How does the SBR reduce total nitrogen?
Nitrogen reduction in wastewater is a two-step process that requires an aerobic step followed by an anaerobic step. Since the aeration step comes first, this makes the process more complicated, since the primary settling portion of treatment plants is anaerobic.
If left alone in wastewater, nitrogen causes the following problems:
- Depletion of oxygen in the water.
- Causes algae blooms and eutrophication.
- Pollutes drinking water and can cause blue baby syndrome.
Nitrogen enters wastewater in some organic form, but once it hits the water, it quickly becomes ammonia or ammonium, depending on the pH of the water.
The Process of Nitrogen Reduction
2NH3 + 3O2 –> 2NO2 + 2H2O
2NO3- + O2 –> 2NO3- + 2H2O
2NO3- + 2CH2O + 2H+ –> N2O + 2CO2 + 3H2O
In order to promote nitrogen removal, a wastewater treatment plant has to create the environment that allows each step to take place. SBR’s create the conditions for these processes in a sequence of time throughout a cycle in a single reactor chamber, ergo the name Sequencing Batch Reactor.