利用FeS去除水中硝基苯的试验研究

为研究FeS还原去除硝基苯的性能,采用批次试验的方法,考察了各因素对FeS去除硝基苯性能的影响.结果表明,在初始硝基苯浓度为0.96 mmol·L-1条件下,当FeS用量为1.2 g时,反应180 min后,硝基苯去除率达到90%.初始硝基苯浓度、FeS用量、温度、FeS重复使用次数对硝基苯去除率有较大影响.初始硝基苯浓度在0.74～1.74 mmol·L-1之间变化时,初始硝基苯浓度每增加0.1 mmol·L-1,硝基苯去除率下降4.7%.FeS用量在0.3～1.5 g内变化时,FeS用量每增加0.3 g,硝基苯去除率增加近20%;FeS用量为1.8 g时,硝基苯去除率为100%.温度在10～25℃范围内变化时,温度每升高1℃,硝基苯去除率增加1.6%;温度为30℃时,硝基苯去除率为100%.硝基苯去除率随FeS重复使用次数的增加而下降.转速在10～80 r.min-1内变化时,转速变化对硝基苯去除率的影响较小,硝基苯去除率稳定在75%左右.FeS对模拟化工废水有较好的处理效果,反应60 min后,硝基苯去除率为100%.     

Shewanella oneidensis MR-1对硫化汞的生物利用性研究

在实验室模拟条件下,研究了铁还原菌奥奈达希瓦式菌Shewanella oneidensis MR-1对固态硫化汞的生物溶解、生物甲基化作用及其影响因素.结果表明,铁还原菌S.oneidensis MR-1在含硫培养基中生长良好,低浓度硫素能够促进其生长,高浓度时细菌生长则受到抑制,这种抑制主要表现在菌株生长曲线迟缓期的延长;铁还原菌S.oneidensis MR-1能够利用固态硫化汞,促进其溶解并迅速进行汞甲基化;在S.oneidensis MR-1的耐硫化物范围内,菌株对硫化汞的生物溶解作用随着硫化钠浓度的增大而增强,但生物甲基化作用只在低浓度硫化钠时受到促进,硫化钠浓度过高时则会受到抑制;此外,弱酸性环境比酸性及中碱性的环境更有利于S.oneidensis MR-1对硫化汞的生物溶解及甲基化.     

一株耐铬细菌的鉴定及其还原铬性能分析

从浙江温州工业区六价铬废水污染的土壤中采样分离得到一株耐铬细菌Y73.16S rRNA基因序列分析表明,该菌株为Staphylococcus(葡萄球菌)属菌,最高可在加有1600 mg·L^-1六价铬(K₂Cr₂O₇)的 LB培养基中生长.该菌为好氧生长,但在3种不同的氧压力下,包括有氧、无氧和兼性无氧(先有氧生长)的条件下都可以还原六价铬,而在兼性无氧(先有氧生长)的条件下达到最高还原效率,可在96 h内将1000 mg·L^-1的六价铬还原83%.另外,该菌株能在较宽的pH值(5~11)和温度(10~50℃)范围内还原六价铬,而最佳反应条件是pH=7 和30℃.随着接种量的增加,六价铬的还原率增加,但接种量超过10%时再增加接种量对六价铬还原的影响不明显.供试的大多数金属离子(50 mg·L^-1)对该菌株还原六价铬的影响也不明显.上述结果说明,菌株Y73有其独特的还原铬性能,以及在处理六价铬污染废水中的应用潜力.     

直接大红4BE的磷钨酸均相光催化还原脱色

以磷钨酸(H3PW12O40,PW12)为光催化剂,异丙醇(Isopropanol)作为电子给体的条件下对偶氮染料直接大红4BE进行均相光催化还原脱色研究,考察PW12用量、IS浓度、直接大红4BE和盐浓度等因素的影响,结果表明杂多蓝(PW1-2)对直接大红4BE具有明显的还原脱色作用.pH=2.0,直接大红4BE初始浓度50 mg·L-1,PW12浓度为600 mg·L-1,IS浓度为0.13mol·L-1,50 min直接大红4BE的脱色率可达到90.39%.4BE的光催化还原脱色速率随PW12和IS浓度的增加而增加,最后趋于恒定;直接大红4BE初始浓度增加,其光反应一级速率常数降低;PW12、IS和4BE浓度之间存在交互影响.离子强度增加,4BE脱色速率减小,表现为负的盐效应,推测4BE与光反应生成的杂多蓝(PW1-2)进行复合,然后发生电子转移引起偶氮染料还原脱色和杂多蓝氧化复原.本研究结果表明PW12/IS/UV能够有效用于偶氮染料直接大红4BE的还原脱色处理.     

Effect of transition metal doping under reducing calcination atmosphere on photocatalytic property of TiO2 immobilized on SiO2 beads

TiO₂ immobilized on SiO₂ (TiO₂/SiO₂) have been prepared by sol-gel method and various ions of transition metals (Cr³⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺) were doped on the photocatalyst using wet impregnation method under reducing calcination atmosphere. The photocatalytic activity of metal doped TiO₂/SiO₂ towards phenol degradation under black light irradiation were investigated and compared with undoped TiO₂/SiO₂. The results showed that the photoresponse of Cu²⁺ and Zn²⁺ doped TiO₂/SiO₂ were larger than undoped TiO₂/SiO₂, indicating that the photogenerated carriers were separated more efficiently in Cu²⁺ and Zn²⁺ doped TiO₂/SiO₂. The reactivity was in the order of Cu²⁺ > Zn²⁺ > Ni²⁺ > Cr³⁺ > Co²⁺. The different photoreactivity was ascribed to combine effect of the different ionic radii and photocorrison tendency of the dopants. The sample was also characterized by surface analytical methods such as X-ray diffraction, scanning electron micrograph/electron dispersive X-ray analyzer and UV-Vis absorption spectrum.     

不同Fe(Ⅲ)对活性污泥异化铁还原及除磷影响研究

以SBBR反应器活性污泥作为铁还原菌菌种来源,采用兼性厌氧/严格厌氧恒温培养试验,投加不同Fe(Ⅲ)考察各条件下的异化铁还原能力同时比较对磷的去除效果.结果表明:2种条件下Fe(Ⅲ)还原能力具有较好的一致性,依次为:Fe(OH)3＞氧化铁皮＞青矿＞红矿,其中严格厌氧条件下较好.同时,除磷效果与其呈正相关,富集培养至7d,Fe(OH)3及氧化铁皮体系出水磷浓度均达到2mg/L以下,之后继续降低,最终达到0.5mg/L以下.结合异化铁还原除磷机理,可以证明,不同Fe(Ⅲ)表面吸附作用对TP的去除贡献较小,其主要作用为铁还原菌驱动下的化学沉淀去除.     

Effects of physical and chemical characteristics of surface sediments in the formation of shallow lake algae-induced black bloom

Surface sediments are closely related to lake black blooms. The dissolved oxygen （DO） distribution and its penetration depth in surface sediments as well as the migration and transformation of redox sensitive elements such as Fe and S at the sediment-water interface are important factors that could influence the formation of the black bloom. In this study, dredged and undredged sediment cores with different surface properties were used to simulate black blooms in the laboratory. The Micro Profiling System was employed to explore features of the DO and ∑H2S distribution at the sediment-water interface. Physical and chemical characteristics in sediments and pore waters were also analyzed. The results showed that sediment dredging effectively suppressed the black blooms. In the undredged treatment, DO penetration depth was only 50 μm. Fe^2＋ concentrations, ∑H2S concentrations, and ∑H2S production rates were remarkably higher in surface sediments and pore waters compared to control and dredged treatments. Furthermore, depletion of DO and accumulation of Fe^2＋ and ∑H2S in surface sediments and pore waters provided favorable redox environments and necessary material sources for the blooms. The study results proved that physical and chemical characteristics in surface sediments are important factors in the formation of the black bloom, and could provide scientific guidance for emergency treatment and long-term pre-control of black blooms.     

Electrochemical and spectroscopic characteristics of dissolved organic matter in a forest soil profile

Dissolved organic matter （DOM） represents one of the most mobile and reactive organic compounds in ecosystem and plays an important role in the fate and transport of soil organic pollutants, nutrient cycling and more importantly global climate change. Electrochemical methods were first employed to evaluate DOM redox properties, and spectroscopic approaches were utilized to obtain information concerning its composition and structure. DOM was extracted from a forest soil profile with five horizons. Differential pulse voltammetry indicated that there were more redox-active moieties in the DOM from upper horizons than in that from lower horizons. Cyclic voltammetry further showed that these moieties were reversible in electron transfer. Chronoamperometry was employed to quantify the electron transfer capacity of DOM, including electron acceptor capacity and electron donor capacity, both of which decreased sharply with increasing depth. FT-IR, UV-Vis and fluorescence spectra results suggested that DOM from the upper horizons was enriched with aromatic and humic structures while that from the lower horizons was rich in aliphatic carbon, which supported the findings obtained by electrochemical approaches. Electrochemical approaches combined with spectroscopic methods were applied to evaluate the characteristics of DOM extracted along a forest soil profile. The electrochemical properties of DOM, which can be rapidly and simply obtained, provide insight into the migration and transformation of DOM along a soil profile and will aid in better understanding of the biogeochemical role of DOM in natural environments.     

铬(Ⅵ)土著还原菌筛选及初步鉴定实验研究

以重铬酸钾为供试物,用固体平板法和还原实验对铬(Ⅵ)土著还原菌进行筛选,用载片培养法、革兰氏染色法、鞭毛染色法、芽孢染色法对还原菌做初步的鉴定,共筛选出16株铬(Ⅵ)土著还原菌,并挑选出还原率相对较高的Z2(35.2%)、Z3(45.2%)、Z4(38.6%)、X8(30.4%)、X10(29.4%)作为铬(Ⅵ)的优势还原菌株。经初步鉴定,土著真菌Z2为黑曲霉(Aspergillusniger),Z3、Z4为镰刀菌属(Fusariumsp.),土著细菌X8、X10为芽孢杆菌(Bacillussp.)。实验的方法和成果将为铬(Ⅵ)污染土壤微生物治理技术的推广应用提供技术支持。     

水中氨氮测定不确定度的评定

采用蒸馏-中和滴定法测定水中氨氮,建立数学模型,找出影响不确定度的来源并进行各分量不确定度的评价,如实反映测量的置信度和准确度.