This decomposition results in simpler compounds. During anaerobic microbial decomposition many compounds are produc ed. The most notable compounds are carbon dioxide, methane, ammonia and hydrogen sulfide. Under cold conditions, bacterial activity is reduced, and can even stop, so complete anaerobic digestion cannot be obtained under Saskatchewan outdoor storage conditions. This situation results in odour emissions from the storage facil ity particularly when the manure is mixed and if the storage facility is not covered.
Aerobic bacteria break down organic material much faster than anaerobic bacteria.
Aerobic bacteria in the presence of dissolved oxygen convert organic matter to a stable for m such as carbon dioxide, water, nitrates and phosphates. Aerobic treatment results in reduced odour emissions, but can result in increased ammonia emissions. Loss of ammonia, which contains nitrogen, reduces the fertilizer value of manure and can contribute to acid rain. In order to stabilize and deodorize the manure, aeration has to be sufficient and long enough so all organic material is degraded. Aeration by circulation can be achieved by impellers that turn and create a vortex in the manure allowing for an even distribution of oxygen.