Have you ever ‘visited’ a sewage treatment plant? In one of my science courses I did and was amazed at the amount of ‘agitation’ that the sewage received. It was always in the state of churning and bubbling, agitated of course by electrical pumps. The bright side of it all [if one can use that term with sewage] is that the process produces methane gas that can be used to generate the electricity used in the plant. Or burned off as in so many places that do not capture the gas.
A discovery has been made of a new type of bacteria, anammox, a name which identifies its anaerobic ammonium oxidation capabilities. This bacteria does not require oxygen [anaerobic] to survive as it does the work of oxidizing the ammonium [nitrogen] which is produced in the sewage treatment process.
An article in NewScience explains:
“Existing treatment plants use a lot of energy to get rid of the ammonium. The process uses bacteria that convert ammonium into nitrate, and the bugs that do this need oxygen, which must be constantly supplied to the treatment tanks by electric pumps. The nitrate is then converted into nitrogen gas by still more bugs, known as denitrifying bacteria. These require methanol, which must also be added to the mix.”
Thus these newly discovered bacteria are really workhorses, to mix a metaphor, that reduce energy consumption and eliminate two additional steps in the process. Hats off to anammox bacteria and to Gijs Kuenen at Delft University of Technology in the Netherlands and his colleagues- the scientists who discovered these ‘green’ bacteria.
The standard sewage process consumes an average of 44 watt-hours per day for each person who adds waste to the sewage system. However the newly discovered bacteria zero this out and, in fact, according to estimates, the process could generate 24 watt-hours per person per day. That is a net gain of 68 watt-hours per person per day. In a large city, that could add up to megawatts of energy saved for other purposes.
“This month the team will begin building a pilot plant to demonstrate the technology at the Dokhaven waste water treatment plant in Rotterdam, the Netherlands”