Secondary treatment is also referred to as biological treatment. This step basically replicates the self-cleaning capacity as it occurs in nature. A high concentration of bacteria in the water, known as activated sludge, in combination with, in case of aerobic treatment, a sufficient oxygen supply, will speed up this natural process.
The secondary treatment processes include the following:
- Aerobic biological treatment
- Bacterial optimisation (Selector)
- Effluent separation
- Anaerobic treatment