SBR (Sequencing Batch Reactor)


The best municipal technology is now available for residential and commercial use.

Sequencing batch reactors (SBR’s) have been around for a long time. They were operating successfully long before flow-through, activated sludge systems were designed. In flow-based systems, variables in the flow can cause upsets and incomplete treatment. Because the SBR process is time-based rather than flow-based, there is much more control of the treatment process – both in multiple and single tank systems. Here’s what the E.P.A. has to say:

“The SBR process has widespread application where mechanical treatment of small wastewater flows is desired. Because it provides batch treatment…it is ideally suited for….wide variations in flow rates… operation in the “fill and draw” mode prevents the “washout” of biological solids that often occurs with extended aeration systems…. Another advantage of SBR systems….is that they require less operator attention yet….produce a very high quality effluent.”

-EPA Manual, “Wastewater Treatment/Disposal for Small Communities,” Office of Research & Development, Office of Water, Sept. 1992

Walden Features:

  • Modular Design tanks operate in parallel, so a single tank can be taken off-line during low-flow seasons or for maintenance. With Walden’s incremental tank system, you can start small and add on as you grow.
  • No Clarifer Tanks means less valuable space required for Walden treatment systems.
  • No Sludge Return Pumps means less operator time needed for managing sludge inventory.
  • Easy Maintenance. Walden’s high quality mechanical components need only routine lubrication and an oil change. Interior finish cleans quickly.
  • All components are non-corrosive.
  • Perfect settling conditions. Because the process is controlled, quiescent settling conditions are obtained.
  • Short Circuiting Eliminated. Baffling and long, narrow tanks prevent short-circuiting.
  • Handles Shock-loading. Time-based, rather than flow-based process.
  • Nutrient Removal capabilities. Easily obtained with change in operating strategy.
  • Filamentous Growth easily controlled. Vary operating strategies to produce results.

How it Works:

Typical SBR Process Special Walden Features
Wastewater fills the tank, mixing with biomass that settles during the previous cycle Walden treatment tanks are made out of non-corrosive fiberglass. Our unique modular design allows for future expansion.
Air is added to the tank to aid biologial growth and facilitate subsequent waste reduction. Corrosion resistant components are the Walden standard. Non-clog coarse bubble insures consistent air flow.
Mixing and aeration stop during this stage to allow solids to settle to the bottom of the tank The baffled influent screening compartment prevents short circuiting and simplifies cleaning of all Walden treatment systems.
Clarified effluent is discharged. Walden’s proprietary floating decant system excludes solids while remaining accessible in the event of pump failure. No need for confined space entry.
If necessary, sludge removal occurs during this stage. Because Walden utilizes extended aeration, sludge production is minimized, which means greater savings in the cost of sludge disposal.


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