Critical Comparison between the Pulsed Electric Field and Thermal Decontamination Methods of Hospital Wastewater

C.A. Gusbetha, W. Freya, T. Schwartzb and A. Riederb a Institute for Pulsed Power and Microwave Technology, Forschungszentrum Karlsruhe, P.O. Box 3640, 76021 Karlsruhe, Germany, b Institute for Technical Chemistry Water Technology and Geotechnology Division, Forschungszentrum Karlsruhe, P.O. Box 3640, 76021 Karlsruhe, Germany

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Filtered wastewater samples were inoculated with Enterococcus faecium and exposed to different pulsed electric field (PEF) treatment energies at 40, 50 and 60°C. A lethal effect of heat treatment on E. faecium can be observed for T > 56°C and a heating duration of 4 min. A treatment with 60°C, 4 min, provokes a bacterial reduction of 4 log. A combined treatment of inoculated wastewater samples with pulsed electric field and heat (40, 50 and 60°C) reduced the bacterial contamination considerably. At a suspension temperature of 60°C pulsed electric field inactivation resulted in a complete bacterial decontamination (8 log reduction rate). Moreover, it was demonstrated that naturally occurring nuclease activities were not changed by the pulsed electric field treatment. In contrast to a thermal treatment with temperature over 72°C, for 4 min., the nuclease activity was reduced up to 90%. In this case, inactivation is only 4 log. The same inactivation rate can be obtained by a combination of heat treatment (60°C) and pulsed electric field treatment (30 J/ml).

DOI: 10.12693/APhysPolA.115.1092 PACS numbers: 87.50.cj, 87.14.ej, 92.40.kc