Methane gas production is a known occupational hazard for workers in the wastewater storage, transport and treatment industries. Anaerobic bacteria are the primary producers of the methane gas in the wastewater system. Methane is highly flammable and explosive at a range of 5-15 percent. It is violently reactive with oxidizers, halogens and some halogen-containing compounds. Most facilities release the methane gas to the atmosphere from the digester by combustion in a gas engine or ﬂared. This results in methane emissions that prevent substantial build-up in the facility and protects workers from its dangerous properties. But some facilities are recapturing the methane gas as a means of powering their own energy needs.
Farmers in Germany learned the hard way recently that methane gas can be an occupational hazard for them as well. The flatulence and belching of the 90 dairy cattle kept in a barn had released enough methane gas that a simple spark from static electricity nearly blew the roof off. None of the workers were injured, but one of the cattle did have minor burns. Definitely something to consider the next time any of us drive by a dairy farm.