Aim: To evaluate the microbial disinfection efficacy of a plasmachemical solution obtained by the activation of water with gliding electric discharges.
Methods and Results: Distilled water was ...activated for 5 min by a nonthermal quenched plasma of the glidarc type operating in humid air and at atmospheric pressure. The plasma‐activated water (PAW) was then used to treat planktonic and adherent cells of Staphylococcus epidermidis, Leuconostoc mesenteroides (as models of Gram‐positive bacteria), Hafnia alvei (a Gram‐negative bacteria) and Saccharomyces cerevisiae (as a yeast model). The treatments were less efficient on adherent cells than on planktonic cells in the case of bacteria, but not of S. cerevisiae. Inactivation was more effective for bacteria than for the yeast.
Conclusions: Significant reductions in microbial populations were achieved in all cases, demonstrating the effectiveness of this new approach to treat contaminated media.
Significance and Impact of the Study: PAW is a promising solution with potential application to the decontamination of equipment and surfaces.
We describe the total lipid content, lipid class composition and fatty acid profiles of adult forage fishes (anchovy, sardine and sprat) sampled in the NW Mediterranean Sea in 2010 and 2011. Inter- ...and intra-species differences were mostly related to sampling period with limited effect of gender or total length. As an assemblage, total lipid content and relative levels of triacylglycerols and fatty acids 16:1n7, 20:5n3 and 14:0 in forage fish were highest in summer and autumn, indicating better feeding conditions and a more pronounced diatom-supported food web. In contrast, total lipid content was lowest at the end of winter and spring, and coincided with high levels of 22:6n3, indicating a more herbivorous diet based on dinoflagellates. Resource partitioning and niche separation, as inferred from fatty acid profiles, were apparent between species. Sardine showed a more diverse, temporally separated feeding strategy than anchovy, and dietary overlap was higher in winter than summer with sardine having higher markers of copepods, 22:1n11 and 20:1n9. Sprat collected in winter occupied a separate niche area to both sardine and anchovy with higher total lipid content and carnivory biomarker 18:1n9. Our results show that the lipid dynamics of forage fishes can be used to gain quantitative insights into sub-system level changes in species interactions, including prey and predator productivity.
Aims: To compare the decontamination performances of glidarc on strains of Erwinia of industrial interest.
Methods and Results: Cultures of Erwinia carotovora carotovora, Erwinia carotovora ...atroseptica and Erwinia chrysanthemi taken in stationary phase were exposed to the plasma generated by electric discharges in a gliding arc reactor prototype. The kinetics of destruction of bacteria were followed by direct platting. All bacterial strains presented a three‐phase destruction kinetics leading to an apparent sterilization within 10 min. Epifluorescent observations using life/dead probes revealed the absence of viable but not cultivable resistant forms. Measurement of the physical parameters of the medium confirmed that the technique was nonthermal but that reactive species responsible for a decrease of the pH were generated. However, even after neutralization the medium did not allow bacterial growth.
Conclusions: The results demonstrate that glidarc allows a rapid and complete destruction of planctonic strains of Erwinias without formation of resistant forms.
Significance and Impact of the Study: The reduction rate obtained by this technique shows the great industrial interest of glidarc for decontamination and suggests that it can be used for sterilization of industrial water effluents.
A preliminary study was carried out to investigate possible decontamination of the waste waters from a Cameroonian brewery by using a non-thermal atmospheric plasma. Samples of waste waters collected ...during periods of intense activity of production were first analysed for organoleptic, physical–chemical and organic parameters, and then exposed to a humid air electric discharge at ambient temperature and pressure. The resultant pollution abatement and germicidal effects are both ascribed to strong oxidising effects of OH and NO radicals formed in the plasma. The BOD removal efficiency of the process with brewery industrial wastewaters under BOD concentration of 385 and 1018
mg
l
−1 were 74% and 98% respectively. The alkaline wastewaters are rapidly neutralised due to the pH lowering effects of the plasma treatment.
►
NO,
OH and derivatives form in electric discharges in air at atmospheric pressure. ► The oxidizing plasma species degrade organic wastes sampled from surface waters. ► The process is followed by ...BOD, COD and TOC measurements for exposures up to 30
min. ► Incorporating powdered oyster shell (OS) controls acidity and hence the kinetic rate. ► Treatment time and OS mass are optimized around 36% TOC abatement within 10
min.
Highly oxidizing gaseous species (
OH,
NO and derivatives) formed in an electrical discharge (a gliding discharge burning in humid air), are suitable for abating the organic pollutant concentration of surface waters sampled in Cameroonian brooks, e.g., 47% (Total Organic Carbon, TOC) within 10
min exposure. The plasma technique coupled with the use of finely powdered oyster shell (OS) acting as a catalyst and an acidity control agent thus yields improved results. This paper is devoted to determining the optimum amount
m (g
L
−1) of incorporated OS before switching on the discharge for given exposure times
t* (min). The process effects are controlled by means of pH, Biological and Chemical Oxygen Demands (BOD, COD), and Total Organic Carbon (TOC) measurements performed for various
t* and
m values and the results are compared with a mere plasma treatment on the same samples. The BOD
5 and TOC values respectively decrease by 86% and 36% for 10
min exposure with 1
g
L
−1 incorporated OS. Treatments with OS stabilize acidity around pH: 6.5 while the pH decrease is more important without OS. BOD
5 and TOC exponentially decrease with
t* with or without incorporated OS, as does COD with OS only. BOD
5 exponentially decreases with increasing
m while COD linearly depends on
t* and
m, and TOC on
m only. Optimized treatment parameters are
t*
=
30
min,
m
=
0.1
g
L
−1.
Gliding arc (glidarc) discharge is a physicochemical technique for decontamination at atmospheric pressure and ambient temperature. It leads to the destruction of bacterial phytopathogens responsible ...for important losses in industrial agriculture, namely, Erwinia spp., without the formation of resistant forms. We investigated the effect of a novel optimized prototype allowing bacterial killing without lag time. This prototype also decreases the required duration of treatment by 50%. The study of the time course effect of the process on bacterial morphology suggests that glidarc induces major alterations of the bacterial membrane. We showed that glidarc causes the release of bacterial genomic DNA. By contrast, an apparent decrease in the level of extractible lipopolysaccharide was observed; however, no changes in the electrophoretic pattern and cytotoxic activity of the macromolecule were noted. Analysis of extractible proteins from the outer membrane of the bacteria revealed that glidarc discharge induces the release of these proteins from the lipid environment, but may also be responsible for protein dimerization and/or aggregation. This effect was not observed in secreted enzymatic proteins, such as pectate lyase. Analysis of the data supports the hypothesis that the plasma generated by glidarc discharge is acting essentially through oxidative mechanisms. Furthermore, these results indicate that, in addition to effectively destroying bacteria, glidarc discharge should be used to improve the extraction of bacterial molecules.
The gliding electric discharge in humid air is a source of activated species forming (e.g.
•
OH,
•
NO and their derivatives H
2
O
2
, ONO
2
H and NO
3
H) which are present in a non-thermal plasma at ...atmospheric pressure. These species are able to degrade organic pollutants in palm oil refinery wastewaters (PORW). The increase in acidity (pH decrease), conductivity and total dissolved solids (TDS) and the decrease in the total organic carbon (TOC) of PORW samples exposed to the discharge are reported. More than 50 % TOC abatement is obtained for 15 min treatment in batch conditions with a laboratory reactor. The organic pollutants of PORW, i.e. mainly fatty acids are degraded according to a pseudo first-order reaction (
k
* = 0.06 min
−1
). Post discharge reactions are also observed after having switched off the discharge, which suggests that the pseudo first-order (
k
≈ 0.05 min
−1
) degradation reactions should be attributed to the diffusion of soluble reactive species, e.g. H
2
O
2
and ONOOH in the liquid target.
A recent non-thermal plasma technique (i.e., a gliding arc discharge which generates reactive species at atmospheric pressure) is tested for pollution abatement of dyes dispersed in synthetic ...solutions and industrial effluents. Yellow Supranol 4 GL (YS) and Scarlet Red Nylosan F3 GL (SRN) are toxic synthetic dyes widely used in the Algerian textile industry and frequently present in liquid wastes of manufacture plants. Classical removal treatment processes are not efficient enough, so that the presence of dyes in liquid effluents may cause serious environmental problems, in connection with reusing waste waters for irrigation. The degradation processes achieved by the oxidising species formed in the plasma are followed by UV/VIS spectroscopy and by chemical oxygen demand measurements. They are almost complete (i.e., 92.5% for YS and 90% for dilute SRN) and rapidly follow pseudo-first-order laws, with overall estimated rate constants 3×10
−4 and 4×10
−4
s
−1 for YS and SRN, respectively. The degradation rate constant for the industrial mixture (i.e.,
k=1.45×10
−3
s
−1) is a mean value for two consecutive steps (2
10
−3 and 6×10
−5
s
−1) measured at the absorption peaks of the major constituent dyes, YS and SRN.
The gliding arc discharge is a cheap and efficient nonthermal plasma technique able to degrade organic compounds dispersed in water at atmospheric pressure. Alizarin Red Sulfonate (ARS) is selected ...as a stable quinonic dye. Exposure of the dye solution to the discharge in a batch reactor induces two successive reaction steps according to the treatment conditions. Direct exposure of the solution to the discharge induces simultaneous bleaching and COD evolution. In postdischarge conditions, that is, after the discharge is switched off, the reactions keep on developing. This study thus underlines two key features: the ability of glidarc discharges to degrade recalcitrant molecules and the low cost of the process which requires short exposure times. A model mechanism involves peroxynitrite as a likely active species formed in the discharge and involved in postdischarge phenomena in aqueous solutions and suggests short exposure times and much longer postdischarge times for optimized pollutant abatement.
The gliding discharge is a quenched plasma source suitable for the plasma treatments of liquids since it is operated in quasi-normal
T and
P conditions. Discharges in wet air provide a flow of ...strongly oxidizing radicals, e.g., NO
and HO
, able to oxidize and mineralize many organic pollutants in aqueous solution. The present paper reports on the destruction of nicotine, a toxic alkaloid from tobacco used as insecticide. Mineralization was monitored by total organic carbon (TOC) analysis and obeyed an overall first order kinetics mechanism. Carbon dioxide formation was followed by specific reactive Dräger tubes. The influence of the airflow rate was considered.
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