how to keep anammox in the treatment process

How to use anammox in wastewater treatment?

Different setups have been developed to apply Anammox in wastewater treatment. In the “two reactor nitritation-Anammox process“, ammonium is first partially oxidised to nitrite in an aerated reactor (partial nitritation). In a second stage the nitrite is reduced to elemental nitrogen using the remaining ammonium in the Anammox reactor.

What is the anammox process?

Anammox (Anaerobic Ammonium Oxidation) Bacteria combine ammonia and nitrite directly into dinitrogen gas. This allows a new and very efficient treatment possibility of wastewater. Large-scale treatment with the Anammox process is very complex in design, operation and maintenance.

What are the advantages of anammox?

Factsheet Block Body The Anammox process requires much less oxygen than conventional nitrification/denitrification processes resulting in important energy savings. Because autotrophic bacteria carry out Anammox, there is no need for organic carbon sources, which saves on chemical dosage costs.

How to cultivate anammox bacteria?

Therefore, anammox bacteria cannot be cultivated using standard microbiological techniques such as plating. Instead, they are cultivated in bioreactor systems where they can reach an enrichment level ranging between 74% (sequencing batch reactor – flocular biomass) and 98% (membrane bioreactor – planktonic cells).

What is anammox in wastewater treatment?

Anammox (Anaerobic Ammonium Oxidation) Bacteria combine ammonia and nitrite directly into dinitrogen gas. This allows a new and very efficient treatment possibility of wastewater. Large-scale treatment with the Anammox process is very complex in design, operation and maintenance.

What is the anammox process?

Anammox (anaerobic ammonium oxidation), which is a reaction that oxidizes ammonium to dinitrogen gas using nitrite as the electron acceptor under anoxic conditions, was an important discovery in the nitrogen cycle.

What is the role of anammox bacteria?

Anaerobic ammonia-oxidizing (anammox) bacteria are able to oxidize ammonia and reduce nitrite to produce N2 gas. After being discovered in a wastewater treatment plant (WWTP), anammox bacteria were subsequently characterized in natural environments, including marine, estuary, freshwater, and terrestrial habitats.

Where does anammox reaction occur?

The anammox process was originally found to occur only from 20 °C to 43 °C but more recently, anammox has been observed at temperatures from 36 °C to 52 °C in hot springs and 60 °C to 85 °C at hydrothermal vents located along the Mid-Atlantic Ridge.

Is anammox an nitrification?

Furthermore, the anammox process offers an attractive alternative to current wastewater treatment systems for the removal of ammonia-nitrogen (NH4-N). It also saves ~75% nitrification and 100% denitrification of the nitrogen cycle.

What are the electron donor and acceptor in the anammox process?

Anammox bacteria convert ammonium (NH4+) to dinitrogen gas (N2) using intracellular electron acceptors such as nitrite (NO2−) or nitric oxide (NO).

Which two nitrogen species are required substrates in anammox?

The use of ammonium and nitrite as sole substrates might suggest a simple metabolic system, but the contrary seems to be the case. Genome analysis and ongoing biochemical research reveal an only partly understood redundancy in respiratory systems, featuring an unprecedented collection of cytochrome c proteins.

Who discovered anammox bacteria?

Jos Schalk11In collaboration with the Fuerst group10, Jos Schalk11 discovered that this compartment contained large quantities (more than 10–15% of total cell protein levels) of a hydroxylamine oxidoreductase (HAO)-like enzyme, which we postulated was responsible for the oxidation of hydrazine to N2 gas.

In what way can nitrogen fixation happen?

Nitrogen fixation is the process by which nitrogen is taken from its molecular form (N2) in the atmosphere and converted into nitrogen compounds useful for other biochemical processes. Fixation can occur through atmospheric (lightning), industrial, or biological processes.

Where do ammonia oxidizing bacteria live?

THE ECOLOGY. Ammonia oxidising microorganisms are ubiquitous in the environment, including soils, freshwater and marine habitats, engineered ecosystems such as wastewater treatment plants and even human skin (Leininger et al.

What is the goal of anammox?

The goal of anammox is the removal of nutrients, i.e., nitrogen in the form of NH 4 + - N and NO 2 − - N. Therefore, under certain conditions the application of the anammox process is limited, for example, anaerobic digester effluent treatments. The supernatant from anaerobic digester effluents consists of high COD/biological oxygen demand (BOD) and NH 4 + - N. The removal of COD/BOD is not possible with anammox and, at the same time, a complex COD/BOD (the digester effluents are of mixture of many compounds and not always limited to formate, acetate, and propionate) can inhibit the growth of anammox. Moreover, as per the metabolic reaction of anammox ( Eq. [15.3] ), nearly 89% of nitrogen is removed as NH 4 + - N and NO 2 − - N whereas 11% of nitrogen is released in the form of NO 3 − - N. Under such stringent disposal limits, complete nitrogen removal is impossible with the nitrifying/anammox biomass. A complete organic and nitrogen removal from any source could be achieved by coupling anammox and denitrification. Moreover, the adaptation of simultaneous partial nitrification, anammox, and denitrification (SNAD) cultures in a single reactor could be helpful for achieving the goal of energy-neutral or energy-generating wastewater treatment systems with the capability of producing clean water ( Fig. 15.2 ). Therefore, the development of a system with anammox and denitrification is really useful, and can also offer complete organics and nitrogen removal from wastewater (s).

What is anammox in wastewater?

Biological nitrogen removal by the anaerobic ammonium oxidation (anammox) process is becoming increasingly recognized for applications in wastewater treatment plants (WTPs). This group of microorganisms has been widely found in a range of natural ecosystems and human-made systems with niche specificity. The metabolic reactions catalyzed by anammox bacteria based on stoichiometry and the PCR-based molecular tools used for identification/quantification are described in this chapter. Physical and chemical characteristics of conventional WTPs and the occurrence of anammox are analyzed and discussed. The advantages and limitations of the anammox system compared with conventional nitrogen removal processes are also addressed in detail. Finally, the current developments in anammox systems in various reactor systems, anammox coupling with other processes, and successful cases of anammox occurring in conventional WTPs in Taiwan are discussed. Future perspectives in applications of anammox for sustainable nitrogen removal and energy minimization are outlined.

What are the end products of anaerobic digestion?

The end products of anaerobic digestion are ammonia and methane. Methane is a renewable source of energy and it can be collected for electricity production in the gas phase. However, recovery of dissolved methane is difficult and it slowly releases into the environment and contributes to the greenhouse effect [133]. Therefore, it is desirable to remove dissolved methane along with ammonia from the digester effluent. A new process named nitrite-dependent anaerobic oxidation of methane (n-damo) has been developed. This n-damo process is catalyzed by Candidatus “ Methylomirabilis oxyfera ” bacteria [133]. Studies [133], [134] suggest the feasibility of coculturing n-damo and anammox bacteria for simultaneous removal of ammonia and methane in the near future.

What temperature does anammox reactor work?

As of this writing most of the anammox reactors are operated at a higher temperature range (≥30°C) and treat high-strength wastewater. The optimum range for the growth of anammox bacteria is between 30 and 40°C [9], [127]. The activities of the metabolic enzymes of anammox bacteria reduce as temperature decreases from the optimum value. Therefore, nitrite uptake by anammox bacteria ceases at lower temperature, and its accumulation in the reactor causes process inhibition [128]. Several reports suggest that the nitrogen removal rate of anammox reactors significantly decreases when temperature decreases from ≥30 to ≤20°C [129], [130]. Reactor operation in wastewater treatment plants at higher temperature (≥30°C) is not economical, whereas operation at lower temperatures (≤20°C) is challenging. On the other hand, few wastewater streams such as municipal wastewater have low ammonia concentration ( ≤ 50 mg NH 4 + - N / L).

What is fish technique?

FISH is a useful tool for culture-independent in situ identification of the target bacteria in environmental samples. Many investigations have used the FISH technique to collect both qualitative and quantitative data on anammox bacteria in environmental samples [25]. For this widely used technique on anammox bacteria, the specificity of the fluorochrome-labeled DNA oligonucleotide probe is one of the most important factors for successful application in practice [71], [72]. Most of the available probes used in FISH detection target the 16S rRNA genes of anammox bacteria, but a probe for the 23S rRNA gene has also been developed, i.e., the L-∗-Amx-1900-a-A-21 [73]. However, the high divergence (<87.1% similarity) among genera of anammox bacteria prevents the discovery of new anammox species [40], [74]. The FISH technique has been widely used to assess the abundance of anammox bacteria in various environmental samples, which has provided a quantitative distribution of anammox bacteria globally [75], [76]. Probe signal intensity can be enhanced by polynucleotide FISH [77] and catalyzed reported deposition FISH [78], [79], or by minimizing probe penetration problems and increasing hybridization efficiencies with different probe chemistries, nucleic acid FISH [80], and locked nucleic acid FISH [81]. Integration of FISH with other approaches can be carried out to gain more insight into the metabolic activity of anammox bacteria and extend the applications of FISH as a powerful technique.

What are the genes used in PCR for anammox?

In addition to the PCR amplification of the 16S rRNA gene, widely used in detection of anammox bacteria, functional gene biomarkers provide a more accurate account of the presence of anammox bacteria. Based on the anammox reactions, four core catalytic proteins are promising candidates for new PCR primer design: nitrite and nitrate reductases, hydrazine hydrolase, and hydrazine dehydrogenase [34]. Hydrazine dehydrogenase (HZO), also called the hydroxylamine oxidoreductase-like protein (HAO), targets three different clusters of HAO/HZO proteins [57], [58], but only HZO cluster 1 is considered the most suitable biomarker for anammox bacteria phylogenetic analysis. As of this writing, the hzo gene has been successfully used to detect anammox bacteria from various environmental samples, including wastewater treatment plants [17], [58], [59], [60], mangrove sediment [55], [61], estuaries [61], [62], coastal and deep ocean sediments [16], [55], [62], [63], hydrothermal vents [62], and oil reservoirs [15]. They collectively indicate that the hzo gene is a competitive functional biomarker for anammox bacteria detection because it gives a higher resolution for the community structure of anammox bacteria than that given by 16S rRNA genes [55].

Where are anammox bacteria found?

Anammox bacteria are ubiquitous and widely distributed in ecosystems including both surface and subsurface, freshwater and marine, natural wetlands, and artificial systems of wastewater treatment plants . This indicates their adaptability and evolution from the very beginning; the early anammox cells with the capability of coupling NH 4 + and NO 2 − / NO 3 − to form N 2 may have utilized the available inorganic N at low concentration and then evolved to those adapted to higher concentration of inorganic N and also assimilation of low-molecular-weight organic acids. The five known genera of anammox bacteria show a very clear phylogenic distinction in that the Scalindua genus is apparently distantly related to the other four genera. Such relationship is also correlated to their tolerance or adaptability to available inorganic N in the culture medium, in that Scalindua prefers a low concentration of inorganic N, e.g., open oceans [17] and freshwater wetlands [10], [12] without anthropogenic influence, whereas the other four grow actively in wastewater treatment plants and coastal wetlands and rivers where pollution by wastewater and surface runoff is apparent [17]. The evolutionary relationships among the anammox bacteria can provide key information on the driving force for the biological change in this group of microorganisms. Such information may enlighten us on climate change or anthropogenic impacts on the planet Earth.

What is anammox bacteria?

The discovery of the type of bacteria now commonly called anammox bacteria is quite recent. In the mid-1990s anaerobic oxidation of ammonium ion was observed in a wastewater denitrifying pilot plant1. Subsequently the bacteria commonly called anammox bacteria were isolated and identified2. At about that time, it was also discovered that anammox bacteria are responsible for the conversion of a great deal of ammonia and nitrite nitrogen to nitrogen gas in our oceans and seas. The characteristic of anammox bacteria that is of particular interest for wastewater treatment is their ability to convert ammonium ion and nitrite ion into nitrogen gas in an anaerobic environment.

What are the characteristics of anammox bacteria that are of particular interest for wastewater treatment?

The characteristic of anammox bacteria that is of particular interest for wastewater treatment is their ability to convert ammonium ion and nitrite ion into nitrogen gas in an anaerobic environment.

What happens if ammonia is oxidized?

If only half of the ammonia nitrogen in a wastewater flow were oxidized just to nitrite, then the remaining ammonia nitrogen and the nitrite nitrogen that has been formed could be converted to nitrogen gas by anammox bacteria in an anaerobic (absence of oxygen) environment. It turns out that this can be accomplished in a practical manner resulting ...

What is the next normal step in the nitrogen cycle?

The next normal step in the nitrogen cycle is oxidation of the ammonia nitrogen to nitrite ion (NO2-) by the appropriate aerobic bacteria and then oxidation of the nitrite ion to nitrate ion (NO3-) by another variety of aerobic bacteria. These oxidation processes taken together are called nitrification and require oxygen in order to take place.

How does nitrification work?

The nitrification that is required of most secondary wastewater treatment plants can be accomplished in a typical activated sludge wastewater treatment process by ensuring that there is adequate aeration to provide the necessary oxygen and by maintaining a long enough sludge retention time so that the slower growing nitrifying bacteria aren’t washed out of the system. With these steps the bacterial oxidation of ammonia nitrogen to nitrate (nitrification) will take place along with the bacterial oxidation of hydrocarbon BOD, as shown in the process flow diagram at the left. Nitrification, however, doesn’t remove the nitrogen from wastewater. It simply removes the oxygen demand, by converting ammonia nitrogen to nitrate nitrogen. If discharge of wastewater treatment effluent containing nitrate is a problem for the receiving body of water, then another process, denitrification, is also required.

Can anammox bacteria convert ammonia to nitrogen?

If only half of the ammonia nitrogen in a wastewater flow were oxidized just to nitrite, then the remaining ammonia nitrogen and the nitrite nitrogen that has been formed could be converted to nitrogen gas by anammox bacteria in an anaerobic (absence of oxygen) environment.

How does anammox work?

Anammox bacteria perform anaerobic ammonium oxidation in three consecutive reactions: the reduction of nitrite to nitric oxide, the condensation of nitric oxide and ammonium to the “rocket fuel” hydrazine, and the oxidation of hydrazine to dinitrogen gas ( Fig. 4 ). The oxidation of hydrazine releases four electrons that are proposed to be transferred to a membrane-bound cytochrome bc1 complex. Cytochrome c-type proteins might serve as intermediate electron carriers, also facilitating the shuttling of electrons to the reduction of nitrite (one electron) and the synthesis of hydrazine (three electrons). The electron transport could facilitate the translocation of protons by the bc1 complex across the anammoxosome membrane, giving rise to a proton motive force. This proton motive force could then be used by membrane bound ATPases to produce ATP in the cytoplasm. Some of the electrons from hydrazine oxidation are proposed to be shuttled towards carbon dioxide reduction for carbon fixation through the Wood–Ljungdahl pathway. To replenish these electrons, some of the nitrite is oxidized to nitrate. Finally, it is proposed that anammox bacteria have a detoxification system that keeps inhibitory compounds like hydroxylamine at low concentrations. This might be done through the very abundant cytochrome c-containing protein kustc1061 which can convert hydroxylamine to nitric oxide.

What is anammox in biology?

Abstract. 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.

What enzymes are involved in the anammox process?

Figure 10. The anammox process in planctomycetes. The enzymes nitrite reductase (NirS), hydrazine hydrolase (Hzh), and hydrazine oxidoreductase (Hzo) are represented with their putative subunit structures and cofactors. The proton-pumping cytochrome bc1 and the ATP synthase (ATPase) complexes are also shown in the anammoxosome membrane. QH 2 /Q represents the quinol/quinone pool.

What is the simplified model of the anammox cell plan and energy metabolism?

Simplified model of the anammox cell plan and energy metabolism. The anaerobic ammonium oxidation takes place inside the anammoxosome compartment and proceeds in three consecutive steps: The reduction of nitrite to nitric oxide by a nitrite reductase (Nir), the condensation of nitric oxide and ammonium to hydrazine by hydrazine synthase (HZS) and the oxidation of hydrazine to dintrigen gas by hydrazine dehydrogenase (HDH).

How many species of anammox are there?

So far, nine different anammox species divided over five genera have been enriched, but none of these are in pure culture. This number is only a modest reflection of a continuum of species that is suggested by 16S rRNA analyses of environmental samples. In their environments, anammox bacteria thrive not just by competition, but rather by delicate metabolic interactions with other N-cycle organisms. Anammox bacteria owe their position in the N-cycle to their unique property to oxidize ammonium in the absence of oxygen. Recent research established that they do so by activating the compound into hydrazine (N 2 H 4 ), using the oxidizing power of nitric oxide (NO). NO is produced by the reduction of nitrite, the terminal electron acceptor of the process. The forging of the N N bond in hydrazine is catalyzed by hydrazine synthase, a fairly slow enzyme and its low activity possibly explaining the slow growth rates and long doubling times of the organisms. The oxidation of hydrazine results in the formation of the end product (N 2 ), and electrons that are invested both in electron-transport phosphorylation and in the regeneration of the catabolic intermediates (N 2 H 4, NO). Next to this, the electrons provide the reducing power for CO 2 fixation. The electron-transport phosphorylation machinery represents another unique characteristic, as it is most likely localized on a special cell organelle, the anammoxosome, which is surrounded by a glycerolipid bilayer of ladder-like (“ladderane”) cyclobutane and cyclohexane ring structures.

What is anammox bacteria?

Anaerobic ammonium-oxidizing (anammox) bacteria oxidize ammonium with nitrite under anoxic conditions. The anammox process is currently used to remove ammonium from wastewater and contributes significantly to the loss of fixed nitrogen from the oceans. In this chapter, we focus on the ecophysiology of anammox bacteria and describe new methodologies ...

What is the role of anammox in the nitrogen cycle?

Anammox planctomycetes play an important role on the global cycling of nitrogen in the environment, especially within marine ecosystems, where they are a major microbial component of the world’s oceanic oxygen minimum zones (OMZs) and marine sediments ( Francis et al., 2007; Kuypers et al., 2005; Lam et al., 2009; Op den Camp et al., 2006; Schmid et al., 2007 ). OMZs are expected to increase with global warming so understanding their implications for nutrient cycling in the oceans is important for modeling climate change effects ( Lam et al., 2009 ). Marine anammox plancomycetes comprise a previously unsuspected important missing link in the global nitrogen cycle. It has been estimated that 50% of the molecular dinitrogen in the atmosphere originating from the oceans may have its origin in the ammonium-oxidizing activities of anammox plantomycetes ( Dietl et al., 2015 ). This activity may be linked to other elements of the marine ecosystem, such as the sinking behavior of zooplankton during diurnal cycles ( Bianchi et al., 2014 ). The anammox oxidation of ammonium may in addition have a role to play in nitrogen remediation of nitrogen-polluted groundwater ( Smith et al., 2015 ). This is important for modeling groundwater contributions to eutrophication of freshwater bodies, and perhaps via manipulation of anammox processes in such groundwater to enable remediation.

Ammonia Nitrogen in Wastewater and The Need For Treatment

Nitrification and Denitrification in The Traditional Nitrogen Removal Process

Background on Anammox Bacteria and Their Discovery

An Alternative Nitrogen Removal Process Using Anammox Wastewater Treatment

• Instead of oxidizing all of the ammonia nitrogen in a wastewater flow to nitrate and then denitrifying that nitrate nitrogen to nitrogen gas, as described above, anammox bacteria present an interesting alternative. If only half of the ammonia nitrogen in a wastewater flow were oxidized just to nitrite, then the remaining ammonia nitrogen and the ni...

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