厌氧氨氧化工艺的启动及有机物浓度对其影响研究

鉴于反硝化菌与厌氧氨氧化菌具有相似的生理特性,采用CSTR反应器研究了以异养反硝化污泥启动厌氧氨氧化系统的可行性,并考察了其对高氨氮废水的处理潜能。反应器运行170 d后,试验结果表明,此方法可快速培育出具有厌氧氨氧化活性的污泥,NH_4~+-N和NO_2~--N的去除率分别可达99.20%和99.69%。在此基础上考察了有机物浓度对厌氧氨氧化性能的影响,结果表明:低浓度(ρ(COD)≤150 mg/L)有机物可促进厌氧氨氧化活性,而高浓度(ρ(COD)≥200 mg/L)有机物抑制厌氧氨氧化进程,该系统最适ρ(COD)/ρ(NH_4~+-N)为2.14,此时NH_4~+-N和NO_2~--N的去除率分别为99.41%和99.65%。     

Methanation and chemolitrophic nitrogen removal by an anaerobic membrane bioreactor coupled partial nitrification and Anammox

● Efficient carbon methanation and nitrogen removal was achieved in AnMBR-PN/A system. ● AOB outcompeted NOB in PN section by limiting aeration and shortening SRT. ● The moderate residual organic matter of PN section triggered PD in anammox unit. ● AnAOB located at the bottom of UASB played an important role in nitrogen removal. An AnMBR-PN/A system was developed for mainstream sewage treatment. To verify the efficient methanation and subsequent chemolitrophic nitrogen removal, a long-term experiment and analysis of microbial activity were carried out. AnMBR performance was less affected by the change of hydraulic retention time (HRT), which could provide a stable influent for subsequent PN/A units. The COD removal efficiency of AnMBR was > 93% during the experiment, 85.5% of COD could be recovered in form of CH₄. With the HRT of PN/A being shortened from 10 to 6 h, nitrogen removal efficiency (NRE) of PN/A increased from 60.5% to 80.4%, but decreased to 68.8% when the HRT_PN/A further decreased to 4 h. Microbial analysis revealed that the highest specific ammonia oxidation activity (SAOA) and the ratio of SAOA to specific nitrate oxidation activity (SNOA) provide stable NO₂⁻-N/NH₄⁺-N for anammox, and anammox bacteria (mainly identified as Candidatus Brocadia) enriched at the bottom of Anammox-UASB might play an important role in nitrogen removal. In addition, the decrease of COD in Anammox-UASB indicated partial denitrification occurred, which jointly promoted nitrogen removal with anammox.     

Improving Anammox start-up with bamboo charcoal

Three Upflow Anaerobic Sludge Blanket (UASB) reactors were compared for Anammox enrichment using synthetic wastewater with Spherical Plastic (SP) and Bamboo Charcoal (BC) addition, and without carrier (CK). After four months of operation, the Anammox activity occurred in all reactors allowing continuous removal of ammonium and nitrite. Ammonium and nitrite removal efficiencies were all higher than 98% in steady phase with the effluent concentrations below 1 mg L⁻¹. The start-up time could be shortened from 117 to 97 d in CK and SP reactor to 85 d in BC amendment reactor. Quantitative PCR (q-PCR) analyses indicated a significant increase in the number of Anammox bacteria in BC amended reactor as compared with CK and SP during the entire start-up periods. The copy numbers of Anammox of 16S rRNA gene in the reactor with BC amendment could reach up to 6 × 10⁹ copies g⁻¹ Volatile Suspended Solids, around 22.5 times and 12.3 times greater than that in CK and SP reactor, respectively. BC addition could accelerate the start-up of Anammox and significantly increase the Anammox bacteria number.     

Bamboo charcoal addition enhanced the nitrogen removal of anammox granular sludge with COD: Performance, physicochemical characteristics and microbial community

The effects of different chemical oxygen demand (COD) concentrations on the anammox granular sludge with Bamboo Charcoal (BC) addition were evaluated in UASB reactor. The results showed that the average total nitrogen (TN) removal efficiency was reduced from 85.9% to 81.4% when COD concentration was increased from 50 to 150 mg/L. However, the TN removal efficiency of BC addition reactors was dramatically 3.1%–6.4% higher than that without BC under different COD concentrations. The average diameter of granular sludge was 0.13 mm higher than that without BC. The settling velocity was increased by elevated COD concentration, while the EPS and VSS/SS were increased with BC addition. The high-throughput Miseq sequencing analyses revealed that the bacterial diversity and richness were decreased under COD addition, and the Planctomycetes related to anammox bacteria were Candidatus Brocadia and Candidatus Kuenenia. The Metagenomic sequencing indicated that the abundance of denitrification related functional genes all increased with elevated COD, while the abundance of anammox related functional genes of decreased. The functional genes related to anammox was hydrazine synthase encoding genes (hzsA, hzsB and hzsB). The average relative abundance of hzs genes in the reactor with BC addition was higher than the control at COD concentrations of 50 mg/L and 150 mg/L. The functional genes of denitrification mediated by BC were higher than those without BC throughout the operation phase. It is interesting to note that BC addition greatly enriched the related functional genes of denitrification and anammox.     

味精废水处理工艺及运行的研究

味精废水有机物及氨氮含量高,给废水达标处理带来一定难度。文章以味精厂生产废水的实际处理工艺为例,重点研究味精废水混凝预处理、厌氧处理、好氧处理、厌氧氨氧化(Anaerobic Ammonium Oxidation,Anammox)脱氮工艺等四位一体工艺的运行参数及处理效果。研究结果表明,工艺能够稳定运行,并且COD及氨氮去除率达96%以上,处理后出水满足《味精工业污染物排放标准》(GB 19431-2004)。     

Coupled relationships among anammox, denitrification, and dissimilatory nitrate reduction to ammonium along salinity gradients in a Chinese estuarine wetland

Salinization in estuarine wetlands significantly alters the balance between their nitrogen (N) removal and retention abilities but these processes have not yet been characterized effectively. In the present study, the potential rates of sediment denitrification, anaerobic ammonium oxidation (anammox), and dissimilatory nitrate reduction to ammonium (DNRA) were mapped using N isotope tracing methods along salinity gradients across the Yellow River Delta wetland (YRDW) in China. The contribution of anammox to total dissimilatory N transformations in YRDW was merely 6.8%, whereas denitrification and DNRA contributed 52.3% and 40.9%, respectively. The potential rate of denitrification (5.82 μmol/kg/h) decreased significantly along salinity gradients and markedly exceeded DNRA potential rate (2.7 μmol/kg/h) in fresh wetlands, but was lower than that of DNRA in oligohaline wetlands (3.06 and 3.18 μmol/kg/h, respectively). Moreover, a significantly positive relationship between salinity and DNRA/denitrification was obeserved, indicating that increased salinity may favor DNRA over denitrification. Furthermore, total sulfur (TS) content and ratio of total organic carbon to total nitrogen (C/N) increased with the salinity gradient and showed evident positive relationships with the DNRA/denitrification ratio. In this study, we proved that increased salinization resulted in the dominance of DNRA over denitrification, possible through the addition of S and alteration of the C/N in estuarine wetlands, leading to increased N retention in estuarine wetlands during salinization, which would enhance the eutrophication potential within wetlands and in downstream ecosystems.     

羟胺对一体式部分亚硝化-厌氧氨氧化工艺的原位恢复及运行稳定性的影响

一体式部分亚硝化-厌氧氨氧化（CPNA）工艺的脱氮性能常因亚硝酸盐氧化菌（NOB）大量增殖导致的NO₃^--N积累而恶化.本研究通过连续试验考察长期低剂量投加羟胺（NH₂OH）对CPNA工艺原位恢复及其长期运行稳定性的影响.结果表明,低剂量投加NH₂OH（1.5 mg·L^-1）可快速原位恢复CPNA工艺,TN去除率在45 d内从18.6%恢复至82.2%,ΔNO₃^--N/ΔNH₄⁺-N比值从0.73±0.05下降至0.13±0.03;以相同方式在100 d内持续投加NH₂OH,CPNA工艺的TN去除率长期保持在82.2%±4.9%,ΔNO₃^--N/ΔNH₄⁺-N比值可长期稳定在0.13±0.03.16S rRNA高通量测序结果表明,羟胺投加期间,脱氮功能菌群变化显著,Nitrospira的丰度从28.22%下降到2.74%,厌氧氨氧化菌Candidatus Kuenenia丰度从初始的3.43%明显增长到22.86%.低剂量投加羟胺可有效促进CPNA工艺的快速原位恢复,并保持其长期稳定运行.     

Field scale interaction and nutrient exchange between surface water and shallow groundwater in the Baiyang Lake region, North China Plain

Fertilizer input for agricultural food production, as well as domestic and industrial surface water pollutants in the North China Plain, increases pressures on locally scarce and vulnerable water resources. In order to: (a) understand pollutant exchange between surface water and groundwater, (b) quantify nutrient loadings, and (c) identify major nutrient removal pathways by using qualitative and quantitative methods, including the geochemical model PHREEQC, a one-year study at a wheat (Triticum aestivum L.) and maize (Zea mays L.) double cropping system in the Baiyang Lake area in Hebei Province, China, was undertaken. The study showed a high influence of low-quality surface water on the shallow aquifer. Major inflowing pollutants into the aquifer were ammonium and nitrate via inflow from the adjacent Fu River (up to 29.8 mg/L NH₄-N and 6.8 mg/L NO₃-N), as well as nitrate via vertical transport from the field surface (up to 134.8 mg/L NO₃-N in soil water). Results from a conceptual model show an excess nitrogen input of about 320 kg/ha/a. Nevertheless, both nitrogen species were only detected at low concentrations in shallow groundwater, averaging at 3.6 mg/L NH₄-N and 1.8 mg/L NO₃-N. Measurement results supported by PHREEQC-modeling indicated cation exchange, denitrification, and anaerobic ammonium oxidation coupled with partial denitrification as major nitrogen removal pathways. Despite this current removal capacity, the excessive nitrogen fertilization may pose a future threat to groundwater quality. Surface water quality improvements are therefore recommended in conjunction with simultaneous monitoring of nitrate in the aquifer, and reduced agricultural N-inputs should be considered.     

接种不同普通活性污泥培养厌氧氨氧化污泥的研究

采用厌氧氨氧化反应器（ASBR）,分别以普通厌氧活性污泥、混合污泥、好氧活性污泥为种泥,通过对氨氮,NO2^--N等指标监测、分析及污泥颜色的观察,研究采用不同普通活性污泥为种泥启动ASBR的可行性及差异。结果表明．ASBR反应器A和B成功启动,C因反应器故障．启动失败。采用厌氧活性污泥为接种污泥（反应器A）,当进水N的容积负荷为kg／（m^3·d）时,氨氮平均去除率为14.4％。P（NO2^--N）：p（NH4^＋-N）变化量为1．24。采用混合污泥为接种污泥（反应器B）．N的容积负荷于前者相同时,氨氮去除率平均29．7％,p（NO2^--N）：p（NH4^＋-N）变化量为1．27。采用混合普通活性污泥作为种泥培养厌氧氨氧化污泥优于单一厌氧普通活性污泥。     

In situ nitrogen removal processes in intertidal wetlands of the Yangtze Estuary

Estuarine and intertidal wetlands are important sites for nitrogen transformation and elimination. However, the factors controlling nitrogen removal processes remain largely uncertain in the highly dynamic environments. In this study, continuous-flow experiment combined with ¹⁵N isotope pairing technique was used to investigate in situ rates of denitrification and anaerobic ammonium oxidation (anammox) and their coupling with nitrification in intertidal wetlands of the Yangtze Estuary. The measured rates varied from below the detection limit to 152.39 µmol N/(m²·hr) for denitrification and from below the detection limit to 43.06 µmol N/(m²·hr) for anammox. The coupling links of nitrogen removal processes with nitrification were mainly dependent on nitrate, organic carbon, sulfide, dissolved oxygen and ferric iron in the estuarine and intertidal wetlands. Additionally, it was estimated that the actual nitrogen removal processes annually removed approximately 5% of the terrigenous inorganic nitrogen discharged into the Yangtze Estuary. This study gives new insights into nitrogen transformation and fate in the estuarine and intertidal wetlands.