Sándor Beszédes

CORRELATION BETWEEN DIELECTRIC PROPERTIES AND AEROBIC BIODEGRADABILITY OF MEAT PROCESSING SLUDGE

The dielectric properties, namely the dielectric constant and the dielectric loss factor are important for predicting the behavior of materials during microwave processing, because both of them determine the interaction between the molecules with the oscillating electromagnetic field. Because the dielectric properties are not known for food industry sludge, our main aim was to measure the dielectric constant and dielectric loss factor for meat industry sludge, and to investigate the correlation between the dielectric parameters and the biodegradability indicators. Our experimental results show, that despite of the high moisture content of sludge, temperature depending behavior of uf065’ was different that of can be known for water. Sludge had a decreasing tendency in the temperature range of 20-60 ̊C, but over a critical value of the temperature increasing induced an increment in the value of uf065’. Our experimental results verified that the change of sCOD/tCOD has a good linear correlation with the dielectric loss factor. Similar to the trends determined for the solubility change, a good correlation was found between the dielectric loss factor and the change of biodegradability measured by the BOD/tCOD parameter. Our experimental results verified that the change in the value of dielectric loss factor correlate with the disintegration degree and the biodegradability of sludge, as well Correlation between the electrical parameters and biodegradability indicators enable to develop a real-time and inline measuring and control system for batch and continuous flow microwave sludge conditioning technology.

DEVELOPMENT OF BIODEGRADABILITY INDICATORS FOR MICROWAVE SLUDGE CONDITIONING

Microwave irradiation has a good potential to increase the ability of organic matter for biological degradation. Because of the strong disintegration effect of microwave irradiation on extracellular polymeric substances (EPS), which form complex sludge structure, and also on microbial cell walls has led to enhanced solubility of organic matters, given by the ratio of soluble to total chemical oxygen demand (SCOD/TCOD). From the aspect of the further utilization of sludge, the change of biochemical oxygen demand (BOD), which correlates the degradable organic matters of sludge under aerobic condition, can be considered advantageous. For comparison purpose, and for modeling and optimization of process, it is needed to create novel control parameters, by which can be measured the changes in organic matter fraction of sludge independently from the varying characteristic or different origin of raw sludge. Based on our results, it has established that in the range of 90-1050 kJkg-1, and 0.5-5 Wg-1 for IMWE and MWPL, the surface fitted by constructed model can be characterized by a maximum value for BDI. Microwave treatment carried out over a certain value of MWPL and IMWE has resulted in lower biodegradability. Optimum range of IMWE and MWPL was concluded as 600-650 kJ and 2.5-3.0 Wg-1, respectively, and both process parameters have significant effect on the change of BDI and SLI, as well.