Removal pattern of vinasse phenolics by Phlebia rufa, characterization of an induced laccase and inhibition kinetics modeling.

Vinasse from the distillation of winemaking residues is a wastewater characterized by high levels of aromatic compounds. Batch cultures of Phlebia rufa showed a significant (p < 0.05) correlation between laccase activity and initial vinasse concentration. The pattern of biodegradation of hydroxybenzoic acids, hydroxycinnamic acids and flavonoids, assessed by HPLC-DAD, revealed that p-hydroxybenzoic acid is the most recalcitrant compound. Vinasse-induced laccase showed electrophoretic homogeneity and molecular weight of 62 kDa after being purified 21-fold. Optimum pH for oxidation of 2,6-dimethoxyphenol (2,6-DMP) was 3.5 and optimum temperature was 50 °C, with an activation energy of 42.8 kJ mol-1. Catalytic efficiency of 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) oxidation is about two orders of magnitude higher than 2,6-DMP oxidation, being their Km values 36.2 ± 2.6 µM and 303.0 ± 44.7 µM, respectively and kcat values 486.1 s-1 and 179.6 s-1, respectively. Akaike information criterion and Akaike weights were used to discriminate inhibition models that best fitted 2,6-DMP oxidation in the presence of inhibitors. Inhibition constants of mixed-type inhibitors azide and fluoride, and competitive-type inhibitor chloride, showed the following inhibitors potency: azide > fluoride > chloride. Taken together, this study is consistent with the assumption that P. rufa could be a useful tool for aerobic degradation of phenolic-rich wastewaters.

Fungal biodegradation and multi-level toxicity assessment of vinasse from distillation of winemaking by-products.

The wastewaters from distilleries of winemaking by-products, a scarcely studied type of vinasse, were treated by white-rot fungal strains from species Irpex lacteus, Ganoderma resinaceum, Trametes versicolor, Phlebia rufa and Bjerkandera adusta. The main objectives of this study were to evaluate fungal performance during vinasse biodegradation, their enzyme patterns and ecotoxicity evolution throughout treatment. Despite all strains were able to promote strong (>80%) dephenolization and reduction of total organic carbon (TOC), P. rufa was less affected by vinasse toxicity and exhibit better decolorization. In batch cultures at 28 °C and pH 4.0, the first phase of P. rufa biodegradation kinetics was characterized by strong metabolic activity with simultaneous depletion of TOC, phenolics and sugars. The main events of second phase are the increase of peroxidases production after the peak of laccase activity, and strong color removal. At the end of treatment, it was observed highly significant (p < 0.001) abatement of pollution parameters (83-100% removal). Since water reclamation and reuse for e.g. crop irrigation is a priority issue, vinasse ecotoxicity was assessed with bioindicators representing three different phylogenetic and trophic levels: a marine bacterium (Aliivibrio fischeri), a freshwater microcrustacean (Daphnia magna) and a dicotyledonous macrophyte (Lepidium sativum). It was observed significant (p < 0.05) reduction of initial vinasse toxicity, as evaluated by these bioindicators, deserving special mention an almost complete phytotoxicity elimination.

Winery wastewater treatment by combination of Cryptococcus laurentii and Fenton's reagent.

Winery wastewaters (WW) have high levels of organic matter, resulting in high COD and BOD and suspended solids. This paper studies the combination of biological and chemical processes in WW treatment. Among 10 yeast isolates, Filobasidium sp. (AGG 577) and Cryptococcus laurentii (AGG 726) were selected due to their superior performance in COD removal. During WW degradation, COD and total polyphenols (TPP) content removal of 89-90% for Filobasidium sp. and 90-93% for C. laurentii were obtained. However, despite similar degradation efficiency for both yeasts, COD kinetics and pH evolution during treatment reveals that C. laurentii presents a faster response than Filobasidium sp. The toxicity (inhibition of Vibrio fischeri luminescence) of C. laurentii treated WW decreases to an inhibition value below 2.5%. However, treated WW exceeds the legal limits, making necessary an additional treatment. In this case, the selection of Fenton's reagent as a chemical final polish step process is a good compromise between efficiency and lower practical complexity. The best results for both COD and TPP removal were obtained with H2O2 initial concentration of 39.2mM and a H2O2:Fe(2+) molar ratio of 15:1. The combined C. laurentii - Fenton's reagent treatment of WW achieved a total reduction of 98% and 96%, for COD and TPP, respectively.