Anaerobic ammonium oxidation discovered in a denitrifying fluidized bed reactor

Abstract

Until now, oxidation of ammonium has only been known to proceed under aerobic conditions. Recently, we observed that NH: was disappearing from a denitrifying fluidized bed reactor treating effluent from a methanogenic reactor. Both nitrate and ammonium consumption increased with concomitant gas production. A maximum ammonium removal rate of 0.4 kg N. me3 . d-' (1.2 mM/h) was observed. The evidence for this anaerobic ammonium oxidation was based on nitrogen and redox balances in continuous-flow experiments. It was shown that for the oxidation of 5 mol ammonium, 3 mol nitrate were required, resulting in the formation of 4 mol dinitrogen gas, Subsequent batch experiments confirmed that the NH: conversion was nitrate dependent. It was concluded that anaerobic ammonium oxidation is a new process in which ammonium is oxidized with nitrate serving as the electron acceptor under anaerobic conditions, producing dinitrogen gas.This biological process has been given the name 'Anammox' (anaerobic ammonium oxidation), and has been patented.

An overlooked nitrogen loss linked to anaerobic ammonium oxidation in estuarine sediments in China

“…Over a decade later, the existence of anammox bacteria was also predicted via chemical reaction thermodynamic calculations (Broda 1977). Heterotrophic denitrification was considered to be the only known pathway for the loss of fixed nitrogen to the atmosphere for decades until the discovery of anammox bacteria in a wastewater treatment plant (Mulder et al 1995). Subsequently, anammox bacteria were detected with broad biogeographic distribution in various natural ecosystems, including marine sediments (Thamdrup and Dalsgaard 2002;Trimmer and Nicholls 2009;Brabandere et al 2014;Shao et al 2014;Dang et al 2016), estuarine sediments (Dale et al 2009;Dang et al 2010;Li et al 2011;Wang et al 2012a, b;Dang et al 2013), and paddy soils (Zhu et al 2011;Nie et al 2015;Yang et al 2015).…”

Modeling denitrification in aquatic sediments

“…The possibility of anammox was 9 originally suggested by Richards et al (1965) and invoked by various investigators based 10 on pore water solute profiles (Bender et al 1989) before the discovery of organisms that 11 can carry out this process. Anammox was first observed in a wastewater bioreactor 12 (Mulder et al 1995). Anammox organisms have been purified from wastewater reactor 13 biomass and identified in several natural marine systems, such as the suboxic zone of the 14 Black Sea and the Benguela upwelling system (Kuypers et focused on source-transport models for streams, lakes and rivers.…”

Experimental Study on Hydrodynamic Performance and Heat Transfer Mechanism of Vapor-liquid-solid Three-Phase Fluidized Bed

“…The inert particles fluidized bed evaporation experiment device is designed and built combined with the characteristics of food material concentration [13]. In this experiment, the heat transfer mechanism and hydrodynamic performance of inert particle fluidized bed evaporator during extraction of concentrated green tea are studied, and the impact of various experimental operation parameters on the evaporation and heat transfer performance as well as pressure dropping are analyzed [14]. Moreover, the dimensionless analysis method is used to establish a correlation formula between the heat transfer coefficient and the pressure drop dimensionless number of inert particle fluidized bed evaporator according to the characteristics of inert particles fluidized bed.…”