MAN HOLE DEATHS- THE DARK SIDE OF FERMENTATION GASES

Again we are awakened by the news of the death of workers working in the man hole.
SUBANG JAYA: A Bangladeshi kitchen hand and a Nepalese security guard died while two other foreigners were hospitalised after inhaling dangerous fumes in a manhole behind the Subang Parade shopping complex. ( The Star 11 Feb 2011)
The most likely cause of the death is probably difficulty in breathing due to low oxygen content and the high concentration of methane gas in the man hole.
It is not surprising that there is a connection between the low oxygen gas and the production of methane. Methane as an anaerobic gas are only produced by the very strict and obligate anaerobes such as the methanogen bacteria. The very low dissolved oxygen promotes the anaerobic digestion process to produce methane bacteria and methane gas.
Despite what is being said above even though the conditions are anaerobic, methane would still not be produced if there is no decaying or rotting organic matter. There is the need for water, as well as the organic substrate to produce the methane.
It is easy to imagine where the organic matter comes from or even the source of water.
The often high temperature in the manholes and conduits help in the acceleration of the organic decay resulting in the higher production rate of methane.
Methane as a gas need the escape route. This is one reason why septic tanks, landfills are often equipped with these pipes to prevent the buildup of methane gas in enclosed spaces. Adding insult to injury most of these manholes are often not serviced and air tight which prevent the methane gas from escaping
It is easy to detect ammonia or hydrogen sulphide due to their foul odour, but in the case of carbon dioxide and methane you cannot smell it, and it might be too late to realize that they are there…
It is essential that most involved in the design and servicing of these sewers, man holes to be educated, aware and properly trained and equipped in the face of these silent killers….

Type rest of the post here.