I was surprised and shocked when I read the news that the deaths were attributed to inhaling (CO2) carbon dioxide (and lack of oxygen) in the tank. The advice given was to use a small flame and see if the flame extinguishes before entering the tank. (Note: fire extinguishers produce CO2). This shows sheer ignorance on the part of the authorities and the general public, since I have not read anything to the contrary. If the advice given by the fire superintendent is to be followed there will surely be an explosion.
The gases produced in the sewer tank (also known as sewer gases) are hydrogen sulfide and methane. Both are colorless, highly toxic and extremely flammable materilas. These gases are produced due to anaerobic fermentation. Hydrogen sulfide at lower concentrations is known for its pungent (smell of rotten eggs) but not smelt at higher concentrations. It can quickly overcome unprepared workers. Since septic tanks are now the preferred method to dispose human waste, it can be a serious problem. To mitigate the dangers of inhaling toxic gases, the workers should wear gas masks with portable air. Most preferably, the owners of the septic tanks should seek advice from the Pollution Control Authorities before embarking on the cleaning of the tank. With fore-knowledge lives will be saved in the future. I think this information should be widely publicized. Themistocles
