Continuous flow electrocoagulation in the treatment of wastewater from dairy industries.

Dairy industry wastewater contains high levels of organic matter, consisting mainly of fat, protein and products of their partial microbial decomposition. In the present study, the use of continuous electrocoagulation is proposed for the primary treatment of dairy wastewater. The electrochemical treatment was carried out in a continuous flow cell with aluminum electrodes. The influence of the voltage, the distance between the electrodes and the hydraulic residence time (HRT) on the process performance was assessed, by measuring the removal of color, turbidity, total organic carbon (TOC) and chemical oxygen demand (COD). The optimum voltage, distance between the electrodes and HRT were 10 V, 1 cm and 90 min, respectively, yielding a current density of 13.3 A.m(-2). Under these conditions, removal of color, turbidity, TOC and COD were 94%, 93%, 65% and 69%, respectively, after a steady state was reached in the continuous flow reactor.

Production of inulinase by solid-state fermentation: effect of process parameters on production and preliminary characterization of enzyme preparations.

This work was aimed at producing inulinase by solid-state fermentation of sugarcane bagasse, using factorial design to identify the effect of corn steep liquor (CSL) and soybean bran concentration, particle size of bagasse and size of inoculum. Maximum inulinase activity achieved was 250 U per g of dry substrate (gds) at 20% (w/w) of CSL, 5% (w/w) of soybean bran, 1 x 10(10) cells mL(-1) and particle size of bagasse in the range 9/32 mesh. The use of soybean bran decreased the time to reach maximum activity from 96 to 24 h and the maximum productivity achieved was 8.87 U gds(-1) h(-1). The maximum activity was obtained at pH 5.0 and 55.0 degrees C. Within the investigated range, the enzyme extract was more thermostable at 50.0 degrees C, showing a D-value of 123.1 h and deactivation energy of 343.9 kJ gmol(-1). The extract showed highest stability from pH 4.5 to 4.8. Apparent K(m) and V(max) are 7.1 mM and 17.79 M min(-1), respectively.