Biological wastewater treatment is a process that seems simple on the surface since it uses natural processes to help with the decomposition of organic substances, but in fact, it’s a complex, not completely understood process at the intersection of biology and biochemistry.
Biological treatments rely on bacteria, nematodes, or other small organisms to break down organic wastes using normal cellular processes. Wastewater typically contains a buffet of organic matter, such as garbage, wastes, and partially digested foods. It may also contain pathogenic organisms, heavy metals, and toxins. The goal of biological wastewater treatment is to create a system in which the results of decomposition are easily collected for proper disposal. Scientists have been able to control and refine both aerobic and anaerobic biological processes to achieve the optimal removal of organic substances from wastewater.
The biological processes used to treat wastewater include subsurface applications, such as septic or aerobic tank disposal systems; many types of aeration, including surface and spray aeration; activated sludge processes; ponds and lagoons; trickling filters; and anaerobic digestion. Constructed wetlands and various types of filtration are also considered biological treatment processes.
These processes are usually divided into anaerobic and aerobic processes. “Aerobic” refers to a process in which oxygen is present, while “anaerobic” describes a biological process in which oxygen is absent.