| With the shortage of water resources and deterioration of drinking water quality, the removal of microorganism and toxic substances produced by microorganism is a key point and also a difficult point in water treatment without secondary pollution, but the existing processing method can not meet the requirements. Pulsed discharge technology, one of advanced oxidation technologies, has aroused more and more concerns by researchers in the world for its simplicity of operator, efficient treatment, non-secondary pollution and so on.This paper discussed the inactivation of Escherichia coli (E. coli), Microcystis aeruginosa (MA) and removal of Microcystins-LR (MC-LR) by plasma generated by pulsed discharge. The effects of electric parameters and gas-liquid parameters on the survival efficiency and inactivation rate constants of E. coli by bipolar pulsed discharge were studied. The results show that the gas bubbling can obviously improve the survival efficiency and inactivation rate constant under the discharge condition and the optical gas bubbling rate is 0.75 m3/h. The survival efficiency of E. coli decreases and the inactivation rate constants of E. coli increases by the upgrading peak pulse voltage and pulse repetitive rate. The initial conductivity has no marked effect on the survival efficiency and the inactivation rate constants of E. coli and the survival efficiency in alkalescent solution is higher than that in the acidulous solution. The cell density of E.coli decreased 4.001g, the survival efficiency of E. coli is lower than 0.01% and the inactivation rate constant of E. coli is 1.36×10-1 min-1 under the condition of 54 kV peak pulse voltage, 50 Hz pulse repetitive rate, 0.75 m3/h gas bubbling rate and 25 min treatment time.The effects of gas-liquid two-phase and gas-liquid-solid three-phase discharge reaction system on the discharge characteristic, inactivation of MA and hydrogen peroxide concentration were studied. The effects of location of the double dielectric layers, single or double dielectric layers, discharge electrode diameter, material and number on the inactivation of MA were discussed and the multi-electrodes three-phase discharge reaction system was confirmed to inactivate MA. In the multi-electrodes three-phase discharge reaction system, the inactivation efficiency of MA increases with the upgrading of discharge time, peak pulse voltage, pulse repetitive rate and gas bubbling rate (be below 0.75 m3/h). In the range of optimum growth pH, the inactivation efficiency of MA in the alkalescent algal solution is higher than that in the acidulous algal solution. More than 93.40% of optical density, 100% of cell density and Chlorophyll-a of MA are removed at the end of the fifth day incubation as a function of 40 min treatment under the condition of 40 kV peak pulse voltage, 50 Hz pulse repetitive rate, 0.75 m3/h gas bubbling rate. To determine the mechanism of inactivation of MA by plasma generated by pulsed discharge, the biomass of MA (cell density, optical density, Chlorophyll-a), cellular morphology, the residual effect, content of MDA, electrolysis on the membrane permeability, absorption spectrum and changes in DOC were measured.Comparing extractive methods of MC-LR and enrichment methods of extract, MC-LR is extracted by acetic acid and extract of MC-LR is gradually rinsed by light concentration of methanol and eluted by high concentration of methanol from solid phase extraction cartridge. Electric parameters and liquid parameters of MC-LR removal by pulsed discharge were studied. The results show that the removal efficiency and removal rate constants of MC-LR increases with the increasing of the peak pulse voltage and pulse repetitive rate or the decreasing of initial conductivity. The removal efficiency of MC-LR in the alkalescent solution is higher than that in the acidulous solution. MC-LR at a concentration of 0.2 mg/L is totally removed at a treatment time of 20 min under the condition of 40 kV peak pulse voltage, 50 Hz pulse repetitive rate, 0.75 m3/h gas bubbling rate. The value of TOC and TC was decreased and IC was increased, showing that the intrinsic structure of MC-LR is destroyed by hydrogen peroxide, ozone and hydrogen radicals generated by pulsed discharge.
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