高效脱水霉菌的筛选及其脱水机理分析

用常规分离纯化方法从某池塘底泥筛选分离霉菌,根据菌落颜色和形态特征的不同共分离得到49株菌株。通过剩余污泥脱水实验获得高效脱水霉菌菌株D41,在24 h内使污泥比阻降低49.2%,含水率由最初的82.9%降至78.3%。通过机理研究发现,霉菌D41的投入使剩余污泥中多糖含量降低36.9%,从而改善剩余污泥脱水性能。     

中空纤维膜超滤聚丙烯酸钠溶液

研究聚丙烯酸钠（PAAS）溶液的超滤行为,考察各操作参数对膜通量（J）和截留系数（R）的影响,结果表明,J随运行时间延长衰减不明显,随压差增大呈线性递增,随温度升高而增大,pH高于5时J基本不变;R随压差增大或温度升高均下降,随pH增大而增大。建立膜阻力（rf）模型,研究影响rf的主要因素,发现,rf随压差增大而增大,随温度升高而减少,pH低于5时rf随pH增大而迅速下降。研究PAAS溶液浓缩过程,当体积浓缩因子为16时,J衰减明显,截留液PAAS浓度（Cr）呈线性递增,渗透液PAAS浓度（Cp）在较长时期内基本不变,至浓缩后期,Cp轻微下降。以去离子水对浓缩液予以洗涤,随着洗涤液体积增大,Cr轻微下降,Cp逐渐趋于零。     

连续在线滤袋式淤泥脱水技术

以太湖淤泥为研究对象,研究了絮凝剂和滤袋性质对淤泥脱水性能的影响,并进行了滤袋脱水中试研究。结果表明,淤泥的含水率为90％时,在PAM和PAC最佳添加量55mg／L和1000mg／L条件下,淤泥比阻从8．7×10^7S2／g降低到2．0×10^7S2／g,Zeta电位从-28．77mV变成-4．68mV,滤袋平均过滤速度提高了137．9％,脱水性能显著提升。不同含水率下的实验得出了淤泥的最佳絮凝剂添加曲线;特殊材料滤袋相比于普通材料滤袋,滤袋的脱水综合能力大幅度提升,平均过滤速度达到0．479m^3／（m^2·h）,淤泥回收率为98．7％,泥饼含水率为71．6％;中试实验表明,淤泥经过4h过滤后,淤泥的含水率降到较低的65％,最终回收率可达到98．6％,滤液中污染物浓度满足国家排放标准。与传统技术相比,本技术具有脱水周期短、成本低、操作简单、安全性强等优点。     

Relationship between antibiotic residues and occurrence of resistant bacteria in Nile tilapia (Oreochromisniloticus) cultured in cage-farm

The aim of this study was to investigate the relationship between antibiotic residues found in the muscle of cage-farm-raised Nile tilapia (Oreochromisniloticus), the occurrence of resistant bacteria, and the sanitary practices adopted by farmers in Ilha Solteira reservoir, Brazil. Nine fish (three small fish, 40–200 g; three medium-sized fish, 200–500 g; and three large fish, 500–800 g) were collected from four cage farms every three months from April 2013 to January 2014. Ten antibiotic residues were determined using liquid chromatography-mass spectrometry, and bacteria were isolated and tested for antibiotic resistance to determine the multiple antibiotic resistance (MAR) index. Only three antibiotics (oxytetracycline, tetracycline, and florfenicol) were detected in the muscle of Nile tilapia, and their residues were the highest in small fish; however, the MAR index was higher in large fish. In addition, a direct positive relationship between the MAR index and the concentration of antibiotic residues in Nile tilapia was found. Overall, the adoption of prophylactic management practices improved the sanitary status of cage farms, reducing bacterial infections and hampering the development of antibiotic-resistant bacteria.     

西藏林芝地区空气动力学阻抗估算模型适用性分析

空气动力学阻抗的准确估算是目前卫星反演地表显热通量的关键,为了准确反演藏东南地区的地表显热通量,利用2013年6月10日西藏林芝地区的草地、麦田、河滩、林地阴坡和阳坡5种下垫面的边界层观测数据,分析常用的Thom_1975,Thom_1977和Choudhury空气动力学阻抗估算模型的适应性。结果表明:林地阴坡Choudhury模型估算值与涡动相关测量的结果有较好的一致性,其他下垫面建议采用Thom(1975)模型。     

印刷电路组件吸湿性尘粒人工模拟试验中关键因素的控制

吸湿性尘粒人工模拟试验(简称湿尘试验)是一种新型的环境试验。通过对试验方法和试验过程中各环节的研究,确定了试验时应把握的关键因素,并最终总结了试验中关键因素控制的方法。这些方法可为湿尘试验的开展提供借鉴作用。     

不同阳极微生物燃料电池产电性能的比较

微生物燃料电池在处理废水的同时可以产生电能,有希望同时解决废水再利用和能量再产生的问题。采用单室无膜空气阴极微生物燃料电池,处理模拟生活污水,探讨MFC处理模拟废水的效果。研究了以碳布(MFC1)、碳布负载碳纳米管(MFC2)、碳纳米管(MFC3)和泡沫镍(MFC4)作为4种不同的阳极材料,对MFC系统的启动、内阻和产电特性进行比较。结果表明,4种不同阳极MFC在水力停留时间24 h的条件下,对COD有很好的去除作用,其中MFC2的COD去除效率最大,为91.4%。在不影响MFC系统处理废水效果的前提下,实验得到4种阳极MFC系统中MFC2具有最小的内阻,为173.7Ω;并且其功率密度也大于其他3种MFC,达到401.2 mW/m2。     

好氧反硝化菌TAD1的同步硝化反硝化性能

研究发现嗜热螯台球菌(Chelatococcus daeguensis)TAD1具有同步硝化反硝化性能,可将水中的氨氮去除。重点考察50℃下,碳氮比、碳源、初始pH值、DO浓度等因素对菌株TAD1同步硝化反硝化脱氮性能的影响规律及菌株TAD1的耐氨能力,最后用Minitab软件进行综合优化。结果表明,菌株TAD1在高浓度氨氮(500～3 000 mg/L)下仍具有很高的脱氮能力,pH值和碳源用量是影响TAD1同步硝化反硝化最显著的因素,综合优化后总氮最大去除率达到了70%,证实利用菌株TAD1的同步硝化反硝化性能具有潜在的废水脱氮应用前景。     

Cow excrements enhance the occurrence of tetracycline resistance genes in soil regardless of their oxytetracycline content

Fertilizing soils with animal excrements from farms with common antibiotic use represents a risk of disseminating antibiotic resistance genes into the environment. In the case of tetracycline antibiotics, it is not clear, however, whether the presence of antibiotic residues further enhances the gene occurrence in manured soils. We established a microcosm experiment in which 3 farm soils that had no recent history of fertilization with animal excrements were amended on a weekly basis (9 times) with excrements from either an oxytetracycline-treated or an untreated cow. Throughout the study, the concentration of oxytetracycline in excrements from the treated cow was above 500 μg g⁻¹ dw, whereas no oxytetracycline was detected in excrements from the healthy cow. Both excrements contained tetracycline resistance (TC-r) genes tet(L), tet(M), tet(V), tet(Z), tet(Q) and tet(W). The excrements from the treated cow also contained the tet(B) gene, and a higher abundance of tet(Z), tet(Q) and tet(W). Three weeks after the last excrement addition, the individual TC-r genes differed in their persistence in soil: tet(Q) and tet(B) were not detectable while tet(L), tet(M), tet(Z) and tet(W) were found in all 3 soils. There were, however, no significant differences in the total number, nor in the abundance, of TC-r genes between soil samples amended with each excrement type. The oxytetracycline-rich and the oxytetracycline-free excrement therefore contributed equally to the increase of tetracycline resistome in soil. Our results indicate that other mechanisms than OTC-selection pressure may be involved in the maintenance of TC-r genes in manured soils.     

Antibiotic resistance and genetic diversity of Escherichia coli isolates from traditional and integrated aquaculture in South China

This study investigated antibiotic resistance profiles including antibiotic resistance frequencies, resistance genes and resistance patterns in Escherichia coli strains isolated from traditional and integrated aquaculture systems in South China by using antibiotic susceptibility testing and real time polymerase chain reaction (PCR) technique. The E. coli isolates were found to be resistant to at least one antibiotic among 12 antibiotics. Higher resistance frequencies to ampicillin, sulfamethoxazole, trimethoprime, streptomycin and tetracycline were found compared to the rest antibiotics. Among the 10 tetracycline resistance genes detected in the resistant isolates, the most prevalent tetracycline resistance genes were tetA, tetW and tetB with the frequency of 69.7%, 63.5% and 21.9%, respectively. Three sulfonamide resistance genes were detected in these resistant isolates, with their detection frequencies in the following order: sul2 (55.3%) > sul3 (28.2%) > sul1 (6.2%). Four resistance genes mainly encoding extended-spectrum β-lactamases (ESBLs) were detected in these resistant isolates, with the detection frequencies of blaTEM (28.4%) > blaOXA (9.7%) > blaCTX (9.3%) > blaCARB (5.2%) > blaSHV (0.0%). It was found that the integrated aquaculture system exhibited generally higher prevalence of antibiotic resistance than the traditional aquaculture system. An integrated aquaculture system could facilitate development of bacterial resistance and spread of the antibiotic resistance genes, and consequently become an important reservoir of resistance genes.