As a sustainable nitrogen removal technology, anammox granular sludge (AnGS) has been widely used in treating various wastewater due to its high nitrogen removal rate and resilience to hydraulic and loading disturbances. However, the relatively slow granulation rate of AnGS is a major bottleneck for its broader applications. Nitric oxide (NO), a key nitrogen-cycle intermediate and microbial signaling molecule, can directly serve as an electron acceptor for anammox bacteria, potentially enhancing metabolic activity. Furthermore, direct gas sparging provides shear force to AnGS that can facilitate biomass aggregation and granule formation. This study demonstrated that NO sparging could accelerate AnGS granulation by coupling metabolic stimulation with shear-induced aggregation. Through long-term cultivation and adaption, the NO-fed reactor (R1) achieved highly efficient and stable NO removal, with a maximum NO removal efficiency of 93.6%. In addition, NO sparging increased the proportions of large-size (∼38%) and medium-size (∼48%) granules in R1, compared to 30% and 25%, respectively, in the control group (R2) without NO sparging (2000 ppm). The AnGS in R1 exhibited enhanced structural stability and elevated metabolic activity. 'Candidatus Kuenenia' was identified as the most abundant in medium-size granules (with a relative abudance of 5.5%). Metatranscriptomic analysis further validated that NO sparging upregulated genes involved in nitrogen metabolisms (e.g., hdh, hzsB) and fundamental energy metabolism (e.g., cooS) within the granular sludge system. Overall, this study demonstrates that NO can be leveraged as a dual metabolic and physical control strategy to accelerate anammox granulation, providing new insights for the integrated management of gaseous and aqueous pollutants.

Due to increasingly stringent discharge standards for total nitrogen (TN) in wastewater treatment plant effluents and presence of residual organic pollutants (e.g., humic acid, HA, a typical refractory organic) in secondary effluents, new challenges have emerged for water reclamation. These residual organics contribute to membrane fouling in subsequent microfiltration units and serve as precursors to disinfection by-products, making the simultaneous and efficient removal of nitrate and refractory organic contaminants critical for improving reclaimed water quality. In this study, we employed iron-carbon micro-electrolysis (IC-ME) to achieve synchronous removal of nitrate and HA in a continuous-flow reactor system. The reactor was operated for 233 d, including 32 d of validation with real wastewater. With synthetic wastewater containing 20 mg/L NO3−–N and 15 mg/L HA, the system achieved 96.3

Anthropogenic activities generate large amounts of ammonium-containing wastewater and nitric oxide (NO)containing flue gas, which have posed adverse effects on both ecological and public health. Leveraging a novel function of Anammox bacteria, this study demonstrated simultaneous removal of NO in gas and ammonium in wastewater through Anammox process. In two laboratory membrane biofilm reactors (MBfRs), hollow fiber membranes were used to supply NO of 1000 ppm and facilitate the gas transfer efficiency. Over 231-day operation, two reactors achieved an average removal efficiency of NO at 88.2 % +/- 1.5 % and 88.0 +/- 1.9 %. Furthermore, the addition of NO led to increasing extracellular polymeric substance (EPS) content in biofilms. Anammox bacteria were the key functional microorganisms in the two reactors for simultaneous removal of ammonium and NO. The total abundance of 'Candidatus Jettenia', 'Candidatus Brocadia', and 'Candidatus Kuenenia' exceeded 48 %. Particularly, 'Ca. Kuenenia' exhibited superior tolerance to NO compared to other Anammox genera. Life cycle assessment showed that the integrated water and gas treatment using NO-dependent Anammox process enables to reduce by 1.7 times and 20.2 times lower carbon emissions, compared to wastewater treatment by traditional partial nitritation and Anammox (PN/A) and flue gas treatment by selective noncatalytic reduction (SNCR), respectively. This study demonstrated the feasibility of the NO-dependent Anammox process to simultaneously remove ammonium and NO, opening a new avenue to achieve the integrated treatment of flue gas and wastewater via a synergistic manner.

Anaerobic digestion (AD) of swine manure has been a challenging problem. Under high organic loading rate (OLR) conditions, increasing direct interspecies electron transfer (DIET) can enhance methane production and overcome challenges in the AD process. Conductive materials and Methanosarcina barkeri (M.barkeri) have been identified to play crucial roles in stimulating DIET. Herein, the feasibility of adding riboflavin-loaded granular activated carbon (RF-GAC) and M.barkeri solely and simultaneously to AD of swine manure was investigated respectively. Throughout the process, the RF-GAC, M.barkeri, and RF-GAC + M.barkeri groups averaged 1.33, 1.34, and 1.68 times the methane production of the control group. When OLR reached 2.92 kg VS/(m3 & sdot;d), the control's performance deteriorated while the RF-GAC + M.barkeri group stayed stable, and the volatile fatty acid concentration kept below 5 mM. Metabolic pathway analysis showed that mtd and mer, genes associated with the CO2 reduction pathway, and cdhA and acs, genes associated with the acetyl carbonyl pathway, were significantly up-regulated by RF-GAC + M.barkeri. The gene abundance of F420 hydrogenase (EC: 1.12.98.1), which serves as a crucial enzyme for electron transfer during the DIET process, was also notably up-regulated. The research results are of great significance in guiding the practical application of conductive materials and M.barkeri to increase AD efficiency through stimulating DIET.

Greenhouse gas (GHG) emission reduction from petrochemical wastewater treatment is imperative to alleviate industrial pollution problems. The aim of this study is to assess the GHG emissions and environmental impacts of a petrochemical wastewater treatment plant in eastern China and to give effective optimization recommendations. A comprehensive assessment of the carbon emissions of the baseline scenario was firstly carried out, followed by a synergy analysis of the synergies between water, energy and carbon. The three retrofit scenarios demonstrated varying levels of GHG reduction relative to the baseline: 30.5 % for S1 (energy recovery), 28.9 % for S2 (advanced technologies), and 10.9 % for S3 (water reuse). The final retrofit scenario achieves near-net-zero emissions while enabling significant energy recovery. These findings underscore the importance of integrating advanced technologies and energy-efficient processes in order to transform wastewater treatment systems into sustainable, carbon-neutral operations.

In this study, matrix degradation, microbial community development, and distribution using an individual-based model during biofilm formation on carriers at varying depths within a single-stage partial nitrification/anammox system were simulated. The findings from the application of individual-based model fitting, fluorescence in situ hybridization, and high-throughput sequencing reveal the presence of aerobic bacteria, specifically ammonia-oxidizing bacteria, as discrete particles within the outer layer of the carrier. Facultative anaerobic bacteria exemplified by anaerobic ammonia-oxidizing bacteria, are observed as aggregates within the middle layer. Conversely, anaerobic bacteria, represented by denitrifiers, are enveloped by extracellular polymeric substances within the inner layer. The present study extends the application of individual-based model to the formation of polyurethane-supported biofilms and presents valuable avenues for the design and advancement of pragmatic engineering carriers.

Combining iron-carbon micro-electrolysis and autotrophic denitrification is promising for nitrate removal from wastewater. In this study, four continuous reactors were constructed using CO2 and weak magnetic field (WMF) to address challenges like iron passivation and pH stability. In the reactors with CO2 + WMF (10 and 35 mT), the increase in total nitrogen removal efficiency was significantly higher (96.2 ± 1.6 % and 94.1 ± 2.7 %, respectively) than that of the control (51.6 ± 2.7 %), and Fe3O4 converted to low-density FeO(OH) and FeCO3, preventing passivation film formation. The WMF application decreased the N2O emissions flux by 8.7 % and 20.5 %, respectively. With CO2 + WMF, the relative enzyme activity and abundance of denitrifying bacteria, especially unclassified_Rhodocyclaceae and Denitratisoma, increased. Thus, this study demonstrates that CO2 and WMF optimize the nitrate removal process, significantly enhancing removal efficiency, reducing greenhouse gas emissions, and improving process stability.

Denitrifying biofilms, in which autotrophic denitrifiers (AD) and heterotrophic denitrifiers (HD) coexist, play a crucial role in removing nitrate from water or wastewater. However, it is difficult to elucidate the interactions between HD and AD through sequencing-based experimental methods. Here, we developed an individual-based model to describe the interspecies dynamics and priority effects between sulfur-based AD (Thiobacillus denitrificans) and HD (Thauera phenylcarboxya) under different C/N ratios. In test I (coexistence simulation), AD and HD were initially inoculated at a ratio of 1:1. The simulation results showed excellent denitrification performance and a coaggregation pattern of denitrifiers, indicating that cooperation was the predominant interaction at a C/N ratio of 0.25 to 1.5. In test II (invasion simulation), in which only one type of denitrifier was initially inoculated and the other was added at the invasion time, denitrifiers exhibited a stratification pattern in biofilms. When HD invaded AD, the final HD abundance decreased with increasing invasion time, indicating an enhanced priority effect. When AD invaded HD, insufficient organic carbon sources weakened the priority effect by limiting the growth of HD populations. This study reveals the interaction between autotrophic and heterotrophic denitrifiers, providing guidance for optimizing wastewater treatment process.

The partial nitritation anammox (PN/A) process has been widely used in wastewater treatment owing to its notable advantages, including a low aeration rate and the non-requirement of an additional carbon source. In practical implementation, the accumulation of nitrite affects the nitrogen-removal efficiency and the amount of N2O released during the PN/A process. By implementing wastewater reflux, the concentration of nitrite can be decreased, thereby achieving a balance between the nitrogen-removal efficiency and N2O release. In this study, the CANON process was conducted with varying reflux ratios in the range of 0 to 300% and ~300 mg/L ammonium in the influent. The highest removal efficiency of ammonium and total nitrogen (98.2±0.8 and 77.8±2.3%, respectively) could be achieved at a reflux ratio of 200%. Further, a reflux ratio of 200% led to the lowest N2O emission factor (2.21%), with 31.74% reduction in N2O emission compared to the process without refluxing. Additionally, the reactor at a reflux ratio of 200% presented the highest relative abundance of anaerobic ammonium-oxidizing bacteria (30.98%) and the lowest proportion of ammonium-oxidizing bacteria (9.57%). This study aimed to elucidate the impact of the reflux ratio on the nitrogen-removal efficiency of the CANON process and to theoretically explain the influence of different reflux ratios on N2O release. These findings provide a theoretical framework for enhancing the nitrogen-removal efficiency and mitigating carbon emissions in practical applications of the CANON process.

Anaerobic ammonium oxidation (anammox) is an innovative nitrogen removal process that is widely used in wastewater treatment due to its energy-saving potential and ability to reduce carbon emissions. However, research on the application of anammox in full-scale industrial wastewater treatment plants (WWTPs) is limited, and its environmental impacts are yet to be fully understood. This study evaluates the performance and environmental burdens of one-stage partial nitritation and anammox (PN/A) in a full-scale WWTP treating coal chemical wastewater, with different demonstration periods. Compared with conventional nitrification-denitrification, the energy footprint and carbon footprint of the PN/A process were significantly lower and effluent quality was improved. Based on the four-quadrant clustering method, the overall performance of the studied WWTP achieved the greatest synergy during the stable operation period. Life cycle assessment has shown that the PN/A process significantly reduces the system's contribution to environmental indicators. According to the sensitivity analysis, the fluctuations in energy consumption and chemical usage have significant environmental impacts, with differential sensitivity in the environmental impacts of two demonstration periods. Therefore, considering the specific situation of the WWTPs, optimizing the parameters/indicators most sensitive to environmental impact is essential to reducing environmental loads. Importantly, this work demonstrated that PN/A can improve the operational performance of full-scale industrial WWTPs with lower environmental burdens, providing valuable guidance for the development of sustainable wastewater treatment processes.

The partial nitritation/anammox (PN/A) process has been widely used in wastewater treatment owing to its notable advantages, including a low aeration rate and the non-requirement of an additional carbon source. In practical implementation, nitrite accumulation affects the nitrogen-removal efficiency and the amount of N2O released during the PN/A process. By implementing wastewater reflux, the nitrite concentration can be decreased, thereby achieving a balance between the nitrogen-removal efficiency and N2O release. This study conducted the CANON process with varying reflux ratios of 0 to 300 % and ~300 mg/L ammonium in the influent. The highest removal efficiency of ammonium and total nitrogen (98.2 ± 0.8 and 77.8 ± 2.3 %, respectively) could be achieved at a reflux ratio of 200 %. Further, a reflux ratio of 200 % led to the lowest N2O emission factor (2.21 %), with a 31.74 % reduction in N2O emission compared to the process without refluxing. Additionally, the reactor at a reflux ratio of 200 % presented the highest relative abundance of anaerobic ammonium-oxidizing bacteria (30.98 %) and the lowest proportion of ammonium-oxidizing bacteria (9.57 %). This study aimed to elucidate the impact of the reflux ratio on the nitrogen-removal efficiency of the CANON process and to theoretically explain the influence of different reflux ratios on N2O release. These findings provide a theoretical framework for enhancing the nitrogen-removal efficiency and mitigating carbon emissions in practical applications of the CANON process.

Microplastics are emerging contaminants, which can also absorb other contaminants, threatening the health of river ecosystems. However, research on the pollution of microplastics in rivers in northern China is still lacking. In this study, based on the sampling and analysis of water samples in 19 sites in six rivers in Tongzhou district, Beijing, the composition, spatial variation, and potential sources of microplastics were explored. The results showed that all sites were contaminated by microplastics, and the abundance of microplastics in the Xiaozhong River was the highest among all sites (3.50×104 n·m-3), which was 4.04 times that in the Yunchaojian River. The proportion of microplastics with particle sizes smaller than 2000 μm was 90.49%, and microplastics with particle sizes larger than 4000 μm were only found in two out of 19 sampling sites. The microplastics were fiber, film, fragment, and granule shaped. The proportion of fiber microplastics was the highest (90.23%) among all shapes. Most (84.29%) of the microplastics were transparent and blue. Rayon was the most common microplastic in each site, and its proportion in each site was over 66.67%. The proportions of other types of microplastics differed largely among different sites. Spatially, the abundance and types of microplastics in the upper reaches were higher than those in the lower reaches. According to spatial variations in shapes, types, colors, and abundance of microplastics, the potential sources of microplastics were identified. The potential sources of fiber microplastics were washing clothing and using fishing gear and dust-proof nets.

Anaerobic ammonium oxidation (Anammox) is an innovative autotrophic nitrogen removal process widely used in wastewater treatment because it conserves energy and reduces carbon emissions. In this study, life cycle assessment (LCA) was used to assess the environmental status of the full-scale industrial wastewater treatment plant (WWTP), and the environmental impacts of the one-stage partial nitrification/Anammox (CANON) and nitrification-denitrification (AO) were evaluated in a parallel operation. The LCA disclosed that CANON presented less load to five environmental indicators than AO and generated 59.7 % fewer carbon emissions than AO. Sensitivity analysis revealed that fluctuations in chemical consumption strongly affected AO, and wind or solar power could reduce the environmental impact by > 30 %. This study demonstrated, for the first time, that CANON is more environmentally efficient than nitrification-denitrification operating in parallel at a full-scale industrial WWTP and can provide reference and guidance for the development of sustainable wastewater treatment processes.

Total nitrogen (TN) removal from municipal wastewater after organic recovery is challenging because of the low ratio of chemical oxygen demand (COD) to TN. Anaerobic ammonium oxidation (Anammox) is promising because it has no organic requirement, but its performance in treating effluents following COD captured remains unclear. This study used mainstream partial Anammox to remove nitrogen from effluent following magnetic separation within a continuous-flow anoxic-oxic reactor. Compared with traditional nitrification and denitrification, partial Anammox increased TN removal efficiency by 15.0% and contributed 23.6% of TN removal. Quantitative polymerase chain reaction revealed that the copy number of the Anammox gene (hzsB) increased substantially, while those of the nitrite oxidation (nxrA) and denitrification (narG and nirS) genes decreased. High-throughput sequencing identified Candidatus Brocadia as the dominant genus of anaerobic ammonium-oxidizing bacteria. These findings demonstrate the effectiveness of mainstream partial Anammox for treating COD-captured effluents and its potential in municipal wastewater treatment.

自然界中部分生物体能够产生矿物质形成矿化保护壳,保护壳在提高生物体对外界不利环境的抗性和改善生命功能方面展现出良好的效果.为了利用保护壳的诸多优势,科研人员深入研究生物矿化机理,开发出多种仿生矿化方法,为不能 自然产生矿化壳的生物体制备人工保护壳,具有保护壳的生物体在疾病治疗、环境保护和新能源等领域展现出广阔的应用前景.主要围绕微生物细胞保护壳的制备方法和功能价值进行讨论.首先从制备机理、制备过程和适用范围方面介绍细胞保护壳的主要制备方法,然后阐明矿化壳在保护细胞免受外界侵害和室温储存细胞方面的应用价值,最后对具有保护壳的微生物在环境污染治理方面的应用进行展望.

Extracellular DNA (exDNA) can induce bias when evaluating the microbiota in wastewater treatment systems, particularly when cell lysis caused by thermal hydrolysis pretreatment (THP) releasing abundant DNA. However, the influence of such exDNA is still unknown. Accordingly, this study applied a pretreatment strategy for DNA extraction with proteinase K and DNase Ⅰ to minimize the influence of exDNA when evaluating the sludge microbiota. Lactobacillus and Peptostreptococcus were confirmed as the main THP-resistant microorganisms. Gram-positive bacteria were more resistant to THP, implying that the presence of a cell wall could promote THP resistance in bacteria. Moreover, the ability to form spores did not affect the resistance of bacteria to THP. These findings showed that resistant microbiota could be effectively evaluated by excluding exDNA, which can provide important insights into the understanding of microbiota dynamic and the effects of pretreatment on the precision of microbiota analysis in sludge.

H-2-based autotrophic denitrification is promising to remove nitrate from water or wastewater lacking organic carbon sources, and pH is one of its most important process parameters. HCl and CO2 addition are known as adequate pH control methods for practical purposes. However, because of H-2, added CO2 may participate in microbial metabolisms and affect denitrification mechanisms. Here, a combined micro-electrolysis and autotrophic denitrification (CEAD) reactor, in which H-2 is generated based on galvanic-cell reactions between zero-valent iron and carbon, was optimized and continuously operated for 233 days by adding HCl or CO2 to control pH in the range of 7.2-8.2. Microbial communities were compared between the two pH-control methods through high-throughput sequencing of 16S rRNA, nirS, and nirK genes. Under a low COD/N ratio of 0.5 in the influent (with similar to 36 mgNO(3)(-)-N/L), when adding HCl, the total nitrogen (TN) removal efficiency reached 91.4% +/- 0.9% with a 28-h hydraulic retention time (HRT). When adding CO2, the TN removal efficiency was improved to 96.5% +/- 1.7% with 24-h HRT. Significant differences of 16S rRNA and nirS genes between the two pH-control stages indicated the variation of microbial communities and nirS-type denitrifiers. With HCl addition, Thiobacillus, unclassified Comamonadaceae, Arenimonas, Limnobacter, and Thermomonas, which were reported previously as likely autotrophic or heterotrophic denitrifiers, were most dominant in the biofilms. With CO2 addition, the biofilms became dominated by Anaerolineaceae and Methylocystaceae (related to organic carbon metabolism), Denitratisoma (likely heterotrophic denitrifier), and uncultured bacteria TK10 and AKYG587. The results suggest that the added CO2 not only contributed to pH control but also participated in microbial metabolisms. This study provides useful insights into microbial mechanisms and further optimization of H-2-based autotrophic denitrification in water and wastewater treatment. (C) 2019 Elsevier Ltd. All rights reserved.

Microbial protein is proposed as an alternative protein source with low environmental impact. Methane oxidizing bacteria are already produced at commercial scale from natural gas. However, their productivity is limited because of the creation of explosive atmospheres in the fermenters during production. This work demonstrates the applicability of bioreactors with a membrane-based gas supply via diffusion. Methanotrophic bacteria were successfully cultivated, with growth yields from 0.26 to 0.43 g-VSS g-CH4-1, slightly below those observed in analogous fermenters relying on bubbling. However, ammonia yields ranged from 5.2 to 6.9 g-VSS g-NH3-1, indicating higher nitrogen assimilation than in conventional fermenters. Indeed, protein content increased during the operational period reaching up to 51% of dry weight. The amino acid profile included the majority of the essential amino acids, demonstrating suitability as feed ingredient. Never during the operational period was an explosive atmosphere established in the reactor. Thus, bubble-free membrane bioreactors are a promising technology for microbial protein production relying on explosive gas mixtures.

Aiming for total nitrogen (TN) pollution control in the urbanized stream, this study proposed and verified a strategy of cultivating and acclimating sulfur-based autotrophic denitrifiers by using river-bottom sediments as seed sludge, and investigated temperature effects on sulfur-based autotrophic denitrification (SAD). With thiosulfate as an electron donor, seven SAD batch reactors were operated and studied at both 15 °C and 30 °C, to compare reactor performance and their microbial community analysis results. In the first batch, three parallel reactors (A1, A2, and A3) were operated at 30 °C for 30 days. The dynamic analysis showed that sequentially decreasing temperature to 20, 15, and 10 °C had significant adverse effects on nitrate-loading rates. In the second batch, two groups of parallel reactors were operated at 30 °C (B1 and B2) and 15 °C (C1 and C2) for 45 days. High TN removal efficiencies (>95%) were achieved in all four reactors, with comparable nitrate loading rates and less nitrite accumulation at 15 °C. High-throughput sequencing revealed that genus Thiobacillus was predominant (66.3–90.0%) in all seven reactors. However, at the operational taxonomic unit level, microbial communities at 15 °C and 30 °C were significantly different, indicating that dissimilar strains were cultivated. Our findings suggested that deliberately cultivating cold-adapted denitrifiers helps SAD to achieve high TN removal at psychrophilic temperatures and thus, is important for future applications in practical TN pollution control in urbanized streams.

尿素废水的处理是当前亟需解决的难题,其中生物处理法因具有工艺流程短,成本低,抗冲击负荷,不产生二次污染等优点,在尿素废水的处理中备受青睐.本文基于尿素生物水解法原理,从机理上深入分析了脲酶的发展历程,酶学结构与水解机制,并对传统生物尿素脱氮法的应用进行了系统梳理.此外,为了更好地理解厌氧氨氧化菌降解尿素的潜能及在实际工程中的应用,本文分别从微生物学和工程应用的角度总结了相关研究结果.最后提出了尿素废水生物处理研究的建议与展望,以期为实际工程应用提供有力的理论基础和技术支持.