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Search results for: two-step nitrification
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Mathematical modelling of two-step nitrification-denitrification for treatment of sludge digester liquors: influence of nitrite (NO2-N) on the process kinetics
PublicationSeparate treatment of the sludge digester liquors is an alternative for expansion of the mainstream treatment line. In order to reduce the oxygen demand for nitrification and organic carbon demand for denitrification, a shortcut in the nitrogen conversion pathway has been promoted in recent years, i.e. nitrification-denitrification via NO2-N instead of NO3-N. Although NO2-N is a common intermediate product of nitrification and...
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New insights into modeling two-step nitrification in activated sludge systems – The effects of initial biomass concentrations, comammox and heterotrophic activities
PublicationIn this study, the conventional two-step nitrification model was extended with complete ammonia oxidation (comammox) and heterotrophic denitrification on soluble microbial products. The data for model calibration/validation were collected at four long-term washout experiments when the solid retention time (SRT) and hydraulic retention time (HRT) were progressively reduced from 4 d to 1 d, with mixed liquor suspended solids (MLSS)...
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Two-step mechanism of J-domain action in driving Hsp70 function
PublicationJ-domain proteins (JDPs), obligatory Hsp70 cochaperones, play critical roles in protein homeostasis. They promote key allosteric transitions that stabilize Hsp70 interaction with substrate polypeptides upon hydrolysis of its bound ATP. Although a recent crystal structure revealed the physical mode of interaction between a J-domain and an Hsp70, the structural and dynamic consequences of J-domain action once bound and how Hsp70s...
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Fermentative Conversion of Two-Step Pre-Treated Lignocellulosic Biomass to Hydrogen
PublicationFermentative hydrogen production via dark fermentation with the application of lignocellulosic biomass requires a multistep pre-treatment procedure, due to the complexed structure of the raw material. Hence, the comparison of the hydrogen productivity potential of different lignocellulosic materials (LCMs) in relation to the lignocellulosic biomass composition is often considered as an interesting field of research. In this study,...
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Theoretical description of fundamental-harmonic impedance of a two-step electrode reaction
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Characterization of bacterial structures in two-stage moving-bed biofilm reactor (MBBR) during nitrification of the landfill leachate
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Derivation of continuous explicit two-step Runge-Kutta methods oforder three
PublicationW pracy podana jest konstrukcja ciągłych rozszerzeń dla nowych reprezentacji dwukrokowych metod Rungego-Kutty rzędu trzeciego. Podane zostały metody oceny błędu lokalnego metody oraz opisany został sposób implementacji tych metod dla zmiennego kroku. Przeprowadzono szereg eksperymentów numerycznych pokazujących ich efektywność i konkurencyjność dla programu dde23 z Matlabu.
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Stability analysis of two-step Runge-Kutta methods for delay differential equations
PublicationW pracy badana jest własność stabilności dwukrokowej metody Rungego-Kutty względem liniowego równania testowego o zespolonych współczynnikach. Udowodniono, że jeśli pewne warunki są spełnione to każda A-stabilna dwukrokowa metoda Rungego-Kutty zastosowana do równania różniczkowego z opóźnieniem jest P-stabilna.
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Two-step synthesis of niobium doped Na–Ca–(Mg)–P–Si–O glasses
PublicationNiobium doped biosolubility glasses in the Na–Ca–(Mg)–P–Si–O system were prepared by using an untypical two-step synthesis route. The parent glass was melted in air atmosphere at 1350 °C followed by re-melting the glass in Nb crucible with the addition of metallic Mg/Ca powder in the nitrogen atmosphere. The second melting step was carried out at 1450–1650 °C, using an induction furnace. The topography and structure of the obtained...
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WORK MOTIVATION PROFILES AND WORK PERFORMANCE IN A GROUP OF CORPORATE EMPLOYEES: A TWO-STEP CLUSTER ANALYSIS
PublicationFew studies have applied a person-centered approach to work motivation using cluster or profile analyses. Thus, little is known about which configurations of work motivations characterize professionals. The aim of this study is to establish the structure of work motivation profiles under the framework of self-determination theory and to examine the relationship between work motivation and subjective work performance. The study...
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Construction of highly stable parallel two-step Runge-Kutta methods for delay differential equations
PublicationW pracy pokazano, że każda A-stabilna dwukrokowa metoda Rungego-Kutty dla równań różniczkowych zwyczajnych rzędu p1 i rzędu etapowego q=p1 może być uogólniona do P-stabilnej metody dla równań różniczkowych z opóźnieniem zbieżnej jednostajnie z rzędem p=p1.
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Two-stage quasi-Z-source network based step-up DC/DC converter
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Two-Step Model Based Adaptive Controller for Dissolved Oxygen Control in Sequencing Wastewater Batch Reactor
PublicationDissolved Oxygen (DO) concentration is a crucial parameter for efficient operation of biological processes taking place in the activated sludge Wastewater Treatment Plant (WWTP). High-quality DO control is difficult to achieve because of complex nonlinear behavior of the plant and substantial influent disturbances. A method to improve the Direct Model Reference Adaptive Control (DMRAC) technology in application to DO tracking for...
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The fixed state in impedance measurements of a two-step electrode reaction proceeding with accompanying adsorption of an intermediate product
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Two-step Conversion of Crude Glycerol Generated by Biodiesel Production into Biopolyols: Synthesis, Structural and Physical Chemical Characterization
PublicationIn this work biopolyols were synthesized via two-step process from crude glycerol and castor oil. For better evaluation of analyzed process, the impact of its time and temperature on the structure and properties of biopolyols was determined. Obtained results fully justified conducting of synthesis in two steps. Prepared materials were characterized by hydroxyl value and water content comparable to polyols industrially applied in...
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Nutrient recovery from deammonification effluent in a pilot study using two-step reject water treatment technology
PublicationThe aim of this study was to assess the possibility of phosphorus and nitrogen recovery from the liquid fraction of digestates (reject water) pilot study using a two-step technology, where the precipitation of biogenic compounds in the form of magnesium ammonium phosphate (struvite) will be preceded by a deammonification process. The tests confirmed the possibility of nutrient recovery from deammonification effluent. A removal...
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Advantages of continuous Fenton reaction over the traditional batch process in wastewater treatment in a single and two-step mode
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An experimental and theoretical study of the hetero Diels–Alder reactions between (E)-2-aryl-1-cyano-1-nitroethenes and ethyl vinyl ether: one-step or zwitterionic, two-step mechanism?
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Methylene blue decomposition on TiO2/reduced graphene oxide hybrid photocatalysts obtained by a two-step hydrothermal and calcination synthesis
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Rheological properties, oxidative and thermal stability, and potential application of biopolyols prepared via two-step process from crude glycerol
PublicationIn this work, previously synthesized biopolyols were analyzed in terms of their rheological and thermal properties, very important from the technological point of view. For better evaluation of performed synthesis, the influence of its time and temperature on the properties of biopolyols was determined. In the end, obtained materials were used to prepare rigid polyurethane-polyisocyanurate (PUR-PIR) foams, to evaluate their potential...
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Novel two-step synthesis method of thin film heterojunction of BiOBr/Bi2WO6 with improved visible-light-driven photocatalytic activity
PublicationA novel two-step ionic liquid assisted procedure was applied for a controllable synthesis of BiOBr/Bi2WO6 heterojunction thin films. The preparation route involved an anodic oxidation of tungsten foil and hydrothermal transformation of as-anodized oxide in the presence of bismuth precursor and ionic liquid, N-butylpyridinium bromide [BPy][Br]. The BiOBr plates with irregular shapes adhered to the surface of flower-like Bi2WO6 and...
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Profiling and Qualitative Assessment of Enzymatically and Thermally Oxidized Egg Yolk Phospholipids using a Two‐Step High‐Performance Liquid Chromatography Protocol
PublicationA two‐step high‐performance liquid chromatography (HPLC) method for the profiling and qualitative assessment of oxidized phospholipids (oxPL) present in foods was developed. The applicability of the investigated two‐step HPLC protocol was verified for separation of enzymatically and thermally oxidized hen egg yolk phospholipids (PL) as a relevant food model. In the first step, seven individual PL classes were separated using hydrophilic...
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Structure and properties comparison of poly(ether-urethane)s based on nonpetrochemical and petrochemical polyols obtained by solvent free two-step method
PublicationThe application of thermoplastic polyurethanes (TPU) is becoming more and more extensive, and the decreasing of used petrochemical monomers and reduction of energy for the polymerization and processing processes is getting increasingly important. In this paper, we confirmed the positive influence of high bio-based monomers contents (by replacing petrochemical polyol and glycol by bio-based counterparts) on processing and properties...
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Direct determination of paraquat herbicide by square-wave voltammetry by two-step transfer mechanism at heterogeneous boron-doped carbon nanowall electrodes
PublicationBoron-doped carbon nanowalls (B:CNW) versus boron-doped diamond (BDD) materials were investigated for the effective electrochemical detection of highly toxic herbicide paraquat (PQ). Depending on the surface morphology and functional groups of BDD and B:CNWs, the electrochemical absorption and detection of the target analyte PQ revealed different detection mechanisms. The surface absorption mechanism was mainly observed for BDD,...
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One-Step Synergistic Effect to Produce Two-Dimensional N-Doped Hierarchical Porous Carbon Nanosheets for High-Performance Flexible Supercapacitors
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Interference-Free Determination of Trace Copper in Freshly Ripened Honeys by Flame Atomic Absorption Spectrometry Following a Preconcentration by Solid-Phase Extraction and a Two-Step Elution Process
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Incorporation of the complete ammonia oxidation (comammox) process for modeling nitrification in suspended growth wastewater treatment systems
PublicationThe newly discovered process complete ammonia oxidation (comammox) has changed the traditional under-standing of nitrification. In this study, three possible concepts of comammox were developed and incorporated as part of an extended two-step nitrification model. For model calibration and validation, two series of long-term biomass washout experiments were carried out at 12 ◦C and 20 ◦C in a laboratory sequencing batch reactor....
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Metody oczyszczania odcieków z procesów przeróbki osadów w komorach fermentacji
PublicationOdcieki z beztlenowych procesów przeróbki osadu w komorach fermentacji (tzw. wody poosadowe) są istotnym źródłem azotu dopływającego do części biologicznej oczyszczalni ścieków. Odpowiednie oczyszczanie tych wód może więc, w bardzo istotny sposób wpłynąć na warunki eksploatacji oczyszczalni. Konwencjonalny proces usuwania amoniaku za pomocą dwóch faz, tj. nitryfikacji i denitryfikacji, są coraz częściej zastępowane przez jednoetapowy...
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Application of mechanistic and data-driven models for nitrogen removal in wastewater treatment systems
PublicationIn this dissertation, the application of mechanistic and data-driven models in nitrogen removal systems including nitrification and deammonification processes was evaluated. In particular, the influential parameters on the activity of the Nitrospira activity were assessed using response surface methodology (RSM). Various long-term biomass washout experiments were operated in two parallel sequencing batch reactor (SBR) with a different...
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Effects of Different Aeration Modes on Ammonia Removal from Sludge Digester Liquors in the Nitritation-Anammox Process
PublicationSludge digester liquors can be responsible for up to one third of the nitrogen load to the biological step of wastewater treatment plants (WWTPs). The conventional process for ammonia removal via two sequential processes, i.e. nitrification and denitrification, is increasingly being challenged by a one-step process in which ammonium is oxidized directly to nitrogen gas e.g. ammonium oxidation (anammox) process. In this novel process,...
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A Comparison of the Efficiency of Deammonification under Different Aeration Strategies in a Laboratory-Scale Sequencing Batch Reactor
PublicationAn important source of nitrogen load entering the biological part of wastewater treatment plants (WWPTs) is derived from the anaerobic sludge digestion processes. Sludge digestion liquors constitute only 1-2% of the inflow to the plant, but the load of nitrogen directed with them to the main stream may be as high as 10-20% of the total nitrogen load. Therefore, numerous studies have focused on treatment of sludge digestion liquors...
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The coexistence and competition of canonical and comammox nitrite oxidizing bacteria in a nitrifying activated sludge system – Experimental observations and simulation studies
PublicationThe second step of nitrification can be mediated by nitrite oxidizing bacteria (NOB), i.e. Nitrospira and Nitrobacter, with different characteristics in terms of the r/K theory. In this study, an activated sludge model was developed to account for competition between two groups of canonical NOB and comammox bacteria. Heterotrophic denitrification on soluble microbial products was also incorporated into the model. Four 5-week washout...
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Inhibition effect of free ammonia on deammonification process under different intermittent aeration strategies in sequencing batch reactor
PublicationThe deammonification process involves two steps. The first step is the partial nitrification of ammonia (NH4-N) by ammonia oxidizing bacteria (AOB) to produce nitrite (NO2-N) and the second step is the anammox process to “anaerobically” oxidize ammonia to nitrogen gas with nitrite as an electron acceptor (Lackner et al., 2014). Free ammonia (FA) plays a significant role in the stable, long-term deammonification system operation....
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Modelling AOB-NOB competition in shortcut nitrification compared with conventional nitrification-denitrification process
PublicationIn particular, mainstream deammonification and/or shortened nitrificationdenitrification via nitrite (so-called “nitrite shunt”) is a promising new treatment concept that has the potential to revolutionise how nitrogen removal is achieved at WWTPs. Understanding the role of the AOB/NOB competition in the nitrogen cycle in wastewater treatment systems will change operational strategies of the novel nitrogen removal processes. The...
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Nitrogen mass balance and mathematical model of a Structured- Bed Reactor (SBRRIA)
PublicationAn up-flow structured-bed reactor subjected to recirculation and intermittent aeration (SBRRIA) was operated under varying influent conditions. The influent COD/N ratio was adjusted by maintaining a stable organic loading rate (average of 1.07 kgCOD m-3 d-1) and changing the nitrogen loading rate from 0.1 to 0.4 kg N m-3. Therefore, three different COD/N ratios were tested: 9.7±1 (Scenario 1); 7.6±1 (Scenario 2) and 2.9±1 (Scenario...
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Kinetic characterization of hydrogen sulfide inhibition of suspended anammox biomass from a membrane bioreactor
PublicationThe inhibition effects of hydrogen sulfide (H2S) on anammox-enriched biomass from a laboratory membrane reactor were analyzed in a series of batch respirometric experiments. The determined half maximal inhibitory concentration (IC50) was 4.67 mg H2S-S L−1 at the constant pH = 7.0 and the total sulfide concentration varying between 1 and 15 mg TS-S L−1. In another test, the IC50 was found to be 4.25 mg H2S-S L−1 under a constant...
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Combining Computational Fluid Dynamics with a Biokinetic Model for Predicting Ammonia and Phosphate Behavior in Aeration Tanks
PublicationThe aim of this study was to use computational fluid dynamics for predicting the behavior of reactive pollutants (ammonia and phosphate) in the aerobic zone of the bioreactor located at the Wschod wastewater treatment plant in Gdansk, Poland. The one-dimensional advection-dispersion equation was combined with simple biokinetic models incorporating the Monod-type expressions as source terms for the two pollutants. The problem was...
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The Relationship between Gene Activity and Nitrous Oxide Production during Nitrification in Activated Sludge Systems
PublicationNitrite is an important factor which inhibits the first stage of the nitrification, the effect is stronger with the decrease of the DO concentrations. NO2- presence at concentration above 15 mg N – NO2 in the aeration tanks stimulates N2O production regardless of the DO concentration. The significant nirS gene induction, observed especially during the experiments with the nitrite addition indicates that N2O production is basically...
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ADAPTATION OF THE ACTIVATED SLUDGE TO THE DIGESTATE LIQUORS DURING THE NITRIFICATION AND DENITRIFICATION PROCESSES
PublicationThe activated sludge process of the digestate liquors after chemical separation was conducted using a 10 L lab-scale sequencing batch reactor (SBR) and a 0.50 m3 pilotscale SBR independently (with pH control). Due to the relatively high concentration of free ammonia (FA), clear inhibitory effects of the digestate liquors on the nitrifying bacteria were observed. The adaptation of the activated sludge to the toxicity was evaluated...
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Mutual Interaction between Temperature and DO Set Point on AOB and NOB Activity during Shortcut Nitrification in a Sequencing Batch Reactor in Terms of Energy Consumption Optimization
PublicationRecently, many wastewater treatment plants (WWTPs) have had to deal with serious problems related to the restrictive requirements regarding the euent quality, as well as significant energy consumption associated with it. In this situation, mainstream deammonification and/or shortened nitrification-denitrification via nitrite (so-called “nitrite shunt”) is a new promising strategy. This study shows the mechanisms and operating conditions...
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Advances in analysis, quantification and modelling of N2O emission in SBRs under various DO set points
PublicationNitrous oxide (N2O), considered a major greenhouse gas (GHG) in wastewater treatment plants (WWTPs), is produced during both nitrification and denitrification processes; hence, it needs to be controlled by internal and external strategies. Various factors, such as DO, temperature, and pH, could be incorporated into the mitigation of emissions in WWTPs. In this research, potential operational strategies were investigated in order...
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Nitrogen transformations and mass balances in anaerobic/anoxic/aerobic batch experiments with full-scale biomasses from BNR activated sludge systems.
PublicationThe aim of this study was to investigate nitrogen mass balances occurring inside full-scale BNR activated sludge systems, with special attention to colloidal and dissolved organic nitrogen (CON and DON) transformations. For this purpose, laboratory experiments were carried out using process biomass from two large BNR plants in northern Poland. Two parallel batch reactors were operated in a 3-phase (anaerobic/anoxic/aerobic) cycle....
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Nitrogen transformations and mass balances in anaerobic/anoxic/aerobic batch experiments with full-scale biomasses from BNR activated sludge systems.
PublicationThe aim of this study was to investigate nitrogen mass balances occurring inside full-scale BNR activated sludge systems, with special attention to colloidal and dissolved organic nitrogen (CON and DON) transformations. For this purpose, laboratory experiments were carried out using process biomass from two large BNR plants in northern Poland. Two parallel batch reactors were operated in a 3-phase (anaerobic/anoxic/aerobic) cycle....
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Nitrogen removal via the nitrite pathway during wastewater co-treatment with ammonia-rich landfill leachates in a sequencing batch reactor
PublicationThe biological treatment of ammonia-rich landfill leachates due to an inadequate C to N ratio requires expensive supplementation of carbon from an external carbon source. In an effort to reduce treatment costs, the objective of the study was to determine the feasibility of nitrogen removal via the nitrite pathway during landfill leachate co-treatment with municipal wastewater. Initially, the laboratory-scale sequencing batch reactor...
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Temperature Impact of Nitrogen Transformation in Technological System: Vertical Flow Constructed Wetland and Polishing Pond
PublicationThe article describes the results of the research, purpose of which was to evaluate influence of the temperature on the effectiveness of nitrification and denitrification in the sewage treatment system consisting of vertical flow constructed wetland and polishing pond. During the analysed period, the efficiency of removing total nitrogen was low and amounted to 12.7%. In the polishing pond in the summer period, content of total...
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Nitrification, denitrification, and dephosphatation capability of activated sludge during co-treatment of intermediate-age landfill leachates with municipal wastewater
PublicationThis study focuses on the possible use and efficacy of the co-treatment of landfill leachate (intermediate-age) with municipal wastewater. The nitrification, denitrification, and dephosphatation capability of activated sludge acclimated with a mixture of raw municipal wastewater (RWW) with gradually increasing amounts of raw landfill leachate (RLL) (from 0.5 to 5% v/v) were tested. Biochemical tests were conducted simultaneously...
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Landfill leachate treatment at a pilot plant using hydrophyte systems
PublicationConstructed wetlands can provide an effective and economical solution to landfill leachate treatment. In the article the performance of a CW for leachate treatment, consisting of two horizontal flow constructed wetlands (HF-CW) beds, working at the municipal landfill in Gdansk-Szadolki in the period 2004-2005 is being discussed. The plant has been operating since 2001. Clogging problems and surface flow occurred in the system...
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The occurrence and role of Nitrospira in nitrogen removal systems
PublicationApplication of the modern microbial techniques changed the paradigm about the microorganisms performing nitrification. Numerous investigations recognized representatives of the genus Nitrospira as a key and predominant nitrite-oxidizing bacteria in biological nutrient removal systems, especially under low dissolved oxygen and substrate conditions. The recent discovery of Nitrospira capable of performing complete ammonia oxidation...
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The metagenomic approach to characterization of the microbial community shift during the long-term cultivation of anammox-enriched granular sludge
PublicationA metagenomic approach was used to investigate how the microbial community composition changes when an anammox-based granular sludge reactor is seeded with nitritation-anammox biomass from a wastewater treatment plant. In the seed sample, the abundance of Candidatus Kuenenia stuttgartiensis was similar to Candidatus Jettenia caeni (12.63 vs. 11.68%). This biomass was typical in terms of microbial nitrogen conversion; both ammonia...
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Integrating conventional nitrogen removal with anammox in wastewater treatment systems: Microbial metabolism, sustainability and challenges
PublicationThe various forms of nitrogen (N), including ammonium (NH4+), nitrite (NO2−), and nitrate (NO3−), present in wastewaters can create critical biotic stress and can lead to hazardous phenomena that cause imbalances in biological diversity. Thus, biological nitrogen removal (BNR) from wastewaters is considered to be imperatively urgent. Therefore, anammox-based systems, i.e. partial nitrification and anaerobic ammonium oxidation (PN/anammox)...