Treatment technology for ballast water is in need. High-voltage pulsed discharge has great potentiality to inactivating micro-algae living in ballast water. In this study, effects of discharge reactor parameters and ballast water parameters to discharge characteristics were studied, the efficiency of the micro-algae inactivation was confirmed preliminarily, and the principle of designing discharge reactor parameters was discussed. The main conclusions are: UP increased with the increasing of d, while decreased with the increasing of r; IP increased with the increasing of r, while decreased with the increasing of d; UP and IP both increased with the increasing of U. E decreased with the increasing of d; when d=2mm, the value of E was far larger than that of d≥6mm; when d was 2mm,larger r, larger E; when d was between 6-20mm, larger r, smaller E. The optimized structure of discharge reactor should be r=3mm and d=6mm. Up increased with the increasing of Q while decreased with the increasing of T. η increased with the increasing of U and d, decreased with the increasing of r.
Invasive aquatic species discharged through ship ballast water is one of the most serious problems posed nowadays in the marine environment. Inactivation effect on microalgae by combined PEF and engine waste heat pretreatment was studied. Effect factors such as pulsed peak voltage, pulsed frequency, electrode gap and heating temperature were explored, and its mechanism of inactivate the microalgae was analyzed. The results show that at the same experimental parameters, the inlet temperature of PEF treatment stage keeps at 24°C, the inactivation percentage is difficult to achieve 90% unless the electric field strength rises to 22 kV/cm. Once the PEF treatment sample is preheated to 48°C, the inactivation percentage will be up to 99% as the electric field strenth is just 10 kV/cm.
A sequencing fed biofilm batch reactor (SFBFBR) seeded with returning activated sludge of a WWTP was started up to enrich Anammox (Anaerobic Ammonium Oxidation) bacteria and to investigate the nitrogen removal characterization of the Anammox biofilm system. Initially, the operation period was controlled at 3 days and the mineral medium (30 mg/l ammonium, 30 mg/l nitrite, about 2 L) was supplied continuously to SFBFBR in the first 68 hours. After 44 days’ cultivation, ammonium and nitrite concentration were decreased simultaneously without COD and DO, which means the anammox activity presented in the reactor. From t=55 days, in order to further enrich anammox bacteria, the substrate load began to increase by reducing the operation period from 3 days to 1 day and increasing the ammonium and nitrite concentrations. At the end of the experiment, the reactor was able to treat nitrogen loading rates up to 200±10 mg N/(L.d). The ammonium and nitrite reacted in the stoichiometrical of 1:1.135.
The present work investigates the effects of microwave-assisted annealing on the granulation and photocatalytic performance of anodic TiO2 nanotubes. The results indicate that although microwave-assisted heating can transform the amorphous TiO2 nanotubes into completely anatase one within 5min, it brings the collapse and granulation of TiO2 nanotubes, which weaken their photocatalytic activity. Meanwhile, the detachment and evolution of F- rich layer to a layer of TiO2 membrane with rounding-off surface, and the stripping of TiO2 nanotube bottom from its body are also observed.
The porous ceramic support was realized at various temperature range from 1200°C~1300°C using α-Al2O3 as main material, carbon powder as pore-former, kaolin clay and titanium dioxide as sintering aids and polyvinyl alcohol (PVA) as adhesives. The microstructures of sintered body were significantly affected by the amount of pore-former and sintering temperature. The results indicated that the porosity dramatically increased and the pore radius increased from 2.9 μm to 3.2 μm as carbon powder addition increased from 3 wt.% to 12 wt.%. Correspondingly, their pure water flux depending on the pore structure parameters of the support increased from 1.37 to 4.53 m3.m-2.h-1.bar-1. To prepare porous alumina support with 40% open porosity, carbon powder up to 10 wt.% is appropriate. Sintering experiments showed that the optimum sintering conditions are the sintering temperature of 1300 °C and 2 h holding time at this temperature.
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