Aerobic digestion is usually employed as a second-stage Wastewater Treatment process and kicks in after larger contaminants have been removed from the waste stream using filtration or sedimentation techniques.
Aerobic treatments are popular because they offer a cheap and efficient way of removing contamination in situations where there is lots of organic material in the wastewater.
It is a biological process where microorganisms degrade organic contaminants in the absence of oxygen. In a basic anaerobic treatment cycle, wastewater enters a bioreactor receptacle. The bioreactor contains a thick, semi-solid substance known as sludge, which is comprised of anaerobic bacteria and other microorganisms. These anaerobic microorganisms, or “anaerobes,” digest the biodegradable matter present in the wastewater, resulting in an effluent with lower biological oxygen demand (BOD), and chemical oxygen demand (COD), and/or total suspended solids (TSS), as well as biogas by-products.
Anaerobic technologies are typically deployed for streams with high concentrations of organic material (measured as high BOD, COD, or TSS), often prior to aerobic treatment. Anaerobic treatment is also used for specialized applications, such as treatment of waste streams with inorganics or chlorinated organics, and is well-suited for treating warm industrial wastewater