Anaerobic Ammonium Oxidation Process Research Articles

Impacts of erythromycin antibiotic on Anammox process: Performance and microbial community structure

The occurrence and accumulation of antibiotics in wastewater treatment plant have been a growing concern. Erythromycin (ERY), a representative class of Macrolides, was picked out to investigate the long-term effects on anaerobic ammonium oxidation (Anammox) process in this study. Anaerobic ammonia-oxidizing bacteria (AAOB) was initially inhibited when suffered the ERY in 0.001 and 1 mg L−1, but rapidly recovered after 12 and 10 days’ exposure, respectively. The restoration time of AAOB under the stress of ERY in 1 mg L-1 was shorter than that in 0.001 mg L−1. Significant suppression without recovery was observed as the concentration of ERY was increased to 10 mg L−1. The deterioration was continued with the increasing concentrations. However, the pace of deterioration was tended to ease in each phase. Therefore, it can be speculated that Anammox microorganisms resisted the biotoxicity of ERY to some extent via gene mutations or secreted more extracellular polymeric substances.

Optimization of the Mainstream Anaerobic Ammonia Oxidation Process and Its Changes of the Microbial Community

The completely autotrophic ammonium removal over nitrite(CANON)biofilm reactor acclimated by high-strength ammonia wastewater was used to treat low-strength ammonia wastewater. The treatment can be divided into three stages:① the nitrogen removal efficiency of anaerobic ammonia oxidation was low during the continuous aeration stage with inorganic wastewater as raw water (0-59 d) and with an aeration amount of 30 mL·min-1 and ammonia concentration of 80 mg·L-1 (until day 56), the TN removal load was only 0.13 kg·(m3·d)-1; ② during the continuous aeration stage with domestic wastewater as raw water (60-110 d), the addition of organic carbon improved the TN removal load to 0.22 kg·(m3·d)-1 on day 79; the removal rate of NH4+-N then reached 100% when the aeration volume improved to 100 mL·min-1 on day 103; however, the TN removal efficiency and TN removal load decreased to 42.36% and 0.14 kg·(m3·d)-1, respectively. ③ To increase both the NH4+-N and TN removal efficiency during the intermittent aeration stage with domestic wastewater as raw water (110-160 d), the aeration amount was increased to 50 mL·min-1, while aeration was continued for 30 min and was stopped for the next 30 min; on day 131, the NH4+-N removal efficiency increased to 86.34%, the TN removal efficiency and removal load reached 85.87% and 0.3 kg·(m3·d)-1 respectively; on day 141, the aeration was increased to 100 mL·min-1 and the removal efficiency of NH4+-N reached 100%, while the removal efficiency and removal load of TN were 64.28% and 0.22 kg·(m3·d)-1, respectively, indicating that the intermittent aeration strategy effectively improves the nitrogen removal performance of the CANON reactor. To analyze the variation of the microbial community during different stages, the samples of three stages (0, 56, and 152 d) were analyzed using high-throughput sequencing technology. The results show that:① Candidatus Brocadia is less affected than Candidatus Kuenenia during the low-strength ammonia stages with inorganic and domestic wastewater as raw water; ② Nitrosominas and Nitrospira were the dominant bacteria of AOB(ammonia oxidizing bacteria) and NOB (nitrite oxidizing bacteria), respectively. Domestic wastewater had a greater impact on Nitrosomonas than on Nitrospira; ③ Denitrifying bacteria were present during the whole stage; Pseudomonas and Paracoccus were the most adaptable, even though their relative abundances during each stage were below 0.5%.

Effect of Substrate Ratio on Removal of Nitrogen and Carbon Using Anaerobic Ammonium Oxidation and Denitrification

Real domestic sewage was treated in a sequencing batch reactor (SBR). When the partial nitrification of SBR was achieved, the effluent was fed with quantitative NaNO2, which served as the influent of the anaerobic ammonium oxidation (ANAMMOX) process of the anaerobic SBR (ASBR). The effect of different substrate ratios on the removal of nitrogen and carbon using anaerobic ammonium oxidation and denitrification was investigated under conditions with a temperature of 24℃ and pH of 7.2±0.2. The results showed that ① the nitrogen removal efficiency was optimum when the influent NO2--N/NH4+-N was 1.4-1.6. The average effluent concentrations of NH4+-N, NO2--N, and chemical oxygen demand (COD) were 2.14, 1.07, and 30.50 mg·L-1, and their removal rates were 93.62%, 97.79%, and 74.75%, respectively. The △NO2--N/△NH4+-N and △NO3--N/△NH4+-N ratios were 1.60 and 0.17, respectively. Total nitrogen was removed by the joint action of denitrifying and ANAMMOX bacteria. ② When the influent ratio of NO2--N/NH4+-N increased, the contribution of ANAMMOX to nitrogen removal decreased, but the contribution of heterotrophic denitrification to nitrogen removal increased gradually. ③ The NH4+-N and NO2--N degradation processes corresponded with zero-order reactions and fitted the linear relationship in the typical cycle. Their specific degradation rates were 0.404 and 0.599 mg·(g·h)-1, respectively. Their ratio was 1.48, and the specific degradation rate of COD gradually increased.

Effect of Salinity on Nitrogen Removal Performance of a Pilot-scale Anaerobic Ammonia Oxidation Process and Its Recovery Kinetics

The denitrification characteristics of anaerobic ammonia oxidizing bacteria (AnAOB) treating high salinity wastewater were investigated in an pilot-scale anaerobic sequencing batch reactor (ASBR, 530 L) by gradually increasing the Cl- concentration. The results showed that AnAOB can adapt to the high salinity (Cl- concentration of 10000 mg·L-1) environment for high-efficiency denitrification by means of gradual salinity acclimation and total nitrogen (TN) removal rate of up to 92.3%. In particular, the denitrification performance was influenced by two gradients of Cl- concentrations, namely 6000 mg·L-1 and 10000 mg·L-1, but it could be gradually recovered as the acclimatization process continued. The modified Boltzmann model accurately fit the activity recovery process of AnAOB after being inhibited by the different salinities, and the correlation coefficient R2 was above 0.96. The fitted recovered median values tc for Cl- concentrations of 6000 mg·L-1 and 10000 mg·L-1 were 28.765 d and 44.495 d. NRRmax for these concentrations was 0.145 kg·(m3·d)-1 and 0.212 kg·(m3·d)-1, and NRRmin was 0.021 kg·(m3·d)-1 and 0.085 kg·(m3·d)-1, respectively. After salinity acclimation, the dominant bacteria of AnAOB were Candidatus Brocadia and Candidatus Jettenia (the abundances were 14.76% and 2.7%, respectively), the granulation degree and sludge density increased to varying degrees, and the sludge color was reddish brown.

Mass transfer affects reactor performance, microbial morphology, and community succession in the methane-dependent denitrification and anaerobic ammonium oxidation co-culture

Denitrifying anaerobic methane oxidation (DAMO) combining anaerobic ammonium oxidation (Anammox) process is a novel nitrogen removal technology. However, the roles of methane transfer (gas phase) and nitrogen transfer (liquid phase) in the heterogeneous process remain unclear. In this study, granular DAMO and Anammox co-cultures were inoculated from a hollow-fiber membrane bioreactor into a sequence batch reactor (SBR). Since the methane transfer became limited in SBR, the nitrate removal rate first decreased and then increased to 10 mg/(L∙day), while the ammonium removal rate did not recover and was around 2 mg/(L∙day). The activity of DAMO archaea and Anammox bacteria decreased noticeably. Furthermore, granular aggregates dispersed into small granules and ultimately became flocs with poor settleability in SBR. The content of extracellular polymeric substances decreased, especially that of proteins and humics. DAMO archaea decreased by 94.6% and Anammox bacteria decreased by 72%. In summary, the limitation of methane transfer affected DAMO and Anammox processes more notably than nitrogen transfer, resulting in lower nitrogen removal, granule disruption, and microbial community succession.

Evidence of differential adaptation to decreased temperature by anammox bacteria

Low temperature is recognized as one of the major barriers for the application of the anaerobic ammonium oxidation (anammox) process to treat mainstream wastewater. Studies are yet to reveal the underlying biological limitations and molecular mechanisms associated with the inhibition of low temperature on the anammox process. In this study, metaproteomics was used to examine proteome modulation patterns of the anammox community occurring at different temperatures. The anammox community remarkably altered their proteomes when the temperature decreased from 35 °C to 20 °C. This was especially for proteins involved in energy conversion, transcription and translation and inorganic ion transport. However, at 15 °C the anammox activities became distinctly inhibited, and there was evidence of energy limitations and severe stress in Candidatus Kuenenia and to a lesser degree in Candidatus Brocadia. Candidatus Jettenia exhibited more changes in its proteome at 15 °C. From the proteomes, at the lower temperatures there was evidence of stress caused by toxic nitrogen compounds or reactive oxygen species in the anammox bacteria. Hydroxylamine oxidoreductase (HAO)-like proteins and an oxidative stress response protein (a catalase) were in high abundance to potentially ameliorate these inhibitory effects. This study offers metaproteomic insight into the anammox community-based physiological response to decreasing temperatures.

Transformation of Ammonia in Wetland Sediments for Treatment of Mining Wastewater

Nitrogen elements play an important role in the biogeochemical cycle of artificial wetlands. In this study, we investigated the anaerobic transformation of ammonia nitrogen and its main pathways in sediment in an artificial wetland. Results showed that the anaerobic ammonia oxidation (ANAMMOX) process and iron reduction occurred in wetland sediment, coupled with anaerobic ammonia oxidation (Feammox). Feammox used Fe(Ⅲ) to oxidize ammonia nitrogen to produce nitrogen; intermediate products were nitrate, nitrite, and N2O. Addition of ferrihydrite promoted the Feammox process and ammonia nitrogen loss caused by Feammox was enhanced from 1.69 to 2.72 mg·(kg·d)-1. When ferrihydrite was added, a loss of 28% of total nitrogen (TN) in the wetland occurred, associated with Feammox, increasing to 42%. Anaerobic ammonia oxidation was significantly inhibited with addition of ferrihydrite and TN loss in the system decreased by about 25%. Results showed that the formation of goethite by mineralization of ferrihydrite inhibited the ANAMMOX process, promoting Feammox to lead to competing electronic donors for the S-ANAMMOX process, causing inhibition of the S-ANAMMOX process. This achieves the purpose of reducing TN loss in the wetland system. In addition, this may have some significance for further understanding the interaction between iron reduction and the nitrogen cycle in the wetland.

Treatment of Landfill Leachate Using Activated Sludge Technology: A Review.

Landfill leachate contains a large amount of organic matter and ammoniacal nitrogen. As such, it has become a complex and difficult issue within the water treatment industry. The activated sludge process has been found to be a good solution with low processing costs and is now therefore the core process for leachate treatment, especially for nitrogen removal. This paper describes the characteristics and treatment of leachate. Treatment of leachate using the activated sludge process includes the removal of organic matter, ammoniacal nitrogen, and total nitrogen (TN). The core method for the removal of organic matter involves anaerobic treatment supplemented with an aerobic process. Ammoniacal nitrogen is commonly removed using a conventional aerobic treatment, and advanced TN removal is achieved using endogenous denitrification or an anaerobic ammonium oxidation (ANAMMOX) process. Since biological processes are the most economical method for TN removal, a key issue is how to tap the full potential of the activated sludge process and improve TN removal from leachate. This complex issue has been identified as the focus of current scholars, as well as an important future direction for leachate research and development.

Insight into the impact of Fe3O4 nanoparticles on anammox process of subsurface-flow constructed wetlands under long-term exposure.

The increasing use of Fe3O4 nanoparticles (NPs) had posed an emerging challenge to wastewater treatment processes, and their potential impact on anaerobic ammonium oxidation (anammox) process of unplanted subsurface-flow constructed wetlands (USFCWs) was investigated firstly under the long-term exposure of different Fe3O4 NP concentrations. It was found that Fe3O4 NP exposure could improve total nitrogen (TN) removal. The abundance of Candidatus Anammoxoglobus increased significantly at 10mg/L Fe3O4 NPs, while decreased under 1mg/L Fe3O4 NP exposure. Desulfosporosinus and Exiguobacterium increased to some extent at 1mg/L Fe3O4 NPs, suggesting that Fe-anammox played an important role in TN removal. The ROS production increased with the increase of Fe3O4 NP concentration, and the integrity of cell membrane was good under Fe3O4 NP exposure. The functional genes that related to inorganic ion transport and metabolism and lipid transport and metabolism were upregulated, and cell motility decreased after long-term exposure of 1mg/L Fe3O4 NPs. Graphical abstract ᅟ.

Impacts of the heavy metals Cu (II), Zn (II) and Fe (II) on an Anammox system treating synthetic wastewater in low ammonia nitrogen and low temperature: Fe (II) makes a difference

In this study, the impacts of heavy metals (1 mg L−1) on the nitrogen removal, bioactivity of anaerobic ammonia-oxidizing bacteria (AAOB) and the microbial community of anaerobic ammonium oxidation (Anammox) process were investigated. It was observed that short-term exposure in Cu (II) and Zn (II) both improved AAOB bioactivity, while long-term exposure significantly lowered the nitrogen removal to 0.218 and 0.302 kg m−3 d−1, when treated the wastewater with 100 mg L−1 nitrogen under 14–16 °C. Fe(II) had slight impact on Anammox in short-term experiment but deeply enhanced nitrogen removal during the long-term contact, and finally increased the that to 0.58 kg m−3 d−1. The impact on Anammox was Cu(II) > Zn(II) > Fe(II). Cu(II) and Zn(II) lowered the share of Candidatus Kuenenia to 3.32% and 3.80%, while Fe(II) improved that to 11.30% from 7.99%. Extracellular polymeric substance in biofilm had prominent iron adsorption capacity, which was the key factor that help AAOB resist Fe(II).

Construction of the biosystem with low consumption and high efficiency of nitrogen and carbon removal and its application in teaching

Shortcut nitrification and denitrification coupled with anaerobic ammonia oxidation process is a new biological process for the removal of nitrogen and carbon in wastewater treatment, with the advantages of low energy consumption, low sludge production, which can greatly reduce the cost of wastewater treatment. Through the designed experiment of the system and the evaluation experiment of carbon and nitrogen removal effect, which were convenient for students to understand more clearly and provided hands-on activities for students. Experiment showed that the system with the removal of nitrogen and carbon functioned well, and enhanced students’ knowledge of the process, to motivate their interests in learning professional knowledge. In the period of experiment design and literature review, the abilities of independent thinking and problem solving were improved and the enthusiasm, initiative and creativity in scientific research also got enhanced.

Seasonal variation of anaerobic ammonium oxidizing bacterial community and abundance in tropical mangrove wetland sediments with depth

Anaerobic ammonium oxidation (anammox) process was found to make a nonnegligible contribution to nitrogen loss in estuarine and coastal ecosystems in recent years. In order to better understand ecological characteristics of anammox bacteria in coastal ecosystems, 16S rRNA gene clone library and real-time quantitative PCR (qPCR) were used to investigate the diversity and abundance of anammox bacteria in sediments of the Dongzhai Harbor mangrove wetland in Hainan, China. Sediments at different depths along a transect from mangrove trees to mudflats were studied in March (spring) and August (summer). The dominant genera of anammox bacteria observed in both seasons were Kuenenia spp. and Scalindua spp. The diversity and abundance of anammox bacteria showed not only seasonal variations, but also differences with depths and habitats. Anammox bacteria appeared to be more abundant and had higher diversity in August than in March. In addition, lower layer (40–45 cm) sediments and mangrove sediments had higher abundance and diversity of anammox bacteria than surface layers (0–2 cm) and non-mangrove areas. It was suggested that water pH, salinity and sediment nitrite, nitrate and ammonium might be key factors shaping the community structure and distribution of anammox bacteria. This study further indicated that the mangrove ecosystem might provide a favorable niche for anammox bacteria and thus plays an important role in nitrogen cycling. Overall, these results extend our current knowledge about the structure and dynamics of anammox bacterial community in the mangrove ecosystem.

Evaluating the effects of metal oxide nanoparticles (TiO2, Al2O3, SiO2 and CeO2) on anammox process: Performance, microflora and sludge properties

The increasing use of engineered metal oxide nanoparticles (MONPs) in consumer products raises great concerns about their environmental impacts, but their potential impacts on anaerobic ammonium oxidation (anammox) process in wastewater treatment remain unclear. In this study, the presence of MONPs (1, 50, 200 mg L−1) exhibited no visible effects on the nitrogen removal performance of anammox reactors, but high levels (200 mg L−1) of SiO2NPs, Al2O3NPs and CeO2NPs had a distinct effect on shaping the anammox community. Long-term exposure of MONPs caused different responses in the relative abundance of Ca. Kuenenia, the level of functional gene HzsA and the activities of three key enzymes involved in anammox metabolism, but no significant inhibition effects on specific anammox activity were detected. Overall, the effects of MONPs on anammox community structure and sludge properties depended on their types and levels and followed the order SiO2 > CeO2 > Al2O3 > TiO2.

Influence of sulfadimethoxine (SDM) and sulfamethazine (SM) on anammox bioreactors: Performance evaluation and bacterial community characterization

The specific inhibitory effects of sulfonamides on anaerobic ammonium oxidation (anammox) process remain unknown. This study investigated the inhibitory characteristics of sulfadimethoxine (SDM) and sulfamethazine (SM) in two anammox bioreactors with NH4+-N (160 mg/L) and NO2−-N (210 mg/L) in influent. Results indicate that anammox bacteria in both bioreactors adapted to low antibiotic concentrations (less than 3 mg/L). At concentrations between 5 and 7 mg/L, SDM inhibited the growth of anammox bacteria and resulted in a decrease of Candidatus Brocadia abundance from 2.57% to 0.39%. In contrast, at concentrations of 5–9 mg/L, SM inhibited the denitrification process more severely than SDM, resulting in higher accumulation of nitrite and nitrate. The purpose of this study was to elucidate the inhibitory effects of sulfonamides on the anammox process and to provide a reference for the stable operation of anammox bioreactors for the treatment of sulfonamide-containing wastewater.

Impacts of different morphologies of anammox bacteria on nitrogen removal performance of a hybrid bioreactor: Suspended sludge, biofilm and gel beads

The difficulties in the anaerobic ammonium oxidation (anammox) process mainly consist of low microbial growth rates and long start-up times of bioreactors. The morphologies of anammox bacteria might affect nitrogen removal performance and microbial community. In this study, three morphologies of anammox bacteria, namely, suspended sludge, biofilm and suspended sludge embedded in gel beads, were compared in a hybrid bioreactor under anoxic conditions (DO concentration < 0.1 mg L−1). The results show that the average total inorganic nitrogen removal efficiency of a hybrid bioreactor reached 67 ± 15% with a maximum value of 80% for continuous synthetic wastewater feeding, and that the specific total inorganic nitrogen removal rate reached 15.75 mg·(gVSS·h)−1 regardless of the organic matter stress. Batch tests indicate that mainly suspended sludge (67%) and biofilm (26%) contributed to the anammox process, with the specific total inorganic nitrogen removal rate reaching 10.55 and 4.05 mg·(gVSS·h)−1, respectively. However, the embedding of sludge in gel resulted in nitrification instead of anammox with a nitrification rate of 0.20 ± 0.01 mg·(L·h)−1 due to the expansion of gel beads floating on the water surface. Therefore, a pore-forming technique was developed to produce more channels for gas dispersion inside the gel beads. In terms of microbial community, Candidatus Kuenenia involved in the anammox group was the most abundant genus in biofilm (43.4%) and suspended sludge (15.7%), while Nitrospira occupied the largest proportion in gel beads (25.6%). This study offers useful information for the selection of anammox bacteria morphology.

Influence of Tourmaline on the Activity of ANAMMOX Bacteria and ANAMMOX Reaction

AbstractThe performance of the anaerobic ammonium oxidation (ANAMMOX) process was investigated in two identical sequencing batch reactors (SBRs) [designated as SBR1 (tourmaline addition) and SBR2 (...

Increased salinity triggers significant changes in the functional proteins of ANAMMOX bacteria within a biofilm community

Anaerobic ammonium oxidation (ANAMMOX) processes can potentially be influenced by salinity related to variable salinity in water environment. Here, we used 16S rRNA sequencing analysis combining with iTRAQ-based quantitative proteomic approach to reveal the response of microbial community and functional proteins to salinity, which was increased from 0 to 20 g L−1 with a step of 5 g L−1 (designed as S5, S10, S15 and S20) compared to control reactor (without salinity stress desined as S0). The 16S rRNA sequencing analysis showed that a high salinity (20 g L−1, S20) decreased the abundance of genus Candidatus Jettenia but increased that of Candidatus Kuenenia. A total of 1609 differentially expressed proteins were acquired in the three comparison groups (S5:S0, S20:S0 and S20:S5). Of these, 39 proteins co-occurred in the three salt-exposed samples. Hydrazine dehydrogenase (HDH; Q1PW30) and nitrate reductase (Q1PZD8) were up-regulated more than 3-folds in the exposure of 20 g-NaCl/L. The functional enrichment analysis further showed that some proteins responsible for ion binding, catalysis and oxidation-reduction reaction were up-regulated, which explained the physiological resilience of ANAMMOX bacteria under salinity stress. Additionally, ANAMMOX bacteria responded to salinity by modulating the electron transport systems, indicating that the cells retained a high potential for proton pumping, as well as the ATP production. Furthermore, the over-expression of HDH which associated with ANAMMOX metabolism, was potentially related to the increased abundance of halophilic Candidatus Kuenenia. These findings provide a comprehensive baseline for understanding the roles of salinity stresses in shaping the functional proteins of ANAMMOX bacteria.

Modeling and multi-objective optimization for ANAMMOX process under COD disturbance using hybrid intelligent algorithm.

Anaerobic ammonium oxidation (ANAMMOX) has been regarded as an efficient process to treat nitrogen-containing wastewater. However, the treatment process is not fully understood in terms of reaction mechanisms, process simulation, and control. In this paper, a multi-objective control strategy mixed soft-sensing model (MCSSM) is developed to systematically design the operating variations for multi-objective control by integrating the developed model, a least square support vector machine optimized with principal component analysis (PCA-LSSVM) and non-dominated sorting genetic algorithm-II (NSGA-II). The results revealed that the PCA-LSSVM model is a feasible and efficient tool for predicting the effluent ammonia nitrogen concentration ([Formula: see text]) and the total nitrogen removal concentration (CTN, rem) with determination coefficients (R2) were 0.997 for [Formula: see text] and 0.989 for CTN, rem, and gives us the reasonable solutions in influent by using NSGA-II. To achieve a better removal effect, the influent pH should be kept between 7.50 and 7.52, the COD/TN ratio is suggested to maintain at 0.15 and the NH4+-N/NO2--N ratio is suggested to maintain at 0.61. The developed MCSSM approach and its general modeling framework have a high potential of applicability and guidance to bioprocess in wastewater treatment, and numerical models can be structured for predicting and optimization and experiments can be conducted for data acquisition and model establishment.

Resuscitation of starved anaerobic ammonium oxidation sludge system: Impacts of repeated short-term starvation

Starvation of biomass is common during underloading of bioreactors or sludge storage in biological wastewater treatment industries. The aim of this work was to study the impact of starvation modes on the nitrogen removal capacity of anaerobic ammonium oxidation (anammox) process in sequencing batch reactor (SBR). The repeated short-term starvation and reactivation experiments were performed to evaluate the response of anammox sludge system in the condition of 27 ± 1.5 °C and 320 min HRT. Moreover, the nitrogen removal ability of the anammox process was reactivated rapidly in the low substrate condition, then the total nitrogen (TN) removal efficiency reached 82.5%, with the effluent TN of around 14.6 mgNL−1. The repeated short-term starvation (1 day–4 days) and recovery mode could improve the tolerance and apparent activity of anammox sludge system. The dominant species of general anaerobic ammonium oxidation bacteria (AnAOB) was Candidatus Brocadia, which had better self-adaption to repeated starvation.

Research advances and challenges in anammox immobilization for autotrophic nitrogen removal

AbstractApplication of the anaerobic ammonium oxidation (anammox) process using suspended or attached growth technology has limitations of slow growth rate such as biomass washout, and large footprint. This has led to the development of smaller, compact immobilized systems. In recent years, wastewater treatment using anammox immobilized cells has received much attention due to its advantages of high biomass content, retention of biomass by prevention of washout, good solid–liquid separation and lower toxicity to microorganisms. This article critically reviews the existing literature on autotrophic nitrogen removal using anammox bacteria in its immobilized form. Different methods of using immobilized anammox bacteria were identified. Characteristics of various polymeric gels such as solubility, biodegradability, stability, diffusivity and growth of biomass in the polymeric gel were studied. However, there is insufficient study of disposal methods and costs involved in anammox immobilization to guide future implementation of immobilized anammox technologies for autotrophic nitrogen removal. © 2018 Society of Chemical Industry