The gas phase dynamics of an inverted, stagnation point flow CVD reactor were studied by both experiment and modeling. The axial centerline temperature profile in the reactor was measured by analysis of the rotational Raman spectra from the carrier gas (N or H ) as a function of the inlet flow velocity and the reactor aspect ratio. It was found that a larger temperature gradient 2 2 normal to t...

Steady and transient mass transport phenomena within an inverted, stagnation-flow, cold-wall CVD reactor were investigated by observing the concentration of a tracer species (CH4) with in situ Raman spectroscopy. The transient studies revealed that the use of matched reactor inlet velocities is crucial to minimize recirculating flow patterns and that the magnitude of the gas velocity is also im...

It is important to control biofilm cohesiveness to optimize process performance. In this study, a membrane-aerated biofilm reactor inoculated with activated sludge was used to grow mixed-culture biofilms of different ages and thicknesses. The cohesions, or cohesive energy levels per unit volume of biofilm, based on a reproducible method using atomic force microscopy (F. Ahimou, M. J. Semmens, P...

Field measurements of ammonia (NH3), nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) were made from raw pig slurry storage, from different biological aerobic treatments and from stores holding the treated products. Biological treatments consisted of intermittent aeration by (i) submerged ejector aerator, (ii) surface aerator and (iii) fine-bubble diffuser. Emissions were measured fr...

The stabilization of swine wastewaters from swine confined housing by the combination of a upflow anaerobic sludge blanket (UASB) reactor and waste stabilization ponds is a viable alternative to minimize the environmental impact caused by inadequate disposal of swine wastewaters. In the present study, the polluting load of pre-decanted swine wastewater treated with a series of two 0.705 m(3) UA...

We introduce a very simple open two-dimensional gel reactor for studying chemical patterns that arise in reaction-diffusion systems. The reactor consists of a thin disk-shaped layer of polyvinyl alcohol gel with one face in direct contact with a well-stirred flow reactor containing reactants of the chlorite-iodide-malonic acid system; the other face of the gel is in contact with a piece of tran...

Gas holdup and mixing time were characterized in a forced circulation internal loop draft-tube reactor (unaerated aspect ratio≈ 6, downcomero-riser cross-sectional area ratio = 0.493) as functions of the forced liquid superficial velocity in the riser (ULr) and the gas superficial velocity in he riser (UGr). Data were obtained in air–water system. The operation ranges were 0≤ULr ≤ 0.051 m/s and...