Denitrifying phosphate accumulating organisms and its mechanism of nitrogen and phosphorus removal / 生物工程学报

Water eutrophication poses great threats to protection of water environment. Microbial remediation of water eutrophication has shown high efficiency, low consumption and no secondary pollution, thus becoming an important approach for ecological remediation. In recent years, researches on denitrifying phosphate accumulating organisms and their application in wastewater treatment processes have received increasing attention. Different from the traditional nitrogen and phosphorus removal process conducted by denitrifying bacteria and phosphate accumulating organisms, the denitrifying phosphate accumulating organisms can simultaneously remove nitrogen and phosphorus under alternated anaerobic and anoxic/aerobic conditions. It is worth noting that microorganisms capable of simultaneously removing nitrogen and phosphorus absolutely under aerobic conditions have been reported in recent years, but the mechanisms remain unclear. This review summarizes the species and characteristics of denitrifying phosphate accumulating organisms and the microorganisms capable of performing simultaneous nitrification-denitrification and phosphorous removal. Moreover, this review analyzes the relationship between nitrogen removal and phosphorus removal and the underlying mechanisms, discusses the challenges of denitrifying phosphorus removal, and prospects future research directions, with the aim to facilitate process improvement of denitrifying phosphate accumulating organisms.

Mechanism of trehalose-enhanced metabolism of heterotrophic nitrification-aerobic denitrification community under high-salt stress / 生物工程学报

Heterotrophic nitrification-aerobic denitrification (HN-AD) bacteria are aerobic microorganisms that can remove nitrogen under high-salt conditions, but their performance in practical applications are not satisfactory. As a compatible solute, trehalose helps microorganisms to cope with high salt stress by participating in the regulation of cellular osmotic pressure, and plays an important role in promoting the nitrogen removal efficiency of microbial populations in the high-salt environment. We investigated the mechanism of exogenous-trehalose-enhanced metabolism of HN-AD community under high-salt stress by starting up a membrane aerobic biofilm reactor (MABR) to enrich HN-AD bacteria, and designed a C150 experimental group with 150 μmol/L trehalose addition and a C0 control group without trehalose. The reactor performance and the community structure showed that NH4+-N, total nitrogen (TN) and chemical oxygen demand (COD) removal efficiency were increased by 29.7%, 28.0% and 29.1%, respectively. The total relative abundance of salt-tolerant HN-AD bacteria (with Acinetobacter and Pseudofulvimonas as the dominant genus) in the C150 group reached 66.8%, an 18.2% increase compared with that of the C0 group. This demonstrated that trehalose addition promoted the enrichment of salt-tolerant HN-AD bacteria in the high-salt environment to enhance the nitrogen removal performance of the system. In-depth metabolomics analysis showed that the exogenous trehalose was utilized by microorganisms to improve proline synthesis to increase resistance to high-salt stress. By regulating the activity of cell proliferation signaling pathways (cGMP-PKG, PI3K-Akt), phospholipid metabolism pathway and aminoacyl-tRNA synthesis pathway, the abundances of phosphoethanolamine, which was one of the glycerophospholipid metabolites, and purine and pyrimidine were up-regulated to stimulate bacterial aggregation and cell proliferation to promote the growth of HN-AD bacteria in the high-salt environment. Meanwhile, the addition of trehalose accelerated the tricarboxylic acid (TCA) cycle, which might provide more electron donors and energy to the carbon and nitrogen metabolisms of HN-AD bacteria and promote the nitrogen removal performance of the system. These results may facilitate using HN-AD bacteria in the treatment of high-salt and high-nitrogen wastewater.

Craft Brewery Wastewater Treatment: a Fixed-Bed Single-Batch Reactor with Intermittent Aeration to Remove COD and TN

Abstract This study evaluated an intermittently aerated, fixed-bed, single-batch reactor, with mini BioBob© as biofilm media support, as an alternative treatment of craft brewery wastewater. In order to remove chemical oxygen demand (COD) and total nitrogen (TN), seven conditions were performed in a central composite experimental design (CCD) with different aeration times (1, 2 and 3 h in a 4 h cycle) and hydraulic retention times (HRT) (12, 16 and 20 h). The results showed that the removal of COD and TN were positively affected by increased aeration time and HRT. The condition that presented the best quality effluent was Condition No. 1 (20 h HRT and 3 h aeration), with 209 ± 28 mg COD L-1; 3.00 ± 0.15 mg TKN L-1 ; and 0.67 ± 0.11 mg NO3-N L-1. Kinetic assays showed that the highest values for the substrate removal rate constant, kCOD = 0.1774 h-1 were obtained with the longest aeration time (3 h). The most probable number (MPN) test showed a higher concentration of denitrifying bacteria (heterotrophic), 3.3 x 106, than for AOB and NOB bacteria (autotrophic), which were 4.9 x 103 and 2.7 x 103, respectively. Moreover, it was possible to verify that correcting the influent alkalinity with 7.14 mg CaCO3 for each 1 mg of TKN resulted in better process efficiency. It was concluded that COD and TN can be removed from craft brewery wastewater using an intermittently aerated, fixed-bed, single-batch reactor with mini Biobob© as biofilm media support.

Advances in denitrification microorganisms and processes / 生物工程学报

Denitrification is an indispensable part of most sewage treatment systems. The biological denitrification process has attracted much attention in the past decades due to the advantages such as cost-effectiveness, process simplicity, and absence of secondary pollution. This review summarized the advances on biological denitrification processes in recent years according to the different physiological characteristics and denitrification mechanisms of denitrification microorganisms. The pros and cons of different biological denitrification processes developed based on nitrifying bacteria, denitrifying bacteria, and anaerobic ammonia-oxidizing bacteria were compared with the aim to identify the best strategy for denitrification in a complex wastewater environment. The rapid development of synthetic biology provides possibilities to develop highly-efficient denitrifying strains based on mechanistic understandings. Combined with the applications of automatic simulation to obtain the optimal denitrification conditions, cost-effective and highly-efficient denitrification processed can be envisioned in the foreseeable future.

Correlación entre los microorganismos oxidantes del amonio y los factores ambientales durante el compostaje de estiércol de ganado / Correlation between ammonia-oxidizing microorganisms and environmental factors during cattle manure composting

Abstract Cattle manure composting was performed in an aerated vessel. Community structure and diversity of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated using polymerase chain reaction and denaturing gradient gel electrophoresis (PCR-DGGE) techniques targeting the ammonia monooxygenase alpha subunit (amoA) gene and the correlation between AOB and AOA communities and environmental factors was explored. Thirteen (13) AOB sequences were obtained, which were closely related to Nitrosomonas spp., Nitrosomonas eutropha, and Nitrosospira spp. and uncultured bacteria, among which Nitrosomonas spp. were predominant. Excessively high temperature and high ammonium concentration were not favorable for AOB growth. Five AOA sequences, belonging to Candidatus Nitrososphaera gargensis and to an uncultured archaeon, were obtained. During composting, community diversity of AOB and AOA fluctuated, with AOA showing a higher Shannon-Wiener index. The AOB community changed more dramatically in the mesophilic stage and the early thermophilic stage, whereas the most obvious AOA community succession occurred in the late thermophilic stage, the cooling stage and the maturity stage. Water content, total nitrogen (TN) and ammonium concentration were more relevant to the AOB community structure, while higher correlations were observed between ammonia, nitrate and TN and the AOA community. AOB community diversity was negatively correlated with pH (r = -0.938, p < 0.01) and water content (r = -0.765, p < 0.05), while positively correlated with TN (r = 0.894, p < 0.01). AOA community diversity was negatively correlated with ammonium concentration (r = -0.901, p < 0.01). Ammonium concentration played an important role in the succession of AOB and AOA communities during composting.

Resumen Se llevó a cabo un compostaje de estiércol de ganado en un recipiente aireado. Se investigó la estructura de la comunidad y la diversidad de bacterias oxidantes del amoníaco (AOB) y las arqueas oxidantes del amoníaco (AOA) mediante el uso de las técnicas de reacción en cadena de la polimerasa y la electroforesis en gel con gradiente de desnaturalización (PCR-DGGE) dirigidas al gen de la subunidad alfa de la amonio monooxigenasa (amoA), y se exploró la correlación entre las comunidades AOB, AOA y los factores ambientales. Se obtuvieron 13 secuencias de AOB, las cuales se relacionaron estrechamente con Nitrosomonas spp., Nitrosomonas eutropha y Nitrosospira spp., y bacterias no cultivadas, entre las cuales fueron predominantes las Nitrosomonas spp. La temperatura excesivamente alta y la concentración de amonio elevada no fueron favorables para el crecimiento de las AOB. Se obtuvieron 5 secuencias de AOA, pertenecientes a Candidatus Nitrososphaera gargensis y un Archaeon no cultivado. Durante el compostaje, la diversidad de AOB y AOA fluctuó y las AOA mostraron un índice de Shannon-Wiener más alto. La comunidad de AOB cambió significativamente en la etapa mesofílica y la etapa termofílica temprana, mientras que la sucesión más obvia de la comunidad AOA ocurrió en la etapa termofílica tardía y las etapas de enfriamiento y de maduración. El contenido de agua, el nitrógeno total (TN) y la concentración de amonio fueron más relevantes para la estructura de la comunidad AOB, mientras que se observaron correlaciones mayores entre amoníaco, nitrato y TN, y la comunidad AOA. La diversidad de la comunidad AOB se correlacionó negativamente con el pH (r= -0,938; p < 0,01) y el contenido de agua (r = -0,765; p < 0,05), mientras que se relacionó positivamente con TN (r = 0,894; p < 0,01). La diversidad de la comunidad AOA se correlacionó negativamente con la concentración de amonio (r = -0,901; p < 0,01). La concentración de amonio desempenó un papel importante en la sucesión de las comunidades AOB y AOA durante el compostaje.

Advances in heterotrophic nitrification-aerobic denitrifying bacteria for nitrogen removal under extreme conditions / 生物工程学报

Heterotrophic nitrification-aerobic denitrification (HN-AD) is an enrichment and breakthrough theory of traditional autotrophic nitrification heterotrophic denitrification. Heterotrophic nitrification-aerobic denitrifiers with the feature of wide distribution, strong adaptability and unique metabolic mechanism have many special advantages, including fast-growing, rapid biodegradability and long lasting activity, which can rapidly remove ammonia nitrogen, nitrate nitrogen (NO₃⁻-N) and nitrite nitrogen (NO₂⁻-N) under aerobic conditions simultaneously. Therefore, HN-AD bacteria show the important potential for denitrification under extreme conditions with high-salt, low-temperature or high-ammonia nitrogen environment, and HN-AD bacteria attract extensive attention in the field of biological denitrification of wastewater. In this review, we first introduce the previously reported HN-AD bacterial species which have denitrification performance in the extreme environments and state their typical metabolic mechanism. Then, we systematically analyze the nitrogen removal characteristics and potential under extreme conditions. We also briefly describe the progress in the application of HN-AD bacterial. Finally, we outlook the application prospects and research directions of HN-AD denitrification technology.

Emisión de óxido nitroso, nitrificación, desnitrificación y mineralización de nitrógeno durante el cultivo del arroz en 2 suelos de Uruguay / Nitrous oxide emission, nitrification, denitrification and nitrogen mineralization during rice growing season in 2 soils from Uruguay

Los procesos microbianos como la mineralización, la nitrificación y la desnitrificación regulan la dinámica del nitrógeno en el suelo. Estos 2 últimos son los principales responsables de la emisión de óxido nitroso (N2O). En este trabajo se determinaron los flujos de N2O en momentos clave del ciclo de cultivo del arroz en 2 sitios que diferían principalmente en el contenido de materia orgánica del suelo (MO), en las localidades de Salto (mayor MO) y de Treinta y Tres. Dichos momentos clave fueron a la siembra, en macollaje, en primordio floral y a la madurez. También se determinó el potencial de mineralización neta de N y las actividades y los números más probables (NMP) de oxidantes de NH4+ y de desnitrificantes. El potencial de mineralización de N, así como la actividad y el NMP de oxidantes de NH4+, no variaron con el tipo de suelo. Sin embargo, la actividad y el NMP de desnitrificantes fueron mayores en el suelo con mayor contenido de MO, independiente de la etapa del cultivo. A su vez, en las etapas finales del ciclo del cultivo, el NMP de desnitrificantes aumentó coincidiendo con el mayor potencial de mineralización y el mayor contenido de N mineral del suelo. Solo se observó un incremento en el flujo de N2O en el suelo de Salto a la madurez del arroz y cuando el suelo ya había sido drenado (44,2g N-N2O/ha d, frente a 20,8g N-N2O/ha d en Treinta y Tres). Esta investigación señala la importancia de estudiar las emisiones en distintos tipos de suelos y de continuar la medición luego del drenaje del cultivo de arroz para la elaboración de los inventarios de gases de efecto invernadero.

Microbial processes such as mineralization, nitrification and denitrification regulate nitrogen dynamics in the soil. The last two processes may produce nitrous oxide (N2O). In this work N2O fluxes were quantified at four moments of the rice cycle, sowing, tillering, panicle initiation and maturity, in two sites that differed mainly in their soil organic matter (OM) content, Salto (higher OM) and Treinta y Tres. Potential net N mineralization, ammonium oxidation and denitrification as well as the most probable numbers (MPN) of ammonia oxidizers and denitrifiers were determined. Potential N mineralization did not vary with the soil type and increased at rice maturity. Neither ammonia oxidation potential nor MPN were different among the soils. However, the soil with higher OM exhibited higher activity and MPN of denitrifiers, irrespective of the rice stage. In turn, at the latest phases of the crop, the MPN of denitrifiers increased coinciding with the highest mineralization potential and mineral N content of the soil. Significant differences in N2O flux were observed in Salto, where the highest emissions were detected at rice maturity, after the soil was drained (44.2 vs 20.8g N-N2O/ha d in Treinta y Tres). This work shows the importance of considering the soil type and end-of-season drainage of the rice field to elaborate GHGs (greenhouse gases) inventories.

Assessment of microalgae and nitrifiers activity in a consortium in a continuous operation and the effect of oxygen depletion

Background: Industrial wastewaters with a high content of nitrogen are a relevant environmental problem. Currently, treatments to remove nitrogen are not efficient, so is necessary to develop alternative methods. The objective of this study is to investigate a consortium of microalgae - nitrifying, that due to the symbiosis between them could be an interesting alternative. Results: In this study, it was possible to obtain a consortium of nitrifying bacteria (NB) and microalgae (MA) capable of operating with low requirements of dissolved oxygen, using aerobic sludge from wastewater treatment plants. During the operation, this consortium presents removal percentages above 98% of ammonia, even at concentrations of DO of 0.5 mg O2 L-1. It is estimated that the removal was caused both by the action of nitrifying bacteria and microalgae. It was determined that approximately 60% of the ammonia feed was oxidized to nitrate by nitrifying bacteria, while the algae assimilated 40% of the nitrogen feed at steady state. A methodology for measuring the specific activities of nitrifying bacteria and microalgae by comparing the rates in the variation inorganic nitrogen compounds was established with satisfactory results. An average specific activity of 0.05 and 0.02 g NH4 + gVSS-1 d-1 for nitrifying bacteria and microalgae was determined, respectively. Conclusions: The consortium it can be obtained in a single continuous operation, and has a high capacity for nitrogen removal with low oxygen content. The consortium could prove to be a more economical method compared to traditional.

Performance of different biofilters in a recirculating system for rainbow trout farming / Desempeño de diferentes biofiltros en un sistema de recirculación para cultivo de trucha arcoiris

ABSTRACT Objective. To evaluate the performance of different biofilters in a recirculating aquaculture system (RAS) for trout farming. Materials and methods. It was used a 1m3 plastic tank for fries farming; fabric bags to solids retention; a submersible pump; a constant water level and flow distribution box; six up flow biofilters in 3" PVC tube; sand of D10=0.45mm as carrier. The reactors were operated at local temperature and with hydraulic retention time (HRT) of 11 min, the biofilters were inoculated in the next way: R1-Control: RAS water; R2-Fish culture farm sludges; R3- Water from aerated lagoon of Antanas landfill (AL); R4-Aquarium sediments; R5- Aerated lagoon of AL sludges; R6-Sludges from sulfidogenic reactor of AL. The weight gain (WG) and the food conversion (FC) were evaluated, some physic-chemical parameters were monitored and the nitrogen and suspended solids removal efficiency were evaluated. Results. The WG of the cultured animals was 1.58 g/d and the FC was 1.41. There were no differences for ammonium and nitrite removal between the reactors; the average removal efficiencies were: ammonium 4.78%, nitrite 27.2%, nitrate 32.3%, suspended solids 37.5%; R4 and R5 reactors presented the best performance on nitrate removal, with average efficiencies of 47.4% and 42.8%. R3 presented the best SS removal with an average of 58.2%. Conclusions. The RAS water treatment system guaranteed appropriated liquid quality conditions for trout farming; the most efficient reactor for removal of the different forms of nitrogen was the inoculated with the aerated lagoon of AL sludges.

RESUMEN Objetivo. Evaluar el desempeño de diferentes biofiltros en un sistema de recirculación (SRA) para cultivo de trucha arcoiris. Materiales y métodos. Se utilizó: un tanque de 1m3 para cultivo de alevines, bolsas de lienzo para retención de sólidos, bomba sumergible, caja de nivel constante y distribución de flujo, seis biofiltros en tubo de PVC de 3", arena con D10=0.45mm como medio soporte. Los biofiltros se operaron a temperatura ambiente y con tiempo de retención hidráulica (TRH) de 11 min, se inocularon así: R1-Control: Aguas del SRA; R2-Lodos estación piscícola; R3-Agua Laguna aireada relleno sanitario Antanas (RSA); R4-Sedimentos acuarios; R5-Lodos laguna aireada RSA; R6-Lodos reactor sulfidogénico RSA. Se evaluó la ganancia de peso (GP) y la conversión alimenticia (CA), se monitorearon parámetros físico-químicos y se evaluó la eficiencia de remoción de nitrógeno y sólidos suspendidos. Resultados. La GP de los animales fue de 1.58 g/d y la CA de 1.41. No hubo diferencias para remoción de amonio ni nitritos entre reactores; las eficiencias medias de remoción fueron: amonio 4.78%, nitrito 27.2%, nitrato 32.3%, sólidos suspendidos 37.5%. Los reactores R4 y R5 presentaron mejor remoción de nitratos, con eficiencias medias de 47.4% y 42.8%. El R3 reportó la mejor remoción de SS con promedio del 58.2%. Conclusiones. El sistema de tratamiento del agua en el SRA garantizó condiciones de calidad del líquido, apropiadas para el cultivo de la trucha; el reactor más eficiente para la remoción de las formas de nitrógeno evaluadas fue el inoculado con lodos de la laguna aireada del RSA.

Estratégias de tratamento de lixiviado de aterro sanitário com foco na matéria orgânica biodegradável e nitrogênio amoniacal / Strategies of landfill leachate treatment focused on biodegradable organic matter and ammonia nitrogen

Sistemas de tratamento de esgotos, quando aplicados ao tratamento de lixiviado de aterro sanitário, não têm apresentado bons resultados. Por conta disso, faz-se necessário o desenvolvimento de alternativas para o tratamento de lixiviado. Objetivo avaliar o pós-tratamento de lixiviado de aterro sanitário por wetland construído de fluxo subsuperficial horizontal e reator biológico de leito móvel (RBLM). Materiais e métodos foram realizados dois experimentos com tratamento de lixiviado após remoção de amônia por dessorção. No experimento 1 utilizou-se wetlands construídos de fluxo horizontal em escala de bancada (volume total de 30,8 L), plantados com Cyperus papyrus, Heliconia psittacorum e Gynerium sagittatum, e um controle sem vegetação, preenchidos com pedrisco calcário. O sistema foi alimentado com lixiviado diluído em água em diferentes proporções (entre 10 por cento e 30 por cento ) com concentração média de DQO entre 336 e 750 mg.L-1 e nitrogênio amoniacal (N-NH4) entre 47 e 199 mg.L-1. A operação ocorreu em três etapas: (1ª) alimentação contínua e TDH médio entre 2,7 e 5,3 d; (2ª) regime de ciclos de recirculação do efluente, para avaliar o efeito do aumento de TDH para 21 dias; (3ª) alimentação contínua de duas unidades wetlands em série, visando elevar o TDH (entre 8,1 e 9,9 d) sem recirculação. O experimento 2 foi implantado em escala piloto, com uma unidade de dessorção de amônia seguida de um Reator Biológico de Leito Móvel (RBLM) e um biofiltro anóxico. O RBLM (volume efetivo de 380 L) foi preenchido em 50 por cento com anel pall. Resultados e discussão No experimento 1, obteve-se baixa remoção de DQO com médias inferiores a 40 por cento e concentração final entre 270 e 750 mg.L-1...

sewage treatment systems, when applied to the treatment of landfill leachate, have not shown good results. Thus it is necessary to develop alternatives for the treatment of leachate. Objective To assess the post-treatment of landfill leachate by horizontal subsurface flow constructed wetland and moving bed biofilm reactor (MBBR). Materials and methods Two experiments were conducted with treatment of the leachate after removal of ammonia by stripping. In experiment 1, horizontal flow constructed wetlands, at bench scale (total volume of 30.8 L), planted with Cyperus papyrus, Heliconia psittacorum and Gynerium sagittatum, and a control without vegetation, were filled with calcareous gravel. The system was fed with leachate diluted in water with different proportions (between 10 per cent and 30 per cent ) with mean COD concentration of between 336 and 750 mg.L-1 and ammonia nitrogen (NH4-N) between 47 and 199 mg L-1. The operation was divided in three stages: (1st) continuous feeding with mean HRT between 2.7 and 5.3 d; (2nd) regime of effluent recirculation to evaluate the effect of increasing the HRT to 21 days; (3rd) continuous feeding with two wetlands units in series, aimed HRT increasing (between 8.1 and 9.9 d) without recirculation. Experiment 2 was implemented on a pilot scale, with a unit of ammonia stripping followed by MBBR and an anoxic biofilter. The MBBR (380 L working volume) was filled 50 per cent with pall ring. Results and discussion In experiment 1, the COD removal was low, with averages below 40 per cent , with effluent concentration between 270 and 750 mg.L-1...

Effects of growing time on Panax ginseng rhizosphere soil microbial activity and biomass / 中国中药杂志

Using the field sampling and indoor soil cultivation methods, the dynamic of ginseng rhizosphere soil microbial activity and biomass with three cultivated ages was studied to provide a theory basis for illustrating mechanism of continuous cropping obstacles of ginseng. The results showed that ginseng rhizosphere soil microbial activity and biomass accumulation were inhibited observably by growing time. The soil respiration, soil cellulose decomposition and soil nitrification of ginseng rhizosphere soil microorganism were inhibited significantly (P <0.05), in contrast to the control soil uncultivated ginseng (R0). And the inhibition was gradual augmentation with the number of growing years. The soil microbial activity of 3a ginseng soil (R3) was the lowest, and its activity of soil respiration, soil cellulose decomposition, soil ammonification and soil nitrification was lower than that in R0 with 56.31%, 86.71% and 90. 53% , respectively. The soil ammonification of ginseng rhizosphere soil microbial was significantly promoted compared with R0. The promotion was improved during the early growing time, while the promotion was decreased with the number of growing years. The soil ammonification of R1, R2 and R3 were lower than that in R0 with 32.43%, 80.54% and 66.64% separately. The SMB-C and SMB-N in ginseng rhizosphere soil had a decreased tendency with the number of growing years. The SMB-C difference among 3 cultivated ages was significant, while the SMB-N was not. The SMB of R3 was the lowest. Compared with R0, the SMB-C and the SMB-N were significantly reduced 77.30% and 69.36%. It was considered by integrated analysis that the leading factor of continuous cropping obstacle in ginseng was the changes of the rhizosphere soil microbial species, number and activity as well as the micro-ecological imbalance of rhizosphere soil caused by the accumulation of ginseng rhizosphere secretions.

Application and obstacles of ANAMMOX process / 生物工程学报

Anaerobic ammonium oxidation (ANAMMOX), as its essential advantages of high efficiency and low cost, is a promising novel biological nitrogen elimination process with attractive application prospects. Over the past two decades, many processes based on the ANAMMOX reaction have been continuously studied and applied to practical engineering, with the perspective of reaching 100 full-scale installations in operation worldwide by 2014. Our review summarizes various forms of ANAMMOX processes, including partial nitritation-ANAMMOX, completely autotrophic nitrogen removal over nitrite, oxygen limited autotrophic nitrification and denitrification, denitrifying ammonium oxidation, aerobic deammonification, simultaneous partial nitrification, ANAMMOX and denitrification, single-stage nitrogen removal using ANAMMOX and partial nitritation. We also compare the operating conditions for one-stage and two-stage processes and summarize the obstacles and countermeasures in engineering application of ANAMMOX systems, such as moving bed biofilm reactor, sequencing batch reactor and granular sludge reactor. Finally, we discuss the future research and application direction, which should focus on the optimization of operating conditions and applicability of the process to the actual wastewater, especially on automated control and the impact of special wastewater composition on process performance.

Effect of oxygen on partial nitrification in a membrane bioreactor / 生物工程学报

We studied the effects of the oxygen on partial nitrification in a membrane bioreactor (MBR), to find out critical dissolved oxygen (DO) concentrations for the optimal partial nitrification by monitoring the oxygen uptake rate (OUR) and oxygen supply rate (OSR). The nitrite accumulation occurred at a DO concentration of 1 mg/L, while the ratio of nitrite to ammonia in effluent was close to 1 at a DO concentration of 0.5 mg/L which was suitable to serve as the feed of an ANNAMOX system. When the mixed liquid suspended solids(MLSS) was 20 g/L in MBR, OUR and OSR were 19.86 mg O2/(L·s) and 0.369 mg O2/(L·s) respectively, indicating that the oxygen supply was the bottleneck of partial nitrification. "Low DO and high aeration rate" were suggested as a control strategy to further improve the efficiency of partial nitrification.

Start-up of a full-scale system for short-cut nitrification and Anammox in treatment of pharmaceutical wastewater / 生物工程学报

In order to broaden the application area of the new nitrogen removal technology, a full-scale system for short-cut nitrification and anaerobic ammonium oxidation (Anammox) was investigated in the nitrogen removal from a strong-ammonium pharmaceutical wastewater. When the influent ammonium concentration was (430.40 ± 55.43) mg/L, ammonia removal efficiency was (81.75 ± 9.10)%. The short-cut nitrification and Anammox system could successfully remove nitrogen from the pharmaceutical wastewater. The start-up of short-cut nitrification system took about 74 d and the nitrite accumulation efficiency was (52.11 ± 9.13)%, the two-step mode using synthetic wastewater and actual wastewater was suitable for the start-up of short-cut nitrification system. The start-up of Anammox system took about 145 d and the maximum volumetric nitrogen removal rate was 6.35 kg N/(m3·d), dozens of times higher than those for the conventional nitrification-denitrification process. The strategy achieving Anammox sludge by self-growth and biocatalyst addition was suitable for the start-up of Anammox system.

Desempeño de un reactor biológico secuencial (RBS) en el tratamiento de aguas residuales domésticas / Performance of a Sequencing Batch Reactor (SBR) in the treatment of domestic sewage

Se estudió la remoción biológica de materia orgánica y nutrientes de un agua residual doméstica empleando un Reactor Biológico Secuencial (RBS) a escala piloto. El estudio fue dividido en cuatro fases en las que se modifico la carga orgánica y la duración de las etapas anaerobia, aerobia y anoxica que conforman cada ciclo de tratamiento, considerando edades de lodo de 10 y 7,5 días. Durante las Fases I y II se operó el sistema con bajos valores de carga másica: 0,364 y 0,220 kg.DQO/Kg.SSV.dia, mientras que durante las Fases III y IV se emplearon cargas mayores: 0,665 y 0,737 kg.DQO/Kg.SSV.dia respectivamente. Los resultados obtenidos muestran que las mayores eficiencias de remoción de materia orgánica en términos de DBO se alcanzaron durante la Fases III (91%) y IV (82%), con remoción de fósforo superior a 40%. En cuanto al proceso de nitrificación durante las Fases I y II se registraron tasas de 0,032 y 0,024 kg.N-NH3/kg.SSV.dia, esto debido al menor contenido de materia orgánica y a la baja relación DBO/NKT, mientras que durante las Fases III y IV estas fueron menores: 0,015 kg.N-NH3/kg.SSV.dia durante la Fase III y 0,020 kg.N-NH3/kg.SSV.dia en la Fase IV, sin embargo, fue en estas fases donde se alcanzaron los mayores niveles de desnitrificación durante la etapa anóxica, favorecido por una relación C/N adecuada, próxima de 4 kg.DBO/kg.N-NO3- y la presencia de un substrato de fácil biodegradación. Los resultados obtenidos muestran los RBS como una alternativa eficiente y viable en el tratamiento de aguas residuales domésticas.

It was studied the biological removal of organic matter and nutrients from domestic wastewater using a Sequential Biological Reactor (SBR) at pilot scale. The study was divided into four phases in which the organic load and the duration of anaerobic, aerobic and anoxic cycle were modified, considering sludge ages of 10 and 7.5 days. During Phases I and II the system was operated with low mass load values: 0.364 and 0.220 kg.COD/kg.VSS.day, while during Phases III and IV were used heavier loads: 0.665 and 0.737 kg.COD/Kg.VSS.day respectively. The results obtained show that the removal efficiencies of organic matter in terms of BOD were achieved during Phase III (91%) and IV (82%) with phosphorus removal exceeding 40%. As for the nitrification process during Phases I and II showed rates of 0.032 and 0.024 kg.N-NH3/kg.VSS.day, this due to lower organic matter content and low BOD/TKN, while during phases III and IV these were lower: 0.015 kg.N-NH3/kg.VSS.day during Phase III and 0.020 kg.N-NH3/kg.VSS.day in Phase IV, however, was in these phases which reached the highest levels of denitrification during the anoxic phase, favored by a C/N appropriate next of 4 kg.BOD/kg.N-NO3- and the presence of an easily biodegradable substrate. The results show the RBS as an efficient and viable process in the treatment of domestic wastewater.

Nitrificação e desnitrificação simultânea em reator com biomassa em suspensão e fluxo contínuo de esgoto / Simultaneous nitrification and denitrification in reactor with biomass in suspension and continuous flow of sewage

Recentemente foi desenvolvido na Europa o processo conhecido por Nitrificação e Desnitrificação Simultânea (NDS), em que o lodo ativado opera com tempo de retenção de sólidos suficientemente altos para que a nitrificação ocorra mesmo com baixa concentração de oxigênio dissolvido nos tanques de aeração, situação em que é possível a manutenção de condições anóxicas no interior dos flocos e a ocorrência da desnitrificação. Em países de clima tropical, muitas estações de tratamento de esgoto foram construídas ou estão sendo projetadas para operarem sob as condições da variante do processo de lodo ativado conhecida por aeração prolongada, reconhecidamente eficiente na remoção de matéria orgânica e na nitrificação do esgoto. Tais estações podem ser adaptadas para estas novas condições, de forma a se obter o benefício técnico da desnitrificação e o ganho econômico relativo à redução no consumo de energia elétrica para aeração. Este estudo avaliou as condições de remoção de nitrogênio via NDS em um sistema de lodo ativado com aeração prolongada alimentada em fluxo contínuo com diferentes idades do lodo 40, 30 e 20 dias, tratando esgoto sanitário. O processo de tratamento permaneceu estável durante todo o período de observação. Os resultados experimentais demonstram que é possível manter baixas concentrações de OD no tanque de aeração em uma faixa relativamente estreita (0,3-0,8 mg.L-1), e, consequentemente desenvolver os processos de nitrificação e desnitrificação sob as mesmas condições (NDS) com alta eficiência e estabilidade. A remoção de DQO e DBO foi acima de 90 por cento . Os valores de crescimento específico máximo (m20) das bactérias autotróficas nitritantes e nitratantes, resultaram muito próximos aos descritos na literatura, sendo para a idade do lodo de 20 dias os valores de 0,68 d-1 para as bactérias nitritantes e de 0,62 d-1 para as bactérias nitratantes. Os valores das taxas de utilização máxima de amônia foram maiores do que as obtidas com o nitrito e, pode-se observar que o acúmulo de nitrato devido à diminuição da amônia foi mais rápido do que o com nitrito. Desse modo, conclui-se que a nitrificação foi governada pelas bactérias autotróficas nitritantes. A taxa de utilização de nitrato foi maior tendo como substrato material rapidamente biodegradável. Confirmando que a disponibilidade de carbono tem papel fundamental nas taxas de desnitrificação no processo de NDS.

Abundance and diversity of ammonia-oxidizing bacteria in relation to ammonium in a Chinese shallow eutrophic urban lake

The measures of most-probable-number and restriction fragment length polymorphism analysis were used to analyze the abundance and diversity of ammonia-oxidizing bacteria in sediment of a Chinese shallow eutrophic urban lake (Lake Yuehu). Among the 5 sampling sites, ammonia concentration in interstitial water was positively proportional not only to the content of organic matter, but also to ammonia-oxidizing bacteria numbers (at a magnitude of 10(5) cells g-1 dry weight) in sediment significantly. Furthermore, the diversity of ammonia-oxidizing bacteria were determined by means of PCR primers targeting the amoA gene with five gene libraries created and restriction pattern analysis. The 13 restriction patterns were recorded with 4 ones being common among all sampling sites. The 8 restriction patterns including 4 unique ones were found at the site with the highest NH4+ concentrations in interstitial water, while, there were only common patterns without unique ones at the site with the lowest NH4+ concentrations in interstitial water. Phylogenetic analysis showed that the amoA fragments retrieved belong to Nitrosomonas oligotropha & ureae lineage, N. europaea lineage, N. communis lineage and Nitrosospira lineage, most of which were affiliated with the genus Nitrosomonas. The N. oligotropha & ureae-like bacteria were the dominant species. Thus, the abundance and diversity of sediment AOB is closely linked to ammonium status in eutrophic lakes.

investigation on the nitrogen content of a petroleum refinery's wastewater and its removal by biological treatment

This investigation was performed on the biological removal of nitrogen from refinery's wastewater by the nitrification and denitrification process. In a petroleum refinery, removing of hydrocarbons is the main concern and nitrogen content is supposed to be negligible. The aim of this work was to search for nitrogen in Tehran Refinery wastewater and employing a biological technology to reduce this pollutant. Samplings were done in different points of wastewater treatment plant; influent to aeration unit, effluent of aeration unit and effluent of clarifiers. The results showed that despite of a high average removal efficiency of COD > 93%, the nitrogen removal during conventional activated sludge process was not efficient and sludge rising due to denitrification was observed within the clarifier. The analysis conducted in laboratory scale showed that a simultaneous nitrification and denitrification [SND] process could easily be realized in the same activated sludge plant by using the flocculating sludge and control of dissolved oxygen concentration. It was found that the higher MLSS value [10.0 g/L] and mixing rate [300 rpm] is effective in improving total nitrogen removal and overall SND performance. Our experimental results indicated that the SND process is very efficient for nitrogen removal from industrial wastewater

Performance of moving bed biofilm reactors for biological nitrogen compounds removal from wastewater by partial nitrification-denitrification process

In this research, the continuously operated laboratory scale Kaldnes [k1] moving bed biofilm reactors [MBBRs] under partial nitrification-denitrification process were used for treatment of synthetic wastewater containing ammonium and glucose. The Anoxic and Aerobic reactors were filled to 40 and 50% [v/v] to attach and retain biomass with k1 biofilm carriers, respectively. The favorite internal recycle ratio and hydraulic residence time [HRT] to eliminate nitrogen compounds were 300% of inflow rate and 20 hours, respectively. Optimal dissolved oxygen [DO] was 1-1.5 mg/L in the aerobic reactor. No sludge was returned into the system and only an internal recycling was performed from aerobic to anoxic reactor. The results showed that the maximum and average specific nitrification rate [SNR] in the aerobic reactor were 49.4 and 16.6 g NOx-N/KgVSS.day, respectively and the maximum and average specific denitrification rate [SDNR] as 156.8 and 40.1gNOx-N/KgVSS.day in the anoxic reactor, respectively. The results also showed that it is possible to reach a stable partial nitrification with high ratio of NO2-N/NOx-N [80% to 85%] during high load ammonium and low DO concentration [<1.5 mg/L] in the aerobic reactor. During optimum conditions, the average removal efficiency of total nitrogen [TN], ammonia and soluble organic carbon [SCOD] occurred as 98.23%, 99.75% and 99.4%, respectively. This study showed that the partial nitrification/denitrification process in the moving bed biofilm reactors system has an acceptable performance for treatment of wastewater with high load of organic carbon and organic nitrogen compounds

Tratamento terciário de efluentes de estações de tratamento por lodo ativado para fins de reuso como água de reposição em torres de resfriamento / Tertiary treatment of effluentes from water treatment by slime activated for ends of reuso as water of replacement in cooling towers

No presente trabalho são apresentados estudos do tratamento terciário de efluentes de estações de tratamento de esgotos domésticos por processo de lodo ativado, variação aeração prolongada, com objetivo de reuso na alimentação em torres de resfriamento de circuitos semi-abertos, substituindo na recomposição, águas potáveis fornecidas por empresas de saneamento. Neste sentido foi proposta a aplicação de tratamento terciário por clarificação físico-química: coagulação, floculação e decantação, filtração e desinfecção por cloro, de forma a obter água com qualidade compatível para utilização em torres de resfriamento de acordo com as normas vigentes. A metodologia utilizada para a obtenção dos resultados foi experimental, onde construiu-se uma unidade piloto conforme a proposta e operou-se o processo com três efluentes de estações de tratamento por aeração prolongada com idades de lodo e níveis de nitrificação diferentes. Todos os experimentos foram precedidos por exames laboratoriais de jarteste utilizando-se sulfato de alumínio, cloreto férrico e policloreto de alumínio como coagulantes, isoladamente ou com auxiliares de floculação da classe catiônica ou aniônica...