Authors: Wolfgang Frey Christian Gusbeth Thomas Schwartz
Publish Date: 2013/05/10
Volume: 246, Issue: 10, Pages: 769-781
Abstract
An important issue for an economic application of the pulsed electric field treatment for bacterial decontamination of wastewater is the specific treatment energy needed for effective reduction of bacterial populations The present experimental study performed in a field amplitude range of 40 E 200 kV/cm and for a suspension conductivity of 001 = κ e 02 S/m focusses on the application of short pulses 25 ns T 10 μs of rectangular bipolar and exponential shape and was made on Pseudomonas putida which is a typical and widespread wastewater microorganism The comparison of inactivation results with calculations of the temporal and azimuthal membrane charging dynamics using the model of Pauly and Schwan revealed that for efficient inactivation membrane segments at the cell equator have to be charged quickly and to a sufficiently high value on the order of 05 V After fulfilling this basic condition by an appropriate choice of pulse field strength and duration the log rate of inactivation for a given suspension conductivity of 02 S/m was found to be independent of the duration of individual pulses for constant treatment energy expenditure Moreover experimental results suggest that even pulse shape plays a minor role in inactivation efficiency The variation of the suspension conductivity resulted in comparable inactivation performance of identical pulse parameters if the product of pulse duration and number of pulses was the same ie required treatment energy can be linearly downscaled for lower conductivities provided that pulse amplitude and duration are selected for entire membrane surface permeabilizationThe authors acknowledge the efforts of Silke Kirchen and SilkeMareike Marten for CFU analysis the help of Rüdiger Wüstner in preparing and performing the pulse experiments and the detailed discussions of Aude Silve on membrane charging The authors appreciate the helpful scientific discussions on bacterial inactivation within the framework of COST TD1104 This study was funded by BMBF grant 02WT0675 administered by the Karlsruhe Institute of Technology
Keywords: