Characterization of dissolved organic matter fractions from Lake Hongfeng, Southwestern China Plateau

With XAD-series and ion exchange resins, dissolved organic matter (DOM) from Lake Hongfeng in Southwestern China Plateau was isolated into 6 fractions, i.e., humic acid (HA), fulvic acid (FA), hydrophobic neutrals (HON), hydrophilic acids (HIA), hydrophilic bases (HIB) and hydrophilic neutrals (HIN). Those fractions were characterized by high performance size exclusion chromatography, fluorescence spectroscopy and UV absorbance. Among the 6 fractions, FA was predominant and accounted for 51% of the total DOM. The weight-average (M_w) and number-averaged (M_n) molecular weight of these fractions ranged from 1688 to 2355 Da and from 1338 to 1928 Da, respectively. A strong correlation was observed between specific UV absorbance at 280 nm, E₂/E₃ (absorbance at 250 nm to 365 nm), and the molecular weight for DOM fractions. UV-Vis fulvic-like fluorescence peaks were found in all fractions. Protein-like fluorescence peaks existed in HON may indicate that microbial activity was severely in Lake Hongfeng. There was a significant relationship between fluorescence intensities and specific UV absorbance at 254 nm for those DOM fractions, suggesting their similar luminescence characteristics. The values of fluorescence index (f_450/500) indicated that hydrophobic fractions may derive from terrestrial sources, and the hydrophilic fractions from microbial and terrestrial origins. Those results suggest that there were inter-relationships between molecular weight, fluorescence and absorbance characteristics, and also subtle consistencies between the hydrophilic and hydrophobic properties and the sources for these 6 fractions from Lake Hongfeng.     

沸石床多级生物膜焦化废水处理系统的NH+4-N去除稳定性研究

焦化废水处理中预处理蒸氨工艺不稳定容易引起生物处理出水NH⁺₄-N的波动,为了在有机物去除的同时提高生物系统对NH⁺₄-N的去除效果和稳定性,采用对NH⁺₄-N有良好吸附性能的天然斜发沸石为生物填料构建沸石床多级生物膜系统,考察了进水负荷对系统运行稳定性的影响、抗冲击负荷能力以及系统的功能分区和污染物迁移转化规律.结果表明,当系统进水NH⁺₄-N负荷≤0.21 kg/(m³·d)、COD负荷≤1.35　kg/(m³·d)时,出水NH⁺₄-N和COD的平均浓度分别为(2.2±1.2)mg/L和(228±60)mg/L,平均去除率分别达(99.1±0.5)%和(86.0±2.6)%.在低、高两次NH⁺₄-N冲击负荷［0.03　kg/(m³·d)和0.06　kg/(m³·d)］条件下,系统对NH⁺₄-N的平均去除率仍然分别高达99.0%和92.9%,高于对比系统的96.8%和89.3%,表现出良好的抗NH⁺₄-N冲击负荷性能与处理稳定性.系统好氧单元反应器沿程出现脱碳/硝化功能区(C/N区)和硝化功能区(N区),其中N区的NH⁺₄-N 降解速率为C/N区的2～8倍.系统进水中相对分子质量＜1×10³、 1×10³～1×10⁴、 ＞1×10⁴的TOC浓度分别为227.6、104.8和35.0 mg/L,处理出水中的TOC浓度分别为31.2、 22.9和31.5 mg/L,其中相对分子质量＜1×10³和1×10³～1×10⁴这2个范围的有机物降解良好,出水残余物质主要为相对分子质量＞1×10³的有机物.     

芳烃化合物水溶解度及分配系数的估算

将分子连接性指数法(Molecular Connectivity Index,MCI)与几何平均连接性指数法(Geometrical Mean Connectivity Index,GMCI)相结合,改进了GMCI的点价计算方法。使用新方法计算了34种芳烃化合物0～4阶指数的点价值,并分别通过对溶解度和点价值,分配系数和点价值进行逐步多元回归分析,建立了新的指数和溶解度、分配系数之间的定量关系模型,回归方程的相关系数为0.961、0.962,都达到了良好级,估计标准误差为0.3454、0.2674,优于MCI法和GMCI法。     

生活垃圾焚烧厂渗滤液生化出水的混凝机理研究

分别采用Al₂(SO₄)₃、FeCl₃、PAC、PAFC对垃圾焚烧厂渗滤液生化出水进行混凝研究,并建立混凝处理模型.结果表明,在pH值为6时,单独投加500 mg/L的Al₂(SO₄)₃、FeCl₃、PAC、PAFC时,COD去除率分别为20％、17％、30％、40％.焚烧厂渗滤液生化出水中有机物主要是由相对分子质量小于2 000的可溶性物质组成;通过透射电镜扫描技术(TEM)和Zeta电位分析,发现中和及网捕桥联是渗滤液混凝处理的主要作用机理;相比无机盐混凝剂,聚合物混凝剂具有较强的电中和以及网捕架桥功能.     

Comparing results of cultured and uncultured biological methods used in biological phosphorus removal

Increasing attention has been paid to phosphate-accumulating organisms(PAOs)for their important role in biological phosphorus removal.In this study,microbial communities of PAOs cultivated under different carbon sources(sewage,glucose,and sodium acetate) were investigated and compared through culture-dependent and culture-independent methods,respectively.The results obtained using denaturing gradient gel electrophoresis(DGGE)of polymerase chain reaction-amplified 16S rDNA fragments revealed that the diversity of bacteria in a sewage-fed reactor(1#)was much higher than in a glucose-fed one(2#)and a sodium acetate-fed one(3#);there were common PAOs in three reactors fed by different carbon sources.Five strains were separated from three systems by using a phosphate- rich medium;they were from common bacteria isolated and three isolates could not be found in DGGE profile at all.Two isolates had good phosphorus removal ability.When the microbial diversity was studied,the molecular biological method was better than the culture-dependent one.When phosphorus removal characteristics were investigated,culture-dependent approach was more effective. Thus a combination of two methods is necessary to have a comprehensive view of PAOs.     

超声波-缺氧/好氧消化过程污泥胞外聚合物和溶出物的变化研究

为研究超声波促进污泥缺氧/好氧消化的机制,采用均匀试验得到的最佳超声波参数与缺氧/好氧消化衔接进行间歇试验,通过生物化学分析法研究了消化过程污泥EPS指标(多糖、蛋白质、DNA和总量)和相应溶出物的变化趋势,同时以未经超声处理的消化过程作对照.均匀试验结果表明,在超声波声能密度0.1 W/mL,超声处理时间15 min...     

Effect of dissolved organic matter on mercury release from water body

Dissolved organic matter (DOM) plays an important role in the process of mercury release from water body. In this study, the influence of DOM from different sources (DOMR, DOMS and DOMH, extracted from rice straw, compost and humic soil respectively) on mercury reduction was investigated. The molecular weight distribution and chemical composition of DOM from each source were determined using ultrafiltration membrane technique and elemental analysis respectively. The result showed that mercury release from DOM-added samples was much lower than the control; the lowest mercury release flux was observed in the treatment of DOMH, 25.02% of the control, followed by DOMS and DOMR, 62.46% and 64.95% of the control, respectively. The higher saturation degree and lower molecular weight of DOMH was responsible for the highest inhibition degree on the mercury release. The link between DOMH, concentration and mercury flux was also estimated and the result showed that mercury flux was increased with DOMH at lower concentration, while decreased with DOMH at higher concentration. Different mechanism dominated the influence of DOM on mercury release with variation of DOM concentration.     

东江水源水中有机物分子量分布特征研究

采用超滤膜法考察了东江水源水中有机物分子量分布特点,研究了东江泄洪和不泄洪水源水中有机物分子量分布的变化特征。结果表明,东江水源水在不泄洪期间水源水中的溶解性有机物主要为小分子量的有机物。而在泄洪期间,东江水源水中溶解性有机物主要为大分子量的有机物。UV254的分布和有机物分子量分布一致,DOC与UV254具有良好的相关性。泄洪期间水源水中SUVA值小于3,水体中有机物很难通过常规混凝工艺去除,此结果与水厂的实际运行情况相吻合。     

张家口市北新屯地区蔬菜种植区锗元素富集特征及成因分析

选取张家口市北新屯地区蔬菜种植基地为研究区,分为重点区和区域范围以及上游地区,共采集表层土壤样品132件,垂向土壤剖面16条,地表剖面3组,彩椒果实、紫甘蓝果实和玉米果实样品各4件,在分析土壤、岩石和作物样品的Sc、 Cr、 Mo、 Cd、 V、 Zn、 Sr、 Pb、 Co、 Ni、 Cu、 Ge和REE等元素基础上,通过所参照的锗富集标准,发现区域富锗率不高(19.7%),而重点区富锗率较高(52%).区域范围和重点区土壤中Ge与稀土元素呈现较为明显的空间分布一致性,进一步对比土壤与作物中Ge和稀土元素相关性特征发现,稀土含量排序为：紫甘蓝>彩椒>玉米,而Ge吸收强度排序为：玉米(微弱吸收)>紫甘蓝(极弱吸收)>彩椒(极弱吸收),作物对Ge和稀土元素的吸收并没有明显的协同性.通过对研究区土壤28种元素和指标的PMF和RDA分析表明,区域Ge的来源以天然地质背景因素为主(66.3%),人为活动影响因素(27%)和大气干湿沉降因素(6.7%)为辅,重点区Ge的来源以天然地质背景因素(33.8%)和人为活动影响因素(27.2%)为主,大气干湿沉降因素(18.5%)...     

基于原位被动采样技术研究巢湖沉积物和水体中PAHs的垂直分布及其界面交换

沉积物-水体界面处分子扩散是污染物的一个重要地球化学过程,也是判断沉积物是否为上层水体中污染物汇或源的主要依据.本研究利用低密度聚乙烯膜(LDPE)为吸附相的原位被动采样器,同步确定了巢湖西半湖南淝河入湖口处不同深度的上层水体和沉积物孔隙水中13种多环芳烃(PAHs)浓度,并计算了它们在沉积物-水体界面的分子扩散通量.结果表明,3种性能参考化合物(PRCs)在上层水体中的解析速率较沉积物孔隙水中大,相应地,水体中LDPE膜对PAHs的吸附速率高于沉积物孔隙水.水体中13种PAHs总浓度(130～250 ng·L~(-1))低于沉积物孔隙水(180～253 ng·L~(-1)),且均以低环PAHs为主.2～3环PAHs浓度在上层水体中无明显的垂直变化,但4～6环PAHs浓度呈现随深度增加而降低的趋势.沉积物孔隙水中PAHs浓度的垂直变化规律反映了历史强排放过程.研究区域PAHs在沉积物-水体界面的交换通量变化范围为-384～1445 ng·m~(-2)·d~(-1),除Flu和Pyr外,其它PAHs均从沉积物向水体释放,反映了底部沉积物是上层水体中PAHs的重要二次污染源.