Soil scientists Ariel Szogi (left) and Matias
Vanotti examine a packed-bed bench reactor containing the anammox bacteria
immobilized in polymer gel beads.
Image courtesy Matias Vanotti.
Bacteria Propel Gains in Ammonia Removal
Pons July 22, 2005
Using an innovative bacterial process, Agricultural Research Service
(ARS) scientists are paving the way for
new, cost-efficient and large-scale methods of removing ammonia from livestock
In tests with anammox--a technology that uses rare anaerobic bacteria
to convert nitrite and ammonium to harmless dinitrogen gas--soil scientists
Szogi at ARS'
Plains Soil, Water and Plant Research Center in Florence, S.C., have scored
They're the first researchers to isolate from animal wastewater the
planctomycetes bacteria used in the anammox process. They've also highlighted
anammox's commercial potential by removing nitrogen from wastewater at rates
similar to those obtained using conventional methods.
Short for "anaerobic ammonium oxidation," anammox was discovered in
the Netherlands during the 1990s. The process is more energy-efficient than
traditional biological nitrogen-removal systems because only part of the
ammonium in wastewater needs to be nitrified, and it removes ammonium without
needing costly aeration or additives.
In tests in Florence and at a swine farm near Kenansville, N.C.,
Vanotti and Szogi achieved the high nitrogen-removal rates by improving the
bacteria's environment for reproduction. The bacteria's slow multiplication
makes their cultivation difficult. The scientists' isolation of the bacteria
from wastewater during these tests may make possible economical treatments for
high-ammonia effluents, because it shows that it may not be necessary to
cultivate the bacteria off-site. Vanotti added that although the researchers
have used anammox to remove up to 500 grams of nitrogen per cubic meter daily
from wastewater, their goal is to triple this rate within the next year.
The scientists have also launched a cooperative three-year project
with EMBRAPA, Brazil's agricultural
research agency, to develop a new-generation, cost-effective anammox-based
treatment of livestock wastewater. Vanotti said this treatment may reduce
nitrogen-treatment costs four-fold.
He discussed the anammox results earlier this week at the annual
international meeting of the American Society of
Agricultural Engineers, in Tampa, Fla.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.