Wastewater primary treatment flotation

Figure 21.8 shows a typical sequence of the major equipment systems in a wastewater treatment plant.36 The function of primary treatment is to remove suspended solids from the wastewater, and then to remove organic materials by biological secondary treatment. Primary treatment processes used by kraft mills typically involve screening followed by either sedimentation or flotation.40... 

In addition, oily sludge from a wastewater treatment facility that results from treating sour wastewaters may be a hazardous waste (unless recycled in the refining process). These include API separator sludge, primary treatment sludge, sludge from various gravitational separation units, and float from dissolved air flotation units. 

Low concentrations of oil can be removed by dissolved air flotation (DAF). In this process, an effluent recycle is pressurized in the presence of excess air, causing additional air to go into solution, in accordance with Henry s Law. When this water is discharged to the inlet chamber of the flotation unit at close to atmospheric pressure, the dissolved air comes out of solution in the form of tiny air bubbles which attach themselves to and become enmeshed in suspended solids and oil globules. The primary design criteria is the air/solids ratio, which is defined as the mass of air released divided by the mass of solids fed. Sufficient air must be released to capture the solids in the influent wastewater. The performance of DAF for the treatment of several... 

Ionizing radiation, gamma radiation source or electron beam, is an excellent tool for the purification of polluted water and wastewater.It involves the reaction of primary radiolytic water products, i.e., ( OH, e, H) with the pollutants and the formation of secondary short-hved species from the pollutants. The secondary process causes the formation of precipitates that absorb pollutants. The general principal is that radiolytic treatment, in combination with traditional methods such as flotation, coagulations, adsorption, and aeration, is employed for the purification of water... 

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