ISBR, the number 1 choice Connected Worldwide ISBR Bio-selector Technology

ISBR, the number 1 choice

For high quality effluent at low capital investment and operating costs using state-of-the-art advanced sequencing batch reactor technology

Connected Worldwide have supplied many plants throughout Europe, Africa and Asia


Minimal footprint, less equipment, less maintenance and minimal power use

Bio-selector Technology

For maximum process efficiency, enhanced sludge stability, inherent N & P removal without mixers

Improved SBR Wastewater Treatment

Water & Wastewater Treatment’s office is specialized in improved SBR wastewater treatment systems by using biological treatment processes to remove pollutants and impurities, resulting in a high quality treated effluent. With more than 30 years of experience in the improved SBR wastewater treatment industry, our team of engineers and scientists aim to provide the best possible treatment systems and technical expertise to our clients around the world.
For municipal or industrial wastewater treatment projects we offer design and supply of our ISBR, improved SBR wastewater treatment (improved sequencing batch reactor). Our services are well known to consultants and civil works contractors in the field of wastewater treatment. Improved SBR wastewater treatment, ISBR, is essentially an updated version of the CASS (Cyclic Activated Sludge System). We have built around 200 improved SBR wastewater treatment plants around the world, including two 150 MLD (150,000 m3/day) multi-level plants in Bangkok.

The improved SBR essentially comprises a three zone SBR basin with continuous inflow of wastewater.The water level is the same in all three zones. They are hydraulically connected, so they all start at BWL at the start of the cycle and rise to a max TWL just before the start of decant. but they don’t always fill to TWL, only during peak flows, generally the water level will be less than TWL.And also because it fills during settle, the max aeration level is always less than the TWL.

There is a recycle of sludge back from the decanter end of the basin back to the first zone, an un-aerated anaerobic selector zone. In the bio-selector, influent wastewater and RAS are intimately mixed but not aerated. Biological phosphorus release takes place. After the selector, the RAS/influent flows into the secondary zone which is aerated, but not enough to make the tank aerobic, it operates under anoxic conditions. The sludge recycle flow rate is around 15-20% of influent flowrate and operates throughout the cycle, aeration, settle, decant. We achieve Nitrogen-DN with the recycle sludge and bio-selector zone. No mixers needed. Only 4 hours process operation cycle.

ISBR the nr.1 choice for high quality effluent at low capital investment and operating costs using state-of-the-art improved sequencing batch reactor technology.

Improved SBR wastewater treatment offers valuable benefits in relation to footprint, less power use and maintenance due to less equipment. Bio-selector technology for maximum process efficiency, enhanced sludge stability, inherent N & P removal without the use of mixers. Optional disinfection by hypochlorite or UV and sludge treatment by filter presses or drying beds.

ISBR Design and Operation

The Improved Sequencing Batch Reactor (ISBR) is a biological wastewater treatment process which incorporates innovative process sophistication in a low cost, small footprint design, providing operational simplicity, flexibility and reliability not available in conventional activated sludge systems. The system has been used to treat domestic, municipal and a wide variety of industrial wastewater.

ISBR Process Cycle Operation

The ISBR utilizes a simple repeated time-based sequence of operation, which incorporates:

  • FILL – AERATION (for biological reactions)
  • FILL – SETTLING (for solids-liquid separation)
  • FILL – DECANTING (to remove treated effluent)

Completion of these three operations in the sequence described above constitutes a “cycle”, which is then repeated.

Preliminary Treatment

Primary sedimentation will NOT be required prior to the ISBR process, and secondary clarification / sedimentation will NOT be required after the ISBR process.

Waste Activated Sludge (WAS) Treatment

Waste (excess) sludge is reasonably well stabilized (due to the long sludge age in the ISBR) and the volume is minimal. This feature enables low cost waste sludge management options to be used for example, aerobic digestion / storage, then thickening/dewatering and disposal. The WAS will be automatically pumped to a storage tank before dewatering and disposal.

Phosphorus removal

The ISBR has inherent biological phosphorus removal which takes place in the tanks.

Future Expansion

For the future expansion, other ISBR basins would be added to the system. This will involve simply adding more tanks as and when required in a modular way utilizing common wall construction to minimize civil costs. Additional equipment (e.g. pumps, valves, decanters, aeration devices) would be added for each new tank, and the control system (PCC and MCC panels) would be upgraded with new starters etc.