氮负荷对短程反硝化耦合厌氧氨氧化生物膜系统脱氮性能的影响

短程反硝化作为厌氧氨氧化反应基质亚硝酸盐(NO2--N)获取的新途径,近年来受到广泛关注.短程反硝化与厌氧氨氧化耦合的污水脱氮工艺具有重要应用潜力.然而,城市污水基质浓度较低且波动频繁,有效实现厌氧氨氧化菌持留与富集是该工艺稳定脱氮的关键.针对上述问题,构建了基于生物膜的短程反硝化耦合厌氧氨氧化工艺,采用2种结构不同的生物填料为载体,对比系统长期脱氮性能,重点考察氮负荷降低过程中系统氮素转化规律及菌群活性变化,深入分析生物膜胞外聚合物(extracellular polymeric substances,EPS)产生特性.结果表明,以含氨氮(NH4+-N)与硝酸盐氮(NO3--N)废水为处理对象,乙酸钠为有机碳源,分别采用聚氨酯海绵填料(R1)和聚乙烯空心环填料(R2)成功构建了短程反硝化耦合厌氧氨氧化生物膜系统.进水NH4+-N与NO3--N由150 mg/L逐渐降低至50 mg/L、氮负荷由0.6 kg/(m3·d)降为0.2 kg/(m3·d)时,R1和R2维持高效稳定脱氮,低负荷阶段平均总氮(TN)去除率分别为87.6％和83.6％.厌氧氨氧化作用始终为主要脱氮途径,其占两系统TN去除的贡献率分别高达98.2％和97.4％.生物膜短程反硝化速率随氮负荷减少而降低,但高NO2--N积累特性未受影响,R1系统NO2--N积累效率达到95.1％且高于R2(89.8％),其厌氧氨氧化活性降低程度小于R2,表明聚氨酯填料更适合低负荷下该工艺长期运行.低负荷下微生物分泌更多EPS,蛋白质含量增加有助于系统应对氮负荷变化.综上,短程反硝化耦合厌氧氨氧化生物膜工艺处理低基质废水时具有稳定高效的重要优势,为解决厌氧氨氧化应用的瓶颈问题提供了新方法,具有研究意义和应用价值.     

低氨氮条件下厌氧氨氧化生物滤池快速启动

在14.2~23.9℃下,将厌氧氨氧化(ANAMMOX)菌颗粒污泥接种于火山岩填料生物滤池,以期缩短其启动时间.启动初期,当进水ρ(NH4+-N)=70 mg/L、ρ(NO2--N)=90 mg/L时,TN去除负荷为0.12 kg/(m3.d);自启动第105天,TN去除负荷达到2.22 kg/(m3.d),实现了厌氧氨氧化生物滤池的快速启动.结果表明,根据氮气产量、生物膜表观颜色、脱氮速率和pH值的变化,可将启动过程分为ANAMMOX菌的驯化与快速扩增2个阶段.     

无纺滤布生物膜反应器对厌氧氨氧化脱氮负荷提高的实现

采用无纺滤布生物膜反应器,研究了厌氧氨氧化工艺脱氮负荷提高的可行性.研究结果表明,封存污泥经过15 d培养,可成功实现厌氧氨氧化活性恢复,氨氮去除率可以指示活性恢复程度.厌氧氨氧化无纺滤布ASBR反应器具有较高的脱氮潜能,试验阶段氮容积去除负荷最高可以达到2.06 kg/(m3·d).     

硫自养反硝化同步脱氮除硫启动试验

目的 研究单一反应器内硫自养反硝化同步脱氮除硫的启动方法 及过程,同时考察脱氮除硫效果.方法 选择厌氧生物滤池为生物反应器,采用普通厌氧消化污泥为接种污泥,以自配的含S2--S和NO3--N的废水为进水,进水容积负荷分别为0.24 kg/(m3·d)、0.105 kg/(m3·d),经过15 d的间歇运行和15 d的连续运行,对硫自养反硝化的启动过程进行研究.结果 经过30 d的运行启动,S2--S和NO3--N的去除率基本稳定在90%及80%以上,去除负荷分别为0.238 kg/(m3·d),0.093 3 kg/(m3·d),S0及NO2--N的生成率分别为75%与64%左右.结论 反应器在短时间内成功筛选并富集了硫自养反硝化菌,S2--S和NO3--N达到很高的去除负荷,硫自养反硝化反应器成功启动.     

微氧条件下培养AOB-Anammox颗粒污泥

采用絮状硝化污泥和厌氧氨氧化颗粒污泥为接种污泥,利用膨胀颗粒污泥床反应器,在微氧曝气条件下,培养自养脱氮(氨氧化AOB-厌氧氨氧化Anammox)颗粒污泥.在无机高氨氮进水条件下,维持反应器运行58 d,成功培养出AOB-Anammox颗粒污泥.在模拟生活污水条件下,颗粒污泥脱氮效果稳定,氨氮和总氮去除率最高可达92.3%、71.2%,平均总氮去除负荷达1.237 kg·N/(m~3·d).SEM及FISH结果表明:AOB-Anammox颗粒污泥微生物组成以2种菌群为主,AOB细菌密集排布于颗粒污泥表面,Anammox细菌均匀分布在颗粒污泥内部.     

常温低基质启动AAOB颗粒污泥性能分析

为研究在常温低基质（NH+₄-N、NO-₂-N为（40±10）mg/L）启动AAOB颗粒污泥的过程,采用SBR反应器逐渐缩短实验周期来启动AAOB颗粒污泥,并且对系统中的氮去除率、氮负荷及各个阶段厌氧氨氧化过程动力学特性进行分析.同时,对各个阶段的颗粒污泥形态、平均粒径、EPS含量以及EPS的三维荧光特性进行分析.结果表明,逐渐缩短实验周期（24 h→12 h→10 h→8 h）,氮负荷由0.074 g/(L·d)提高到0.204 g/(L·d).Grau second-orders模型较好地表征启动厌氧氨氧化(AAOB)颗粒污泥过程,基质去除速率常数k₂值由0.15上升为0.22,脱氮性能逐步提高.污泥的MLSS、MLVSS由初期2 989,2 348 mg/L最后稳定到2 0,1 776 mg/L,随着反应进行,厌氧氨氧化污泥充分利用基质,颗粒污泥逐渐稳定,最终污泥颗粒平均粒径达410 μm.PN质量分数以及PN与PS比呈现先上升后趋于稳定的趋势,且PN质量分数以及PN与PS比随着粒径增大而变大.利用PARAFAC法分析污泥EPS中三维荧光成分,其由辅酶NADH、核黄素和腐殖酸组成.     

亚硝化颗粒污泥系统中氮损失特性分析

对亚硝化颗粒污泥系统在启动和运行过程中氮的损失特性进行了考察.结果表明,当进水氨氮容积负荷为1.2 kg/(m3·d)时,系统氮损失率保持在20％左右,而且在第45～58天期间氮损失率有上升趋势.分析认为氮的损失主要归因于发生在颗粒污泥内部的反硝化过程,而氨氮吹脱、厌氧氨氧化等对其贡献微弱.随着颗粒污泥粒径的逐渐增长和结构的愈加密实,反硝化效果不断增强.另外,亚硝化颗粒污泥系统具有良好的COD去除效果,COD容积负荷为2.4 kg/(m3·d)时,COD去除率稳定在70％左右.COD好氧降解量的减少被增强的缺氧降解过程(反硝化)所弥补.     

厌氧氨氧化颗粒污泥上浮机理及控制策略进展

为了解决厌氧氨氧化颗粒污泥容易破坏并发生上浮,造成系统出水不稳定甚至崩溃的问题,主要针对厌氧氨氧化颗粒污泥上浮机理及控制策略进行综述.研究结果发现:厌氧氨氧化颗粒污泥上浮的主要机理是当氮负荷率(nitrogen loading rates,NLRs)过高时,厌氧氨氧化颗粒污泥产生大量氮气(N_2)无法释放,在颗粒污泥内部形成气囊或附着于颗粒污泥表面,致使颗粒污泥密度降低,导致上浮.相应控制策略包括:控制颗粒污泥粒径(1.5~4.0mm);适当控制NLRs(以N计,下同)(4.0~34.5 kg/(m~3·d));适当提高进水磷和钙的质量浓度(ρ(KH_2PO_4)=10mg/L,ρ(CaCl_2·2H_2O)=0.15~5.65 mg/L);选择带有搅拌功能的反应器;调整排水口位置并控制排水时间等.     

无机碳对SNAD工艺硝氮积累问题恢复的影响

为研究充足的无机碳对同步亚硝化-厌氧氨氧化与反硝化(SNAD)工艺的恢复与稳定运行的影响,向硝酸盐氮积累而崩溃的SNAD反应器中投加过量无机碳,对反应器的运行情况进行研究.结果表明:在无机碳质量浓度为理论需要量的350%~410%的条件下运行36 d后,出水硝酸盐氮由12.1 mg/L下降至3.47 mg/L,特征比由2.31升高至20.77;继续投加无机碳至理论需要量的200%~310%,运行42 d后,总氮去除负荷由0.176 g/(L·d)升高至0.299 g/(L·d);投加无机碳前后,好氧氨氧化活性(AOR,RAO)与厌氧氨氧化活性(ANR,RAN)分别由0.061 4和0.040 6 g/(g·d)升高至0.081 1和0.065 9 g/(g·d).结果表明,充足的无机碳投加在有效解除SNAD工艺硝酸盐氮积累问题的同时,可以促进好氧氨氧化菌(AOB)和厌氧氨氧化菌(An AOB)的活性.     

生物转盘中厌氧氨氧化污泥特性及菌种的初步鉴定试验研究

对厌氧生物转盘系统中具有厌氧氨氧化功能的污泥进行生物特性及分子生物学的初步鉴定试验研究.结果表明:污泥呈砖红色,系统中除附着在盘片上的生物膜外,槽间还存在颗粒污泥及少量絮体;镜检发现细菌主要为短杆状和球状两种形态,革兰氏阴性;SEM发现颗粒污泥多孔隙,颗粒和生物膜表面荚膜包围有球菌;间歇试验表明最大氨氧化速率为0.210 kg NH+4-N·kg-1VSS·d-1,总氮污泥去除负荷达0.311 kg TN·kg-1VSS·d-1;用厌氧氨氧化菌特异性引物进行PCR扩增,琼脂糖凝胶电泳显示清晰的特异性条带;核酸序列经测序及BLAST功能比对、进一步构建进化树表明该细菌与已报道的厌氧氨氧化菌Candidatus Kuenenia stuttgartiensis同属,与其基因序列相似性为100%,初步鉴定了其种属.     

水热辅助溶胶凝胶法制备纳米钛酸锌及其光催化性能

采用水热辅助的溶胶凝胶法制备纳米钛酸锌（ZnTiO₃）光催化剂,以罗丹明B为目标降解物,运用动力学模型分析罗丹明B（RhB）初始浓度对降解效果的影响。通过SEM、XRD、XPS、UV-Vis DRS对ZnTiO₃进行表征,并使用自由基捕获试验分析其降解机理。结果表明,ZnTiO₃为纯六方相,形貌为类球形,粒径50 nm左右。在催化剂用量为1 g/L、RhB初始浓度为5 mg/L、pH值为3的条件下,光催化反应150 min后,RhB降解率为93.2%。其动力学方程为k=0.132C₀^-1.253。ZnTiO₃光催化剂降解过程中,·OH、h⁺、·O₂^-均起到催化作用,产生·OH、h⁺的量相近且多于·O₂^-,说明·OH、h⁺在催化反应中起主要作用。     

Study on the isothermal oxidation behavior in air of Ti3AlC2 sintered by hot pressing

The isothermal oxidation behavior at 900–1300°C for 20 h in air of bulk Ti₃AlC₂ with 2.8 wt% TiC sintered by means of hot pressing was investigated in the work. The isothermal oxidation behavior generally followed a parabolic rate law. The parabolic rate constants increased from 1.39×10⁻¹⁰ kg²·m⁻⁴·s⁻¹ at 900°C to 5.56×10⁻⁹ kg²·m⁻⁴·s⁻¹ at 1300°C. The calculated activation energy was 136.45 kJ/mol. It was demonstrated that Ti₃AlC₂ had excellent oxidation resistance due to the continuous, dense and adhesive protect scales consisted of a mass of α-Al₂O₃ and a little of TiO₂ and/or Al₂TiO₅. In principle, the oxide scale was grown by the inward diffusion of O²⁻ and the outward diffusion of Ti⁴⁺ and Al³⁺. The rapid outward diffusion of cations usually resulted in the formation of cracks, gaps, and holes.     

Antibiotic properties of Al2O3 doping silver

The preparation technique and properties of Ag-type inorganic antibiotic material carried by Al₂O₃ were studied. The results show that the material has good antibiotic and safety properties, the acute toxicity taken by stomata is LD ₅₀>8 000 mg/kg (little and big white rats), and the normal quantity in subacute toxicity test is 80 mg/(kg · d). The better mass fraction of doping Ag₂O in antibiotic material carried by Al₂O₃ is 4%–8%, and the optimal sintering temperature is from 1 000 °C to 1 100 °C. Foundation item: Project (2002AA327090) supported by National High Technology Research and Development Program of China     

四墙切圆锅炉水冷壁颗粒冲击特性数值模拟

为深入了解水冷壁壁面的颗粒冲击特性,使用AnsysFluent对660 MW超临界锅炉的燃烧过程进行数值模拟,通过Fluent内冲蚀磨损模型得出燃烧器区域壁面的颗粒质量冲击量;利用Fluent软件的Sample功能输出壁面颗粒数据,将点数据导入Excel处理,得到冲击燃烧器区壁面的颗粒最高速度及颗粒速度值的分布情况. 结果表明:燃烧器喷口对侧区域的壁面冲击量最大值为6 kg·m^-2·s,冲击燃烧器区壁面的颗粒最高速度可超过30 m·s^-1,其占比不足冲击总颗粒量的0.3%,20~25 m·s^-1的冲击颗粒占比接近10%,颗粒速度的主体为5 ~ 20 m·s^-1. 壁面颗粒冲击量及颗粒速度模拟结果表明,在后墙第二组燃烧器壁面存在着6 kg·m^-2·s的高颗粒冲击量及25 ~ 29 m·s^-1的高颗粒冲击速度同时作用的区域,易发生严重磨损.     

人工红树林碳通量变化特征及其影响因素分析

红树林是重要的滨海蓝碳生态系统.人工红树林在恢复过程中碳交换过程受到气候、植被等环境的影响,与成熟红树林呈现较大差异.本研究采用闭路涡动相关系统对珠江河口人工红树林湿地生态系统进行二氧化碳(CO2)通量和甲烷(CH4)通量的观测,并基于通径分析方法探讨了环境要素对总初级生产力(GPP)、生态系统呼吸(Re)、CO2和C...     

Sandwich Magnetoeleetric Composites of Polyvinylidene Fluoride, Tb-Dy-Fe Alloy, and Lead Zireonate Titanate

The novel sandwich composites were prepared by sandwiching a polyvinylidene fluoride/Tb- Dy-Fe alloy composite （PVDF/Terfenol-D） between polyvinylidene fluoride/lead zirconate titanate composites （PVDF/PZT）. The maximum magnetoelectric effect voltage coefficient, （dE/dn）33max, of the sandwich composites is higher than that of three-phase composites at their own optimal loading level of Terfenol-D. This is attributed to less interface relaxations of strain and better polarization of the sandwich composites. When the volume fraction of Terfenol-D is higher than 0.10, no coupling interaction for three-phase composites could be observed, but （dE/dn）33max of sandwiched composites still reached 20 mV/（cm.Oe）. At high magnetic field intensity, the magnetoelectric effect voltage coefficient, （dE/dn）33, of sandwich composites is higher than that of three-phase composites; at low magnetic field intensity, （dE/dn）33 of sandwich composites is lower than that of three-phase composites. At their resonance frequency, the （dE/dn）33max of the sandwich composites and the three phase composites are 150 mV/（cm.Oe） and 42 mV/（cmoOe）, respectively. This significant increase of （dE/ dn）33max at resonance frequency confirms the improvement of maximum magnetoelectric effect coefficient via sandwich-structured composites.     

Experiments and reaction characteristics of liquid phase simultaneous removal of SO<Subscript>2</Subscript> and NO

Experiments of simultaneous removal of SO₂ and NO from simulated flue gas, using NaClO₂ solution as the absorbent, were carried out in a self-designed bubble reactor, and high simultaneous removal efficiencies of SO₂ and NO were obtained under the optimal experimental conditions. The mechanism of simultaneous removal based on NaClO₂ acid solutions was proposed by analyzing the removal products. Possibility and limitation of the desulfurization and denitrification using NaClO₂ acid solutions were calculated by thermodynamic methods. Experimental results of reaction kinetics for simultaneous desulfurization and denitrification indicated that the oxidation-absorption processes of SO₂ and NO were divided into two zones, namely the fast and slow reaction zones. In the slow reaction zones both were zero order reactions, and in the fast reaction zones, the reaction order, rate constant and activation energy of SO₂ reaction with absorbent were 1.4, 1.22 (mol·L⁻¹)^−0.4·s⁻¹ and 66.25 kJ·mol⁻¹, respectively, and 2, 3.15×10³ (mol·L⁻¹) ⁻¹·s⁻¹, and 42.50 kJ·mol⁻¹ for NO reaction, respectively. Supported by the National High-Tech Research and Development Program of China (“863” Project) (Grant No. 2007AA061803)     

Structure and dielectric properties of ZnO and Nb<Subscript>2</Subscript>O<Subscript>5</Subscript> doped BaO-TiO<Subscript>2</Subscript> system microwave ceramics

The microwave dielectric properties and microstructure of BaTi4.3ZnyO9.6＋y ＋0.02 mol% SnO2＋0.01 mol% MnCO3＋x mol% Nb2O5（x=0-0.05, y=0-0.08） system ceramics were studied as a function of the amount of ZnO and Nb2O5 doped. Addition of （y=0-0.05） ZnO and （x=0-0.025） Nb2O5 enhanced the reactivity and decreased the sintering temperature effectively. It also increased the dielectric constant ε r and quality factor Q（=1/tan 8） of the system due to the substitution of Ti^4＋ ions with incorporating Zn^2＋and Nb^5＋ ions, which was analyzed by the reaction ZnO＋Nb2O5＋ 3 TiTxTi →ZnTi＋ 2NbTi＋3TiO2. When the system doped with （y=0.05） ZnO and （x=0.025） Nb205 were sintered at 1 160 ℃ for 6 h, the εr. Qf0 value and rfwere 36.5, 42 000 GHz, and＋1.8 ppm/℃, respectively, at 5 GHz.     

藻型湖泊溶解有机碳特征及其对甲烷排放的影响

湖泊碳通量研究已成为全球碳循环研究的前沿和热点问题.本研究以太湖藻型湖区(西北湖区、梅梁湾、贡湖湾、西南湖区和湖心)为研究对象,基于为期一年的连续野外观测,旨在揭示富营养化湖泊DOC变化特征及其对CH₄排放的影响.结果表明,太湖藻型湖区DOC质量浓度均值为4.15 mg/L,且具有显著的空间变化.受外源输送和内部蓝藻增殖影响,西北湖区和梅梁湾DOC质量浓度较高,且其DOC时间变化与流域降雨量紧密相关,尤以西北湖区最为明显(R²=0.67,P<0.01).但在受外源输送影响较小的湖心区域,其DOC的时间变化主要受蓝藻生物量驱动(R²=0.60,P<0.01).太湖藻型湖区CH₄排放均值为0.083 mmol·m^-2·d^-1,不同湖区CH₄排放量差异明显.藻型湖区较高的蓝藻生物量显著提高了CH₄的排放量,且DOC含量是蓝藻影响CH₄产生和排放的主要因子.总体上,太湖藻型湖区DOC的累积致使其是CH₄排放的热点区域,但DOC对CH₄产生和排放的影响受湖泊内部因子和外部因子的综合调控,其潜在的控制机制还需要进一步探讨.