Diffuser (sewage)

About: Diffuser (sewage) is a research topic. Over the lifetime, 6487 publications have been published within this topic receiving 40404 citations.

Effect of organic substances on mass transfer in bubble aeration

Abstract: Dispersion of gas bubbles in water has a wide application in aeration and ozonation processes. The rate of mass transfer in such systems depends strongly on the wastewater quality as well as on the design and operational characteristics of gas liquid contact units. Small amounts of surface active compounds in water were shown to reduce the overall mass transfer coefficient, kLa, in single bubble systems1,2,3 and in swarms of bubbles.4 This effect was attributed to the decrease in the liquid-phase mass transfer coefficient, kL.l~5 The adsorption of the large molecules of surfactants reduced the surface tension of water,1,467 reduced the bubble size,1,3,4,8 lowered the terminal velocity of bub bles,9-11 and increased the drag coefficient.5,10 Accordingly, surfactants were believed to reduce the kL by depressing the hydrodynamic activity, and by offering additional barriers for the passage of gas molecules at the gas-liquid interface. Higher concentrations of the surfactants improved kLa\ this was attributed to the increase in the interfacial area caused by the formation of smaller bubbles.1,4 On the other hand, Zieminski and his co-workers8,12"14 reported a definite improvement in kLa in the presence of various alcohols and carboxylic acids. The authors stated the principle action of such substances to be prevention of bubble coalescence. This study was undertaken to investigate the effects of various organic substances on the characteristics of oxygen transfer from air bubbles to water. The compounds listed in Table 1 were chosen to represent various groups of water contaminants. To elucidate the effective mechanisms, experi ments were conducted by using either a fritted glass diffuser or a capillary for gas dispersion. The effects of gas flow rate, pH, and ionic strength were also examined.

Chemical vapor deposition reactor

Abstract: A reactor, suitable for CVD processes, which presents a high aspect ratio to reactant gasses, is described. Substrates are mounted on oppositely disposed susceptors in a vertical chimney-type reactor. Means are provided to rotate the susceptors about an axis perpendicular to gas flow. Side-loading or top-loading mechanisms are provided for loading and unloading the susceptors through a gate valve. A diffuser below the reaction zone adjusts the gas flow into the reaction zone.

Biological Treatment of Dairy Wastewater by Sequencing Batch Reactor

Abstract: A bench scale aerobic Sequencing Batch Reactor (SBR) was investigated to treat the wastewater from an industrial milk factory. The reactor was constructed from plexi glass material and its volume was 22.5 L. The reactor was supplied with oxygen by fine bubble air diffuser. The reactor was fed with milk factory and synthetic wastewater under different operational conditions. The COD removal efficiency was achieved more than 90%, whereas COD concentration varied from 400 to 2500 mg/l. The optimum dissolved oxygen in the reactor was 2 to 3 mg/l and MLVSS was around 3000 mg/l. Easy operation, low cost and minimal sludge bulking condition make the SBR system an interesting option for the biological medium strength industrial wastewater treatment. The study demonstrated the capability of aerobic SBR for COD removal from dairy industrial wastewater.

The effect of organic substances on the transfer of oxygen from air bubbles in water

Abstract: The liquid film coefficient is related to bubble diameter and velocity in pure water and to the physical properties of the liquid. The addition to water of organic substances which influence the surface tension and viscosity will decrease the size of the air bubble released from a diffuser and reduce the transfer of oxygen into the solution. The maximum reduction in oxygen transfer occurs in the region of maximum surface tension change. The effect of the addition of several organic substances on the oxygen transfer characteristics are shown.

Acoustical panel assembly

Abstract: An acoustical panel assembly having improved structural, decorative and acoustical properties is disclosed. The panel assembly includes a perimeter frame. A thin septum member is supported in the center of the frame. A fibrous glass layer is positioned adjacent each side of the septum member. A molded, semi-rigid, fibrous glass diffuser member is positioned adjacent each of the fibrous glass layers. The assembly includes means for joining adjacent panel assemblies and, in one embodiment, an outer decorative fabric layer is positioned adjacent each of the outer surfaces of the diffuser members.