Working principle and applicable process of aerobic wastewater treatment system

What is aerobic wastewater treatment?

Aerobic wastewater treatment systems use oxygen-supplying bacteria, protozoa and other specialized microorganisms to clean the water (as opposed to anaerobic systems, which do not require oxygen). These systems optimize the natural process of microbial decomposition to break down industrial wastewater pollutants so that they can be removed.

The organic pollutants broken down by these microorganisms are usually measured in terms of biological oxygen demand or BOD, which is the amount of dissolved oxygen required by aerobic organisms to break down organic matter into smaller molecules. High levels of BOD indicate elevated concentrations of biodegradable materials present in wastewater and may be caused by introduced pollutants such as industrial discharges, household fecal waste or fertilizer runoff.

How does an aerobic wastewater treatment system work?

Since these organisms require oxygen, aerobic systems require some method of supplying oxygen to the biomass through the addition of a wastewater treatment basin (which introduces air to the wastewater by creating a large surface area) and/or through the introduction of oxygen to the biomass through a combination of some type of mechanical aeration device.

Depending on the chemical composition of the wastewater in relation to the effluent requirements, biological wastewater treatment systems may consist of several different processes and many types of microorganisms. They also require specific operating procedures that will vary depending on the environment required to maintain optimal biomass growth rates for specific microbial populations. For example, aeration will typically need to be monitored and adjusted to maintain consistent dissolved oxygen levels to keep the system’s bacteria reproducing at the appropriate rate to meet discharge requirements.

In addition to dissolved oxygen, biological systems typically need to balance flow, load, pH, temperature and nutrients. Balancing the combination of system factors is where the biological treatment process can become very complex. Below are examples of some common types of aerobic biological wastewater treatment systems, including a brief description of how they function in an industrial wastewater treatment program, so that you can understand the types of technologies and systems that may benefit your industrial facility.