Anammox

Autotrophic denitrification was measured in the southwestern coastal Black Sea, where the Bosporus Plume injects oxidized chemical species (especially O 2 and NO − 3) into the oxic, suboxic, and anoxic layers. Prominent oxygen intrusions caused an overlap of NO − x and sulfide at the same station where autotrophic denitrification activity was detected with incubation experiments. Several bacteria that have been proposed to oxidize sulfide in other low oxygen environments were found in the Black Sea including SUP05, Sulfurimonas, Arcobacter, and BS-GSO2. Comparison of TRFLP profiles from this mixing zone station and the Western Gyre (a station not affected by the Bosporus Plume) indicate the greatest relative abundance of Sulfurimonas and Arcobacter at the appropriate depths at the mixing zone station.The autotrophic gammaproteobacterium BS-GSO2 correlated with ammonium fluxes rather than with sulfide fluxes and the maximum in SUP05 peak height was shallower than the depths where autotrophic denitrification was detected. Notably, anammox activity was not detected at the mixing zone station, though low levels of DNA from the anammox bacteria Candidatus Scalindua were present. These results provide evidence for a modified ecosystem with different N 2 production pathways in the southwest coastal region compared to that found in the rest of the Black Sea. Moreover, the same Sulfurimonas phylotype (BS139) was previously detected on >30 µm particles in the suboxic zone of the Western Gyre along with DNA of potential sulfate reducers, so it is possible that particle-attached autotrophic denitrification may be an overlooked N 2 production pathway in the central Black Sea as well.

Biological nitrogen fixation (BNF) supplies nutrient-depleted oceanic surface waters with new biologically available fixed nitrogen. Diazotrophs are the only organisms that can fix dinitrogen, but the factors controlling their distribution patterns in the ocean are not well understood. In this study, the relative abundances of eight diazotrophic phylotypes in the subtropical North Atlantic Ocean were determined by quantitative PCR (qPCR) of the nifH gene using probes. A total of 152 samples were collected at 27 stations during two GEOTRACES cruises; Lisbon, Portugal to Mindelo, Cape Verde Islands (USGT10) and Woods Hole, MA, USA via the Bermuda Time Series (BATS) to Praia, Cape Verde Islands (USGT11). Seven of the eight diazotrophic phylotypes tested were detected. These included free-living and symbiotic cyanobacteria (unicellular groups (UCYN) A, B and C, Trichodesmium, the diatom-associated cyanobacteria Rhizoselinia-Richelia and Hemiaulus-Richelia) and a γ-proteobacteria (Gamma A, AY896371). The nifH gene abundances were analyzed in the context of a large set of hydrographic parameters, macronutrient and trace metal concentrations measured in parallel with DNA samples using the PRIMER-E software. The environmental variables that most influenced the abundances and distribution of the diazotrophic phylotypes were determined. We observed a geographic segregation of diazotrophic phylotypes between east and west, with UCYN A, UCYN B and UCYN C and the Rhizosolenia-Richelia symbiont associated with the eastern North Atlantic (east of 40°W), and

Two bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH4–N m2 d1 and 3 g NO3–N m2 d1) and removal efficiencies (>62% for ammonia, 90–100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both ammonia and nitrate seems to have involved not only the conventional pathways of nitrification–denitrification. The nitrogen loading rate of both ammonia (0.8–2.4 g NH4–N m2 d1) and nitrate (0.6–3.2 g NO3–N m2 d1) seem to have influenced the respective removal rates.

Although the most common method of municipal reject water management is treating in the main fl ow of a wastewater treatment plant, an alternative method is purifying it separately in a side-stream. This helps to reduce the load of nitrogen and carbon entering the sewage treatment system. This paper reports the results of the application of the SBR for the treatment of anaerobic sludge digester supernatant. At a reduced dissolved oxygen (DO) concentration of 0.7 mg O 2 /l in the aeration phase, application of mixing phases and pH regulation at the beginning of the SBR cycle (pH 8) allowed to obtain a suitable Anammox infl uent (50/50 ammonium:nitrite). Applying low oxygen concentrations and a one-hour long mixing phase enabled heterotrophic denitrifi cation in the reactor. The partial use of organic compounds in this process resulted in a COD/N ratio in the effl uent of ca. 1, which is favourable for the Anammox infl uent.

The CANON (Completely Autotrophic Nitrogen removal Over Nitrite) process was successfully developed in an air pulsing reactor type SBR fed with the supernatant from an anaerobic sludge digester and operated at moderately low temperatures (18-24 • C). The SBR was started up as a nitrifying reactor, lowering progressively the dissolved oxygen concentration until reaching partial nitrification. Afterwards, an inoculation with sludge containing Anammox biomass was carried out. Nitrogen volumetric removal rates of 0.25 g N L −1 d −1 due to Anammox activity were measured 35 d after inoculation even though the inoculum constituted only 8% (w/w) of the biomass present in the reactor and it was poorly enriched in Anammox bacteria. The maximal nitrogen removal rate was of 0.45 g N L −1 d −1 . By working at a dissolved oxygen concentration of 0.5 mg L −1 in the bulk liquid, nitrogen removal percentages up to 85% were achieved.

Efficient treatment of reject water originating from sludge digestion process was achieved by implementing a moving bed bioreactor. Since the ongoing processes in the reactor were unclear, model development was chosen in order to map them. To describe biofilm processes a newly presented zero-dimensional biofilm model was chosen. Simulation data in the study of Plattes et al. were promising for municipal wastewater but it did not meet the expectations in case of wastewater with high ammonia content. Therefore four step nitrogen removal was implemented in the 0D biofilm model. Steady-state simulation showed that processes over nitrite were of great importance in the system. The results also indicated that to a certain degree ANAMMOX (anaerobic ammonia oxidation) reaction took place as well. The special structure of the moving bed bioreactor with protected microorganism colonies was assumed to be the reason for that.

Reduced fishery harvests and increased consumer demand for seafood have precipitated an increase in intensive fish farming, predominantly in coastal and open ocean net-pens. However, as currently practiced, aquaculture is widely viewed as detrimental to the environment and typical operations are vulnerable to environmental influences, including pollution and endemic diseases. Here we report the development of a land-based, marine recirculating aquaculture system that is fully contained, with virtually no environmental impact as a result of highly efficient biological waste treatment and water recycling. Over 99% of the water volume was recycled daily by integrating aerobic nitrification to eliminate toxic ammonia and, for the first time, simultaneous, anaerobic denitrification and anaerobic ammonium oxidation, to convert ammonia and nitrate to nitrogen gas. Hydrogen sulfide generated by the separated endogenous organic solids was used as an electron source for nitrate reduction via autotrophic denitrification and the remaining organic solids were converted to methane and carbon dioxide. System viability was validated by growing gilthead seabream (Sparus aurata) from 61 g to 412 g for a total of 1.7 tons in a record 131 days with 99% fish survival. Ammonia nitrite and nitrate did not exceed an average daily concentration of 0.8 mg/l, 0.2 mg/l and 150 mg/l, respectively. Food conversion values were 16% lower than recorded levels for net-pen aquaculture and saltwater usage of less than 16 l/every kg of fish produced. The system is site-independent, biosecure, devoid of environmental contaminants and is not restricted to a single species.

Pada penelitian ini akan dijelaskan mengenai bakteri annamox baru dengan relung yang telah ditentukan (spesifik) yaitu oksidasi karbon monoksida (co-oxidation) pada propionate dan ammonium. Hasil pada penelitian ini menunjukan bahwa spesies bakteri anammox Candidatus ‘‘Anammoxoglobus propionicus’’ dapat bersaing dengan bakteri pendenitrifikasi heterotrof maupun dengan bakteri anammox lain dalam mengoksidasi propionate dengan adanya ammonium, nitrit dan nitrat pada suatu habitat tunggal.

Studies on anaerobic ammonium oxidation (ANAMMOX) have been increasing due to its advantages over traditional nitrification-denitrification systems. However, long and difficult start-up periods of ANAMMOX reactors may sometimes be frustrating for researchers dealing with them first time in the lab. Therefore, a guide for starting up ANAMMOX reactors will greatly help them and enhance the use of this technology. Three trials, each has three reactors, have been carried out to reach successful start up in this study. An expected ANAMMOX enrichment could not be achieved in the first and second trials. Under the light of the experiences gained from the unsuccessful ones, the third trial resulted in >95% ammonium removals within 20-50 days. It is possible to startup or to enrich ANAMMOX reactors within 50 days by presented strategy guide.

This study examines control strategies developed for wastewater treatment via partial nitration and the anaerobic ammonium oxidation process with the objective of enhancing nitrogen removal efficiency. The implementation of different control strategies were analyzed and explained with the help of pictorial representations. The benefits of the different control strategies were also briefly discussed. The biological process of nitrogen removal requires appropriate pairing between control and manipulated variables. Furthermore, the approach to follow when selecting suitable candidates and determining the pairing criterion was discussed. Although the conventional feedback−feedforward control logic is easy to implement, incorporation of the nonlinearity and complexity associated with the processes requires the design of advanced control systems.

For more than 100 years it was believed that bacteria were the only group responsible for the oxidation of ammonia. However, recently, a new strain of archaea bearing a putative ammonia monooxygenase subunit A (amoA) gene and able to oxidize ammonia was isolated from a marine aquarium tank. Ammonia-oxidizing archaea (AOA) were subsequently discovered in many ecosystems of varied characteristics and even found as the predominant causal organisms in some environments. Here, we summarize the current knowledge on the environmental conditions related to the presence of AOA and discuss the possible site-related properties. Considering these data, we deduct the possible niches of AOA based on pH, sulfide and phosphate levels. It is proposed that the AOA might be important actors within the nitrogen cycle in low-nutrient, low-pH, and sulfide-containing environments.

Many countries strive to reduce the emissions of nitrogen compounds (ammonia, nitrate, NO x ) to the surface waters and the atmosphere. Since mainstream domestic wastewater treatment systems are usually already overloaded with ammonia, a dedicated nitrogen removal from concentrated secondary or industrial wastewaters is often more cost-effective than the disposal of such wastes to domestic wastewater treatment. The cost-effectiveness of separate treatment has increased dramatically in the past few years, since several processes for the biological removal of ammonia from concentrated waste streams have become available. Here, we review those processes that make use of new concepts in microbiology: partial nitrification, nitrifier denitrification and anaerobic ammonia oxidation (the anammox process). These processes target the removal of ammonia from gases, and ammonium-bicarbonate from concentrated wastewaters (i.e. sludge liquor and landfill leachate). The review addresses the microbiology, its consequences for their application, the current status regarding application, and the future developments.

h i g h l i g h t s COD/N ratio determined denitrifiers' and nitrifiers' species structure in granules. Denitrifiers that were common in granules and aided in granulation were identified. When Anammox and N 2 O-reducing consortia were most numerous, N removal was highest. In constantly aerated granules, nirK gene diversity was higher than that of nirS. As N loading increased, the aerobic to anaerobic ammonium-oxidizer ratio decreased.

Water is not enough. Nowadays, numerous chemicals are used for fire extinction. After use, however, these may unintentionally enter sewerage systems. In order to safely treat firefighting wastewater (FFWW), knowledge of the potential effects of these chemicals on biological treatment processes is essential. This study characterized and mimicked the composition of FFWW containing two powders, three foams and one foam degrader. Nitrogen (162-370 mg NH4(+)-N L(-1)) and phosphorus (173-320 mg PO4(3-)-P L(-1)) concentrations exceeded discharge limits, whereas chemical and biological oxygen demand, suspended solids and detergent concentrations remained sufficiently low. Adequate nutrient removal could be obtained through FeCl3 addition and nitrification/denitrification with acetate as substrate. In batch tests, residual nitrifying activities of 84, 81, 89, 95 and 93% were observed in the presence of powders, foams, foam degrader, synthetic and real FFWW, respectively. All categories showed higher denitrification rates than the control. Although the powders at first seemed to inhibit anammox activity at 82%, after pH correction anammox was fully feasible, allowing nitrogen removal through oxygen-limited nitrification/denitrification (OLAND). Detailed cost calculations indicated that OLAND could save 11% of capital and 68% of operational costs compared to nitrification/denitrification, identifying OLAND as the most recommendable process for nitrogen removal from firefighting wastewaters

Two bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH 4 -N m À2 d À1 and 3 g NO 3 -N m À2 d À1 ) and removal efficiencies (>62% for ammonia, 90-100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both ammonia and nitrate seems to have involved not only the conventional pathways of nitrification-denitrification. The nitrogen loading rate of both ammonia (0.8-2.4 g NH 4 -N m À2 d À1 ) and nitrate (0.6-3.2 g NO 3 -N m À2 d À1 ) seem to have influenced the respective removal rates.

This work describes the successful coupling of partial nitrification (nitritation) and anaerobic ammonium oxidation in a membrane-aerated biofilm reactor (MABR) with continuous aeration. Controlling the relative surface loadings of oxygen versus ammonium prevented complete nitrite oxidation and allowed anaerobic ammoniumoxidizing bacteria (AnaerAOB) to develop and be retained for > 250 days. Daily autotrophic nitrogen removal of 1.7 g N/m 2 (75% of influent N load) was achieved at an oxygen/nitrogen surface loading ratio of 2.2, with up to 85% of the influent N proceeding through AnaerAOB. During early nitritation, nitrogen oxide (NO (g) , NO 2(g) , and N 2 O (g) ) emissions comprised up to 10% of the removed influent nitrogen, but emissions disappeared after proliferation of AnaerAOB. Microbial communities were radially stratified, with aerobic ammonium-oxidizing bacteria (AerAOB) colonizing nearest to and AnaerAOB furthest from the membrane. Despite the presence of nitrite-oxidizing bacteria, this work demonstrated that these autotrophic processes can be successfully coupled in an MABR with continuous aeration, achieving the benefits of competitive specific N removal rates and the elimination of gaseous nitrogen oxide emissions.

this study reports an investigation of the concept, application and performance of a novel bioelectrochemical nitritation-anammox microbial desalination cell (MDC) for resource-efficient wastewater treatment and desalination. Two configurations of anammox MDCs (anaerobic-anammox cathode MDC (AnA mox MDC) and nitration-anammox cathode MDC (NiA mox MDC)) were compared with an air cathode MDC (CMDC), operated in fed-batch mode. Results from this study showed that the maximum power density produced by NiA mox MDC (1,007 mW/m 3) was higher than that of AnA mox MDC (444 mW/m 3) and CMDC (952 mW/m 3). More than 92% of ammonium-nitrogen (NH 4 +-N) removal was achieved in NiA mox MDC, significantly higher than AnA mox MDC (84%) and CMDC (77%). The NiA mox MDC performed better than CMDC and AnA mox MDC in terms of power density, CoD removal and salt removal in desalination chamber. In addition, cyclic voltammetry analysis of anammox cathode showed a redox peak centered at −140 mV Vs Ag/AgCl confirming the catalytic activity of anammox bacteria towards the electron transfer process. Further, net energy balance of the NiA mox MDC was the highest (NiA mox MDC-0.022 kWh/m 3 >CMDC-0.019 kWh/m 3 >AnA mox MDC-0.021 kWh/m 3) among the three configurations. This study demonstrated, for the first time, a N-E-W synergy for resource-efficient wastewater treatment using nitritation-anammox process. Water and wastewater infrastructure accounts for approximately 3-4 percent of national energy demand in the United States 1. More than 50 percent of the supplied energy is used to meet the aeration demands for carbon and nitrogen oxidation processes in wastewater treatment 2. This particular energy demand is anticipated to increase significantly in the near future as many wastewater treatment plants aim to meet the USEPA's strict regulations for nitrogen discharge (1.0 mg/L ammonium nitrogen for discharge to surface water and 10 mg/L total nitrogen (TN) for discharge to soil 1). Current treatment schemes utilize autotrophic nitrification followed by heterotrophic denitrification techniques for nitrogen removal, adding significant demands for aeration energy and supplemental carbon. There is a growing interest to develop energy-positive and resource-efficient processes that minimize energy consumption in conventional processes and nitritation-anammox process is considered as one of the most promising alternatives to conventional biological nitrogen removal process 3. The scientific rationale for the proposed nitritation-anammox process stems from the anammox reaction sto-ichiometry shown in Reaction R1. Strous et al. 4 described the physical purification of anammox bacteria, which oxidize ammonium to nitrogen gas anaerobically, with nitrite (NO 2 −) as an electron acceptor and fixed carbon from CO 2 as a sole carbon source for the growth of anammox biomass (CH 2 O 0.5 N 0.15), making the organism an autotroph (see reaction R1). 1NH 132NO 0066HCO 0 13H 0 26 NO 0 06CH O N 203H O 1 02N (R1) 4 2 3 3 2 0 5 0 15 2 2 +. +. +. →. +. +. +. + − − + −. . This anaerobic oxidation reaction is thermodynamically more favorable than the aerobic ammonia oxidation reaction. The reported Gibb's free energy value for the anammox process is −358 kJ mol −1 NH 4 + 5 , which is higher than the aerobic ammonia oxidation process (ΔG = −235 kJ mol −1 NH 4 +) 6. The oxidation of ammonium

A 1D mathematical model for analysis and prediction of microbial interactions within multispecies biofilms including Anammox pathway is presented. The model combines the related processes of organic carbon oxidation, denitrification, nitrification and Anammox and phenomena of substrate reaction and diffusion, biomass growth and advection, detachment. The biofilm growth process is governed by nonlinear hyperbolic PDEs and substrate dynamics are dominated by semilinear parabolic PDEs. It follows a complex system of PDEs on a free boundary domain. Equations are integrated numerically by using the method of characteristics as strongly suggested by the qualitative analysis of the free boundary value problem. Mass conservation equation plays an important role in checking the accuracy of simulations. The model has been applied to simulate Anammox competition and to evaluate the influence of substrate diffusion on microbial stratification. Specific scenarios are analyzed. The results reveal that in a thick multispecies biofilm, including heterotrophic, aerobic autotrophic nitrifying and Anammox bacteria, oxygen diffusion limitation determines the formation of both aerobic and anoxic microenvironments favouring interspecies competition. In contrast, oxygen excess causes a disturbance on microbial interactions leading to Anammox bacteria loss. The model predictions may help engineers or operators to have a better insight into biofilm dynamics in order to optimize process design or practical operation.

The phylum Planctomycetes of the domain Bacteria consists of budding, peptidoglycan-less organisms important for understanding the origins of complex cell organization. Their significance for cell biology lies in their possession of intracellular membrane compartmentation. All planctomycetes share a unique cell plan, in which the cell cytoplasm is divided into compartments by one or more membranes, including a major cell compartment containing the nucleoid. Of special significance is Gemmata obscuriglobus, in which the nucleoid is enveloped in two membranes to form a nuclear body that is analogous to the structure of a eukaryotic nucleus. Planctomycete compartmentation may have functional physiological roles, as in the case of anaerobic ammonium-oxidizing anammox planctomycetes, in which the anammoxosome harbors specialized enzymes and is wrapped in an envelope possessing unique ladderane lipids. Organisms in phyla other than the phylum Planctomycetes may possess compartmentation similar to that of some planctomycetes, as in the case of members of the phylum Poribacteria from marine sponges. 299 Annu. Rev. Microbiol. 2005.59:299-328. Downloaded from arjournals.annualreviews.org by University of Queensland on 11/29/07. For personal use only.

Life Cycle Assessment (LCA) is a tool to assess the environmental sustainability of a product; it quantifies the environmental impact of a product's life cycle. In conventional LCAs, the boundaries of a product's life cycle are limited to the human/industrial system, the technosphere. Ecosystems, which provide resources to and take up emissions from the technosphere, are not included in those boundaries. However, similar to the technosphere, ecosystems also have an impact on their (surrounding) environment through their resource usage (e.g., nutrients) and emissions (e.g., CH 4 ). We therefore propose a LCA framework to assess the impact of integrated Techno-Ecological Systems (TES), comprising relevant ecosystems and the technosphere. In our framework, ecosystems are accounted for in the same manner as technosphere compartments. Also, the remediating effect of uptake of pollutants, an ecosystem service, is considered. A case study was performed on a TES of sawn timber production encompassing wood growth in an intensively managed forest ecosystem and further industrial processing. Results show that the managed forest accounted for almost all resource usage and biodiversity loss through land occupation but also for a remediating effect on human health, mostly via capture of airborne fine particles. These findings illustrate the potential relevance of including ecosystems in the product's life cycle of a LCA, though further research is needed to better quantify the environmental impact of TES.

The bacteria that mediate the anaerobic oxidation of ammonium (anammox) are detected worldwide in natural and man-made ecosystems, and contribute up to 50% to the loss of inorganic nitrogen in the oceans. Two different anammox species rarely live in a single habitat, suggesting that each species has a defined but yet unknown niche. Here we describe a new anaerobic ammonium oxidizing bacterium with a defined niche: the co-oxidation of propionate and ammonium. The new anammox species was enriched in a laboratory scale bioreactor in the presence of ammonium and propionate. Interestingly, this particular anammox species could out-compete other anammox bacteria and heterotrophic denitrifiers for the oxidation of propionate in the presence of ammonium, nitrite and nitrate. We provisionally named the new species Candidatus ''Anammoxoglobus propionicus''.

CANON Granule Autotrophic nitrogen removal Microbial community Microscale distribution abstract The application of microelectrodes to measure oxygen and nitrite concentrations inside granules operated at 20 C in a CANON (Complete Autotrophic Nitrogen-removal Over Nitrite) reactor and the application of the FISH (Fluorescent In Situ Hybridization) technique to cryosectioned slices of these granules showed the presence of two differentiated zones inside of them: an external nitrification zone and an internal anammox zone. The FISH analysis of these layers allowed the identification of Nitrosomonas spp. and Candidatus Kuenenia Stutgartiensis as the main populations carrying out aerobic and anaerobic ammonia oxidation, respectively. Concentration microprofiles measured at different oxygen concentrations in the bulk liquid (from 1.5 to 35.2 mg O 2 L À1 ) revealed that oxygen was consumed in a surface layer of 100e350 mm width. The obtained consumption rate of the most active layers was of 80 g O 2 (L granule ) À1 d À1 . Anammox activity was registered between 400 and 1000 mm depth inside the granules. The nitrogen removal capacity of the studied sequencing batch reactor containing the granular biomass was of 0.5 g N L À1 d À1 . This value is similar to the mean nitrogen removal rate obtained from calculations based on in-and outflow concentrations. Information obtained in the present work allowed the establishment of a simple control strategy based on the measurements of NH 4 þ and NO 2 À in the bulk liquid and acting over the dissolved oxygen concentration in the bulk liquid and the hydraulic retention time of the reactor.

Anaerobic ammonium oxidizing (anammox) bacteria own a central position in the global N-cycle, as they have the ability to oxidize NH4+ to N2 under anoxic conditions using NO2−. They are responsible for up to 50% of all N2 released from marine ecosystems into the atmosphere and are thus indispensible for balancing the activity of N-fixing bacteria and completing the marine N-cycle. The contribution, diversity, and impact of anammox bacteria in freshwater ecosystems, however, is largely unknown, confounding assessments of their role in the global N-cycle. Here we report the activity and diversity of anammox bacteria in the world’s largest freshwater lake—Lake Superior. We found that anammox performed by previously undiscovered bacteria is an important contributor to sediment N2 production. We observed striking differences in the anammox bacterial populations found at different locations within Lake Superior and those described from other locations. Our data thus reveal that novel anammox bacteria underpin N-loss from Lake Superior, and if more broadly distributed across inland waters would play an important role in continental N-cycling and mitigation of fixed nitrogen transfer from land to the sea.

The performance of two selected high rate anammox reactors, i.e. sequencing batch reactor (SBR) and an upflow biofilter (UBF) were compared operating them simultaneously at 30 °C. The sludge from anaerobic digester of a municipal wastewater treatment plant was used for inoculation and synthetic wastewater was fed to both reactors during the experiment. During start-up, the nitrogen loading rate (NLR) was increased gradually from an initial 140 to 560 mg/l day. The comparison of the performance revealed that the NLRs of SBR (2.7 g/l day) and UBF (2.5 g/l day) were far higher than those of the traditional nitrification/denitrification process. The biomass production of SBR outcompeted that of UBF. SBR took a longer time for start-up, i.e. about 57 days compared with 31 days of UBF. Moreover, SBR tolerated smaller pulse of substrate concentration and hydraulic load, showing a weaker stability compared with UBF.

The existence of anaerobic ammonia-oxidizing (anammox) bacteria was postulated in the late 1970s. Approximately 20 years later, these lithotrophic members of the nitrogen cycle were identified as deep-branching members of the planctomycetes. Recently, full-scale implementation of biological deammonification was successfully achieved in the DEMON® reactor at the wastewater treatment plant in Strass, Austria. The sludge of this reactor contains red

Effluent from a fish tank with Nile tilapia (Oreochromis niloticus) was treated in a system of two parallel fixed-bed anaerobic reactors followed by a suspended stirred, anoxic reactor for solids, organic matter and nitrogen removal. Microbial community structure was compared between the reactors and an enriched anammox culture originated from anaerobic sludge by using the PCR (Polymerase Chain Reaction) and DGGE (Denaturing Gradient Gel Electrophoresis) techniques. DGGE analysis revealed three large microbial clusters, namely, the biomass in the inoculum, the biomass growing in the reactors, and the enriched anammox culture. The similarity between the microbial community recovered from the anaerobic reactors and the anammox community was considered low (32.7%), suggesting differentiation of the bacterial community as a function of the selection of specific anammox groups. The last step in the anoxic reactor had worsened the effluent quality. The potential of organic matter and ammonia removal in a single anaerobic reactor was demonstrated.

This paper describes an experimental method used to evaluate the anaerobic ammonium oxidation (Anammox) decay coefficient by means of a batch test. The test was carried out using an experimental procedure based on manometric measurements of the dinitrogen gas that is produced by the Anammox process. The accuracy of the procedure had previously been assessed, and the method was used to determine the specific Anammox activity (SAA mg N 2 -N g VSS −1 d −1 ,) and the maximum nitrogen production rate (MNPR, NmL N 2 L −1 d −1 ) under several different conditions. A specific batch test, which lasted for 148 days, was performed to assess the decay coefficient. The activity decrease was monitored and the estimated value of the decay coefficient was found to be 0.0048 d −1 at 35 • C, for which the corresponding half-life time of the Anammox biomass was 145 days. This value is higher than other values reported in the literature, but in accordance with the slow growth rate of the Anammox bacteria.

We studied microbial N 2 production via anammox and denitrification in the anoxic water column of a restored mining pit lake in Germany over an annual cycle. We obtained high-resolution hydrochemical profiles using a continuous pumping sampler. Lake Rassnitzer is permanently stratified at ca. 29 m depth, entraining anoxic water below a saline density gradient. Mixed-layer nitrate concentrations averaged ca. 200 mmol L À1 , but decreased to zero in the anoxic bottom waters. In contrast, ammonium was o5 mmol L À1 in the mixed layer but increased in the anoxic waters to ca. 600 mmol L À1 near the sediments. In January and October, 15 N tracer measurements detected anammox activity (maximum 504 nmol N 2 L À1 d À1 in 15 NH 4 + -amended incubations), but no denitrification. In contrast, in May, N 2 production was dominated by denitrification (maximum 74 nmol N 2 L À1 d À1 ). Anammox activity in May was significantly lower than in October, as characterized by anammox rates (maximum 6 vs. 16 nmol N 2 L À1 d À1 in incubations with 15 NO 3 À ), as well as relative and absolute anammox bacterial cell abundances (0.56% vs. 0.98% of all bacteria, and 2.7 Â 10 4 vs. 5.2 Â 10 4 anammox cells mL À1 , respectively) (quantified by catalyzed reporter depositionfluorescence in situ hybridization (CARD-FISH) with anammox bacteria-specific probes). Anammox bacterial diversity was investigated with anammox bacteria-specific 16S rRNA gene clone libraries. The majority of anammox bacterial sequences were related to the widespread Candidatus Scalindua sorokinii/brodae cluster. However, we also found sequences related to Candidatus S. wagneri and Candidatus Brocadia fulgida, which suggests a high anammox bacterial diversity in this lake comparable with estuarine sediments.

The start-up period of Anammox systems is still a big challenge due to the unavailability of large volumes of slowly growing Anammox seed locally in most countries. This study aims to evaluate the effects of seeding strategy on the start-up and enrichment period of Anammox systems by monitoring both process performance and microbial population dynamics. Two different seeding strategies, the use of mixed activated sludge culture from a local STP and the use of enriched Anammox culture transported from abroad, were comparatively studied in SBR systems operated for 410 days. The enriched Anammox seed from abroad inhibited seriously during transportation. Anammox activity re-started after 195 days' recovery period. An active Anammox culture was successfully enriched within 95 days from a local activated sludge source without seeding any Anammox. The Anammox population reached levels of 1011 copies/ng at the end of 410 days' enrichment period. Based on FISH, Ca. Brocadia anammoxi...

The hypothesis is formulated that in case of oxygen limitation in the sediment, nitrifiers switch from nitrification to oxygen-limited autotrophic nitrificationdenitrification (OLAND) in order to survive and maintain activity. During OLAND, ammonium is oxidised using nitrite as e-acceptor to form dinitrogen gas. As an additional advantage they benefit from the gaseous N 2 formed as a means of transport. In this way, the nitrifiers can move out of the sediment and rise through the water column towards more favourable conditions. At the surface, the bacteria could take up oxygen, and recommence nitrification. In order to test this hypothesis, nitrifying sediment with an overlaying water column was simulated in lab-scale columns. Nitrogen transformations and material transport through the water column were followed after addition of different forms of nitrogen under oxygen-limited conditions. 15 N-labelling experiments showed a large contribution of OLAND to the observed nitrogen deficits. Nitrifier enumerations, fluorescent in situ hybridisation and 16S rRNA gene analysis revealed increased populations of ammonia oxidising nitrifiers in the upper water layers. The results presented support the proposed hypothesis of transport using OLAND. Nitrifying activity in the sediment immediately recovered almost completely from prolonged oxygen-limited incubation when oxygen concentrations were increased.

Anammox is a cost-effective and sustainable process for nitrogen removal; however, the production of a physiologically stable inoculum is a critical point in the start-up process. In this work, estuarine sediments were used as incubation seeds to obtain cultures with stable anammox activity. Assays were performed in batch cultures fed with stoichiometric amounts of ammonium and nitrite, analyzing physiological response variables and the microbial community. Estuarine sediments showed a stable anammox process after 90 days, consuming ammonium and nitrite simultaneously with concomitant generation of N2 and nitrate in stoichiometric amounts. In kinetic assays, substrates were fully consumed after 210 hr, exhibiting N2 and nitrate yields of 0.85 and 0.10, respectively. The microbial community analysis using PCR-DGGE indicated the presence of uncultured anammox bacteria and members of the genus Candidatus Jettenia. The results evidenced the achievement of anammox cultures, although their start-up and kinetic characteristics were less favorable than those recorded in man-made systems.

Kinetic models in activated sludge, anaerobic digestion and other environmental modeling fields rely on the proper formulation of stoichiometric coefficients. Elemental balancing provides a simple and rigorous way to establish the stoichiometric coefficients of reactions represented in the Gujer matrix. The deduction of these coefficients is frequently trivial, from basic mass balancing considerations. In more complex cases, such as the Anammox growth reaction, rigorous elemental balancing is required to establish the proper formulation. This paper demonstrates the methodology based on a simple aerobic heterotrophic growth reaction where stoichiometry coefficients (such as the (1-Y H)/Y H term for oxygen) are well known. In the second step the methodology is applied for the Anammox growth reaction. The fraction of N 2 gas in current models originates from the NH þ 4 and the NO 2 2 electron donor/acceptor pair in equal proportion. This paper demonstrates that this stoichiometry is a simplification leading to elemental balance errors. The proper stoichiometric coefficients are derived.

The anaerobic ammonium-oxidizing (anammox) and nitrite-dependent anaerobic methane-oxidizing (n-damo) bacteria in a paddy soil core (0-100 cm) were investigated with newly designed primers targeting the hydrazine synthase bsubunit (hzsB) of anammox bacteria and the recently published primers targeting the pmoA and 16S rRNA genes of n-damo bacteria. The hzsB gene was identified as a proper biomarker to explore the anammox bacterial biodiversity and abundance in soil. The anammox bacteria were present throughout the soil core with the highest abundance of 2.7 9 10 6 hzsB copies g À1 dry soil at 40-50 cm and were not detectable below 70 cm. Sequences related to at least three species of known anammox bacteria, 'Brocadia anammoxidans', 'Brocadia fulgida', and 'Jettenia asiatica' were detected. By combining the analysis of pmoA and 16S rRNA genes, the n-damo bacteria were observed to be present in 30-70 cm with abundance from 6.5 9 10 3 (60-70 cm) to 7.5 9 10 4 (30-40 cm) copies g À1 dry soil. The pmoA sequences retrieved from different depths closely related to each other and formed a unique clade. Our results showed that anammox and n-damo bacteria co-occurred in the paddy soil. Both of them were abundant in deep layers (30-60 cm) and the community structures changed along depths in the soil core.

The anoxic ammonium oxidation (anammox) process has been regarded as an attractive alternative process to treat wastewater containing high ammonium concentrations. By the implementation of anammox process at moderately low temperatures (<25 C), the anammox process will be applied to more various industrial wastewater treatments. In this study, we established enrichment cultures of anammox bacteria from freshwater sediments by using an up-flow column reactor equipped with porous polyester nonwoven fabric at moderately low temperatures. Their nitrogen conversion rates reached 0.07e0.26 kg-N/m 3 /d. Phylogenetic analysis based on 16S rRNA gene from enrichment cultures revealed the presence of various anammox bacteria affiliated with unknown anammox bacteria as well as known anammox candidates, i.e., Candidatus Kuenenia stuttgartiensis and Candidatus Brocadia fulgida, Candidatus Scalindua wagneri. Anammox bacterial populations were influenced by enrichment conditions, i.e., seed sediments and temperature.

Methanol inhibition of anaerobic ammonium oxidation (anammox) activity was characterized. An enrichment culture entrapped in a polyethylene glycol gel carrier was designed for practical uses of wastewater treatment. Batch experiments demonstrated that anammox activity decreased with increases in methanol concentration, and relative activity reached to 29% of the maximum when 5 mM methanol was added. Also, batch experiments were conducted using anammox sludge without immobilization. Anammox activity was evaluated by quantifying 14 N 15 N ( 29 N) emission by combined gas chromatography-quadrupole mass spectrometry, and the anammox activity was found to be almost as sensitive to methanol as in the earlier trials in which gel carriers were used. These results indicated that methanol inhibition was less severe than previous studies. When methanol was added in the influent of continuous feeding system, relative activity was decreased to 46% after 80 h. Although the addition was halted, afterwards the anammox activity was not resumed in another 19 days of cultivation, suggesting that methanol inhibition to anammox activity was irreversible. It is notable that methanol inhibition was not observed if anammox activity was quiescent when substrate for anammox was not supplied. These results suggest that methanol itself is not inhibitory and may not directly inhibit the anammox activity.

For more than 100 years it was believed that bacteria were the only group responsible for the oxidation of ammonia. However, recently, a new strain of archaea bearing a putative ammonia monooxygenase subunit A (amoA) gene and able to oxidize ammonia was isolated from a marine aquarium tank. Ammonia-oxidizing archaea (AOA) were subsequently discovered in many ecosystems of varied characteristics and even found as the predominant causal organisms in some environments. Here, we summarize the current knowledge on the environmental conditions related to the presence of AOA and discuss the possible site-related properties. Considering these data, we deduct the possible niches of AOA based on pH, sulfide and phosphate levels. It is proposed that the AOA might be important actors within the nitrogen cycle in low-nutrient, low-pH, and sulfide-containing environments.

A biofilm with high nitrifying efficiency was converted into a nitritating and thereafter a nitritating–anammox biofilm in a moving-bed biofilm reactor at 26.5 (±0.5)°C by means of a combination of intermittent aeration, low dissolved oxygen concentration, low hydraulic retention time, free ammonia and furthermore, also by elevated HCO concentration. Nitrite-oxidizing bacteria (NOB) were more effectively suppressed by an enhanced HCO concentration range of 1200–2350 mg/L as opposed to free-ammonia-based process control where NOBs recovered from inhibition; the respective total-nitrogen removal rates were 0.3 kg N/(m3·d) and 0.2 kg N/(m3·d). The biofilm modification strategies resulted in a shift in bacterial community as the NOB Nitrobacter spp. were replaced with NOB belonging to the genus Nitrospiraspp. and were closely related to Candidatus Nitrospira defluvii. A community of anaerobic ammonium-oxidizing microorganisms –uncultured Planctomycetales bacterium clone P4 (closely related to Candidatus Brocadia fulgida) – was developed.