Experimental Evaluation of DBD Reactor Applied to Bacterial Inactivation in Water Flowing Continuously

Abstract

In this paper, we present the evaluation of a DBD reactor that generates an energy per pulse of 65.3 mJ in order to inactivate E. coli ATCC 8739 at 10 3 , 10 6 , and 10 8 CFU/mL order concentrations and E. cloacae CDBB-B-963 at 10 3 and 10 7 CFU/mL order concentrations, in a volume of water flowing continuously. Particularly, experimentation is focused in 500 mL, under atmospheric pressure. The DBD reactor was coupled to a peristaltic pump type, a cooling jacket, containers for water in treatment and cooling fluid, and systems to monitor the experimental conditions. The implementation of the experiments was carried out at three different fluid flow rates: 2.0 ± 0.1, 3.5 ± 0.1, and 4.4 ± 0.1 mL/s; in each of them the time required to carry out a cycle of treatment corresponded to 256±7, 143 ± 2, and 113 ± 1 s, respectively. During the DBD application, water flowed continuously at recirculation mode, promoting the continuous oxygen injection at 8.3 mL/s. In the three established fluid flow rates, the efficacy of treatment reached 100% in inactivation of E. coli bacteria at 10 3 and 10 6 order concentrations at the end of the first cycle of treatment. At 10 8 CFU/mL order concentration, complete inactivation of E. coli bacteria was achieved at the end of the fourth cycle of treatment. Meanwhile, E. cloacae bacteria showed an inactivation of 100% at the end of the first cycle of treatment at 10 3 order concentration; when the order concentration increased to 10 7 , the efficacy of the process depended on the fluid flow rate, at 3.5 ± 0.1 and 2.0 ± 0.1 mL/s survival was 0% at the end of the first cycle of treatment; nevertheless, at the highest (4.4 ± 0.1 mL/s), an additional cycle was required.

Hyperthermia studies using inductive and ultrasound methods on E. coli bacteria and mouse glioma cells

“…Concentrations from 1×10 3 to 1×10 6 FCU/mL of Gram negative Escherichia coli ATCC8739 and 1×10 6 to 3×10 6 of MGCs were used. Both microorganisms were prepared as reported elsewhere [11,12]. Depending on sample type, up to four heating treatments were carried out simultaneously for both ECB and MGCs.…”

“…As expected the lowest generated heat was obtained while using cyclohexane with a T cyclohexane = 3.3 • C, followed by glycerin with a T glycerin = 15 • C. Interestingly the generated heat of deionized water was just above that of cyclohexane with T deionized water = 5 • C. This suggests that the generated heat by glycerin must be associated with another property different from the dielectric one. In order to test the heating properties of the MNPs of magnetite with a mean particle size of 8.5 nm [11], these were dispersed in cyclohexane. As seen from Fig.…”

A novel LC‐based bipolar pulsed power supply for dielectric barrier discharge excimer lamps

“…Because of this characteristic, different DBD devices are widely used in many fields, such as material surface modification, 4,5 chemistry, [6][7][8] ozone generation, 9,10 harmful gas treatment, 11 aerospace, 12,13 and water purification. 14,15 Theoretical analysis and experimental results show that once the structure of DBD loads and the characteristics of the discharge gas (including gas type and gas concentration) are determined, the characteristics of an excitation voltage applied in DBD loads become one of the key factors affecting the performances of DBD loads. 16,17 For quite a long time in the past, a low-frequency power supply made of a set-up transformer was widely used to power DBD loads.…”

“…Due to the micro‐discharges, numerous gaseous molecules are dissociated and lots of active particles are generated. Because of this characteristic, different DBD devices are widely used in many fields, such as material surface modification, 4,5 chemistry, 6–8 ozone generation, 9,10 harmful gas treatment, 11 aerospace, 12,13 and water purification 14,15 …”