Anammox
Anammox is an acronym made up of the words Anaerobic ammonium oxidation. The anaerobic ammonium oxidation is a biological process from the area of the nitrogen cycle.
As the name suggests, the Anamoxidation is an oxidation process that takes place without oxygen ( anaerobic). Here, ammonium (NH4 ) is reacted with nitrite (NO2 - ) under anaerobic conditions to molecular nitrogen (N2 ):
Under standard conditions, per mole of oxidized ammonium is doing 357.8 kJ of energy released ( ΔG0 '= -357.8 kJ ).
Anammox organisms
The anammox reaction was first observed in the 1980s in a wastewater treatment plant in Delft in the Netherlands. This is due to the previously neglected bacterium Candidatus Brocadia anammoxidans. Beginning of 2006 were won by a European consortium of researchers insights into the evolution and metabolism of known only a few years bacterium. Besides Brocadia anammoxidans the anammox process was sorokinii also observed in the bacteria Kuenenia stuttgartiensis and Scalindua; while the former are freshwater organisms, Scalindua lives in the sea.
The genotype by Candidatus Brocadia counts anammoxidans clearly to the bacteria, but the microbes possess organelles as ( eukaryotes ) is actually common only in the complicated structured eukaryotes. The cell wall of the bacteria, however, is similar to the purple of archaea. Brocadia anammoxidans uses the anammox reaction to produce energy, the toxic intermediate hydrazine is formed. The key enzyme of the reaction, hydroxylamine oxidoreductase, is located in a special organelle, the Anammoxosom. Ladder-type chains of carbon rings ( ladderanes ), which are anchored to the membrane of the Anammoxosoms via ether bridges, form a unique structure and prevent the hydrazine leaves the organelle.
Importance for wastewater treatment
The anammox process is not only of academic interest, but offers a promising alternative to current methods of wastewater treatment plants to remove nitrogen compounds. Probably for this reason already several patents have been granted in connection with the anammox process. In contrast to the typical biological clarification stages microbes Brocadia anammoxidans requires no oxygen and consumes even to the greenhouse gas carbon dioxide. The costs are reduced to about 10 %, while the carbon dioxide emissions reduced by 88%. For the development of biological processes carried out in the 90s, studies on the microbiological correlations of nitrification / denitrification, and in particular the increasing knowledge of inhibitory mechanisms designed within the nitrogen reaction, the basis for the development of appropriate procedures under targeted use of these mechanisms. Examples here to mention the studies in Vienna ( Nowak and Svardal, 1993; Nowak, 1996), Delft (van Niel et al, 1993;. Van Loosdrecht and Jetten, 1998) and Hanover ( Abeling, 1994; hip, 1999). The world's first commercial-scale plant based on anammox was taken as part of a project funded by the State of North Rhine -Westphalia research project in 2000 on the Ruhrverband conditioning Hattingen in operation. In Gelsenkirchen, the method is applied on a large scale since 2002. This was proved by the University of Duisburg -Essen in 2004. In Rotterdam, one of these advantages since early 2006. At the present time are a variety of methods systems on the market. To what extent they each meet the requirements of an economic and operational stable operation will be revealed in the coming years with increasing experience of large industrial plants using these systems.
Ecological Significance
It was previously assumed that the so-called denitrification ( stepwise bacterial reduction of nitrate to nitrogen gas by organic substances in oxygen deficiency) is responsible for the release of nitrogen alone. The discovery of bacterial anaerobic ammonium oxidation thus has far-reaching consequences for our understanding of the nitrogen cycle. Of particular importance for the global nitrogen cycle has the anammox in the oceans.
The mathematical models that describe the global nitrogen balance must now be revised, because this newly discovered nutrient sink has a direct influence on the calculation of the carbon cycle and hence long -term climate assessments.