Aline Schilling Cassini

Ultrafiltration of Wastewater from Isolated Soy Protein Production: Fouling Tendencies and Mechanisms

Membrane separation processes appear to be a good alternative in wastewater treatment systems. One of the biggest limitations is the decrease in permeate flux, which is caused mostly by concentration polarization and fouling phenomena. The extent of these phenomena are dependent on the interactions between the different solution compounds, membrane-solution interactions, and the operating conditions. The fouling tendencies of three different commercial tubular ceramic membranes (5, 20, and 50 kDa) during the ultrafiltration of an isolated soy protein (ISP) wastewater were evaluated through determination of the water permeate flux before and after the wastewater ultrafiltration and using Hermias Model. The wastewater from ISP production is a complex solution characterized by a very high organic load: reaches COD values greater than 18,000 mg · L−1. The wastewater proteins are small molecules (8 to 50 kDa) that could not be removed during the industrial processing. The recovery of these small proteins and their return to the ISP production process would result in both economical and environmental benefits by increasing the final product yield and reducing significantly the wastewater organic load. All the membranes tested presented a large fouling tendency: 65% (5 kDa membrane), 69% (20 kDa membrane) and 76% (50 kDa membrane). The best fit to Hermias Model for all of the UF membranes was obtained by the complete blocking model.

Drying Characteristics of Textured Soy Protein: A Comparison between Three Different Products

The drying curves of three commercial types of textured soy protein were determined in a pilot air dryer operated at three different temperatures (90, 110, and 130°C), three different drying air velocities (1.00, 1.25, and 1.50 m/s), and different heights of product layer. Drying air temperature influenced significantly all the drying curves; the height of product layer influenced only the drying of TSP types I and II. The effect of drying air velocity was found to be the lowest. A mathematical model was used in the development of a model capable of predicting the drying curves of these products.