UNLABELLED A major percentage (20 to 40%) of global marine fixed-nitrogen loss occurs in oxygen minimum zones (OMZs). Concentrations of O2 and the sensitivity of the anaerobic N2-producing processes of anammox and denitrification determine where this loss occurs. We studied experimentally how O2 at nanomolar levels affects anammox and denitrification rates and the transcription of nitrogen cycl...

Strict environmental restrictions force the aquaculture industry to guarantee optimal water quality for fish production in a sustainable manner. The implementation of anammox (anaerobic ammonium oxidation) in biofilters would result in the conversion of both ammonium and nitrite (both toxic to aquatic animals) into harmless dinitrogen gas. Both marine and freshwater aquaculture systems contain ...

Anaerobic ammonium-oxidizing (anammox) bacteria are key players in the global nitrogen cycle and responsible for significant global nitrogen loss. Moreover, the anammox process is widely implemented for nitrogen removal from wastewaters as a cost-effective and environment-friendly alternative to conventional nitrification-denitrification systems. Currently, five genera of anammox bacteria have ...

Elevated nitrogen removal efficiencies from ammonium-rich wastewaters have been demonstrated by several applications, that combine nitritation and anammox processes. Denitrification will occur simultaneously when organic carbon is also present. In this study, the activity of aerobic ammonia oxidizing, anammox and denitrifying bacteria in a full scale sequencing batch reactor, treating digester ...

The physiology of anaerobic ammonium oxidizing (anammox) aggregates grown in a sequencing batch reactor was investigated quantitatively. The physiological pH and temperature ranges were 6.7 to 8.3 and 20 to 43 degrees C, respectively. The affinity constants for the substrates ammonium and nitrite were each less than 0.1 mg of nitrogen per liter. The anammox process was completely inhibited by n...

Anaerobic ammonium-oxidizing (anammox) bacteria are divided into three compartments by bilayer membranes (from out- to inside): paryphoplasm, riboplasm and anammoxosome. It is proposed that the anammox reaction is performed by proteins located in the anammoxosome and on its membrane giving rise to a proton-motive-force and subsequent ATP synthesis by membrane-bound ATPases. To test this hypothe...

Partial nitritation/anammox (PANAM) technologies have rapidly developed over the last decade, but still considerable amounts of energy are required for active aeration. In this study, a non-aerated two-stage PANAM process was investigated. In the first-stage upflow fixed-film bioreactor, nitratation could not be prevented at ammonium loading rates up to 186 mg N l(-1) d(-1) and low influent dis...

Anaerobic ammonium-oxidizing (anammox) bacteria are the last major addition to the nitrogen-cycle (N-cycle). Because of the presumed inert nature of ammonium under anoxic conditions, the organisms were deemed to be nonexistent until about 15 years ago. They, however, appear to be present in virtually any anoxic place where fixed nitrogen (ammonium, nitrate, nitrite) is found. In various mar`ine...

Using new data for the concentrations and δN of the main nitrogen species of NO3 , NH4 , PON (particulate organic nitrogen) and N2 in the Black Sea, we studied the distributions of concentrations and δ N using a coupled physical–biogeochemical model including known biogeochemical processes and nitrogen isotopic fractionation. In the deep anoxic water N2 is supersaturated. This supersaturation r...

This study deals with the influence of heterotrophic growth on autotrophic nitrogen removal from wastewater in a granular sludge reactor. A mathematical model was set-up including autotrophic and heterotrophic growth and decay in the granules from a partial nitritation-anammox process. A distinction between heterotrophic bacteria was made based on the electron acceptor (dissolved oxygen, nitrit...