Sustainable Discoloration of Textile Chromo-Baths by Spent Mushroom Substrate from the Industrial Cultivation of Pleurotus ostreatus

Abstract

Synthetic dyes are recalcitrant to degradation and toxic to different organisms. Physical-chemical treatments of textile wastewaters are not sustainable in terms of costs. Biological treatments can be more convenient and the lig-nin-degrading extracellular enzymatic battery of basidiomycetes are capable to discolor synthetic dyes. Many basidi-omycetes are edible mushrooms whose industrial production generates significant amount of spent mushroom substrate (SMS) with residual high levels of lignin-degrading extracellular enzymatic activities. We have demon-strated that the low cost organic substrate, the SMS deriving from the cultivation of the basidiomycetes Pleurotus ostreatus, is able to discolor anthraquinonic, diazo and monoazo-dyes when incubated in dying chromo-reactive and chromo-acid baths containing surfactants and anti-foams, where the concentrations of the different dyes are exceeding the one recovered in the corresponding wastewaters. Laccase was the lignin-degrading extracellular enzyme involved in the discolouring process. The exploitation of the low cost SMS in the treatment of textile wastewaters is proposed. Accordingly, a toxicological assessment, based on a cyto-toxicity test on a human amnion epithelial cell line (WISH) and the estimation of the germination index (GI%) of Lactuca sativa, Cucumis sativus and Sorghum bicolor, has been performed, showing the loss of toxicity of the chromo-baths after being discoloured by the SMS

Water recycle as a must: decolorization of textile wastewaters by plant‐associated fungi

“…In the case of B. adusta , biodegradation of effluent A found an evidence with the enzyme promoted breakdown of the dye structures, resulting in different UV–visible absorption patterns between the spectra of treated and un‐treated effluents. These findings would be in accordance with previous reports in the literature documenting the decolorizing abilities of white‐rot fungi by means of extracellular peroxidases and laccases . On the other hand, A. nidulans gave indication of a biosorption process for effluents C, triggering a rapid depletion of the dye here contained.…”

Assessment of the efficacy of Aspergillus sp. EL-2 in textile waste water treatment

“…This is another verification of the need to use more than one mode of treatment to ensure complete degradation and not only color removal. These results are in agreement with Di Gregorio et al (2010) who stated that phytotoxicity decreases after efficient discoloration. Figure 4 represents the growth of seeds when watered with Aspergillus sp.…”

“…While color removal and complete destruction of dye molecules is important, the toxicity assessment of dyes and dye intermediates has become an extremely important matter, especially that most dyes have no safety data sheet (Mathur et al 2005). Therefore, detoxification of the treated effluent should be coupled to color removal (Di Gregorio et al 2010). The carcinogenic tests could be performed through detecting microbial changes, phytotoxicity or chromosomal aberrations in mammalian cells (Chen et al 2003a;Schnieder et al 2004;Mathur et al 2005).…”

Degradation of a textile reactive azo dye by a combined biological-photocatalytic process: Candida tropicalis Jks2 -Tio2/Uv

“…Consequently, it is important to remove dyestuff from the wastewater before discharging it to the environment [4]. The strong electron-withdrawing groups characterizing the chemical structure of dyes protect them from the bacterial oxygenases [5]. Therefore, conventional activated sludge systems have difficulty in handling such wastewater, particularly in removing the color [4].…”