Environment

"New" microbe could find use in more efficient sewage treatment

"New" microbe could find use i...
Lead scientists Assoc. Prof. He Jianzhong (left) and Dr. Wang Qingkun, with a wastewater sample containing SND5 bacteria
Lead scientists Assoc. Prof. He Jianzhong (left) and Dr. Wang Qingkun, with a wastewater sample containing SND5 bacteria
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Lead scientists Assoc. Prof. He Jianzhong (left) and Dr. Wang Qingkun, with a wastewater sample containing SND5 bacteria
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Lead scientists Assoc. Prof. He Jianzhong (left) and Dr. Wang Qingkun, with a wastewater sample containing SND5 bacteria

Nitrogen and phosphorus are two of the key pollutants that have to be removed from sewage, and doing so typically involves two separate steps. Thanks to a newly-discovered bacterium, however, both could soon be removed at once.

Currently, most wastewater treatment plants use one type of microbe in one reactor to remove nitrogen from ammonia, and another type in another reactor to remove phosphorous from phosphates. Building and running the two reactors makes the whole treatment process more complex and expensive than it would be otherwise.

As a result, some plants instead combine both microbe types in a single reactor. Because the microorganisms compete with one another for resources, maintaining an optimal balance between them can be tricky. As a result, such two-in-one reactors typically aren't as efficient at pollutant removal.

Recently, however, scientists at the National University of Singapore discovered a new strain of nitrogen- and phosphorous-neutralizing bacterium called Thauera sp. strain SND5. It was found in a wastewater treatment plant in Singapore, after unexpectedly low levels of the two pollutants were noted in aerobic tanks at the facility.

The scientists now hope that plants could efficiently and effectively treat sewage utilizing a single reactor containing the bacteria. As an added bonus, those facilities would likely use considerably less electricity than is currently the case – this is due to the fact that SND5 has relatively low oxygen requirements, so the wastewater doesn't need to be as thoroughly aerated.

Additionally, while some of the presently used reactors incorporate microbes that release the greenhouse gas nitrous oxide, the "new" bacterium emits innocuous nitrogen gas.

The findings are described in a paper that was recently published in the journal Water Research.

Source: National University of Singapore

1 comment
bahbah
Waste water treatment plants use aeration to cultivate aerobic activated sludge. These contains thousands of different bacteria species that adapt themselves to the pollutants. It is unheard of using just one species of bacteria for the activated sludge. Now even if it was and only the phosphorus remained, that is easily deposited with lime giving calcium phosphate which is a valuable product. I am a little confused.