Role of Bipolar Pulsed DBD on the Growth of Microcystis aeruginosa in Three-Phase Discharge Plasma Reactor

Abstract

Algae in drinking water supplies often bring about impact on the water treatment. In this study, a bipolar pulsed dielectric barrier discharge system in threephase discharge plasma reactor was constructed for investigating its ability to control excessive growth of cyanobacteria, Microcystis aeruginosa. Experimental results show there was almost no change in optical density immediately after the interruption of electrical discharge, but the decreasing trend of optical density, cell density and chlorophyll-a content was obvious during the incubation period, indicating a significant residual effect of electrical discharge process on the algal growth inhibition. Scanning electron microscopy investigation of algae revealed surface damage, apparent leakage of intracellular contents and pores formed after electrical discharge process, which showed that algal cells had no potential to survive and grow. Compared with the control sample, it was observed that electrical discharge on the algal extracellular products has almost no residual effect and the growth rate of algae slightly decreased before three days storage. Hydrogen peroxide was produced by electrical discharge in the lM level and showed a first-order decay. But at such level, the external addition of hydrogen peroxide alone is not likely to cause the residual effect. These results implicated that the growth inhibition of M. aeruginosa was mainly caused by electrical discharge process, and it made the algal cells lose ability to survive, demonstrating the considerable potential of such an alternative process for efficient water purification.Keywords Bipolar pulsed dielectric barrier discharge AE Microcystis aeruginosa AE The residual effect AE Hydrogen peroxide

The mechanisms of ozonation on cyanobacteria and its toxins removal

“…(2) Investigating the ozonation on the algae cellular morphology and byproducts formation. [20]. The composition of the BG-11 medium used in algal growth was shown in Table 1.…”

New insight into the residual inactivation of Microcystis aeruginosa by dielectric barrier discharge

“…Therefore, there is an urgent need to develop efficient techniques to control and reduce the adverse impact of blooms. To suppress or remove cyanobacteria blooms, various methods have been adopted such as chemical treatment 3 4 5 , UV radiation 6 7 , ultrasound irradiation 8 9 10 , electron beam irradiation 11 and non-thermal plasma oxidation technology 2 12 13 14 15 16 . However, the chemical methods such as excessive use of algaecides can lead to secondary pollution, while the physical methods such as UV radiation, sonication and electron-beam irradiation have the limitation for bloom control with high efficiency or on a large scale.…”

Three cell flying capacitor inverter for dielectric barrier discharge plasma applications

“…2. The system is supported by a sinusoidal waveform generator which provides a reference f SW = 200 kHz signal to an operational amplifiers stage, where three 2 3 π out of phase sinusoidal signals are generated. The latter are applied to a logarithmic amplifier stage, which in turn produces triangular waveforms meant to act as carrier signals to be compared to the modulating one (produced by a digital frequency divider, and later on integrated, so to obtain a sinusoidal waveform with frequency f m = 1 16 f SW = 12.5 kHz).…”

“…As the simulation outcome in Fig. 3.a depicts, three triangular mutually 2 3 π out of phase signals are compared independently from the modulating sinusoidal signal at the frequency f m . When the modulating amplitude exceeds that of the carrying signal, a voltage pulse is generated in order to start the power switch and therefore increase the power supply.…”

“…Plasmas in a dielectric barrier discharge cell (DBDC) are generated by applying high voltage (HV) to a pair of electrodes, separated by a gap, where at least one of these is covered by a dielectric sheet, usually made of quartz, glass or ceramic. These discharges are frequently used in industrial ozone generation [1] or in the treatment of air pollutants [2], in particular, solvents or volatile organic compounds (VOC) which are mainly produced around chemical plants [3]. The conditions required to produce non-equilibrium plasmas are easier to attain with DBDC than by alternative methods such as low pressure discharges, high pressure discharges with fast pulses, or electron beam injection.…”