Adsorption-microbial fermentation based multi-step approach to dye remediation for safe and environment compatible waste water treatment

Abstract

Environmental pollution is a major problem with increasing human population and correspondingly increasing industrial activities. Chemical industrial dyes can cause allergies, cancers, etc., in humans and adversely affect aquatic life when dye rich effluents are released into water bodies. Though natural and safe dyes are being explored yet the bulk of industrial dyes is chemical based. The current study explores cheap lignocellulosics for dye decolorization and use of resulting dye-adsorbed biomaterials as substrate in microbial fermentation (SSF). Further, we evaluated a reuse of such dye-laden lignocelluloses for 2nd dye adsorption-microbial fermentation cycle to potentially enhance economic viability of the process. Rice husk and Wheat bran showed above 90% dye adsorption while the others gave 85-90% dye removal. All the dye adsorbed substrates were successfully fermented by Phanerochaete chryosporium to produce significant laccase activity. A 2nd cycle of dye adsorption yielded improved dye decolorization for some substrates while some loss (not more than ∼23%), was reported for other substrates. The findings are very encouraging as the comparative evaluation of various lignocellulosics as adsorbents and fermentation substrates provide promising alternative to dye pollution mitigation. The reuse of such agri-residues highlights eco-friendliness & economic efficiency of the process for removing dyes from wastewater.

Keywords

• Industrial dyes
• Lignocellulosic waste
• Solid state fermentation
• Recycling
• Environment sustainability