Chapter 20

Wastewater and Solid Waste Management

Anaerobic Wastewater Treatment

Anaerobic wastewater treatment is the biological treatment of wastewater without the use of air or elemental oxygen. Anaerobic treatment is characterized by biological conversion of organic compounds by anaerobic microorganisms into biogas which can be used as a fuel-mainly methane 55-75 vol% and carbon dioxide 25-40 vol% with traces of hydrogen sulfide (3).

Upflow Anaerobic Sludge Blanket

In the Upflow Anaerobic Sludge Blanket (UASB) reactor, the wastewater flows in an upward mode through a dense bed of anaerobic sludge. This sludge is mostly of a granular nature (1-4 mm) having superior settling characteristics (> 50 m/h). The organic materials in solution are attacked by the microbes, which release biogas. The biogas rises, carrying some of the granular microbial blanket.

Fluidized Bed Reactor

In a Fludized Bed Reactor (FBR), wastewater flows in through the bottom of the reactor, and up through a media (usually sand or activated carbon) that is colonized by active bacterial biomass. The media provides a growth area for the biofilm. This media is "fluidized" by the upward flow of wastewater into the vessel, with the lowest density particles (those with highest biomass) moving to the top.

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