Aeration unit processes

In contrast to vacuum flotation, dissolved-air flotation units can be operated on a continuous basis by the application of pressure. This consists of pressurizing and aerating the process stream and introducing it into the flotation vessel that is maintained at the atmospheric pressure. The reduction of pressure results in the formation of fine air bubbles and the collection of fine particulates to be floated and removed as sludge. 

In contrast to vacuum flotation, dissolved-air flotation units can be operated on a continuous basis by the application of pressure. This consists of pressurizing and aerating the process stream and introduc-... 

Equalisation tank and its hold-up volume should be adequate for storing effluent generated in 24 h at least so that shock loads are taken of Process flow scheme for the treatment in general giving proposed pH adjustment, aerobic or anaerobic process employed, aeration unit, active carbon unit, sludge disposal luiit. 

A subsequent patent, U.S. Patent 2,828,246 described a commercial process for bacitracin production. A 1,230 gallon portion of a medium containing 10% soybean oil meal, 2.50% starch and 0.50% calcium carbonate having a pH of 7.0 was inoculated with a culture of bacitracin-producing bacteria of the Bacillus subtilis group and the inoculated medium incubated for a period of 24 hours with aeration such that the superficial air velocity was 12.1. An assay of the nutrient medium following the fermentation revealed a yield of bacitracin amounting to 323 units/ml. This was more than twice the yields previously obtained. 

Overaeration of an unstable standpipe is a common response to process or catalyst changes not easily recognized. Factors influencing standpipe operation such as catalyst mass flux rate, catalyst density and PSD, standpipe aeration and pressure profile, and unit configuration should be thoroughly evaluated before making large adjustments to the aeration. 

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