不同电子供体对厌氧系统生物脱氮效率及微生物群落分布状态的影响

在厌氧条件下,分别以葡萄糖、甲醇和邻苯二甲酸氢钾作为电子供体对NO3--N进行厌氧反硝化实验,每种电子供体设定两个C/N比,分别为4∶1和10∶1.实验结果表明:在2种C/N比情况下,葡萄糖与甲醇作为电子供体时,总氮的去除速率一致,且都比邻苯二甲酸氢钾作为电子供体时要快.当C/N=4时,总氮的去除速率要快71%,而当C/N=10时,总氮的去除速率的差距只有7%.不同有机物作为反硝化的电子供体时,活性污泥样本中的微生物菌落检出情况表现出3个反应体系中具有各自优势的厌氧菌群、硝化及反硝化菌群明显特征.该微生物群落的分布特点反映出不同有机物作为电子供体时反应系统状态的差异性.     

基于生物-生态耦合工艺的农村生活污水处理研究

开发低投资、低能耗、低维护的生活污水处理工艺是解决农村污水处理问题的关键。采用无动力升流式厌氧生物滤池(UAF)与潜流式人工湿地(SFW)耦合工艺处理农村生活污水,考察了耦合工艺在不同水力停留时间(HRT)下对生活污水的处理效果,并通过增加SFW内的植株密度改善脱氮除磷效果。结果表明:UAF与SFW耦合工艺无动力消耗,免维护,适合农村地区的生活污水处理,对氮、磷的去除主要依靠SFW阶段完成,通过增加芦苇的植株密度可以明显增强SFW内生物的脱氮除磷能力,并保证UAF与SFW耦合工艺的处理性能稳定在较高水平。在t(HRT)UAF=18h,t(HRT)SFW=3d的条件下,UAF与SFW耦合工艺出水COD、氨氮、总氮、总磷的平均质量浓度分别为44.07,4.25,13.36和0.44mg/L,达到《城镇污水处理厂污染物排放标准》(GB 18918-2002)一级A标准。     

渝东北地区龙马溪组页岩储层微观孔隙结构特征

为了系统描述渝东北地区下志留统龙马溪组海相页岩的微观孔隙结构,应用氩离子抛光聚焦离子束扫描电镜(FIB-SEM)、低温N2吸附及高压压汞实验定性和定量测试WX-1井岩心样品的孔喉形态、连通性、比表面积及孔径分布.通过对比分析不同实验测试的孔径分布,实现对页岩样品从微孔到宏孔的精细描述,并探讨了影响孔隙发育的控制因素.研究结果表明,龙马溪组页岩储层主要发育有机质孔、黏土矿物层间孔、黄铁矿晶间孔、颗粒边缘溶蚀孔及微裂缝等5种孔隙类型.受到后期压实作用的影响,有机质孔隙发育具有微观非均质性.纳米孔隙类型复杂、形态多样,主要为开放透气性孔,但存在细颈状墨水瓶孔及少量一端封闭的不透气性孔等影响页岩气的渗流;孔径分布具有“双峰”特点,纳米孔主要孔径为2～10 nm、30～90 nm,即直径＜100 nm的孔隙提供了大部分总孔体积,为页岩储层主要发育的孔隙类型.孔隙发育受多种因素的控制,直径≤50 nm微孔、中孔的发育与有机质有关,有机碳含量与微孔、中孔的孔体积呈正相关性;直径＞50 nm宏孔的发育与黏土矿物含量有关,随着黏土矿物含量的增加,宏孔的体积、比表面积也随之增大.     

三级SBR除磷脱氮工艺处理生活污水

根据生物除磷和反硝化脱氮的机理,污水的脱氮除磷存在基质竞争和泥龄方面的矛盾.为解决该矛盾开发了一种新的污水生物处理反应工艺--三级序批式活性污泥法(三级SBR法),并运用该方法处理了生活污水.该工艺将具有硝化、聚磷和去碳功能的细菌种群分别控制在三级反应器中优势生长并结合反硝化除磷技术.实验表明,处理效果稳定,COD 、TN 、TP去除率平均为87%、80%、86%,并可以减少能耗,节约碳源.该工艺能取得较好的同时脱氮除磷效果,且操作简便,运行费用低,有较好的应用前景.     

两级SBR无外加碳源除磷脱氮的运行模式

在已有的两级SBR除磷脱氮工艺研究成果的基础上,分析了该工艺除磷与脱氮的优势和原运行模式存在的不足,提出了采用两级SBR工艺优化除磷与脱氮的改进运行模式,讨论了采用改进后的运行模式,在无需外加碳源条件下,实现对城市污水同步高效除磷与脱氮的可行性,分析了对该两级工艺实行实时过程控制的可行性。     

热处理条件对IrO2-pH电极性能的影响

在700℃炉冷、870℃空冷和炉冷三种热处理条件下,制备了氧化铱pH微电极,并对比了微电极的线性范围及响应时间.结果表明:热处理条件对Ir氧化物膜的均匀性有很大影响,进而影响其开路电位的稳定性及响应速度.700℃炉冷和870℃空冷制得的电极氧化膜表面粗糙,孔隙率不均匀并伴随有裂纹;而870℃炉冷条件下制得的电极具有表面氧化膜均匀、响应时间短以及线性好等优点.铱氧化物的形成机理是Ir丝被空气中的O2氧化,而高温Li2CO3起到一种溶剂的作用.铱氧化物电极的H+响应是由于电极表面水合氧化铱与溶液中H+发生化学反应,反应为Ir4+与Ir3+之间的转变.     

尿素深施条件下模拟稻田中氮磷的动态特征及其降污潜力分析

采用室外微区模拟试验,于水稻返青生长期,采用尿素造型深施方式,在3、7和11cm等3个不同施肥深度处理(分别表示为t-3、t-7、t-11)条件下,对田面水和土壤中氮、磷、以及悬浮物(SS)等主要污染物的动态特征及其降污潜力进行了研究。结果表明,尿素深施后5～7d内,田面水中氮素呈总体下降趋势,于第7d后达较低的浓度水平;硝氮(NO3--N)各处理间浓度差异较小,但整体上要高于铵氮(NH4+-N),就污染源而言,田面水NO3--N负荷不容忽视。田面水氮素浓度与尿素深施处理没有相关性。与对照处理撒施(表示为t-c)相比,深施处理的田面水中氮素浓度可分别降低NO3--N 29%～47%、NH4+-N 64%～89%、总氮(TN)79%～97%。t-3和t-7的田面水总磷(TP)和可溶性磷(DP)浓度都处于较高水平,与t-7和t-3相比较,t-11可分别降低TP浓度32%～73%、DP浓度92%～99%以及SS浓度50%～80%。因此,尿素造型深施至11cm左右,具有显著的减排降污潜力,是控制农田面源污染的有效措施之一。     

松嫩草地碳和水通量对全球变化的响应

全球变暖和氮格局的改变对生态系统碳通量的变化具有深远的影响,长期的模拟增温和氮沉降实验对预测21世纪全球气候变化下草地生态系统生产力和碳匮缺的响应有着至关重要的意义.在中国东北松嫩草地开展4年的增温和施氯实验,通过测定羊草草地光合特性,试图揭示全球变化对羊草草地的碳、水通量产生的影响.试验采用一个封闭的光合测定系统(LI-6400)测定草地的碳、水通量变化,通过计算CO2的变化量确定净生态系统CO2交换量.结果表明,增温降低了净生态系统CO2交换量(NEE),净生态系统生产力(GEP)和生态系统蒸腾作用(ET),升高了生态系统呼吸(ER)和水分利用效率(WUE);施氮处理刺激了NEE、ER、GEP和WUE;增温加施氮处理,氮素的添加缓解了因增温对生态系统产生的负效应.碳、水通量对全球变化的响应是通过改变生物群落中优势物种羊草的数量实现的,全球变化能在短期内迅速改变松嫩草地的碳通量.这些结果都有助于理解未来生态系统碳循环对全球气候变化的反馈.     

Serum levels of perfluorinated compounds in the general population in Shenzhen, China

Perfluorinated compounds (PFCs) have been detected in many environmental matrices, biota, and nonoccupationally exposed populations in China recently. However, little is known about the distribution and levels of various PFCs in the general population living in areas where there is PFC exposure. In the present study, the levels and prevalence of ten target PFCs were determined in 227 serum samples from a population of nonoccupationally exposed individuals in Shenzhen, China. Results indicated that human exposure to PFCs was prevalent in Shenzhen. Perfluorooctanoate (PFOA) was the dominant PFC contaminant in the serum samples, with a median concentration of 6.72 ng/mL, followed by perfluorooctane sulfonate (PFOS) with a median concentration of 2.07 ng/mL. Other PFCs were detected at much lower concentrations, with median concentrations ranging from 0.02 to 0.87 ng/mL. Statistically, no significant (P>0.05) gender differences were observed for any of the PFCs. Significant (P<0.01) positive correlations were found between age and serum concentrations of the target PFCs, except for perfluorobutane sulfonate (R = 0.16, P = 0.01), perfluorohexanoic acid (R = 0.08, P = 0.22), and perfluoroheptanoic acid (R = 0.11, P = 0.10). Based on the one-compartment pharmacokinetic model, the total daily intakes of PFOA and PFOS for the general population in Shenzhen were calculated as 0.63 and 0.20 ng/kg body weight/day, respectively.     

A gas chromatography/mass spectrometry method for the simultaneous analysis of 50 phenols in wastewater using deconvolution technology

Phenolic compounds exist widely in the influents and effluents of sewage treatment plants (STPs) and most are un-regulated. In this study, a gas chromatography-mass spectrometry (GC-MS) method for the simultaneous analysis of 50 phenolic compounds in wastewater was developed. Deconvolution technology was used to identify contaminants that are covered by co-extracted materials. A mass spectral library containing all 50 silylated phenolic compounds was first established and used for deconvolution. Twelve typical phenolic compounds were selected to optimize the sample preparation procedures. Solid-phase extraction using a C18 cartridge coupled with an HLB cartridge was used for pre-concentration and dichloromethane was used for elution. The solutes were derivatized and analyzed by GC-MS. The blank and matrix spike recoveries ranged from 57.46% to 136.4% and 47.87% to 114.8%, respectively. Method detection limits ranged from 3.64 to 97.64 ng L⁻¹. The relative standard deviations of all the recovery experiments were lower than 13.6%. The instrument limits of quantification ranged from 0.7 to 87.7 pg. The method has been applied to analyze the influents and effluents of 5 Chinese STPs. Except for regulated phenolic compounds (phenol and 2,4,6-trichlorophenol), three un-regulated phenolic compounds, including 2-chlorophenol, 2,5-dichlorophenol and 2,4-dichloro-3-ethyl-6-nitrophenol were identified in the effluent wastewater. The detected concentrations of un-regulated phenolic compounds could possibly cause environmental effects, indicating that immediate attention is required to prevent complications.