City and Borough of Juneau
155 S. Seward Street
Juneau, Alaska 99801
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Wastewater Utility Division

Sequencing Batch Reactor (SBR)

The Sequencing Batch Reactor (SBR) is a fill-and-draw, non-steady state activated sludge process in which one or more reactor basins are filled with wastewater during a discrete time period, and then operated in a batch treatment mode. The SBR accomplishes equalization, aeration and clarification in a timed sequence, in a single reactor basin, whereas a conventional continuous flow process requires multiple structures and extensive pumping and piping systems. A single cycle for each reactor consists of five discrete periods, Fill, React, Settle, Draw, and Idle. The purpose of each period is described in the illustrations below.

Varying the operating strategy enables aerobic, anaerobic or anoxic conditions to be achieved. Precise control of these conditions allows Organism Selection to take place--the proliferation of specific desireable microorganisms is encouraged, while the growth of undesireable mircoorganisms is inhibited. Microorganisims can also be acclimated to a wide range of industrial and chemical processing wastes.

Anoxic Fill Phase:
The reactor is filled with wastewater. Fill can be aerated, anoxic, or a combination of aerated and anoxic. Biodegradation is intiated.

During Anoxic Fill, influent is distributed throughout the settled sludge through the influend distribution manifold. Pumps are not operated, no power is used. Influent is not diluted by mixing, making biological nutrient removal much more reliable.

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React Phase:
Influent flow is diverted to another reactor. Aeration continues in the full reactor until complete biodegradation is achieved; mixed liquor is drawn through the ID/SC and used as motive liquid for the jet aerator.

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Settle Phase:
The aerators are turned off and the perfect quiescent conditions allow the biomass to settle, leaving the treated supernatant above.

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Decant Phase:
Treated effluent is removed from just below the liquid surface by the U.S. Filter/Jet Tech Floating Solids Excluding Decanter.

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Idle/Waste Sludge Phase:
The reactor waits to receive flow. Settled sludge is drawn throught eh ID/SC and pumped to an aerobic digester. The jet motive liquid pump is utilized as a waste sludge pump.

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