藻-菌颗粒污泥胞外聚合物及其表面特性研究

藻-菌颗粒污泥具有能耗低、温室气体排放量少等优点,近年来在污水处理领域受到关注.胞外聚合物(EPS)在保护微生物免受恶劣环境影响及促进细胞聚集方面发挥重要作用,而关于藻-菌颗粒EPS及其表面特性鲜有报道.选取了粒径范围在0.36~0.71、1~1.25、1.6~2.0 mm的3组藻-菌颗粒,分析了其EPS中多糖和蛋白质的含量,并进一步地对其组成差别以及官能团特征进行探究,探讨了EPS提取前后藻-菌聚集体表面电荷的变化.结果表明,随着粒径的增大,藻-菌颗粒污泥EPS中多糖和蛋白质的含量均有增加,而蛋白质与多糖的比值减小.不同粒径的藻-菌颗粒污泥EPS中芳香蛋白与酪氨酸类物质的含量明显增加,腐殖酸类物质含量亦呈总体增加趋势,与胞外蛋白相比,胞外多糖特征峰的波峰强度增加较明显.进一步分析表明,粒径较大的颗粒可能更能抵御外界环境因素的变化,以维持颗粒性能.以上结果表明,粘性和亲水性的多糖、芳香蛋白和酪氨酸类物质可能更有利于藻-菌颗粒的微生物细胞聚集.本文的研究结果进一步地拓展了对藻-菌颗粒污泥的认识,并为其进一步的工程应用提供基础.     

丁烯氟虫腈光降解反应过程及机理

考察了乙腈/水混合溶液中丁烯氟虫腈的光解速率及水体中主要溶解性物质对其光解的影响,通过产物鉴定及模拟计算判定了丁烯氟虫腈光降解反应机理.结果表明,模拟日光下丁烯氟虫腈快速发生光降解,纯水中反应半衰期为17.34 min.腐殖酸通过竞争光吸收来抑制丁烯氟虫腈的光解,NO3-和Cl-对其光解无影响.丁烯氟虫腈光解反应位点位为亚砜基团上的硫原子,主要产物为脱硫化物(MW 442.0),砜化物(MW 506.0)及2种硫化物(MW 473.9和405.8).键级和键长分析也证实丁烯氟虫腈硫原子连接的化学键不稳定,易发生断裂重排反应,生成上述转化产物.     

Settling and dewatering characteristics of granulated methane-oxidizing bacteria

We evaluated the settling ability and dewaterability of granulated methane-oxidizing bacteria (GMOB) after granulation using a continuous-flow reactor. A comparative analysis on settling and dewatering characteristics due to changes in sludge retention time (SRT, 10, 15 and 20 days) during cultivation of GMOB was conducted. In assessing dewaterability, the specific resistance to filtration (SRF) of activated sludge and GMOB was found to be 8.21×1013-2.38×1014 and 4.88 × 1012-1.98×1013 m/kg, respectively. It was confirmed that as SRT decreased, SRF of GMOB increased. In the case of bound extracellular polymeric substance (EPS), activated sludge registered 147.5 mg/g-VSS while GMOB exhibited 171-177.2 mg/g-VSS. In the case of extracellular polymeric substance soluble EPS in effluent, activated sludge measured 62 mg/L and GMOB had 17.4-21.4 mg/L. The particle size analysis showed that mean particle diameters of GMOB were 402, 369, and 350 μm, respectively, at SRTs of 20, 15 and 10 days. In addition, it was found that GMOB had a larger mean particle diameter and exhibited much better settleability and dewaterability than activated sludge did.     

不同粒径黄河沉积物中可提取腐殖质的含量分布及光谱特性

测定了黄河表层沉积物3种粒径组分（Ⅰ：100～300 μm;Ⅱ: 63～100 μm;Ⅲ: <63 μm）中总有机碳和可提取腐殖质的含量,分析了可提取腐殖质的紫外-可见吸收光谱、红外光谱和三维荧光光谱特征,探讨了不同粒径组分沉积物中可提取腐殖质含量分布及其化学组成特性.结果表明,沉积物有机质主要为粘土矿物吸附的天然腐殖质成分,总有机碳中可提取腐殖质的比例随沉积物有机质与矿物质相互作用的增强而降低,顺序为Ⅰ>Ⅱ>Ⅲ.3种粒径组分沉积物中可提取腐殖质的紫外-可见吸收光谱相似但相对峰强不同;红外光谱主要有5个吸收峰,各吸收峰面积百分含量的计算结果表明酚、醇及羧酸类官能团为主要的活性官能团,占可提取腐殖质组成的75%以上;三维荧光光谱主要有3个荧光峰,除了典型的类腐殖质荧光峰（峰A和峰C）外,还有源于小分子类蛋白或酚类物质的荧光峰（峰T′）.比较3种粒径组分沉积物中可提取腐殖质的紫外-可见、红外及三维荧光光谱的特征参数,发现Ⅰ、Ⅱ组分沉积物中可提取腐殖质的芳香度高,脂肪族和芳香族含量高于Ⅲ组分,而Ⅲ组分沉积物可提取腐殖质中酚、醇及羧酸类活性基团含量相对较高.     

荧光猝灭滴定法研究土壤腐殖质与氨基甲酸酯类农药相互作用

为研究氨基甲酸酯类农药在溶解有机质参与下的迁移转化过程,利用荧光猝灭滴定法研究了土壤HS(腐殖质)与氨基甲酸酯类农药的相互作用. 结果表明,呋喃丹和西维因的荧光都能不同程度地被FA(富里酸)和HA(腐殖酸)猝灭,主要猝灭机理为静电结合猝灭. 采用静态猝灭模型计算出氨基甲酸酯类农药与HS的K(结合常数),lg K由大到小为呋喃丹-HA(4.96)>西维因-HA(4.93)>呋喃丹-FA(4.72)>西维因-FA(4.68). HA与氨基甲酸酯类农药的lg K明显大于FA与氨基甲酸酯类农药,表明HS与氨基甲酸酯类农药间的作用力有疏水作用. 进一步研究表明,氢键作用对HS与氨基甲酯类农药结合有一定的影响.      

有机底物对活性污泥胞外聚合物的影响

研究了城市污水中常见的具有不同特性的有机底物(蛋白胨、葡萄糖、乙酸钠,以及乙酸钠和葡萄糖的混合物)分别在四个相同的反应器中所培养的活性污泥胞外聚合物的量和组成．结果表明：有机底物的特性影响胞外聚合物的组成和量,在乙酸钠为底物的污泥中,胞外多糖占大部分(糖类／蛋白质的比值为1．7—8.6,质量比),而以蛋白胨为底物时,胞外蛋白质占主要成分(糖类／蛋白质的比值为0.2-0.5);以乙酸钠为底物形成的胞外聚合物的总量较多,通过扫描电子显微镜和原子力显微镜对活性污泥进行观测,确证了胞外聚合物的存在及其形式,并得到了胞外聚合物层的大致尺寸．     

利用人工神经网络预测芳香化合物的生物可降解性

本文采用简单的化学基团描述符来表征化学物质的结构,以底物的最大比去除速度表征生物可降解性的大小,运用自编的人工神经网络对芳香族化合物的生物可降解性进行了研究。试验过程中,按芳香族化合物最大比底物去除速度的大小将其生物可降解性分为四组：不降解,难降解,可降解,易降解。     

不同填埋年龄的矿化垃圾中胡敏酸的分子荧光光谱研究

对上海市老港填埋场封场6-10年矿化垃圾中的胡敏酸(HA)进行荧光光谱分析,结果表明,不同封场时间的矿化垃圾中HA的荧光光谱均为宽带峰型,pH值对HA荧光光谱的影响较小.而且随着矿化垃圾封场时间的加长,荧光特征峰波长缓慢增加.     

典型岩溶区水环境中全氟化合物分布特征及风险评价

为探究典型岩溶区PFASs（per-and polyfluoroalkyl substances,全氟化合物）分布特征及生态环境与健康风险,采用超高相液相色谱串联质谱对都安县地下水、地表水及污染源中PFASs进行分析测试.结果表明:①PFPeA（Perfluoropentanoic acid,全氟戊酸）是该地区检出率最高的PFASs污染物,检出率为100%,ρ（PFPeA）检出范围为0.067~1.021 ng/L.ρ（PFASs）平均检出情况满足污染源（2.592 ng/L）>地表水（0.737 ng/L）>地下水（0.340 ng/L）,污染物检出种类的平均值满足污染源（7.1个）>地表水（4.4个）>地下水（2.9个）.②研究区内仅有G2、S9、S13、P3采样点ρ（PFASs）可能受点源类污染源的影响较大,整个研究区PFASs分布特征及质量浓度受大气沉降影响较小.地表水及地下水ρ（PFASs）较高的采样点基本集中在人类活动聚集区;由于岩溶作用影响,东南部地下水中ρ（PFASs）相对较低.③地下水、地表水及污染源中PFASs的来源均可以分为两类,一类是以PFOS（perfluorooctane sulfonate,全氟辛烷磺酸）为主产物的五金电镀、消防、采矿、电子等行业,另一类可能主要与农业活动相关,来源于农用塑料品及其降解产物.④在利用当前已有参数进行评价时,都安县水环境中ρ（PFOA）（perfluorooctane acid,全氟辛酸）和ρ（PFOS）尚未达到对生态环境和人体健康具有风险的水平.研究显示,西南岩溶区水环境中ρ（PFOA）和ρ（PFOS）尚未达到对环境及人体健康具有风险的水平,但鉴于岩溶区特殊的水文地质条件,仍需加强产氟工矿企业的控制.      

Ozonation as an efficient pretreatment method to alleviate reverse osmosis membrane fouling caused by complexes of humic acid and calcium ion

Humic acids (HA) didn’t cause obvious reverse osmosis (RO) membrane fouling in 45 h. Osmotic pressure (NaCl) affected slightly the RO membrane fouling behavior of HA. Ca²⁺ promoted aggregation of HA molecules and thus aggravated RO membrane fouling. Ozonation eliminated the effect of Ca²⁺ on the RO membrane fouling behavior of HA. The change of the structure of HA was related to its membrane fouling behavior. Humic acid has been considered as one of the most significant sources in feed water causing organic fouling of reverse osmosis (RO) membranes, but the relationship between the fouling behavior of humic acid and the change of its molecular structure has not been well developed yet. In this study, the RO membrane fouling behavior of humic acid was studied systematically with ozonation as a pretreatment method to control RO membrane fouling. Furthermore, the effect of ozone on the structure of humic acid was also explored to reveal the mechanisms. Humic acid alone (10–90 mg/L, in deionized water) was found not to cause obvious RO membrane fouling in 45-h operation. However, the presence of Ca²⁺ aggravated significantly the RO membrane fouling caused by humic acid, with significant flux reduction and denser fouling layer on RO membrane, as it was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). However, after the pretreatment by ozone, the influence of Ca²⁺ was almost eliminated. Further analysis revealed that the addition of Ca²⁺ increased the particle size of humic acid solution significantly, while ozonation reduced the SUVA₂₅₄, particle size and molecular weight of the complexes of humic acid and Ca²⁺ (HA-Ca²⁺ complexes). According to these results and literature, the bridge effect of Ca²⁺ aggregating humic acid molecules and the cleavage effect of ozone breaking HA-Ca²⁺ complexes were summarized. The change of the structure of humic acid under the effect of Ca²⁺ and ozone is closely related to the change of its membrane fouling behavior.