This study investigated the degradation of NH4+-N in river channels under varying flow velocities, using both a simulated river channel (SRC) and a practical river channel (PRC) to treat discharge from an urban wastewater treatment plant (WWTP). The results showed that NH4+-N degradation follows first-order kinetics, with the degradation coefficient (KNH4+-N) increasing as flow velocity increases. By analyzing the microbial and physicochemical pathways of ammonia nitrogen degradation, the contribution differences between the two can be effectively highlighted. In the SRC, at an NH4+-N concentration of 2.41 +/- 0.48 mgL-1, KNH4+-N rose from 0.10 day-1 (0.01 ms-1) to 0.26 day-1 (0.02 ms-1). In the PRC, at an NH4+-N concentration of 1.86 +/- 0.18 mgL-1, KNH4+-N increased from 0.19 day-1 (0.10 ms-1) to 0.28 day-1 (0.18 ms-1). Ammonia-oxidizing bacteria (AOB), such as Nitrosomonas, were detected with counts increasing at higher flow velocities, while other AOB and nitrite-oxidizing bacteria (NOB) were not detected. This study confirmed that the degradation of NH4+-N in rivers is determined by the influence of flow velocity on the balance of ammonia particles and free ammonia in water, which significantly affects the removal of NH4+-N. The maximum removal efficiency in the study was 35.36%. In conclusion, the findings of this study highlight the significant role of flow velocity in enhancing NH4+-N degradation in river channels, with higher velocities promoting both faster degradation rates and greater ammonia-oxidizing bacteria abundance, ultimately improving the efficiency of NH4+-N removal from urban wastewater discharges.

The concentrations of NO3--N and NH4+-N in many urban rivers variated seasonally throughout the year, the macrogenomic technology was used to determine the abundance and diversity of the genes involved in microbial nitrogen cycling (classified into 51 classes) in an actual urban river, the relationship between nitrogen transfer genes and nitrogen compound was investigated. The resutls showed that during the dry season, the abundance of nar (NO3--N to NO2--N, 1.70 % +/- 0.40 %) and nir (NO2--N to NH4+-N, 3.80 % +/- 0.60 %) genes were dominant, while the abundance of nrfA (dissimilatory reduction of NO3--N, 0.21 % +/- 0.09 %) and hao (hydroxylamine (NH2OH) to NO2--N, 0.10 % +/- 0.02 %) were low, indicating most NO2--N was converted directly to NH4+-N rather than through NH2OH or NO. During the normal season the gltD (NH4+-N to organic N) exhibited a significant positive correlation with BOD (r = 0.88, P < 0.05), and during the dry season the glnA (NH4+-N to organic-N) exhibited a significant negative correlation with NO3--N concentration (r = -0.86, P < 0.05). The nitrogen transfer genes involved in the same pathway do not respond uniformly to seasonal changes, which can serve as an indicator of the health status of aquatic ecosystems, thereby facilitating the identification of potential ecological risks and pollution sources.

Cultivating the aerobic granular sludge (AGS) in continuous flow system remains challenging. This study used an anaerobic oxic (AO) reactor with bottom feed and intermittent anaerobic mixing to treat synthetic municipal wastewater, the granulation progress and treatment performance under on/off ratios of 1:3 (R1), 2:2 (R2) and 4:0 (R3) were investigated. The results showed that by the 40th day, R1 exhibited the best granulation performance with an average particle size (APS) of 153.50 mu m, R2 and R3 exhibited similar size of 120.20 and 123.90 mu m, but R2 was suffered by sludge bulking with the sludge volume index (SVI30) of 220.14 mL.g-1. More hydrophobic substances (tyrosine-like and tryptophan-like proteins) were enriched in the granules of R1, and about 58.50 +/- 0.80 % influent COD was stored in the settled sludge bed during the off-mixing period. Abundant glycogen accumulation organisms (GAOs) and phosphorus accumulation organisms (PAOs) were enriched in R1 (41.54 %), which was significantly bigger than those of R2 (10.66 %) and R3 (21.88 %). However, R2 and R3 exhibited the best total phosphorus (70.20 +/- 3.50 %) and total nitrogen (70.27 +/- 3.94 %) removal performance, respectively. During the high influent COD period in R3, although intermittent mixing facilitated particle size increase, excessive filamentous proliferation disrupted the granular structure, resulting in APS of 129.52 mu m by the 85th day. This study verified the feasibility to enhance granulation through bottom feed and intermittent anaerobic mixing in AO reactor, providing new insights of granulation mechanism in continuous flow system.

An in situ integrated system, consisting of ecological floating islands (EFI), ecological riverbeds (ER), and ecological filter dams (EFD), was built in a ditch only receiving the effluent of sewage plant; the effect of in situ technologies on the distribution of aquatic pathogen was investigated. The results showed the aquatic pathogen decreased along the ditch. Specifically, the relative abundance of Legionella, Aeromonas, and Acinetobacter decreased from 0.032, 0.035, and 0.26 to 0.026

This study focused on the horizontal distribution of nitrogen removal characteristics of biofilm and sludge floc in anaerobic/anoxic/oxic (AAO) process. Fixed carriers were placed in a full-scale AAO system, and the nitrogen removal kinetics associated with microbial community between biofilm and sludge floc along the process were investigated. The results showed sludge floc exhibits superior nitrification capability, particularly around the middle of aerobic tank with specific NH4+-N (NO2--N) oxidation rates of 1.67 mg.g(-1).h(-1)-3.46 mg.g(-1).h(-1) (1.32 mg.g(-1).h(-1)-1.56 mg.g(-1).h(-1)). The biofilm exhibits superior denitrification ability, particularly in anoxic and middle of aerobic tank with specific NO3--N (NO2--N) reduction rates of 4.34 mg.g(-1).h(-1)-10.16 mg.g(-1).h(-1) (2.95 mg.g(-1).h(-1)-4.93 mg.g(-1).h(-1)). In aerobic tank, extracellular polymeric substance (EPS) of sludge floc was positively correlated with specific oxidation rates of NH4+-N (R = 0.93) and NO2--N (R = 0.89), but EPS of biofilm was negatively correlated with specific NH4+-N oxidation rate (R = -0.68). Nitrospira was the dominant nitrifying bacteria in sludge floc which distributed evenly in the AAO process with the relative abundance of 4.28 %-5.95 %, while in biofilm it mainly enriched in anoxic (2.33 %-3.27 %) and aerobic tank (1.04 %-1.89 %). Dechloromonas and Thauera were main denitrifying bacteria in sludge floc (2.77 % +/- 0.61 % and 1.80 % +/- 0.25 %), while Saccharibacteria was dominant denitrifying bacteria in biofilm (4.44 % +/- 1.51 %). Candidatus Kuenenia was Anammox bacteria in both sludge floc (0.01 % +/- 0.01 %) and biofilm (0.02 % +/- 0.01 %). The nitrogen removal potential in each tank was evaluated through comparing the differences between actual concentrations of NH4+-N, NO2--N, NO3--N and the associated half-saturation constants, and the strategy of specifically installing fixed carriers to improve nitrogen removal was proposed.

Various materials such as activated carbon, zeolite, mature granular sludge, and nano-composites are used as inert nucleus to cultivate aerobic granular sludge (AGS), this study operated parallel reactors to cultivate AGS with and without nano-Fe3O4 addition inoculated by activated sludge. This study systematically compared the granulation process, nitrogen removal efficiency, transfer pathways, and microbial community structure under long-term operation. Results demonstrated that nano-Fe3O4 addition significantly promotes AGS formation with over 74.04 % of biomass exceeding 200 mu m, and the average SVI and granule size were 59.08 mL/g and 361.50 mu m after 60 days. The nano-Fe3O4 induced the sludge to secret more humic acid to accelerate electron transfer, and enhanced the nitrification process, particularly the transfer pathway from NO2--N to NO3--N. The specific NO2--N oxidation rate increased from 5.26 mg/(g center dot h) to 9.98 mg/(g center dot h). Furthermore, nano-Fe3O4 significantly altered the microbial community structure, the relative abundance of Nitrosomonas and Nitrospira with nanoFe3O4 were 0.54 % and 1.54 %, compared to 0.30 % and 0.15 % without nano-Fe3O4. Furthermore, Thauera increased from 3.64 % to 14.58 %, which is crucial for AGS formation. Overall, the innovative application of nano-Fe3O4 not only enhances sludge granulation but changing nitrogen transfer pathways, underscoring its potential as a groundbreaking approach in wastewater treatment.

The advanced nitrogen removal is always limited by low carbon to nitrogen ratio (C/N), the feasibility of producing carbon source through fermenting corncob was evaluated in this study. The effect of initial pH, solid content and temperature on the production of volatile fatty acids (VFAs) by alkali pre-treated corncob were investigated, and the denitrification performance with anaerobic fermentation liquid (AFL) and sodium acetate (SA) was compared. The results showed that alkali pretreatment improved the mass transfer inside the corncob, and the solid content had a major impact on VFA production. The denitrification rate of the two systems was related to the influent NO3--N concentration only when the C/N was 6:1 and 8:1, and the removal efficiency was bigger than 95 %. Nevertheless, the nitrite reduction of the AFL system was limited at a C/N of 4:1, and the removal efficiency of NO3--N was only 65.10 %. Moreover, the AFL system enriched a large number of genera involved in nitrogen removal and organic decomposition. The functional analysis showed that the denitrification activity and ability of the AFL system were slightly lower. However, the SA system enriched more pathogenic bacteria, the relative abundances of Arcobacter and Pseudomonas were 28.74 % and 11.85 %, respectively. This study provides a reference for optimizing the design and control of VFAs production by continuous fermentation from agricultural waste.

The three-chamber septic tank has become essential in the middle rural areas of China, although its drainage serves as a potential source of groundwater contamination. A photosynthetic electrochemical system using Chlorella vulgaris was developed to treat synthetic sewage, and the impact of environmental factors on treatment performance was investigated. The results showed that the removal efficiencies of chemical oxygen demand (COD), NH4+-N and PO43--P reached maximum value under 1.00 times/day-1 hydraulic circulation, 0.3g L-1 initial algae dosage and 4,350 Lux light intensity. When the optimal condition were applied to treat the effluent of three-chamber septic tank, the removal efficiencies of COD, NH4+-N, and PO43--P were 61.95%, 88.32%, and 95.36%, respectively. This study provided an optional treatment technology of rural sewage, and future research should focus on the algae separation and recovery in practical applications.

A nitrogen removal biofilter coupled with electrode plates was established to treat a mixture of raw sewage and secondary effluent. The nitrogen removal characteristics and microbial community of the combined electrochemical biofilter (CEBF) and quartz sand biofilter (QSBF) were investigated. The results showed that when the influent concentrations of NH4+-N, NO3--N, and COD were 10, 8, and 60 mg/L, respectively, the average NH4+-N removal rate in CEBF (5.03 mg/(L center dot d)) was higher than that in QSBF (4.28 mg/(L center dot d)). The carbon source had a greater impact on denitrification performance than the electrochemical system when the influent C/N ratio was 4.28. When the influent C/N ratio was 3.67, specific anammox rates of CEBF and QSBF increased to 2.67 mg/(g center dot h) and 2.87 mg/(g center dot h), respectively. Furthermore, the successful construction of the electrochemical system was confirmed by the enrichment of electrochemically active bacteria on the anode plate, including Geobacter (33.73 %) and Desulfuromonas (10.44 %). The relative abundance of denitrifying bacteria (DNB) on the carriers' biofilm was lower in CEBF compared to QSBF. Anammox bacteria (AnAOB) Candidatus_Kuenenia in CEBF (0.06 %) was higher than that in QSBF (0.02 %). This study provided a reference for the application of electrochemical biofilter in nitrogen removal of WWTPs under low C/N.

Given increasingly prominent environmental issues, there is a pressing need to satisfy more stringent emission standards for wastewater treatment plants (WWTP) while concurrently prioritizing energy conservation; a new up-flow layered nitrogen removal filter was constructed on a laboratory scale using gravel (for the bottom and top layers) and embedded bio-organic carriers (for the middle layer) containing microorganisms as fillers to treat the secondary effluent by introducing a portion of raw water. This study investigated the nitrogen removal effectiveness and transfer pathways of synthetic wastewater at varying mixing ratios, promoted the enrichment of Anammox Bacteria (AnAOB) by embedding microorganisms, and analyzed the microbial community structure using high-throughput sequencing techniques. The findings showed that the highest total nitrogen (TN) removal efficiency was achieved with chemical oxygen demand (COD), ammonia (NH4+-N), and nitrate (NO3−-N) contents in the mixture at 77, 10, and 8 mg·L−1, respectively, with an average efficiency of 89.42%. NO3−-N was mostly removed through denitrification (heterotrophic), while NH4+-N was eliminated by partial nitrification (PN) and anaerobic ammonium oxidation (Anammox, autotrophic). According to high-throughput sequencing results, denitrifying bacteria such as Thauera (1.30–6.96%), Flavobacterium (0.18–0.40%), and Parcubacteria (0.14–0.32%) were present in all the filter layers, and Anammox bacteria such as Candidatus_Kuenenia were predominant in the middle layer at a 0.88% abundance, with the aid of organic carriers.

In order to improve the purification performance of the floating island under fluctuated temperature and flow, a floating island system was constructed through Rumex japonicus Houtt (RJH), Iris sibirica (IS), and artificial aquatic mat (AAM) to treat the effluent from secondary clarifier. The performances under different flow in cold season (6.9–17.9 ℃) and warm season (24.6–29.8 ℃) were investigated. The results showed AAM was the main nitrification unit enriched with Nitrosomonas (0.1134–0.1832

ITo solve the problem of low influent C/N ratio for advanced nitrogen removal in wastewater treatment plants, corn cob, and polycaprolactone were used as raw materials to prepare organic slow-release carbon sources for secondary effluent treatment. The nitrogen removal performance of embedding microorganisms（secondary sedimentation tank bacteria suspension） and non-embedding were compared. The results showed that when the influent nitrates were 5 mg/L（low concentration）, 10 mg/L（medium concentration）, and 20 mg/L（high concentration）, the embedding bacterial suspension effectively improved the nitrogen removal efficiency. When the influent nitrate was lower than 10 mg/L, the embedded bacterial suspension with a slow-release carbon source has a good nitrogen removal effect, and the removal rate of nitrate was higher than 97.34%. When the influent nitrate was more than 20 mg/L, the nitrogen removal performance could still be stable with the high carbon release of a solid carbon source. At the same time, due to the high carbon source utilization efficiency, the embedded carbon source has the best total nitrogen removal with a removal rate of 88.80%. Preparation of a solid carbon source embedded with the activated sludge bacterial suspension, sodium dodecyl sulfate（K12） was used to increase the specific surface area, and the proliferation of denitrifying bacteria would be strengthened. Compared with activated sludge microorganisms, the denitrifying bacteria enriched in the long-term operation were Methyloversatilis, with a relative abundance of 16.06%.

清潩河是典型的基流匮乏型河流,水生态环境质量空间差异明显,为探究浮游生物群落结构特征及其与水环境的关联性,于2021年7月在清潩河(许昌段)开展浮游生物及环境因子调查,基于综合水质标识指数及生物多样性指数分析水体污染程度,并利用典范对应分析法分析干流与支流河段浮游生物群落结构的关键影响因子.结果显示:本次调查共检出浮游植物8门204种,群落结构为绿藻-硅藻-蓝藻型;检出浮游动物4 门88种,群落结构以轮虫、原生动物为主;浮游生物多样性指数及综合水质标识指数均显示清潩河(许昌段)水质为轻度污染,但浮游生物优势种显示其有富营养化可能.典范对应分析结果显示,不同河段影响浮游生物优势种密度的关键影响因子有所不同:干流及支流浮游植物群落结构分别受WT、TP、DO、NO3--N和CODCr、TN、NO2-N、原生动物的影响,干流及支流浮游动物群落结构分别受TSS、甲藻和NO2--N、CODCr、金藻、隐藻的影响.

There are a number of small and medium-sized rivers throughout China, which are the closest to humans. But they are also affected by man-made transformation and production and life activities and show more obvious ecological degradation. Taking the Xuchang section of the Qingyi River as the study area, a mass-balance food web model was established with "Ecopath with Ecosim" according to the data of aquatic organisms collected in the summer and autumn of 2021. The achieved results reveal that the Qingyi River ecosystem mainly consists of five integrated nutrient levels (1.00-3.29), and due to the low transfer efficiency of trophic levels I and II, the energy flow to the higher nutrient level was seriously hindered, and the conversion efficiency of the whole system was only 1.08% and 1.82%. The mixed trophic impacts did not alter in summer and autumn, and predators except Culter alburnus exhibited a strong inhibitory effect on the bait organisms. A comprehensive analysis of multiple indicators, including parameters close to maturity, resilience and stability of the system, indicate that the total flow rates of the Qingyi River ecosystem were 2 571.06 and 1 472.58 t·km-2 in summer and autumn, respectively, and the size of the ecosystem in summer is greater than that in autumn and Finn′s cycling index (FCI) and Finn′s mean path length (FML) also revealed that the ecosystem maturity and stability in summer were superior to those in autumn. Finally, according to the food web model, three key functional groups at various nutrient levels in the Qingyi River ecosystem have been selected as phytoplanktons, molluscs, and Culter albus, while maintaining the appropriate requirements of key functional habitats and growth habits, the pertinent suggestions for restoring the ecosystem, such as limiting the growth of dominant phytoplankton species, increasing mollusk predator pressure, and restoring the Culter alburnus population are presented. The findings of this study could provide decision-making basis and scientific support for the ecological restoration of the Qingyi River and similar rivers.

[Objective] The spatiotemporal characteristics and factors influencing the value of forest carbon sequestration in Henan Province were analyzed in order to provide a reference for promoting the realization of “carbon peak and carbon neutrality”. [Methods] The value of forest carbon sequestration in Henan Province from 2010 to 2020 was evaluated through the stock expansion method and the afforestation cost method, and the temporal variation characteristics of forest carbon sequestration value were analyzed. The Moran index was used to explore the spatial aggregation characteristics, and an extended STIRPAT model was constructed to analyze the factors affecting the value of forest carbon sequestration. [Results] ① The value of forest carbon sequestration in Henan Province showed a continuous rising trend which increased from 4.18 billion yuan in 2010 to 6.71 billion yuan in 2020. Carbon sequestration values exhibited a pattern of “higher in the west and south, lower in the east and north” in Henan Province, and there was a significant positive spatial aggregation effect. The areas with significant high carbon sequestration values were located in Western and Southern Henan Province, while there were only two areas with significant low carbon sequestration values. ② In addition to the negative impact of carbon sink intensity on the value of forest carbon sequestration in Henan Province, the proportion of forest area, urbanization ratio, forestry industry ratio, and per capita GDP all showed positive impacts. The proportion of forest area was the most important factor promoting the growth of forest carbon sequestration values. [Conclusion] There is great potential for forest carbon sequestration in Henan Province, and the realization of forest carbon sequestration should be promoted regionally in the future.

投加缓释碳源是降低低碳氮比废水总氮(TN)的有效途径.使用聚己内酯(PCL)、玉米芯(CC)和二价铁盐(FeSO4、FeCl2)为电子供体,以聚乙烯醇和海藻酸钠为骨架,经过化学交联制备了PCL-CC基质(PC)、PCL-CC-FeSO4基质(PCF-S)和PCL-CC-FeCl2基质(PCF-C)3种固体缓释碳源,构建了铁-碳协同脱氮除磷的反硝化滤池,并将其用于处理模拟废水,比较了PC、PCF-S和PCF-C在连续流反硝化滤池中的有机物释放特性与其强化脱氮除磷的性能.结果表明:PC、PCF-S和PCF-C 3种基质均可长期稳定释碳达48 d以上;在PCF-C与PCF-S缓释碳源滤池中,铁自养反硝化和异养反硝化之间存在明显的协同作用,2种反硝化作用的结合可显著增强滤池对氮磷的去除效果,3种碳源基质中PC反硝化潜能最好;相较于中低浓度阶段,高浓度进水阶段3种碳源滤池对氮素的去除率均有所下降,脱氮效果变差,这是由于高浓度进水阶段2种PCF基质出现铁壳积累现象,其积累程度由有机物释放速率和脱氮负荷共同决定.

This paper examines the effect of infrequent extreme rainstorms on the operational efficiency of two wastewater treatment plants located in the central plains of China. The study focuses on the performance of oxidation ditch and multi-stage AO processes, and develops a model for assessing their sludge concentration correction. The study found that during extreme rainstorms, influent flow increased to 1.6 times the design standard, and temperature decreased abruptly from 28.2°C to 21.1°C. The COD reduction was better in the ditch, achieving 76.2%, compared to the multistage AO process, which achieved 92.5% COD reduction. The impact on the removal of NH4+-N was low, while the effect on the removal of total nitrogen (TN) and total phosphorus (TP) from the oxidation ditch was higher. The effluent TN was above the design standard at 12.44±2.13mg/L at the end of the rainstorm. The study suggests increasing the concentration of sludge return flow and stopping internal return flow as an effective measure to prevent sludge loss and reduce the impact of the rainstorm. The study also proposes measures to prevent rainwater from entering the plant and adding a carbon source to maintain the activated sludge system's stability. In conclusion, this study highlights the impact of rare extreme rainstorms on wastewater treatment plants' performance and provides practical solutions to mitigate the negative effects on the activated sludge system.

为明确生态修复类型河流的微生物群落结构、功能及其影响因素,以许昌市清潩河为例,采用高通量测序的方法研究生态修复措施对河流水体和沉积物微生物群落结构的影响,并在此基础上分析碳氮硫功能菌群在生态修复措施中的净化作用及水体病原菌分布状况.结果表明:在人类干扰较少的河段,近自然河岸带对陆源污染起着较好的拦截效果,生态滤坝设施的截留和复氧能力有助于河流对化学需氧量(COD)的去除;城区段河流受人类活动影响水质变化较大,生态修复措施净化效果不明显;城郊段人类干扰较少,河流自净能力提升,总磷(TP)、氨氮(NH4+-N)等指标逐渐恢复原有水平.清潩河沉积物中微生物多样性和丰富度均高于水体,且变形菌门(Proteobacteria)是沉积物和水体中的优势物种.部分河段参与氮循环的蓝藻菌门(Cyanobacteria)相对丰度达到 4.7%,说明清潩河仍存在富营养化河段.清潩河水体中相对丰度最高的致病菌群为不动杆菌(Acinetobacter),而沉积物中相对丰度最高的致病菌群为梭状芽孢杆菌属(Clostridium)、黄杆菌属(Flavobacterium)和拟杆菌门(Bacteroidetes),其中拟杆菌门在城区段相对丰度最高.Spearman相关性分析表明,水体中微生物多样性与温度、pH、COD有显著相关性(P<0.05),城郊段沉积物中微生物群落结构的主要影响因子为NH4+-N、总氮(TN)和TP.生态修复河流城区段微生物丰度和多样性较高,致病风险大;城郊段碳氮硫功能菌群丰度高,是物质循环的主要场所.

为了提高厂网一体化系统有机物的利用效率,构建"降解-沉积-冲刷"管网COD变化模型,考察了管网与污水厂对COD去除的贡献规律.结果表明在不受降雨影响时,管内COD呈整体下降趋势,管网对COD去除贡献率为15.91％,且ΔCOD与HRT呈正相关(相关系数0.865).污水厂进水COD浓度越低,其去除单位COD耗电量越高(相关系数-0.862).从合理利用COD强化污水厂脱氮除磷角度出发,建设分散式污水处理厂、选择分流制排水体制是缩短管内污水停留时间、提高污水厂进水碳源的有效方式.

The influent flow of wastewater treatment plant (WWTP) usually fluctuated by rainfall and pipe network, a nitrogen removal biofilter constructed with gravel (bottom) and embedded bio-organic carrier (top) was used to treat the mixture of secondary effluent and urban sewage, the nitrogen removal were investigated under different flow variations (stable, slowly increased, slowly decreased, fluctuated). The results showed during the slowly increased phase, the percentage of NH4+-N removed by partial nitrification (PN) in the gravel layer decreased from 44.92 % to 39.02 %. The carrier layer mainly occurred complete denitrification reaction. In the phase of slowly decreased, the percentage of NH4+-N removed by PN to the total removed NH4+-N in the gravel layer increased firstly and then decreased. In addition, Nitrosomonas (0.64 %), Azospira (1.41 %) in the gravel layer and Dechloromonas (0.65 %), Lysobacter (2.96 %), Candidatus_Kuenenia (0.68 %) in the carrier layer at the end of the experiment were more abundant than those in the initial activated sludge. This study provides a reference for advanced nitrogen removal of WWTPs under fluctuated influent flow.