Stéphanie Ognier

Isolation and identification of an iopromide-degrading strain and its application in an A2/O system

An iopromide (IOPr)-degrading bacterium was isolated from activated sludge of a wastewater treatment plant in Shanghai. Based on its morphology, physiological-biochemical characteristics and a phylogenetic analysis of its 16S rRNA sequence, the bacterium was identified and named as Pseudomonas sp. I-24. The optimum condition for degrading IOPr was at 30°C and pH 7.0. After 5 days, strain I-24 could degrade 30 mg/L IOPr by 99% in a basal salts medium with a 5% (V/V) inoculum and 200 mg/L starch as the primary substrate. When applied to an Anaerobic-Anoxic/Aerobic (A2/O) process, with the coexistence of other bacteria, the strain I-24 got lower (61.3%) IOPr removal, but in two A2/O systems (with and without I-24 inoculation), the CODcr removal were both approximately 95%. The trial dosed with strain I-24 showed better IOPr removal than the un-dosed one. I-24 sustained its abundance in the A2/O system during the experiment.

Reactive Blue Degradation in Aqueous Medium by Fe-Doping TiO 2 Catalytic Nonthermal Plasma

In this paper, Fe-doping TiO2 was introduced into a dielectric barrier discharge (DBD) process for catalytic nonthermal plasma (NTP) degradation of a mode organic pollutant reactive blue (KN-R). Plasma was generated in a DBD reactor; Fe-doping TiO2 was prepared by the sol-gel process. The catalytic-NTP oxidation reactions were studied under various conditions including the examination of the effects of initial pH, KN-R concentrations, and catalyst dose. Typical results indicated the synergy between plasma excitation of KN-R followed by the catalytic action of Fe-doping TiO2, which not only improved the conversion but also increased the mineralization efficiency. The determination of hydrogen peroxide and nitrate ions, and ultraviolet-visible absorption and Fourier transform infrared spectra analyses revealed that catalysts in a plasma system strengthen the mineralization of KN-R.

The development and numerical simulation of a plasma microreactor dedicated to chemical synthesis

Abstract A plasma microreactor dedicated to chemical synthesis has been conceived and developed using soft-lithography techniques. In this study, we propose to use highly reactive species created by the plasma discharge to replace traditionally used chemical initiators. A dielectric barrier discharge plasma was generated under atmospheric pressure and then dispersed into a continuous liquid phase with a T-junction geometry. Injected metal electrodes made it possible for in situ optical observations with an intensified charge-coupled device camera. No signal was detected when analyzing the exhaust liquid by electron spin resonance (ESR) spectroscopy. Numerical simulations confirmed that only low quantities of hydroxyl radicals could diffuse into the liquid phase, giving a concentration of DMPO-OH of 10−6 mol/l, below the detection limit of ESR.

Catalytic microreactor with immobilised silver nanocluster for organic pollutant removal from water

The use of microchannels for catalytic reactions represents a considerable experimental opportunity, because of the high surface area to volume ratio these devices typically have. However, incorporating catalysts into microfluidic devices has proven technically challenging. We report the development of a new type of microfluidic device that has a catalytically active metal surface with a large active area built into one of the walls that constitute the microchannel. We test the catalytical activity on an important chemical reaction for drinking water purification: the catalytic ozonation of a typical organic pollutant that is otherwise difficult to remove from the water. pCBA was chosen as model pollutant since it is known to have slow reaction rates with molecular ozone and hence to pose problems in water purification. We find that the catalytic microreactor increases the overall reaction rate by a factor 350 compared to the bulk reaction, owing to both the catalytic activity and the confinement, and is thus highly efficient even for very short residence times.

KN-B removal from water by non-thermal plasma

The degradation of Reactive Black 5 (KN-B) in water using double-dielectric barrier discharge (DDBD) was studied. Experimental results showed that the KN-B degradation rate increased as the initial pH decreased. Low concentrations of Fe(2+) enhanced the degradation, whereas high concentrations of Fe(2+) hindered the degradation. The results showed that DDBD did not noticeably reduce total organic carbon but did reduce the pH value and improve the biodegradability of the solution significantly. Furthermore, the UV-Vis spectra of the dye showed that the chromophore group was damaged and that the solution was decolorized after the 10-min degradation process.