ABSTRACT In this study, the effects of operating time (t), current density (CD) and initial pH were investigated for soluble organic carbon (SOC) and total phosphorus (TP) removal from swine wastewater, pretreated in an UASB reactor, using an electrocoagulation process with aluminum (Al) and iron (Fe) electrodes. For the optimal conditions, Cu, Zn, Mn, Fe and Al removal, sludge production and energy consumption were evaluated. The removal efficiencies for the Al electrode were 78%, 96%, 84%, 99%, 65% and 84% for SOC, TP, Cu, Zn, Mn and Fe, respectively. For the Fe electrode the removal efficiencies were 57%, 96%, 81%, 99 % and 61% for SOC, TP, Cu, Zn and Mn, respectively. The sludge generated, energy consumption, and theoretical hydrogen yields were 5 g/L, 1-18 kWh/L and 0.7-8.5 kWh, respectively. The electrocoagulation process can be used for soluble organic carbon, phosphorus and metals removal from swine wastewater.

In Brazil, the species Maytenus aquifolia and Maytenus ilicifolia are widely used in popular medicine in the form of teas for stomach and ulcer illness treatment. Despite the great interest in Maytenus aquifolia therapeutic properties and the fact that it is an abundant and native plant growing in Brazil, there is a lack of information in the literature concerning the extraction at high pressures. In this context, this work is focused on the mathematical modelling of the packed-bed extraction of Maytenus aquifolia with compressed CO2. Three mathematical models were used to represent the experimental data. The experiments were performed in a laboratory-scale unit, evaluating the effects of temperature (293 to 323 K), pressure (100 to 250 bar), and extraction time on the yield of the extracts. Results show that the extraction temperature and solvent density exerted a pronounced effect on yield. The mathematical model of Sovová was the most suitable to represent the experimental extraction data of M. aquifolia.

The main focus of this work was to investigate the residual esterification activity and the product conversion after 10 successive cycles of utilization of a commercial lipase in three systems: esterification of 2-ethyl hexanol and palmitic acid in a solvent-free system; esterification of ascorbic acid and palmitic acid in tert-butanol; and transesterification of glycerol and methyl benzoate in 2-propanol. These systems were chosen based on previous results by our research group in terms of product conversion. Before scale-up, there is a need for evaluating several cycles of utilization of the biocatalyst. The esterification of 2-ethyl hexanol showed that after 10 cycles the enzyme retained 90% of its activity. The system consisting of ascorbic acid, palmitic acid, Novozym 435 and tert-butanol showed that a reduction in enzyme activity was accompanied by a reduction in reaction conversion; the same behavior was not observed for the third system.

Enzymes have been extensively used in organic solvents to catalyze a variety of reactions of biological and industrial significance. In this work, the characteristics of free and immobilized inulinase were investigated in buffered solutions of butyl acetate. The influences of the organic solvent content on the optimal temperature and pH, the stabilities to temperature and pH and the kinetic parameters were systematically evaluated. The results showed that the organic solvent content had no effect on the optimal pH, either in the free or immobilized inulinase. For the immobilized enzyme, the optimal temperatures ranged from 55ºC to 60ºC, depending on the content of butyl acetate. At higher butyl acetate content, the stability of the immobilized enzyme increased for both pH and temperature. The organic solvent showed the tendency to increase the values of the kinetic parameters Km and v max for both free and immobilized inulinase.