No abstract

A screening using several fungi (Phanerochaete chrysosporium, Pleurotus ostreatus, Trametes versicolor and Aureobasidium pullulans) was performed on the degradation of syringol derivatives of azo dyes possessing either carboxylic or sulphonic groups, under optimized conditions previously established by us. T. versicolor showed the best biodegradation performance and its potential was confirmed by the degradation of differently substituted fungal bioaccessible dyes. Enzymatic assays (lignin peroxidase, manganese peroxidase, laccase, proteases and glyoxal oxidase) and GC-MS analysis were performed upon the assay obtained using the most degraded dye. The identification of hydroxylated metabolites allowed us to propose a possible metabolic pathway. Biodegradation assays using mixtures of these bioaccessible dyes were performed to evaluate the possibility of a fungal wastewater treatment for textile industries.

The goal of this study is to demonstrate that waste-based biosorbents can be cost-effective and green alternatives to commercial adsorbents for the retention of pharmaceuticals. Adsorption kinetics and equilibrium measurements allowed the determination of the adsorption capacity of commercial adsorbents (GAC-granular activated carbon and two synthetic zeolites) and waste-based biosorbents (SCG-spent coffee grounds, pine bark and cork waste) for the retention of fluoxetine from water. For commercial adsorbents, the maximum adsorption capacities followed the order GAC (233.5 mg/g) > zeolite 13× (32.11 mg/g) > zeolite 4A (21.86 mg/g), while for low-cost biosorbents, the sequence was SCG (14.31 mg/g) > pine bark (6.53 mg/g) > cork waste (4.74 mg/g). The economic feasibility of the adsorbents/biosorbents was examined through a detailed cost analysis. Commercial adsorbents present higher costs per gram of fluoxetine removed (6.85 €/g, 3.13 €/g and 1.07 €/g zeolite 4 A, zeolite 13× and GAC, respectively) when compared to low-cost biosorbents (0.92 €/g, 0.41 €/g and 0.16 €/g for pine bark, cork waste and SCG, respectively). It was found that SCG is the most economically viable option for fluoxetine removal, while cork waste, the second less expensive, is the most environmentally friendly biosorbent since its preparation does not generate any solid or liquid wastes. This manuscript demonstrates that the conversion of waste materials into adsorbents has a double environmental benefit for both improving waste management and protecting the environment.

Half a lJillion ye

Azo dye derivatives of azobenzene constitute the largest group of dyes used in the textile industry and possess recalcitrant chemical groups, such as those of azo and sulphonic acid. Some microorganisms are able to degrade these aromatic compounds. In the present work, decolourisation of culture media containing azo dyes by the ligninolytic fungus Phanerochaete chrysosporium was achieved under nitrogen-limited conditions. The dyes used in the study are derivatives of meta- or para-aminosulphonic or aminobenzoic acids and include in their structures groups such as guaiacol or syringol, which are bioaccessible to the lignin degrading fungus P. chrysosporium. The aim of this study was to pre-adapt the microorganism to the structure of the dyes and to establish the relationships of the chemical structure of the dye present in the pre-adaptation medium with the chemical structure of the dye to be degraded. The azo dye used in the pre-adaptation medium that gave the best overall decolourisation performance was a meta-aminosulphonic acid and guaiacol derivative. The azo dye derivative of a meta-aminobenzoic acid and syringol showed a better performance in the decolourisation assays. Preliminary GC-MS studies indicated the formation of a nitroso substituted catechol metabolite, a precursor of aromatic ring cleavage, which was confirmed to occur by an enzymatic assay. The presence of this type of metabolite allows the establishment of a possible metabolic pathway towards mineralisation.