UASB

Upflow Anaerobic Sludge Blanket for industrial wastewater treatment

Under anaerobic conditions, organic pollutants in wastewater are degraded by microbes producing methane and carbon dioxide. The degradation process is effective compared to the more conventional aerobic processes and produces  only 5-10% of sludge (Metcalf and Eddy). This saves considerably on cost associated with the sludge disposal. In addition, since it does not require aeration, anaerobic process also saves substantial amount of cost associated with aeration, including equipment, maintenance and energy consumption. Since the late 1960’s, a number of high-rate anaerobic reactors have been introduced for wastewater treatment. Among them, the most popular ones is the up flow anaerobic sludge blanket(UASB).

The UASB process has several advantages over other anaerobic processes. It is simple to construct and operate and is able to tolerate high organic and hydraulic loading rates.

The key feature of the UASB process that allows the use of high volumetric COD loadings compared to other anaerobic processes is the development of dense granulated sludge. This has made it possible for the UASB to enhance the quality and the development of sludge with high specific activity and superior settling properties.

FARAN’s UASB reactor consists of a biological reaction zone and a sedimentation zone. The organic compounds in the influent are converted to CH4 and CO2 in the reaction zone as the flow passes upward through the bed of activated sludge. The gas and sludge is separated by the gas-solid-liquid separator device. Biogas with a high concentration of methane which is produced, may be captured and used as an energy source, to generate electricity for export and to cover its own running power. The heat produced as a by-product of electricity generation can be reused to heat the digestion tanks.

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