Vitaly Bystritskii

Degradation of perchloroethylene and dichlorophenol by pulsed‐electric discharge and bioremediation

Pulsed electric discharge (PED) and bioremediation were combined to create a novel two-stage system which dechlorinates the halogenated pollutants, 2,4-dichlorophenol and perchloroethylene, with repetitive (0.1-1 kHz), short pulse ( approximately 100 ns), low voltage (40-80 kV) discharges and then mineralizes the less chlorinated products with aerobic bacteria. A 6.1 mM aqueous dichlorophenol sample was cycled through the PED reactor (60 kV of applied pulsed voltage and 300 Hz) 6 times, resulting in the release of 55% of the initial dichlorophenol chloride ions (1 mM Cl- removed each cycle). The respective average specific efficiency is 0.4-0.6 keV/(Cl- molecule). Pseudomonas mendocina KR1, which grows in minimal medium supplemented with phenol but not with dichlorophenol, increased in cell density in all cultures supplemented with the PED-treated DCP samples and yielded a maximum of two-fold additional Cl- released compared to the PED-related alone. The number of PED-treatment cycles, voltage, and frequency were also varied, showing that both cell densities and overall dichlorophenol dechlorination were highly dependent upon the number of PED-treatment cycles, rather than the tested voltages and frequencies. Using this two-stage treatment system, PED released 31% of the initial chloride ions from dichlorophenol (after three cycles at 40-45 kV and 1.2 kHz) while P. mendocina KR1 in the second stage increased dechlorination to 90%. These results were corroborated by the 35% additional chloride release found with activated sludge cultures. Perchloroethylene (0.6 mM) was similarly treated in a first-stage PED reactor (80% chloride removal after four cycles) followed by biodegradation of the dechlorinated products with a recombinant toluene o-monooxygenase-expressing Pseudomonas fluorescens strain. Gas chromatographic analysis showed that the PED reactor created less-chlorinated byproducts (i.e., trichloroethylene) that were removed (74%) upon exposure to the recombinant bacterium. Copyright 1998 John Wiley & Sons, Inc.

Pulsed power for advanced waste water remediation

We describe a 2-stage technology for degrading water borne chlorinated/aromatic organic pollutants, based on a pulsed power treatment in the first stage followed by bio-treatment. The combination of a strong pulsed corona/streamer discharge in the water aerosol in the first stage with inoculation of partially dechlorinated (15-30%) processed water with bacteria Pseudomonas mendocina KR1 in the second stage demonstrated as high as 90% dechlorination in the first 40 hours after inoculation, whereas the control (nonaerosol-treated sample) had no chloride ions released, and no bacterial growth. The main features and advantages of the novel two-stage approach, and future plans for research are presented and analyzed.

Degradation of 2,4,5-trichlorophenol and 2,3,5,6-tetrachlorophenol by combining pulse electric discharge with bioremediation

Abstract Degradation of 2,4,5-trichlorophenol (2,4,5-TCP) and 2,3,5,6-tetrachlorophenol (TeCP) was studied using a two-stage approach that utilized efficient pulse electric discharge (PED) followed by biological degradation with a consortium from acclimated return activated sludge. The chlorinated phenols were treated in the PED reactor as an aerosol at a voltage of 55–60 kV, a frequency of 385 Hz, a current of 50–60, and with a 200-ns pulse. As determined by gas chromatography and mass spectrometry (GC/MS), the first stage converted 500 ppm 2,4,5-TCP to 163 ppm 2,4,5-TCP and dimethyldecene, dichloronaphthalenol, octyl acetate, and silyl esters. The total carbon content of 2,4,5-TCP after PED treatment was determined to be 228 ± 35 ppm. The remaining 2,4,5-TCP and the products formed were then mineralized by the acclimated activated sludge in shake flasks; the initial rate of degradation of 2,4,5-TCP was calculated to be 5 nmol min−1 mg protein−1 at 163 ppm initial concentration (three orders of magnitude higher than the only rate found in the literature). By combining the two techniques, a synergistic effect (2.3-fold increase in the concentration of 2,4,5-TCP degraded and 3.3-fold increase in total carbon degraded) was observed, in that bacteria without any treatment degraded a maximum of 70 ppm 2,4,5-TCP but after PED treatment 163 ppm 2,4,5-TCP was degraded. TeCP was also mineralized by the acclimated activated sludge after treatment with PED. This two-stage approach was also evaluated using a continuous 1-l fluidized-bed reactor.

Plasma and Ion Beam Injection into an FRC

Experiments on the transverse injection of intense (5–20 A/cm2), wide cross-section (10-cm), neutralized, ∼100-eV H+ plasma and 100-keV H+ ion beams into a preformed B-field reversed configuration (FRC) are described. The FRC background plasma temperature was ∼5 eV with densities of ∼1013 cm−3. In contrast to earlier experiments, the background plasma was generated by separate plasma gun arrays. For the startup of the FRC, a betatron-type “slow” coaxial source was used. Injection of the plasma beam into the preformed FRC resulted in a 30–40% increase of the FRC lifetime and the amplitude of the reversed magnetic field. As for the ion beam injection experiment into the preformed FRC, there was evidence of beam capture within the configuration.

Fatigue properties of 2024-T3, 7075-T6 aluminum alloys modified using plasma-enhanced ion beams

Abstract This paper presents experimental results on the application of Microsecond Plasma Opening Switch (MPOS) technology to Al alloy surface modification. The main objective of the experiments presented here was to study the change in the tensile and fatigue properties of the MPOS-treated Al2024, Al7075 alloy samples. The bending fatigue test was carried out both in air and in corrosive media. The measurements indicate significant improvement of fatigue properties for the treated 7075 alloy in corrosive media (1.5 times higher in fatigue limit). For the 2024 alloy the enhancement in fatigue lifetime for higher stresses was measured. Anodic polarization curve measurements were carried out at various values of fatigue cycles.

Moiré deflectometry diagnostic for transient plasma, using a multipulse N2 laser

We have designed a multipulse laser system to measure nanosecond time scale, plasma‐density gradients by moire deflectometry. The complete system consists of four, transverse‐excited, atmospheric pressure (TEA) N2 laser oscillators and two low‐pressure N2 laser amplifiers; two oscillator pulses are injected into a single amplifier. The amplified pulses are less than 1 ns in duration, with a variable, interpulse time of 4–10 ns. As described here, two TEA oscillators and a single amplifier were used to image air‐density gradients in an expanding, air‐shock wave produced by a spark discharge.

The high power pulsed ion beam mixing of a titanium layer with an aluminum substrate

This paper describes the MPOS application as an ion beam source for Ti film/Al substrate mixing. Single layer 500 nm films of titanium were deposited on aluminum 6061-T6 samples and then irradiated by an ion beam. The ion beam energy was between 200 and 250 keV, the pulse length was 100 ns and the ion current density was between 10 and 150 A/cm2. Characterization of the treated samples was done using the SEM, EDAX and Auger spectroscopy. Numerical calculations of the phase transitions in this system have been done, to estimate the ion current density needed for effective melting and mixing of the films and substrate. According to Auger analysis, significant mixing of the Ti film and Al substrate occurs up to depths of 1.3 μm. Corrosion tests have shown improved corrosion resistance for the mixed layer in comparison with the untreated film.

Modification of materials surface using plasma enhanced ion beams

The paper presents experimental results on the application of microsecond plasma opening switch (MPOS) technology for materials surface modification. The ion beam parameters generated at MPOS are <250 keV energy, and current and energy densities of 150 A/cm/sup 2/ and <2.2 J/cm/sup 2/, respectively. Characterization of the treated samples showed structural changes to a depth of about /spl ap/1 micron. Measurements indicate an increase in microhardness of a factor of about 3 for carbon steel samples. Corrosion resistance increase for the treated samples of at least 3, as measured by mass loss, can be attained for aluminum alloys. Microstructural changes in the surface morphology indicate a reduction in grain size for the treated samples and the appearance of shallow craters. EDAX and Auger analysis of irradiated samples with pre-deposited thin films indicate that mixing due to ion beam irradiation occurs to a depth of up to 1 micron.

Diagnostics for exploding wires (abstract)

Two diagnostics, capable of imaging fast, high temperature, plasmas were used on exploding wire experiments at UC Irvine. An atmospheric pressure nitrogen laser (λ=337.1 nm) was used to generate simultaneous shadow and shearing interferogram images with a temporal resolution of ∼1 ns and a spatial resolution of 10 μm. An x-ray backlighter imaged the exploding wire 90° with respect to the laser and at approximately the same instant in time. The backlighter spatial resolution as determined by geometry and film resolution was 25 μm. Copper wires of diameters (25, 50, and 100 μm) and steel wire d=25 μm were exploded in vacuum (10−5 Torr) at a maximum current level of 12 kA, by a rectified marx bank at a voltage of 50 kV and a current rise time (quarter period) of 900 ns. Copper wires which were cleaned and then resistively heated under vacuum to incandescence for several hours prior to high current initiation, exhibited greater expansion velocities at peak current than wires which had not been heated prior to...

Aerosol plasma for aqueous waste treatment

Summary form only given. We describe 2-stage technology for degradation of aqueous wastes (containing organic pollutants), based on Aerosol Plasma Treatment combined with bio-treatment stage. Short pulsed corona/streamer discharge in aerosol with controlled applied voltage amplitude of 50-90 kV, pulse duration of 100-150 ns, and reprate of 10/sup 2-3/ Hz is organized inside a 40 liter reactor. The aerosol with drops diameter of 10-100 /spl mu/m is provided with a commercial atomizer. 2-3 fold pulsed E-field enhancement near the drops surface combined with large specific water/air surface (10/sup 2-3/ cm/sup 2//g) result in copious generation of energetic and hydrated electrons, active free radicals (O, H, OH), providing efficient degradation and partial dechlorination of the primary organic molecules of the pollutants.