There are many different strategies for providing aeration within different configurations of treatment systems. The simplest consist of aeration devices placed in traditional lagoon or pond structures. Low-level aeration for the purpose of odor control can frequently be accomplished with various types of surface aerators. Air diffusers can be placed along the bottom of ponds or lagoons to provide a medium level of aeration.
Complete treatment, including BOD and nitrogen removal, requires more intensive aeration. High levels of aeration are usually associated with designed reactor systems (e.g., tanks or towers), rather than with pond or lagoon structures. For efficient treatment, these systems are usually designed to retain microbial biomass in the system. Microbes can be retained in the system by allowing them to settle before treated liquid is removed or by immobilizing the microbes on attachment surfaces (sometimes called “fixed media”) or in gels. Examples of such systems include activated sludge (similar to traditional municipal wastewater treatment systems), sequencing batch reactors (SBR), and fixed media reactors.
Use of aerobic treatment for nitrogen removal can be enhanced by combining with other forms of treatment. Solids separation and anaerobic digestion have been used to reduce the load of organic material (BOD) so that oxygen introduced in the aeration step can be used more efficiently for nitrogen removal. This can also make odor reduction more effective.
Aerated systems have not been widely used for manure treatment, and additional field testing is needed.
Additional information on aeration is available in this article:
Aerobic Manure Treatment.
Author: Sarah Liehr, North Carolina State University
