Page 22 - March 2020 - WT Site

Technical Evaluation of Sequential Batch Reactors

Aeration, a component of SBR is considered to be the most energy-intensive process at wastewater treatment
plants as it consumes up to 65% of a plant’s total energy need.
By Dr Madhuri Damaraju

onventional aerobic treatment technologies based on on activated sludge process operating in batches. A 1983 U.S.EPA
activated sludge processes are predominantly applied report, summarized this by stating that “the SBR is no more than
Cfor the treatment of domestic wastewater. However, an activated sludge system which operates in time rather than in
there is a need for more efficient and cost-effective technologies space”. The difference between the two technologies is that the
to coincide with the financial constraints on the expansion of SBR performs equalization, biological treatment, and secondary
sewage treatment coverage in developing countries. Sequential clarification in a single tank using a timed control sequence. Many
Batch Reactor (SBR) is a potential technology which is flexible modifications in the system have been developed later with the
and effective for biological wastewater treatment for removal of anaerobic system, anaerobic-aerobic, intermittently operated,
biological oxygen demand (BOD) and also nutrient removal. SBR continuous flow etc. [1]. Sequential Batch Reactor (SBR) is a
systems are composed of one or more tanks which operate in potential technology which is flexible and effective for biological
batches. Biological Nutrient removal in SBR systems makes it wastewater treatment for removal of BOD and also nutrient
different from conventional activated sludge process, which are removal. SBR systems are composed of one or more tanks
effective in the removal of BOD. SBR involves stages such as fill, which operate in batches. Biological nutrient removal in SBR
react, settle, decant and idle. This study emphasizes the evaluation systems makes it different from a conventional activated sludge
of sequencing batch reactors technically. process, which is effective in the removal of BOD. SBR involves
stages such as fill, react, settle, decant and idle. Different design
1. Introduction: configurations have been developed with specific cycle times with
different lengths. It is an ideal system to control bioreaction inside
Quality of water is of major concern to humankind as it is the reactor. Therefore selecting different reaction condition like
concerned with the welfare of humans. Sources of pollution HRT, cycle times could be used as a tool to get higher removal
include domestic wastes, industrial wastes and agricultural wastes. efficiencies [2].
Industrial wastewater is the foremost concern for treatment as
the wastewater pollutants are high, hence very difficult to treat. 2. Technical Evaluation:
There are many technologies present in the market for treating 2.1. Stages in SBR:
various organic and inorganic pollutants in the wastewater. The
common unit processes include preliminary screening, primary Sequencing batch reactors are technically different from
clarification for physical separation of particles, secondary conventional activated sludge process (ASP). The difference
biological treatment for degradable organics removal and tertiary lies in conducting the experiments from the same basin, unlike
treatment for further removal of pollutants which is optional. having solids removal systems in conventional ASP. The stages
The most commonly adopted technique for secondary biological of treatment and the cycle times may depend on the type of
treatment is either aerobic activated sludge process or anaerobic treatment planned. It can be aerobic or anaerobic or both in
treatment. Sequential Batch reactors (SBR) is a technology-based the same basin which cannot be a case in conventional systems.

24 Water Today - The Magazine March 2020