engleski

Removal of Congo red from aqueous solution using lignocellulosic biosorbent and solid state fermentation of dye-adsorbed biosorbent

Brewers’ spent grain (BSG), being the food industry lignocellulosic waste, was tested for its ability to adsorb azo dye Congo red (CR) from aqueous solutions. Effects of the initial dye concentration (30, 50, 100 and 150 mg L-1), contact time, adsorbent concentration (5, 10, and 15 g L-1), and pH (7, 8, 9 and 10) on dye removal were investigated. Dye removal was rapid within the first 60 min of the contact time. The percentage of dye removal increased with the increase in the adsorbent concentration and decrease in the initial dye concentration. The increase in pH caused reduction of the percentage removal. The percentage of CR adsorptive removal after 240 min contact time was over 85% for all runs. Dye-adsorbed biosorbent was further used as a substrate for solid-state fermentation (SSF) by the white rot fungus Trametes versicolor CCBAS AG613. Prior to solid-state fermentation experiment four white rot fungi strains, Phanerochaete chrysosporium CCBAS 570, T. versicolor CCBAS AG613, T. versicolor TV6 and Ceriporiopsis subvermispora, were screened for their ability to decolourise CR during cultivation (9 days at 27 ⁰C) on agar plates containing dye at final concentrations of 50, 100 and 150 mg L-1. Radial growth and the zone of colour change on agar plates were measured (at two perpendicular directions) every three days. Fungus T. versicolor CCBAS AG613 showed the highest decolourisation index (decolourization diameter/mycelial diameter) and was chosen for further SSF experiment. SSF of dye-adsorbed BSG (250 g BSG soaked in 350 mL of 150 mgL-1 dye solution) was carried out in a horizontal cylindrical glass flask at an ambient temperature. Temperature and weight were monitored on-line, while moisture, protein content, and colour of samples were measured after 7, 14 and 21 days of fermentation. Continuous protein content increase and weight loss were observed as a result of fungal growth and material biodegradation. Complete decolourisation of samples was not observed. However, colour determination showed the continuous increase of total colour change and colour intensity change of fermented samples, compared to their abiotic controls.

adsorptive removal ; biosorbent ; Congo red ; decolourisation ; T. versicolor

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