RESUMEN
The coupling between anammox and nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) has been considered a sustainable technology for nitrogen removal from sidestream wastewater and can be implemented in both membrane biofilm reactor (MBfR) and granular bioreactor. However, the potential influence of the accompanying hydrogen sulfide (H2S) in the anaerobic digestion (AD)-related methane-containing mixture on anammox/n-DAMO remains unknown. To fill this gap, this work first constructed a model incorporating the C/N/S-related bioprocesses and evaluated/calibrated/validated the model using experimental data. The model was then used to explore the impact of H2S on the MBfR and granular bioreactor designed to perform anammox/n-DAMO at practical levels (i.e., 0â¼5% (v/v) and 0â¼40 g/S m3, respectively). The simulation results indicated that H2S in inflow gas did not significantly affect the total nitrogen (TN) removal of the MBfR under all operational conditions studied in this work, thus lifting the concern about applying AD-produced biogas to power up anammox/n-DAMO in the MBfR. However, the presence of H2S in the influent would either compromise the treatment performance of the granular bioreactor at a relatively high influent NH4+-N/NO2--N ratio (e.g., >1.0) or lead to increased energy demand associated with TN removal at a relatively low influent NH4+-N/NO2--N ratio (e.g., <0.7). Such a negative effect of the influent H2S could not be attenuated by regulating the hydraulic residence time and should therefore be avoided when applying the granular bioreactor to perform anammox/n-DAMO in practice.
Asunto(s)
Reactores Biológicos , Sulfuro de Hidrógeno , Metano , Nitratos , Nitritos , Oxidación-Reducción , Sulfuro de Hidrógeno/metabolismo , Anaerobiosis , Metano/metabolismo , Nitratos/metabolismo , Eliminación de Residuos Líquidos/métodos , Nitrógeno/metabolismo , Aguas Residuales/químicaRESUMEN
Nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) process is a promising wastewater treatment technology, but the slow microbial growth rate greatly hinders its practical application. Although high-level nitrogen removal and excellent biomass accumulation have been achieved in n-DAMO granule process, the formation mechanism of n-DAMO granules remains unresolved. To elucidate the role of functional microbes in granulation, this study attempted to cultivate granules dominated by n-DAMO microorganisms and granules coupling n-DAMO with anaerobic ammonium oxidation (Anammox). After long-term operation, dense granules were developed in the two systems where both n-DAMO archaea and n-DAMO bacteria were enriched, whereas granulation did not occur in the other system dominated by n-DAMO bacteria. Extracellular polymeric substances (EPS) measurement indicated the critical role of EPS production in the granulation of n-DAMO process. Metagenomic and metatranscriptomic analyses revealed that n-DAMO archaea and Anammox bacteria were active in EPS biosynthesis, while n-DAMO bacteria were inactive. Consequently, more EPS were produced in the systems containing n-DAMO archaea and Anammox bacteria, leading to the successful development of n-DAMO granules. Furthermore, EPS biosynthesis in n-DAMO systems is potentially regulated by acyl-homoserine lactones and c-di-GMP. These findings not only provide new insights into the mechanism of granule formation in n-DAMO systems, but also hint at potential strategies for management of the granule-based n-DAMO process.
Asunto(s)
Archaea , Bacterias , Oxidación-Reducción , Archaea/metabolismo , Archaea/genética , Anaerobiosis , Bacterias/metabolismo , Bacterias/genética , Metano/metabolismo , Eliminación de Residuos Líquidos/métodos , Nitratos/metabolismo , Compuestos de Amonio/metabolismo , Nitritos/metabolismo , Matriz Extracelular de Sustancias Poliméricas/metabolismo , Reactores Biológicos/microbiología , Aguas Residuales/microbiologíaRESUMEN
Nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) process offers a promising solution for simultaneously achieving methane emissions reduction and efficient nitrogen removal in wastewater treatment. Although nitrogen removal at a practical rate has been achieved by n-DAMO biofilm process, the mechanisms of biofilm formation and nitrogen transformation remain to be elucidated. In this study, n-DAMO biofilms were successfully developed in the membrane aerated moving bed biofilm reactor (MAMBBR) and removed nitrate at a rate of 159 mg NO3--N L-1 d-1. The obvious increase in the content of extracellular polymeric substances (EPS) indicated that EPS production was important for biofilm development. n-DAMO microorganisms dominated the microbial community, and n-DAMO bacteria were the most abundant microorganisms. However, the expression of biosynthesis genes for proteins and polysaccharides encoded by n-DAMO archaea was significantly more active compared to other microorganisms, suggesting the central role of n-DAMO archaea in EPS production and biofilm formation. In addition to nitrate reduction, n-DAMO archaea were revealed to actively express dissimilatory nitrate reduction to ammonium and nitrogen fixation. The produced ammonium was putatively converted to dinitrogen gas through the joint function of n-DAMO archaea and n-DAMO bacteria. This study revealed the biofilm formation mechanism and nitrogen-transformation network in n-DAMO biofilm systems, shedding new light on promoting the application of n-DAMO process.
Asunto(s)
Biopelículas , Reactores Biológicos , Metano , Nitratos , Oxidación-Reducción , Biopelículas/crecimiento & desarrollo , Metano/metabolismo , Anaerobiosis , Nitratos/metabolismo , Reactores Biológicos/microbiología , Nitrógeno/metabolismo , Archaea/metabolismo , Archaea/genética , Archaea/fisiología , Bacterias/metabolismo , Bacterias/genética , Eliminación de Residuos Líquidos/métodosRESUMEN
Nitrate/nitrite-dependent anaerobic oxidation of methane (n-DAMO) is a recently discovered process, which provides a sustainable perspective for simultaneous nitrogen removal and greenhouse gas emission (GHG) mitigation by using methane as an electron donor for denitrification. However, the engineering roadmap of the n-DAMO process is still unclear. This work constitutes a state-of-the-art review on the classical and most recently discovered metabolic mechanisms of the n-DAMO process. The versatile combinations of the n-DAMO process with nitrification, nitritation, and partial nitritation for nitrogen removal are also clearly presented and discussed. Additionally, the recent advances in bioreactor development are systematically reviewed and evaluated comprehensively in terms of methane supply, biomass retention, membrane requirement, startup time, reactor performance, and limitations. The key issues including enrichment and operation strategy for the scaling up of n-DAMO-based processes are also critically addressed. Moreover, the challenges inherent to implementing the n-DAMO process in practical applications, including application scenario recognition, GHG emission mitigation, and operation under realistic conditions, are highlighted. Finally, prospects as well as opportunities for future research are proposed. Overall, this review provides a roadmap for potential applications and further development of the n-DAMO process in the field of wastewater treatment.
Asunto(s)
Compuestos de Amonio , Nitratos , Nitratos/metabolismo , Nitritos/metabolismo , Nitrificación , Anaerobiosis , Metano , Desnitrificación , Compuestos de Amonio/metabolismo , Oxidación-Reducción , Reactores Biológicos , Nitrógeno/metabolismoRESUMEN
Granular sludge combined n-DAMO and Anammox (n-D/A) is an energy-efficient biotechnique for the simultaneous removal of nitrogen and dissolved methane from wastewater. However, the lack of knowledge so far about the metabolic interactions between n-DAMO and Anammox in response to operation condition in granular sludge restrains the development of this biotechnology. To address this gap, three independent membrane granular sludge reactors (MGSRs) were designed to carry out the granule-based n-D/A process under different conditions. We provided the first deep insights into the metabolic interactions between n-DAMO and Anammox in granular sludge via combined metagenomic and metatranscriptomic analyses. Our study unveiled a clear population shift of n-DAMO community from Candidatus Methanoperedens to Candidatus Methylomirabilis from sidestream to mainstream. Candidatus Methanoperedens with relative abundance of 25.2% played the major role in nitrate reduction and methane oxidation under sidestream condition, indicated by the high expression activities of mcrA and narG. Candidatus Methylomirabilis dominated the microbial community under mainstream condition with relative abundance of 32.1%, supported by the high expression activities of pmoA and hao. Furthermore, a transition of Anammox population from Candidatus Kuenenia to Candidatus Brocadia was also observed from sidestream to mainstream. Candidatus Kuenenia and Candidatus Brocadia jointly contributed to the primary anaerobic ammonium oxidation suggested by the high expression value of hdh and hzs. Candidatus Methylomirabilis was speculated to perform ammonium oxidation mediated by pMMO under mainstream condition. These findings might help to reveal the microbial interactions and ecological niches of n-DAMO and Anammox microorganisms, shedding light on the optimization and management of the granule-based n-D/A system.
Asunto(s)
Compuestos de Amonio , Aguas del Alcantarillado , Anaerobiosis , Oxidación Anaeróbica del Amoníaco , Reactores Biológicos , Desnitrificación , Bacterias/genética , Bacterias/metabolismo , Oxidación-Reducción , Metano/metabolismo , Compuestos de Amonio/metabolismo , Nitrógeno/metabolismoRESUMEN
In this work, a bioprocess model was applied to first determine the impacts of influent substrates conditions on the granular bioreactor performing nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) and anammox integrated processes and then investigate the roles of granular sludge properties in regulating the bioreactor performance and start-up process. The ideal influent substrates conditions were identified at NO2--N/NH4+-N of 1:1 and dissolved CH4 concentration of 85 g COD m-3, which achieved 98.6% total nitrogen removal and 87.7% dissolved CH4 utilization. Under such ideal influent conditions, the initial properties of granular sludge didn't significantly affect the granular bioreactor performance. However, inoculation of granular sludge with a relatively small granular sludge size and a high abundance of n-DAMO archaea or/and anammox bacteria could effectively shorten the bioreactor start-up. Meanwhile, reducing the diffusivity of solutes within granular sludge was also beneficial for expediting the start-up process and promoting dissolved CH4 utilization.
Asunto(s)
Compuestos de Amonio , Nitratos , Aguas del Alcantarillado , Nitritos , Anaerobiosis , Metano , Oxidación Anaeróbica del Amoníaco , Desnitrificación , Reactores Biológicos/microbiología , Oxidación-Reducción , NitrógenoRESUMEN
Recently, the nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) processes have become a research hotspot in the field of wastewater treatment. The n-DAMO processes could not only mitigate direct and indirect carbon emissions from wastewater treatment plants but also strengthen biological nitrogen removal. However, the applications of n-DAMO-based biotechnologies face practical difficulties mainly caused by the distinctive properties of n-DAMO microorganisms and the limited/availability of methane with poor solubility. In this sense, the choice of bioreactors will play important roles that influence the growth and functioning of n-DAMO microorganisms, thus enabling dedicated development of the n-DAMO processes and efficient applications of n-DAMO-based biotechnologies. Therefore, this paper aims to discuss the three commonly-applied types of bioreactors, covering the individual working principle and state-of-the-art removal performance of nitrogen as well as dissolved methane observed when adopted for n-DAMO-based biotechnologies. With noted limitations for each bioreactor type, several key perspectives were proposed which hopefully would inspire future investigation and practical applications of the n-DAMO processes.
Asunto(s)
Compuestos de Amonio , Metano , Aguas Residuales , Nitratos , Nitritos , Anaerobiosis , Desnitrificación , Reactores Biológicos , Nitrógeno , Oxidación-Reducción , Óxidos de NitrógenoRESUMEN
As a promising technology, the combination of nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) with Anammox offers a solution to achieve effective and sustainable wastewater treatment. However, this sustainable process faces challenges to accumulate sufficient biomass for reaching practical nitrogen removal performance. This study developed an innovative membrane aerated moving bed biofilm reactor (MAMBBR), which supported sufficient methane supply and excellent biofilm attachment, for cultivating biofilms coupling n-DAMO with Anammox. Biofilms were developed rapidly on the polyurethane foam with the supply of ammonium and nitrate, achieving the bioreactor performance of 275 g N m-3 d-1 within 102 days. After the preservation at -20 °C for 8 months, the biofilm was successfully reactivated and achieved 315 g N m-3 d-1 after 188 days. After reactivation, MAMBBR was applied to treat synthetic sidestream wastewater. Up to 99.9% of total nitrogen was removed with the bioreactor performance of 4.0 kg N m-3 d-1. Microbial community analysis and mass balance calculation demonstrated that n-DAMO microorganisms and Anammox bacteria collectively contributed to nitrogen removal in MAMBBR. The MAMBBR developed in this study provides an ideal system of integrating n-DAMO with Anammox for sustainable wastewater treatment.
Asunto(s)
Compuestos de Amonio , Nitratos , Desnitrificación , Metano , Nitrógeno , Oxidación Anaeróbica del Amoníaco , Anaerobiosis , Reactores Biológicos/microbiología , Oxidación-Reducción , BiopelículasRESUMEN
Mainstream anaerobic wastewater treatment has received increasing attention for the recovery of methane-rich biogas from biodegradable organics, but subsequent mainstream nitrogen and dissolved methane removal at low temperatures remains a critical challenge in practical applications. In this study, granular sludge coupling n-DAMO with Anammox was employed for mainstream nitrogen removal, and the dissolved methane removal potential of granular sludge at low temperatures was investigated. A stable nitrogen removal rate (0.94 kg N m-3 d-1 at 20 °C) was achieved with a high-level effluent quality (<3.0 mg TN L-1) in a lab-scale membrane granular sludge reactor (MGSR). With decreasing temperature, the nitrogen removal rate dropped to 0.55 kg N m-3 d-1 at 10 °C, while the effluent concentration remained <1.0 mg TN L-1. The granular sludge with an average diameter of 1.8 mm proved to retain sufficient biomass (27 g VSS L-1), which enabled n-DAMO and Anammox activity at a hydraulic retention time as low as 2.16 h even at 10 °C. 16S rRNA gene sequencing and scanning electron microscopy revealed a stable community composition and compact structure of granular sludge during long-term operation. Energy recovery could be maximized by recovering most of the dissolved methane in mainstream anaerobic effluent, as only a small amount of dissolved methane was capable of supporting denitrifying methanotrophs in granular sludge, which enabled high-level nitrogen removal.
Asunto(s)
Compuestos de Amonio , Metano , Oxidación Anaeróbica del Amoníaco , Anaerobiosis , Reactores Biológicos , Desnitrificación , Nitrógeno , Oxidación-Reducción , ARN Ribosómico 16S/genética , Aguas del Alcantarillado , TemperaturaRESUMEN
Being an energetic fuel, methane is able to support microbial growth and drive the reduction of various electron acceptors. These acceptors include a broad range of oxidized contaminants (e.g., nitrate, nitrite, perchlorate, bromate, selenate, chromate, antimonate and vanadate) that are ubiquitously detected in water environments and pose threats to human and ecological health. Using methane as electron donor to biologically reduce these contaminants into nontoxic forms is a promising solution to remediate polluted water, considering that methane is a widely available and inexpensive electron donor. The understanding of methane-based biological reduction processes and the responsible microorganisms has grown in the past decade. This review summarizes the fundamentals of metabolic pathways and microorganisms mediating microbial methane oxidation. Experimental demonstrations of methane as an electron donor to remove oxidized contaminants are summarized, compared, and evaluated. Finally, the review identifies opportunities and unsolved questions that deserve future explorations for broadening understanding of methane oxidation and promoting its practical applications.
Asunto(s)
Metano , Aguas Residuales , Anaerobiosis , Biopelículas , Reactores Biológicos , Desnitrificación , Humanos , Oxidación-ReducciónRESUMEN
The integration of nitrate/nitrite dependent anaerobic methane oxidation (n-DAMO) and anaerobic ammonium oxidation (Anammox) provides sustainable solution to simultaneously remove nitrate, nitrite and ammonium. This study demonstrated the sludge granulation process coupling n-DAMO and Anammox from mixed inoculum including river sediment, return activated sludge and crushed anaerobic granule sludge in a novel membrane granular sludge reactor (MGSR). Flocculent biomass gradually turned into compact aggregates and retained as granular sludge with an average diameter of 2.2 mm in MGSR after 684 days' operation. When steady state with a hydraulic retention time of 1.19 days was reached, the MGSR achieved a nitrogen removal rate of 1.77 g N L-1 d-1. Granules with density of 1.043 g mL-1, settling velocity of 72 m h-1 and sludge volume index of 22 mL g-1 leaded to excellent biomass retention (42 g VSS L-1). Pyrosequencing analysis revealed that two dominant microbial groups, n-DAMO archaea and Anammox bacteria, in the microbial community of the granule were enriched to 31.09% and 12.45%. Fluorescence in situ hybridization revealed a homogenous distribution of n-DAMO archaea and Anammox bacteria throughout the granule. The granular sludge coupling n-DAMO and Anammox microorganisms provides significant potential for high rate nitrogen removal from wastewater.
Asunto(s)
Compuestos de Amonio , Metano , Anaerobiosis , Reactores Biológicos , Desnitrificación , Hibridación Fluorescente in Situ , Nitrógeno , Oxidación-Reducción , Aguas del AlcantarilladoRESUMEN
Nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) coupling to Anaerobic ammonium oxidation (Anammox) provides an opportunity for simultaneous nitrogen removal and methane emissions mitigation from wastewater. However, to achieve high nitrogen removal rate in such a process remains a critical challenge in practical application. This work investigated the interactions between n-DAMO and Anammox in membrane biofilm reactor (MBfR) and then developed operational strategies of MBfR for high rate nitrogen removal from landfill leachate. Initially, influent containing nitrate and ammonium facilitated the development of n-DAMO and Anammox microorganisms in MBfR, but nitrogen removal performance is hard to be further improved even deteriorated. Detailed investigations of interactions among n-DAMO and Anammox microorganisms confirmed that extra addition of nitrite into MBfR fed with nitrate and ammonium not only stimulated the activities of Anammox bacteria, but also enhanced the activities of n-DAMO archaea from 172.3 to 356.9 mg NO3--N L-1 d-1. Functional gene analysis also indicated that mcrA and hzsA genes increased after nitrite addition. Based on this finding, influent containing NO3-, NO2- and NH4+ enabled nitrogen removal rates of MBfR increase from 224.9 to 888.2 mg N L-1 d-1. Finally, nitrate in the influent was gradually replaced with nitrite to mimic the effluent from partial nitriation of landfill leachate, but maintain the nitrate availability for n-DAMO archaea through increasing nitrate production from Anammox. These operation strategies enabled MBfR achieve the steady state with a nitrogen removal rate of 6.1 kg N m-3 d-1. Microbial community analysis revealed n-DAMO archaea, n-DAMO bacteria and Anammox bacteria jointly dominated the biofilm, and their relative abundance dynamically shifted with feeding regime. This work provides promising operational strategies for high rate of nitrogen removal from landfill leachate through integrating n-DAMO and Anammox process.
Asunto(s)
Metano , Contaminantes Químicos del Agua , Anaerobiosis , Reactores Biológicos , Desnitrificación , Interacciones Microbianas , Nitrógeno , Oxidación-ReducciónRESUMEN
Due to serious eutrophication in water bodies, nitrogen removal has become a critical stage for wastewater treatment plants (WWTPs) over past decades. Conventional biological nitrogen removal processes are based on nitrification and denitrification (N/DN), and are suffering from several major drawbacks, including substantial aeration consumption, high fugitive greenhouse gas emissions, a requirement for external carbon sources, excessive sludge production and low energy recovery efficiency, and thus unable to satisfy the escalating public needs. Recently, the discovery of anaerobic ammonium oxidation (anammox) bacteria has promoted an update of conventional N/DN-based processes to autotrophic nitrogen removal. However, the application of anammox to treat domestic wastewater has been hindered mainly by unsatisfactory effluent quality with nitrogen removal efficiency below 80%. The discovery of nitrate/nitrite-dependent anaerobic methane oxidation (n-DAMO) during the last decade has provided new opportunities to remove this barrier and to achieve a robust system with high-level nitrogen removal from municipal wastewater, by utilizing methane as an alternative carbon source. In the present review, opportunities and challenges for nitrate/nitrite-dependent anaerobic methane oxidation are discussed. Particularly, the prospective technologies driven by the cooperation of anammox and n-DAMO microorganisms are put forward based on previous experimental and modeling studies. Finally, a novel WWTP system acting as an energy exporter is delineated.