In covered lagoons, which are less efficient than fixed-film anaerobic digesters, the digestive bacteria float around, making only random contact with the manure particles. In fixed-film digesters, the bacterial growth occurs on the surfaces of the internal media that the waste must flow over, thereby assuring frequent contact. In this way, higher volumes of wastewater can be processed.

The key to our waste management system is a natural biological process called anaerobic digestion that relies on microorganisms to transform animal manure into methane gas. Anaerobic digesters, which process waste under oxygen-free conditions, are different than conventional aerobic systems that use oxygen to treat the waste.