. The optimum conditions for biosorption were found to be initial pH (6.0), initial dye concentration (25 ppm) and biomass concentration (0.5 mg/50 mL) at 30±2ºC. The R 2 values for Langmuir and Freundlich isotherms were calculated to be 0.993 and 0.971 respectively, which indicated that the biosorption of Acid Black 52 on autoclaved biomass of A. fumigatus A23 dye could be explained better by Langmuir as compared to Freundlich isotherm equilibrium. Scanning electron microscopic image and Infra-red spectra showed modifications in dead fungal cell as compared to untreated biomass. The autoclaved biomass of A. fumigatus A 23 efficiently removed dye Acid Black 52 and since it is dead biomass it can be used to decolorize composite, toxic raw industrial effluent generated from leather, pharmaceutical and dye manufacturing company.
