Sequential Batch Reactor

Overview :

The biological stage of the wastewater treatment plant is designed as a “sequenced batch reactor “(SBR) and represents one of the most modern treatment concepts being used for sewage treatment plants. The central characteristics of the biological stage can be described as followed:

  • The process takes place in one or more SBR-reactors, depending on the chosen plant design.
  • Each SBR-reactor operates according to the activated sludge process, but with a modified operation-concept, which uses the reactor as an aeration tank as well as a clarification system.
  • Due to the SBR process, an extensive removal of dissolved organic substances from the wastewater can be achieved by nitrification and denitrification as well as by the removal of phosphorus.
  • The special characteristic of the SBR process is due to the fact that the individual process phases of an activated sludge plant (aerobic, anoxic and anaerobic, mixture as well as sedimentation) run along the time axis in one single tank. Thus, the times of the individual process stages are adapted to the load and thus the required effluent parameters can be maintained with security.

The purification of wastewater by SBR process has compared to traditional continuous flow process, a number of economic and technical advantages:

  • Rugged cleaning performance even with fluctuating hydraulic and organic load
  • Significant minimized footprint compared with conventional wastewater treatment plants with lower costs for civil works
  • Technically mature and widely used method
  • Economical operation of the plant
  • Possible modular configuration of the plant adjusted to the current impact load
  • Simple tank construction and geometry
  • Excellent treatment performances due to Nitrification, Denitrification, Phosphate elimination and Disinfection depending on the requirements
  • High operation safety / process stability
  • Easy maintenance

The standard SBR-process can be explained by the following illustrations:

Treatment Process – working Principal

Fill-up phaseMixing phaseBiological treatment phaseSettling phaseDischarging phase
A cycle starts with the filling (Phase 1) via the feeding pump the wastewater free of rejects is fed from the buffer tank into the SBR- tank. The filling occurs in batches, till the maximum filling level of Hw (max) is reached.
Along with the feeding the denitrification is initiated (Phase 2), while the „new “wastewater” is mixed with the available activated sludge volume. This is the Anoxic phase with the optimal ratio between carbon and nitrogen. Denitrification.
Following the time limited denitrification phase the plant is changing to operation mode Aeration and Mixing (Phase 3). The required oxygen for reduction of carbon and the nitrification is thus entered through aeration. The aeration care for an optimal air entry and the mixing of wastewaters.
After the completion of aeration and mixing phase, there starts the sedimentation phase (Phase 4), while the activated sludge is sedimented. This phase lasts about 1,0 to 1,5h. The activated sludge is settling down in the treatment basin. A perfect separation of the activated sludge and the cleared water is obtained.
Within the sedimentation phase there is built a clear water zone, which is evacuated in the following clear water discharge phase (Phase 5). The discharge phase is concluded with the reach of filling level Hw(min) in the SBR tank. To the end of the cycle a defined part of the excess sludge will be pumped out from the SBR into the preliminary sedimentation respective into a provided sludge storage tank. The Cycle is ready to start again.

Technical Specification

Flow : 10 to 5000 M3/day and more
Technology : sequenced batch reactor
Hydraulic retention time in SBR tank   14- 16 hrs
Organic load range : 1 – 20 kg BOD/(m3*d)
Settling process : Batch Settling
Sludge recirculation rate   0 – 15 %
Tank MOC : Concrete/MSEP
Polishing Treatment : Sand & Carbon Filters [ Optional]
Controls : Electrical / Microprocessor / PLC

Salient Features

  • All tank in civil with flexible positioning
  • Proven design
  • Systems available from 10 – 5000 kl/day and more
  • Fully / semi-automatic controls


  • Concert tank design enhance longevity
  • Flexible Positing of tanks
  • Expandable and flexible designs
  • Completely above ground installation.
  • Easy to install &expand.
  • High removal efficiency for nitrogen, BOD & COD,
  • Treated Water reuse in irrigation and grey water applications.
  • Minimum maintenance requirements.
  • Full technical, installation and operation support from trained and experienced Shubham Team.
  • Proven Technology with reliable performance.
  • Reuse of Wastewater in gardening application.


Onsite Sewage Treatment Plants are ideal for the following applications:

  • Housing Project.
  • Schools & hostels.
  • Industrial Office &Parks.
  • Small Communities.
  • Recreational camps & travels trailer parks.
  • Shopping Centres.
  • Restaurants.
  • Resorts, Golf Courses and country clubs.
  • Rural Area Schools
  • Hospitals.

And Many more where sewage disposal & reuse is compulsory