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During the last few years, electroporation has been introduced to the food-processing industry as an effective method to open cell membranes for the extraction of substances. Currently, it has been investigated whether electroporation is also useful as a part of an energy-efficient drying process for plant material for the production of biofuel. To omit the use of additional water, the material has been placed in contact with the electrodes by means of its own juice after a first pressing step. This paper describes a laboratory-scale parameter study on the electroporation-assisted drying of whole maize plants, grass, and lucerne. The influence of the applied electric-field strength and the number of applied pulses on the drying curves is presented. For the electroporated material, an increased yield of juice during a pressing step after the electroporation and a faster drying have been observed. Index Terms--Drying, electroporation, renewable energy.

In this paper, we investigate the effectiveness of pulsed underwater streamer discharges for water disinfection and its scalability to large throughputs. For this paper, we have built a coaxial streamer reactor containing a central cylindrical anode covered by a thin porous layer of almandine. The reactor was supplied by electric pulses with amplitudes of up to 100 kV and pulse durations between 200 and 400 ns at a repetition rate of up to 20 Hz. Different chemical probes have been used as the main diagnostic to determine the production rates and the accumulation of oxidants in the bulk water. It has been found that the number and the length of streamers scaled linearly with the applied voltage amplitude, whereas the pulse duration only affected the streamer length. All oxidant production rates scaled linearly with the number-length product of streamers. OH-radical concentrations of up to 100 mM appear at the streamer-water-boundary. However, because of the limited volume of streamers and the limited range of OH radicals, the most important oxidant with respect to decontamination is [H.sub.2][O.sub.2] which accumulates in the water and, by interacting with the intense UV radiation and the shock waves from the streamers, produces OH radicals in the bulk water. Placing water-filled cuvettes from different materials in the reactor, we found that the contribution of shock waves to the production of oxidants in the bulk water seems more important than the contribution of UV radiation. The production of oxidants can be enhanced by percolating suitable gases through the active zone of the reactor. Most effective is the use of oxygen. About 20 J/[cm.sup.3] of electrical energy was required to reduce the concentration of Pseudomonas putida bacteria by six orders of magnitude. However, up to 180 J/[cm.sup.3] of specific energy input was necessary to reduce the bacterial freight in waste water from a municipal sewage plant by just two orders of magnitude. This has been explained by the high conductivity of waste water which drastically reduces the length of streamers for the same electrical parameters. Therefore, it seems unlikely that underwater streamer discharges alone can become competitive with other advanced oxidation processes like ozonation, UV irradiation, or irradiation with megaelectronvolt electron beams. However, it seems conceivable that a combination of underwater streamer discharges with ozonation or other processes can lead to a more effective and economic decontamination technique. Index Terms--Energetic efficiency, oxidant production, pulsed underwater streamer discharges, water disinfection.

Electroporation (EP) is a new way for preparing sugar beets for the extraction process in a sugar factory, replacing the established thermal process. For an efficient operation, the degree of EP needs to be monitored continuously. In this paper, a new method for this measurement based on a phase angle evaluation is presented. Furthermore, during the long-term operation, the distance of the spark gaps inside the Marx generators has to be compensated for the wear. With the Marx generators operated in triggered mode, the breakdown voltage cannot be measured in a straightforward manner. Instead, the actual voltage is derived from a time measurement and fed into a control loop. Index Terms--Electroporation (EP), Marx generator, sugar beets, trigger.

A Mach-Zehnder interferometer is used to measure the pressure fields surrounding a streamer, which provides a complete understanding of underwater streamer propagation of primary and secondary streamers. The results of the analysis show that expelling of the electric field from the newly generated section helps in moving the streamer, which also involves gas bubbles due to the presence of low conductivity.

Electroporation is a method to induce pores in the membranes of biological cells by applying an electric field. During the last few years, some research and development has been done for sugar beets to transfer this method from the laboratory into the industrial scale in order to replace the thermal denaturation process. High-efficiency pulsed electric fields with short pulse durations are applied to the beets as a whole. This paper deals with some aspects concerning the electrode geometry and a new trigger concept for the Marx generators used to create the required electric fields. Index Terms--Electroporation, Marx generator, sugar beets, trigger.

The treatment of biological cells with strong pulsed-electric fields can lead to irreversible formation of large pores in the cell membrane and thus destroy the cell and give access to its content. This well-known process of electroporation has been successfully applied to the inactivation of bacteria in many laboratories. However, few efforts have been made to utilize the technique on a large industrial scale for the production of nourishment from food plants. We have built the mobile test device Karlsruher Elektroporations Anlage (KEA), which consists of a 300-kV Marx generator operating at 10 Hz and delivering its pulses to a cylindrical reaction chamber with axially and azimuthally distributed electrodes. The reaction chamber has a large cross section, sufficient for the treatment of entire sugar beets in a continuous stream. KEA has been used in an experimental campaign to demonstrate the advantages of electric pulse treatment for the production of sugar from beets compared with conventional techniques. Although the process has not yet been optimized, it was found that appreciable energy savings are possible since the treated beets could be extracted at much lower temperatures with the same result. To demonstrate the technical and economic feasibility on a large scale, we plan to build a pilot plant with a throughput of several tens of tons per hour and to use it in the next seasonal campaign. Although the results are convincing, important details of the effect are not yet understood. In particular, the interaction between the cell membrane and the cell wall in the plant organism under the action of the electric field needs further investigation. Therefore, we also plan to establish a basic research program. Index Terms--Cell membranes, electroporation, plant cells, pulsed electric fields, sugar beets.