No abstract

Enzyme production by immobilized Phanerochaete chrysosporium was evaluated in airlift bioreactor and agitated cultures. Free mycelium and immobilized mycelium on alginate beads were tested in the decolourization of 50 and 500 mg/L of Remazol Brilliant Blue R. Dye concentration did not inhibit the fungi development in all tests. In addition, high decolourization percentage of dye was found with free mycelium (99%) in agitated flasks and with immobilized mycelium in airlift (98%). However, decolourization period by immobilized mycelium (120 h) was greater than that by the free mycelium (14 h). Important manganese peroxidase, lignine peroxidase and laccase activities were identified in decolourization process. Manganese peroxidase appeared to be promoted by high dye concentrations during the treatment with immobilized mycelium, but this enzyme was not detected with free mycelium in airlift. Bioreactor prompted also laccase and lignine peroxidase actions in both tests; free mycelium registered a maximum laccase action of 31.569 × 10 3 U/L in 70 h, whereas immobilized mycelium registered 1.680 × 10 3 U/L in 170 h, while lignine peroxidase secretion by free P. chrysosporium was higher (1.300 × 10 3 U/L) than immobilized mycelium (1.250 × 10 3 U/L). Maximum laccase activity coincided with the maximum percentage of decolourization, however, high peroxidase activity was identified from the start of dye treatment.

In the present work, a strain of the basidiomycete fungus Trametes polyzona was used to decolorize the Amaranth dye. The decolorization was carried out in an Airlift reactor with three flow regimes: 1, 2, and 3 vvm. The results showed that the decolorization was a function of the flow regime. The decolorization times for the regimes of 1, 2, and 3 vvm were 30, 25, and 19 days, respectively. The COD (Chemical Oxygen Demand) decreased from 1600 to 72 mg COD/L. The enzymatic activity kinetics of laccase (Lcc), lignin peroxidase (LiP), and manganese peroxidase (MnP) were determined. In all the treatments, the enzyme LiP was expressed during the first 6 days, at which point 80% decolorization was observed, whereas Lcc and MnP enzymes were produced from day 6 until the end of the decolorization process. The effluent generated showed no inhibitory effects on the growth of the algae Nannochloropsis salina. T. polyzona showed great versatility in the decolorization of synthetic effluents containing the Amaranth dye, and the fungus was able to use this dye as its only carbon source starting at the beginning of the process. LiP was the enzyme that contributed the most to the decolorization process, and on average, 95% decreases in color and the COD were observed.

Modelado de la biodegradación en biorreactores de lodos de hidrocarburos totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

No abstract

Atrazine (ATZ) is an herbicide which is applied to the soil, and its mechanism of action involves the inhibition of photosynthesis. One of its main functions is to control the appearance of weeds in crops, primarily in corn, sorghum, sugar cane, and wheat; however, it is very toxic for numerous species, including humans. Therefore, this work deals with the adsorption of ATZ from aqueous solutions using nanocomposite materials, synthesized with two different types of organo-modified clays. Those were obtained by the free radical polymerization of 4-vinylpyridine (4VP) and acrylamide (AAm) in different stoichiometric ratios, using tetrabutylphosphonium persulfate (TBPPS) as a radical initiator and N,N′-methylenebisacrylamide (BIS) as cross-linking agent. The structural, morphological, and textural characteristics of clays, copolymers, and nanocomposites were determined through different analytical and instrumental techniques, i.e., X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Adsorption kinetics experiments of ATZ were determined with the modified and synthesized materials, and the effect of the ratio between 4VP and AAm moieties on the removal capacities of the obtained nanocomposites was evaluated. Finally, from these sets of experiments, it was demonstrated that the synthesized nanocomposites with higher molar fractions of 4VP obtained the highest removal percentages of ATZ.

2015): Application of immobilized fungi on food efluent treatment using airlift reactor, Desalination and Water Treatment,Depuration capacity of immobilized Phanerochaete chrysosporium was tested on food effluents which showed high COD, sugar, and nitrogen concentration. Comparative study in airlift reactor and agitated flasks was performed to determine an effective depuration treatment with suspended and immobilized biomass into alginate spheres. While enzymetic production was analyzed in these sytems in order to evaluate influence of the immobilization micro-organism, effluent composition, and aeration mechanism. In addition, the use of seed lettuce allowed evaluating the quality and effectiveness of the studied effluent treatment system. In particular, all tests showed that COD and color of the effluent was reduced by airlift cultures. Treatment achieved a decline in 85% of COD in 120 h. While experiments with 33 PCU color showed high efficiency (100%) in decolourization period of 5 h. Maximum laccase production was mainly found in airlift system with suspended biomass, whereas manganese peroxidase was detected on immobilized micro-organism. Toxicity tests revealed that treated food effluent was not phytotoxic; conversely effluent contains sufficiently high concentrations of nutrients to ensure the germination and lettuce growth.

Polysulfone (Pfu) films were modified by grafting poly(vinyl alcohol) (PVA) by the oxidative pre-irradiation technique. To achieve this modification, some parameters were modified such as the radiation dose, the concentration of PVA, the temperature and the reaction time. It was found that the grafted films with 12% presented a greater grafting percentage (0.86%). The modified films were characterized by means of the contact angle, Fourier transform infrared spectroscopy (FTIR-ATR) and scanning electron microscopy (SEM) techniques.