An enzymatic extract produced by Penicillium restrictum having a high level of lipase activity (17.2 U.g-1) was obtained by solid-state fermentation using babassu cake as substrate. The enzymatic extract was used in the hydrolysis of a dairy wastewater with high fat contents (180, 450, 900 and 1,200 mg.L-1). Different hydrolysis conditions were tested, and it was determined that it should be carried out at a temperature of 35ºC, without agitation, with 10% v/v enzymatic extract and a hydrolysis time of 12 hours. Both crude and hydrolysed effluents were then submitted to an anaerobic biological treatment. It was observed that for the enzymatically pretreated effluent there was a significant improvement in the efficiency of the anaerobic treatment. For the highest fat content tested (1,200 mg.L-1), removal efficiencies of 19 and 80% were attained for crude and hydrolysed effluents, respectively. In addition, a tenfold increase in the removal rate of COD from the hydrolysed effluent (1.87 kg COD.m-3.d-1) was observed in relation to the crude effluent (0.18 kg COD.m-3.d-1). The results obtained in this study illustrate the viability of using a hybrid treatment (enzymatic-biological) for wastewaters having high fat contents.

This work studies the use of biological and combined biological/enzymatic treatments in phenol degradation. The systems studied were conventional batch aerobic biological followed or preceded by enzymatic treatment. Tyrosinase extracted from the mushroom Agaricus bispora was employed. Biological treatment efficiently degraded effluents containing up to 420 mg.L-1 of phenol, removing 97% of the COD and 99% of the phenol in 48-hour batches. Alterations in phenol concentration intake reduced treatment efficiency significantly. Enzymatic polishing of biotreated effluent removed up to 75% of the remaining phenol in a four-hour reaction with 46 U.mL-1 of tyrosinase and 50 mg.L-1 of chitosan (used as coagulant). Enzymatic pretreatment with 20 U.mL-1 of tyrosinase reduced the phenol concentration by 25 % after 2 hours of reaction, although initial COD increased up to 58%. The subsequent biological treatment of that enzymatic pretreated effluent reduced COD to 151 mgO2.L-1 and phenol concentration to 1 mg.L-1 in 24-hours batches.

The reaction rate of starch hydrolysis catalyzed by a glucoamylase covalently bound to chitin particles was measured in a Differential Fixed-Bed Reactor (DFBR). Under selected test conditions the initial reaction rate may represent biocatalyst activity. Some aspects which influence measurement of the initial reaction rate of an immobilized enzyme were studied: the amount of desorbed enzyme and its hydrolytic activity, the extent of pore blockage of the biocatalyst caused by substrate solution impurities and the internal and external diffusional mass transfer effects. The results showed that the enzyme glucoamylase was firmly bound to the support, as indicated by the very low amount of desorbed protein found in the recirculating liquid. Although this protein was very active, its contribution to the overall reaction rate was negligible. It was observed that the biocatalyst pores were susceptible to being blocked by the impurities of the starch solution. This latter effect was accumulative, increasing with the number of sequential experiments carried out. When the substrate solution was filtered before use, very reliable determinations of immobilized enzyme reaction rates could be performed in the DFBR. External and internal diffusional resistences usually play a significant role in fixed-bed reactors. However, for the experimental system studied, internal mass transfer effects were not significant, and it was possible to select an operational condition (recirculation flow rate value) that minimized the external diffusional limitations.

This work deals with enzymatic hydrolysis of babassu oil by immobilized lipase in membrane reactors of two types: a flat plate nylon membrane and a hollow fiber polyetherimide membrane on which surface commercial lipases were immobilized by adsorption. Experiments conducted in the hollow fiber reactor showed that during the immobilization step enzyme adsorption followed a sigmoid model, with a maximum adsorption equilibrium time of 30 minutes. Concerning the hydrodynamics of the liquid phases, the results indicate that main diffusional limitations occurred in the organic phase. The amount of protein immobilized and the maximum productivity were, respectively, 1.97 g/m2 and 44 <FONT FACE="Symbol">m</font> molH+/m2.s for the hollow fiber and 1.2 g/m2 and 56 <FONT FACE="Symbol">m</font> molH+/m2.s for the flat and plate membrane. Both reactors were able to perform the hydrolysis reaction, while maintaining absolute separation of the two phases by the membrane