Novel mathematical modeling on pilot-scale of plug-flow aerated submerged biofilm reactor for dissolved organic matter and nitrogen removal

The investigation aimed to present mathematical models for describing the dynamic behavior of the dissolved organic matter removal and nitrification in the Aerated Submerged Bio-Film (ASBF) for a plug-flow reactor. Based on the experimental data from the batch system of the ASBF pilot plant, mathematical models for the plug-flow reactor were developed to predict dissolved organic matter and ammonia nitrogen removal rates as a function of heterotrophic and autotrophic bacteria populations, dissolved organic matter concentrations, ammonia nitrogen concentrations, dissolved oxygen concentrations, and temperature. The mathematical models for dissolved organic matter and ammonia nitrogen removal in ASBF include two differential equations reflecting heterotrophic and autotrophic bacteria populations, and a number of kinetic parameters. Consequently, the results present a better insight into the dynamics behavior of heterotrophic and autotrophic biofilm growth and their practical application to wastewater for dissolved organic matter and ammonia nitrogen removal process. The mathematical model for ammonia nitrogen and dissolved organic matter removals present good results for the plug-flow reactor.     

ORGANIC CARBON SUPPLEMENTATION OF STERILIZED MUNICIPAL WASTEWATER IS ESSENTIAL FOR HETEROTROPHIC GROWTH AND REMOVING AMMONIUM BY THE MICROALGA CHLORELLA VULGARIS1

Heterotrophic growth of the microalga Chlorella vulgaris Beij. in synthetic as well as sterilized municipal wastewater of a nonindustrialized city was measured. The city wastewater contained high levels of ammonium and nitrate, medium levels of phosphate, and low levels of nitrite and organic molecules and could not support heterotrophic growth of C. vulgaris. Evaluation of 11 known carbon sources for this microalga that were added to standard synthetic wastewater containing the same levels of nitrogen and phosphorus as the municipal wastewater revealed that the best carbon sources for heterotrophic growth were Na‐acetate and d ‐glucose. These provided the highest growth rates and the largest removal of ammonium. Growth increased with concentration of the supplement to an optimum at 0.12 M Na‐acetate. This carbon source was consumed completely within 10 d of incubation. Higher concentrations inhibited the growth of C. vulgaris. The microalgal populations under heterotrophic growth conditions were one level of magnitude higher than that under autotrophic growth conditions that served as a comparison. No growth occurred in the dark in the absence of a carbon source. Na‐acetate was superior to d ‐glucose. In municipal wastewater, when Na‐acetate or d ‐glucose was added, C. vulgaris significantly enhanced ammonium removal under heterotrophic conditions, and its capacity was equal to ammonium removal under autotrophic growth conditions. This study showed that sterilized wastewater can be treated by C. vulgaris under heterotrophic conditions if supplemented with the appropriate organic carbon source for the microalgae.     

泉州西湖沉积物中硝化细菌的分布及其作用

比较研究泉州西湖沉积物中氨氧化细菌(AOB)和亚硝酸盐氧化细菌(NOB)的分布及氨氧化潜力和亚硝酸盐(NO2?)氧化潜力。结果表明: 西湖沉积物中存在高浓度的有机质(OM)、总氮(TN)和氨氮。AOB生物量为1.1×106?6.4×106 个/g干土, 显著高于NOB生物量4.2×105?7.4×105 个/g 干土(配对t-检验, P<0.05)。对于NOB, 硝化杆菌属(Nitrobacter)和硝化螺菌属(Nitrospira)同时存在于西湖沉积物中, 以Nitrobacter为优势种群。AOB和NOB生物量的差异一定程度上导致西湖沉积物中氨氧化潜力显著高于NO2?氧化潜力(配对t-检验, P<0.05), NO2?氧化过程成为硝化作用的限制步骤。另外, 西湖沉积物中存在的较高浓度氨氮, 一方面促进了AOB的生长和活性, 导致较高速率的氨氧化过程, 另一方面却对亚硝酸盐氧化过程产生选择性抑制, 这也是导致NO2?氧化潜力较低的主要原因之一。     

A Most Probable Number method (MPN) for the estimation of cell numbers of heterotrophic nitrifying bacteria in soil

A Most Probable Number (MPN) method was developed allowing for the first time estimation of populations of bacteria capable of heterotrophic nitrification. The method was applied to an acidic soil of a coniferous forest exhibiting nitrate production. In this soil nitrate production was unlikely to be catalyzed by autotrophic nitrifiers, since autotrophic ammonia oxidizers never could be detected, and autotrophic nitrite oxidizers were usually not found in appreciable cell numbers. The developed MPN method is based on the demonstration of the presence/absence of nitrite/nitrate produced by heterotrophic nitrifying bacteria during growth in a complex medium (peptone-meat-extract softagar medium) containing low concentrations of agar (0.1%). Both the supply of the growing cultures in MPN test tubes with sufficient oxygen and the presence of low agar concentrations in the medium were found to be favourable for sustainable nitrite/nitrate production. The results demonstrate that in the acidic forest soil the microbial population capable of heterotrophic nitrifcation represents a significant part of the total aerobic heterotrophic population. By applying the developed MPN method, several bacterial strains of different genera not previously described to perform heterotrophic nitrification have been isolated from the soil and have been identified by bacterio-diagnostic tests.     

Effects of roxithromycin on ammonia-oxidizing bacteria and nitrite-oxidizing bacteria in the rhizosphere of wheat

In a pot-cultural experiment, the impact of the antibiotic roxithromycin (ROX) addition was assessed on the diversities of microbial structure and function communities, especially involved in ammonia and nitrite oxidation in wheat rhizosphere soil with and without the addition of earthworms. The abundances of ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and total bacteria were surveyed by the quantitative PCR. The quantities of total bacteria, AOB, and NOB with earthworms were higher than those without earthworms because of the synergistic effect. ROX inhibited the growth of AOB in all treatments, although the quantities of AOB were in a light increase in medium and heavy polluted treatments compared with that in the light polluted treatments. Different from AOB, the quantities of NOB were lowest in light polluted treatments, but the quantities of NOB were rapidly increased in medium and heavy polluted treatments compared with that in the control. These results indicated that the application of ROX principally had a negative effect on nitrification performance by affecting the abundances and relative ratios of both AOB and NOB in soil communities, which affected the N cycle in an agricultural ecosystem. According to the metabolic diversities evaluated by the biologic assay, the tendency of metabolic diversities was quite contrary to the quantities of NOB in all treatments and showed the contrast growing relation of autotrophic and heterotrophic bacteria under ROX pollution pressure in agricultural ecosystems.     

Ecophysiological interaction between nitrifying bacteria and heterotrophic bacteria in autotrophic nitrifying biofilms as determined by microautoradiography-fluorescence in situ hybridization

Ecophysiological interactions between the community members (i.e., nitrifiers and heterotrophic bacteria) in a carbon-limited autotrophic nitrifying biofilm fed only NH(4)(+) as an energy source were investigated by using a full-cycle 16S rRNA approach followed by microautoradiography (MAR)-fluorescence in situ hybridization (FISH). Phylogenetic differentiation (identification) of heterotrophic bacteria was performed by 16S rRNA gene sequence analysis, and FISH probes were designed to determine the community structure and the spatial organization (i.e., niche differentiation) in the biofilm. FISH analysis showed that this autotrophic nitrifying biofilm was composed of 50% nitrifying bacteria (ammonia-oxidizing bacteria [AOB] and nitrite-oxidizing bacteria [NOB]) and 50% heterotrophic bacteria, and the distribution was as follows: members of the alpha subclass of the class Proteobacteria (alpha-Proteobacteria), 23%; gamma-Proteobacteria, 13%; green nonsulfur bacteria (GNSB), 9%; Cytophaga-Flavobacterium-Bacteroides (CFB) division, 2%; and unidentified (organisms that could not be hybridized with any probe except EUB338), 3%. These results indicated that a pair of nitrifiers (AOB and NOB) supported a heterotrophic bacterium via production of soluble microbial products (SMP). MAR-FISH revealed that the heterotrophic bacterial community was composed of bacteria that were phylogenetically and metabolically diverse and to some extent metabolically redundant, which ensured the stability of the ecosystem as a biofilm. alpha- and gamma-Proteobacteria dominated the utilization of [(14)C]acetic acid and (14)C-amino acids in this biofilm. Despite their low abundance (ca. 2%) in the biofilm community, members of the CFB cluster accounted for the largest fraction (ca. 64%) of the bacterial community consuming N-acetyl-D-[1-(14)C]glucosamine (NAG). The GNSB accounted for 9% of the (14)C-amino acid-consuming bacteria and 27% of the [(14)C]NAG-consuming bacteria but did not utilize [(14)C]acetic acid. Bacteria classified in the unidentified group accounted for 6% of the total heterotrophic bacteria and could utilize all organic substrates, including NAG. This showed that there was an efficient food web (carbon metabolism) in the autotrophic nitrifying biofilm community, which ensured maximum utilization of SMP produced by nitrifiers and prevented buildup of metabolites or waste materials of nitrifiers to significant levels.     

Sequentially aerated membrane biofilm reactors for autotrophic nitrogen removal: microbial community composition and dynamics

Membrane‐aerated biofilm reactors performing autotrophic nitrogen removal can be successfully applied to treat concentrated nitrogen streams. However, their process performance is seriously hampered by the growth of nitrite oxidizing bacteria (NOB). In this work we document how sequential aeration can bring the rapid and long‐term suppression of NOB and the onset of the activity of anaerobic ammonium oxidizing bacteria (AnAOB). Real‐time quantitative polymerase chain reaction analyses confirmed that such shift in performance was mirrored by a change in population densities, with a very drastic reduction of the NOB Nitrospira and Nitrobacter and a 10‐fold increase in AnAOB numbers. The study of biofilm sections with relevant 16S rRNA fluorescent probes revealed strongly stratified biofilm structures fostering aerobic ammonium oxidizing bacteria (AOB) in biofilm areas close to the membrane surface (rich in oxygen) and AnAOB in regions neighbouring the liquid phase. Both communities were separated by a transition region potentially populated by denitrifying heterotrophic bacteria. AOB and AnAOB bacterial groups were more abundant and diverse than NOB, and dominated by the r‐strategists Nitrosomonas europaea and Ca. Brocadia anammoxidans, respectively. Taken together, the present work presents tools to better engineer, monitor and control the microbial communities that support robust, sustainable and efficient nitrogen removal.     

Effect of organic matter on growth and cell yield of ammonia-oxidizing bacteria

The effect of various organic compounds on the growth of ammonia-oxidizing bacteria was examined.Nitrosococcus oceanus, a strongly halophilic bacterium, had a very low tolerance to organic matter compared with other organisms tested. Organic compounds scarcely affected the growth of theNitrosomonas strains whereas nitrite formation by bothNitrosococcus mobilis strains was inhibited by nearly all of the substances tested. The growth ofNitrosospira strain Nsp₁ was enhanced more than 30% by acetate and formate, but not growth was detectable in the presence of pyruvate. On the contrary,Nitrosospira strain Nsp₅ was stimulated only by pyruvate. Nitrite formation by the twoNitrosovibrio tenuis strains tested was similar. The growth of both strains was enhanced considerably by formate and glucose; acetate and, to a greater extent, pyruvate inhibited these bacteria.In batch culture, the energy efficiency of autotrophically grown ammonia-oxidizing bacteria varied from strain to strain. The cell yield of mixotrophically grown cultures, per unit of ammonia oxidized, was increased in comparison with autotrophic ones. No heterotrophic growth was detected.     

一株养殖水体中亚硝酸盐去除菌的鉴定及其去除条件

【目的】从养殖污泥中分离筛选优良亚硝酸盐去除菌,并对其去除条件进行研究。【方法】从养殖污泥中分离亚硝酸盐去除菌,进一步通过测定比较分离菌株对亚硝酸盐的去除率,筛选优良的亚硝酸盐去除菌,通过API ID32GN细菌鉴定系统以及16S rDNA序列分析法对其进行鉴定,并采用单因子法研究其去除亚硝酸盐的条件。【结果】从养殖污泥中分离筛选了一株优良的亚硝酸盐去除菌AQ-3,其对50 mg/L亚硝酸盐的去除率高达99.47%。菌株AQ-3被鉴定为鲍曼氏不动杆菌(Acinetobacter baumannii)(GenBank登录号:JF751054.1),其16S rDNA序列与基因库中不动杆菌属菌株的16S rDNA序列有99%?100%的同源性,而且与鲍曼氏不动杆菌KF714株(GenBank登录号:AB109775)的亲缘关系最近。菌株AQ-3去除亚硝酸盐的最适初始pH范围为7?9,最佳碳源为乙酸钠和丁二酸钠,而且随着初始菌浓度的不断增大,菌株AQ-3对亚硝酸盐的去除率显著升高;随着亚硝酸盐浓度的不断增大,菌株AQ-3对亚硝酸盐的去除率逐渐降低。【结论】在丰富亚硝酸盐去除菌种质资源的同时,为该菌在养殖水体中的实际应用提供了理论基础。     

Variation in Heterotrophic and Autotrophic Nitrifier Populations in Relation to Nitrification in Organic Soils

The occurrence of heterotrophic and autotrophic nitrifiers in Pahokee muck and the role of these organisms in the ecosystem were assessed by surveying their population densities under different field conditions and by observing the relationship of these populations with aerobic bacteria and soil moisture. Heterotrophic nitrifier populations varied from 2.0 × 10⁵ to 3.8 × 10⁶ bacteria per cm³ of muck in surface fallow (bare) Pahokee muck during the annual cycle. This population decreased 40-fold between the surface and the 60- to 70-cm depths of soil. Similar variations were noted with autotrophic nitrifier populations. Significant correlations were found between heterotrophic nitrifiers and both soil moisture and aerobic bacteria. These relationships did not exist for the autotrophic nitrifiers. In soil that had been heated to kill the autotrophic nitrifiers, while preserving a population of the heterotrophs, and then amended with sodium acetate or ammonium sulfate or both, no nitrate or nitrite accumulated, although significant increases in heterotrophic nitrifiers were detected. In unheated control soil, nitrate plus nitrite-N increased from 14.3 to 181 μg/g of wet soil, and 48 μg of nitrite-N per g was produced. These data suggest that the autotrophic nitrifiers were the sole population responsible for nitrification in Pahokee muck.     

Analysis of bacteria communities in an up-flow fixed-bed (UFB) bioreactor for treating sulfide in hydrocarbon wastewater

An up-flow fixed-bed (UFB) bioreactor with patented functional polyurethane foam (FPUF) carriers was used to treat sulfide in hydrocarbon wastewater. Community compositions of autotrophic and heterotrophic bacteria were analyzed by polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE). DGGE results showed that a relatively stable bacterial community composed of heterotrophic and autotrophic bacteria formed in the bioreactor by the end of experiment, which ensured 92–100% sulfide removal efficiencies. Furthermore, autotrophic genera of Thiobacillus and Thiomonas, as well as those of the heterotrophic genus of Acinetobacter survived and exhibited high sulfide oxidation activity under all three operational conditions. Different special genera were also observed under each operational condition, such as the halophilic genus of Nesterenkonia. In addition, a new genus of sulfide oxidation bacteria was found in the bioreactor, which had the ability to synthesize cytoplasm from organic compounds. These genera have wide applications for the treatment of sulfide in hydrocarbon wastewater.     

PRODUCTS OF THE OXIDATION OF THIOSULFATE BY BACTERIA IN MINERAL MEDIA

Various cultures (previously described), which oxidize thiosulfate in mineral media have been studied in an attempt to determine the products of oxidation. The transformation of sodium thiosulfate by Cultures B, T, and K yields sodium tetrathionate and sodium hydroxide; secondary chemical reactions result in the accumulation of some tri- and pentathionates, sulfate, and elemental sulfur. As a result of the initial reaction, the pH increases; the secondary reactions cause a drop in pH after this initial rise. The primary reaction yields much less energy than the reactions effected by autotrophic bacteria. No significant amounts of assimilated organic carbon were detected in media supporting representatives of these cultures. It is concluded that they are heterotrophic bacteria. Th. novellus oxidizes sodium thiosulfate to sodium sulfate and sulfuric acid; the pH drops progressively with growth and oxidation. Carbon assimilation typical of autotrophic bacteria was detected; the ratio of sulfate-sulfur formed to carbon assimilated was 56:1. It is calculated that 5.1 per cent of the energy yielded by the oxidation of thiosulfate is accounted for in the organic cell substance synthesized from inorganic materials. This organism is a facultative autotroph. The products of oxidation of sodium thiosulfate by Th. thioparus are sodium sulfate, sulfuric acid, and elemental sulfur; the ratio of sulfate sulfur to elemental sulfur is 3 to 2. The pH decreases during growth and oxidation. The elemental sulfur is produced by the primary reaction and is not a product of secondary chemical changes. The bacterium synthesizes organic compounds from mineral substances during growth. The ratio of thiosulfate-sulfur oxidized to carbon assimilated was 125:1, with 4.7 per cent of the energy of oxidation recovered as organic cell substance. This bacterium is a strict autotroph.     

Fabrication of Bacteria Environment Cubes with Dry Lift-Off Fabrication Process for Enhanced Nitrification

We have developed a 3D dry lift-off process to localize multiple types of nitrifying bacteria in polyethylene glycol diacrylate (PEGDA) cubes for enhanced nitrification, a two-step biological process that converts ammonium to nitrite and then to nitrate. Ammonia-oxidizing bacteria (AOB) is responsible for converting ammonia into nitrite, and nitrite-oxidizing bacteria (NOB) is responsible for converting nitrite to nitrate. Successful nitrification is often challenging to accomplish, in part because AOB and NOB are slow growers and highly susceptible to many organic and inorganic chemicals in wastewater. Most importantly, the transportation of chemicals among scattered bacteria is extremely inefficient and can be problematic. For example, nitrite, produced from ammonia oxidation, is toxic to AOB and can lead to the failure of nitrification. To address these challenges, we closely localize AOB and NOB in PEGDA cubes as microenvironment modules to promote synergetic interactions. The AOB is first localized in the vicinity of the surface of the PEGDA cubes that enable AOB to efficiently uptake ammonia from a liquid medium and convert it into nitrite. The produced nitrite is then efficiently transported to the NOB localized at the center of the PEGDA particle and converted into non-toxic nitrate. Additionally, the nanoscale PEGDA fibrous structures offer a protective environment for these strains, defending them from sudden toxic chemical shocks and immobilize in cubes. This engineered microenvironment cube significantly enhances nitrification and improves the overall ammonia removal rate per single AOB cell. This approach—encapsulation of multiple strains at close range in cube in order to control their interactions—not only offers a new strategy for enhancing nitrification, but also can be adapted to improve the production of fermentation products and biofuel, because microbial processes require synergetic reactions among multiple species.     

Evaluation on factors influencing the heterotrophic growth on the soluble microbial products of autotrophs

In this work, the heterotrophic growth on the microbial products of autotrophs and the effecting factors were evaluated with both experimental and modeling approaches. Fluorescence in situ hybridization (FISH) analysis illustrated that ammonia oxidizers (AOB), nitrite oxidizers (NOB), and heterotrophs accounted for about 65%, 20%, and 15% of the total bacteria, respectively. The mathematical evaluation of experimental data reported in literature indicated that heterotrophic growth in nitrifying biofilm (30–50%) and granules (30%) was significantly higher than that of nitrifying sludge (15%). It was found that low influent ammonium resulted in a lower availability of soluble microbial products (SMP) and a slower heterotrophic growth, but high ammonium (>150 mg N L⁻¹) feeding would lead to purely AOB dominated sludge with high biomass‐associated products contained effluent, although the absolute heterotrophic growth increased. Meanwhile, the total active biomass concentration increased gradually with the increasing solids retention time, whereas the factions of active AOB, NOB, and heterotrophs varied a lot at different solids retention times. This work could be useful for better understanding of the autotrophic wastewater treatment systems. Biotechnol. Bioeng. 2011; 108:804–812. © 2010 Wiley Periodicals, Inc.     

Distinctive microbial ecology and biokinetics of autotrophic ammonia and nitrite oxidation in a partial nitrification bioreactor

Biological nitrogen removal (BNR) based on partial nitrification and denitrification via nitrite is a cost-effective alternate to conventional nitrification and denitrification (via nitrate). The goal of this study was to investigate the microbial ecology, biokinetics, and stability of partial nitrification. Stable long-term partial nitrification resulting in 82.1 +/- 17.2% ammonia oxidation, primarily to nitrite (77.3 +/- 19.5% of the ammonia oxidized) was achieved in a lab-scale bioreactor by operation at a pH, dissolved oxygen and solids retention time of 7.5 +/- 0.1, 1.54 +/- 0.87 mg O(2)/L, and 3.0 days, respectively. Bioreactor ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) populations were most closely related to Nitrosomonas europaea and Nitrobacter spp., respectively. The AOB population fraction varied in the range 61 +/- 45% and was much higher than the NOB fraction, 0.71 +/- 1.1%. Using direct measures of bacterial concentrations in conjunction with independent activity measures and mass balances, the maximum specific growth rate (micro(max)), specific decay (b) and observed biomass yield coefficients (Y(obs)) for AOB were 1.08 +/- 1.03 day(-1), 0.32 +/- 0.34 day(-1), and 0.15 +/- 0.06 mg biomass COD/mg N oxidized, respectively. Corresponding micro(max), b, and Y(obs) values for NOB were 2.6 +/- 2.05 day(-1), 1.7 +/- 1.9 day(-1), and 0.04 +/- 0.02 mg biomass COD/mg N oxidized, respectively. The results of this study demonstrate that the highly selective partial nitrification operating conditions enriched for a narrow diversity of rapidly growing AOB and NOB populations unlike conventional BNR reactors, which host a broader diversity of nitrifying bacteria. Further, direct measures of microbial abundance enabled not only elucidation of mixed community microbial ecology but also estimation of key engineering parameters describing bioreactor systems supporting these communities.     

Rapid start-up of nitrifying MBBRs at low temperatures: nitrification,biofilm response and microbiome analysis

The moving bed biofilm reactor (MBBR), operated as a post carbon removal system, requires long start-up times in comparison to carbon removal systems due to slow growing autotrophic organisms. This study investigates the use of carriers seeded in a carbon rich treatment system prior to inoculation in a nitrifying MBBR system to promote the rapid development of nitrifying biofilm in an MBBR system at temperatures between 6 and 8 °C. Results show that nitrification was initiated by the carbon removal carriers after 22 h of operation. High throughput 16S-rDNA sequencing indicates that the sloughing period was a result of heterotrophic organism detachment and the recovery and stabilization period included a growth of Nitrosomonas and Nitrospira as the dominant ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in the biofilm. Peripheral microorganisms such as Myxococcales, a rapid EPS producer, appear to have contributed to the recovery and stabilization of the biofilm.

     

Achieving the nitrite pathway using aeration phase length control and step-feed in an SBR removing nutrients from abattoir wastewater

Aeration phase length control and step-feed of wastewater are used to achieve nitrogen removal from wastewater via nitrite in sequencing batch reactors (SBR). Aeration is switched off as soon as ammonia oxidation is completed, which is followed by the addition of a fraction of the wastewater that the SBR receives over a cycle to facilitate denitrification. The end-point of ammonia oxidation is detected from the on-line measured pH and oxygen uptake rate (OUR). The method was implemented in an SBR achieving biological nitrogen and phosphorus removal from anaerobically pre-treated abattoir wastewater. The degree of nitrite accumulation during the aeration period was monitored along with the variation in the nitrite oxidizing bacteria (NOB) population using fluorescence in situ hybridization (FISH) techniques. It is demonstrated that the nitrite pathway could be repeatedly and reliably achieved, which significantly reduced the carbon requirement for nutrient removal. Model-based studies show that the establishment of the nitrite pathway was primarily the result of a gradual reduction of the amount of nitrite that is available to provide energy for the growth of NOB, eventually leading to the elimination of NOB from the system.     

Nitrification in histosols: a potential role for the heterotrophic nitrifier.

Insufficient populations of Nitrosomonas and Nitrobacter were found in a Pahokee muck soil (Lithic medidaprit) to account for the nitrate concentration observed. To determine if heterotrophic nitrifiers could account for some of this discrepancy, a method was developed to measure the levels of heterotrophic nitrifiers in soil. A population of 4.1 X 10(5) Arthrobacter per g of dry fallow soil, capable of producing nitrite and/or nitrate from reduced nitrogenous compounds, was observed. Amendment of the much with 0.5% (wt/wt) sodium acetate and 0.1% (wt/wt) ammonium-nitrogen as ammonium sulfate (final concentrations) not only resulted in the usual increase in autotrophic nitrifiers, but also in a fourfold increase in the heterotrophic nitrifying Arrthrobacter. Amendment of like samples with N-Serve [2-chloro-6(trichloromethyl) pyridinel] prevented the increase in Nitrosomonas, but not that in the heterotrophic nitrifiers. Nitrate production in the presence of the inhibitor was diminished but not prevented. An Arthrobacter sp., isolated from the muck, produced nitrite when inoculated at high densities into sterile soil, unamended or amended with sodium acetate and/or ammomium sulfate. These data suggest that the heterotrophic population may be responsible for some of the nitrate produced in these Histosols.     

硝化细菌群的富集及其去除城镇寡营养河道中氨氮污染的应用

[背景]随着工农业的发展,污水排放导致的氨氮超标逐渐成为水体污染的重要因素,脱氮已成为人们研究的重点.目前脱氮方法主要集中于硝化细菌的硝化作用,其将氨氮转化为硝酸盐氮,从而减少水体中氨氮的污染.由于工业废水和农业污水中的有机物含量较高,而且异养硝化细菌具有生长较快等优势,因此对异养菌的研究多于自养菌.然而现有的异养硝化...     

Assessment of the positive effect of salinity on the nitrogen removal performance and microbial composition during the start-up of CANON process

In this study, a non-woven rotating biological contactor reactor was operated for the start-up of completely autotrophic nitrogen removal over nitrite (CANON) process. In this perfectly attached growth system, nitrite oxidizing was identified, which interfered with the nitrogen removal performance. Batch tests indicated that 10 g NaCl per liter salinity was a preferable definite level to stand out ammonium-oxidizing activity and anammox activity, and selectively suppress nitrite-oxidizing activity under oxygen-limited conditions. Reactor operation showed that the maximum TN removal rate was increased from 425 mg N l(-1) day(-1) to 637 mg N l(-1) day(-1) after the addition of 10 g NaCl per liter salinity on analogous technological parameters. Microbiological community analysis revealed that bacteria strains similar to the genus Nitrospira sp. were specialized nitrite oxidizers existing in CANON reactor, which were then eliminated under salinity exposure for their no salinity-tolerant relative. However, anammox bacteria belonging to Planctomycetes and some aerobic ammonium oxidizers belonging to Nitrosomonas could be highly enriched under this oxygen-limited salinity conditions. Salinity-contained high ammonium wastewater will be so considered as suitable influent for CANON process in further industrial application.