Thermal characterization during dehydration of nitrifying and denitrifying microbiological mud encapsulated in silica gel

An alternative method to diminish the nitrogen pollutant levels in waste waters is to encapsulate microorganisms whitin ceramic materials. The sol-gel method has been extensively used for the preparation of such kind of materials permitting a higher stability and viability of useful organisms. In this work, the thermal characterization during dehydration of nitrifying and denitrifying aqueous emulsions of mud encapsulated in sol-gel silica is presented during the process of dehydration in ambient conditions and as a function of temperature. The characterization was performed by a photopyroelectric (PPE) technique, whose detector was made with a 110 mm polyvinyldifluoride (PVDF). The cell was constructed in such a way that the sample was inside the cell, and the bottom of the cell was closed by the PVDF foil. Thermal effusivity as a function of temperature was obtained illuminating the PVDF directly by a modulated 1W tungsten lamp. The sample is enclosed inside a chamber, using a Peltier cell that controls temperature in a range from 40 to 27 degreesC. The sample is on top of the PVDF, which is illuminated by the modulated tungsten lamp. (C) 2004 Elsevier B.V. All rights reserved.