UASB
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The UASB reactor is the most widely and successfully used high rate anaerobic technology for treating several types of wastewater. The success of the UASB reactor can be attributed to its capability to retain a high concentration of sludge and efficient solids, liquid and water phase separation. The UASB reactor consists of a circular or rectangular tank in which waste (water or sludge) flows in upward direction through an activated anaerobic sludge bed which occupies about half the volume of the reactor and consists of highly settleable granules or flocs. During the passage of this blanket the purification takes place by solids removal and then organic matter is converted into biogas and sludge. The produced biogas bubbles transfer to the top of the reactor, carrying water and solid particles (i.e. biological sludge and residual solids). These bubbles strike the degassing baffles at the upper part of the reactor, leading to an efficient gas - Solid separation (GSS). The solid particles drop back to the top of sludge blanket, while the released gases are captured in an inverted cone (GSS) located at the top of the reactor. Water passes through the apertures between the degassing baffles carrying some solid particle which settle there due to increase of the cross sectional area and return back to the sludge blanket, while water leaves the settlers over overflow weirs.
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