Sequential Batch Reactor Treatment Technology


Activated sludge (AS) treatment is processed in a reactor with aeration. The activated sludge in the reactor uses the dissolved oxygen and transfers organics to carbon dioxide, water and other new microbes.The reaction is shown as below:

SBR is developed based on conventional AS. The basic principles are similar to AS, but the difference is that the continuous operation is changed to batch operation. The characteristics and advantages of SBR are:

  1. The reactor type of SBR is CSTR. However, wastewater can be added in a short time and it leads to the decrease of concentration with time. The concentration profile with time is the same as PFR.
  2. The demand of oxygen decreases with the decrease of concentration.
  3. The aeration tank can be used as settling tank, and sludge recycle equipment is not necessary.
  4. Under proper design, SBR also has the function of neutralization tank. If the non-aeration stage is also designed in SBR, the whole system can perform nitrification/denitrification and dephosphorization.

Generally speaking, SBR is processed with the sequential use of different reactors, which also means the operation is periodic. The time needed for a cycle of SBR operation is defined as “Cycle Time”. In one cycle, five stages are performed sequentially, and they are “Fill”, “React”, “Settle”, “Drain”, and “Idle”.

  1. Fill:The reactor is filled periodically.
  2. React:The organics is degraded by microorganisms and transferred to carbon dioxide and water in the “React” stage. The reaction time depends on the COD or BOD amount of the influent.
  3. Settle:The purpose of “Settle” stage is to separate microorganisms and treated water. In this stage, mixing and aeration are not worked.
  4. Drain:The upper clean water in the reactor after settling is discharged until set water level in “Drain” stage. The treated water is drained periodically.
  5. Idle:This stage is for the flexibility of reactor. However, once the idle time is too long, proper mixing and aeration is required.


  1. Chemical Industry
  2. Petrochemical Industry
  3. Pulp & Paper Industry
  4. Food Industry


  • POU CHEN GROUP, VIETNAM (Process Wastewater;700CMD)
  • NIEN HSING TEXTILE CO., LTD.(TAIWAN) (Process Wastewater;2,400CMD)
  • SINONAR CORP. (Process Wastewater;200CMD)
  • CHOU CHIN INDUSTRIAL CO., LTD. (Process Wastewater;1,000CMD)
  • BAOTAI SHOE FACTORY (DONGGUAN CHINA) (Process Wastewater;6,400CMD)
  • UNI-PRESIDENT ENTERPRISES CORP. (Process Wastewater;6,000CMD)
  • SAN SHIN INDUSTRIAL CO., LTD. (IPA wastewater & domestic wastewater;202CMD)