一种高效测试污泥可生物降解性的实验方法研究

污泥的可生物降解性能由其有机组分的生物可及度和组分分子的复杂度共同决定。通过采用化学分级提取方法研究污泥组分的生物可及度,使用不同强度的提取溶液分离出4种化学可及度不同的提取组分,同时结合三维荧光光谱法对各组分中有机物质的复杂度进行分析。分析结果表明:组分的化学可及度与其生物可及度之间存在正相关关系;生物可及度较高,其成分有机物分子结构简单的组分SPOM(soluble particulate organic matter,SPOM)与REOM(readily extractible organic matter,REOM)在厌氧消化过程中降解率较高,分别为59.2%与46.3%的COD;而生物可及度低,组成复杂的组分SEOM(slowly extractible organic matter,SEOM)与PEOM(poorly extractible organic matter,PEOM)的生物降解率分别只有18.4%和5.8%的COD。     

Oxidation state specific analysis of arsenic species in tissues of wild-type and arsenic (+ 3 oxidation state) methyltransferase-knockout mice

Arsenic methyltransferase(As3mt) catalyzes the conversion of inorganic arsenic(i As) to its methylated metabolites, including toxic methylarsonite(MAs~Ⅲ) and dimethylarsinite(DMAs~Ⅲ). Knockout(KO) of As3 mt was shown to reduce the capacity to methylate i As in mice. However, no data are available on the oxidation states of As species in tissues of these mice. Here, we compare the oxidation states of As species in tissues of male C57BL/6 As3mt-KO and wild-type(WT) mice exposed to arsenite(iA s~Ⅲ) in drinking water. WT mice were exposed to50 mg/L As and As3mt-KO mice that cannot tolerate 50 mg/L As were exposed to 0, 15, 20, 25 or30 mg/L As. iA s~Ⅲaccounted for 53% to 74% of total As in liver, pancreas, adipose, lung, heart, and kidney of As3mt-KO mice; tri- and pentavalent methylated arsenicals did not exceed 10% of total As. Tissues of WT mice retained iA s and methylated arsenicals: iA s~Ⅲ, MAs~Ⅲand DMAs~Ⅲ represented 55%‐68% of the total As in the liver, pancreas, and brain. High levels of methylated species, particularly MAs~Ⅲ, were found in the intestine of WT, but not As3mt-KO mice,suggesting that intestinal bacteria are not a major source of methylated As. Blood of WT mice contained significantly higher levels of As than blood of As3mt-KO mice. This study is the first to determine oxidation states of As species in tissues of As3mt-KO mice. Results will help to design studies using WT and As3mt-KO mice to examine the role of iA s methylation in adverse effects of iA s exposure.     

Rapid degradation of dyes in water by magnetic Fe/Fe3O4/graphene composites

Magnetic Fe⁰/Fe₃O₄/graphene has been successfully synthesized by a one-step reduction method and investigated in rapid degradation of dyes in this work. The material was characterized by N₂ sorption–desorption, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), vibrating-sample magnetometer (VSM) measurements and X-ray photoelectron spectroscopy (XPS). The results indicated that Fe⁰/Fe₃O₄/graphene had a layered structure with Fe crystals highly dispersed in the interlayers of graphene, which could enhance the mass transfer process between Fe⁰/Fe₃O₄/graphene and pollutants. Fe⁰/Fe₃O₄/graphene exhibited ferromagnetism and could be easily separated and re-dispersed for reuse in water. Typical dyes, such as Methyl Orange, Methylene Blue and Crystal Violet, could be decolorized by Fe⁰/Fe₃O₄/graphene rapidly. After 20 min, the decolorization efficiencies of methyl orange, methylene blue and crystal violet were 94.78%, 91.60% and 89.07%, respectively. The reaction mechanism of Fe⁰/Fe₃O₄/graphene with dyes mainly included adsorption and enhanced reduction by the composite. Thus, Fe⁰/Fe₃O₄/graphene prepared by the one-step reduction method has excellent performance in removal of dyes in water.     

厌氧氨氧化颗粒污泥的培养及影响因素

在EGSB反应器中快速启动厌氧氨氧化(ANAMMOX)工艺,总氮去除速率为0.931±0.006 kg/(m~3·d),总氮去除效率为90.5%±0.8%。培养得到厌氧氨氧化颗粒污泥和絮状污泥混合物,污泥平均粒径为307.5μm。高质量浓度的NO_2~-(143.25 mg/L)抑制厌氧氨氧化菌活性;N_2H_4可强化厌氧氨氧化,但高质量浓度的N_2H_4抑制厌氧氨氧化菌活性;短期添加丙酸盐(COD质量浓度0~400 mg/L)对厌氧氨氧化速率几乎无影响;厌氧氨氧化速率随Fe~(3+)浓度(0~1.2 mmol/L)的增加而增加。     

响应面法优化仿酶Fe_3O_4/Fe~0非均相类Fenton降解P-NP

采用原位氧化沉淀法制备出仿酶Fe_3O_4/Fe~0,并采用扫描电子显微镜和X射线衍射对样品进行表征,结果表明,Fe_3O_4与Fe~0负载牢固且保持良好的晶型。采用响应面分析法对仿酶Fe_3O_4/Fe~0催化降解P-NP的工艺条件进行优化,方差分析得到二次模型显著,优化条件为:催化剂用量1.2 g/L,反应温度30℃,初始pH=2.9,初始H_2O_2浓度10 mmol/L,对硝基苯酚去除率的实际值与预测值几乎一致。     

淀粉稳定Fe3O4纳米粒子对水中As(V)的吸附特性研究

以可溶性淀粉作为稳定剂制备纳米Fe_3O_4粒子,探讨了反应时间、p H值、初始砷浓度和腐殖酸对Fe_3O_4纳米粒子吸附水体中As(V)的吸附效果影响.实验结果表明,淀粉稳定的Fe_3O_4纳米粒子对水体中As(V)的吸附动力学过程符合准二级动力学,吸附等温线符合Langmuir吸附模型;吸附容量随着溶液p H的增加逐渐降低,在p H为8.0的弱碱性水体中对As(V)的最大吸附容量可达202.56 mg·g~(-1);此外,腐殖酸(HA)能降低纳米粒子对As(V)的吸附能力.     

生物表面活性剂改性对纳米铁/炭去除地下水中NO3--N的影响

纳米铁由于其反应活性强、来源广泛等优点被广泛应用在去除地下水NO-3-N污染中.利用生物表面活性剂对纳米铁进行改性可以避免采用化学表面活性剂改性对环境造成的二次污染.本研究采用鼠李糖脂、茶皂素、无患子3种生物表面活性剂对纳米铁进行改性后附着在活性炭上构成改性纳米铁/炭复合材料,通过批试验、沉降试验、迁移试验等研究生物表面活性剂对纳米铁/炭复合材料的改性作用.结果表明:鼠李糖脂、茶皂素、无患子对纳米铁/炭改性后去除NO-3-N效果最佳时的投加量分别为0.7%、1.0%、0.7%,此时对比三者改性作用,鼠李糖脂改性纳米铁/炭去除NO-3-N效果最佳,无患子改性纳米铁/炭迁移效果最佳;鼠李糖脂投加量在0.1%到1.3%范围内时,改性纳米铁/炭迁移能力随投加量的增加而增大.     

改性磁性纳米颗粒固定内生菌Bacillus nealsonii吸附废水中Cd2+的特性研究

从重金属超累积植物龙葵体内提取内生菌Bacillus nealsonii,采用二氧化硅改性纳米Fe_3O_4颗粒与海藻酸钠将其包埋交联进行固定化,制得一种新型球状生物吸附剂,并应用于废水中Cd~(2+)的吸附处理.同时,通过正交实验研究了该球状生物吸附剂的最佳制备条件和吸附处理条件,并采用扫描电镜等表征手段与构建吸附动力学考察了其吸附特征.结果表明,球状生物吸附剂的最佳制备条件为:改性纳米Fe3O4颗粒质量分数为0.1%,海藻酸钠质量分数为8.0%,菌液接种量为0.4%,交联时间为2 h;其最佳吸附处理条件为p H=6、吸附时间12 h、吸附剂用量(干重)2.5 g·L-1,在Cd~(2+)初始浓度为50 mg·L-1时的吸附率可达96%以上.研究发现,球状生物吸附剂的内外部结构孔隙率较大,有利于促进Cd~(2+)的吸附.该吸附过程遵循准二级反应动力学,以化学吸附为主,符合Freundlich等温吸附模型,最大单分子吸附量可达13.02 mg·g-1.解吸实验结果表明,该吸附剂具有较好的可重复利用性.     

Spatial and temporal distribution of cyanobacteria in Batticaloa Lagoon

The necessity to understand the relationship between cyanobacterial species abundance and water quality variations in coastal lagoons is crucial to develop strategies to prevent further cyanobacterial proliferation. This paper evaluates the relationship between water quality variations on the distribution of cyanobacteria during a 12-month period in Batticaloa Lagoon (Sri Lanka) using Redundancy analysis and Pearson correlations. Drastic variations in pH, temperature, salinity, dissolved oxygen (DO) and total phosphorus (TP) levels were reported, but not turbidity and NO₃⁻. This brackish waterbody is hypereutrophic (TP levels > 0.1 mg/L). The cyanobacterial community contained 13 genera and 22 species. NO₃⁻, TP and turbidity levels positively influenced cyanobacterial abundance during all seasons indicating that nutrient (largely phosphorus) and sediment entry control is highly crucial along with periodic monitoring of cyanobacterial growth.     

WO_3/Ag_3VO_4复合光催化剂的制备及其可见光催化性能

采用超声辅助沉淀法—浸渍法制备了WO3/Ag3VO4复合光催化剂,对其进行了表征,考察了其在可见光条件下对罗丹明B的催化降解性能,并对催化机理进行了探讨。表征结果显示:WO3紧密包覆在Ag3VO4颗粒的表面,并未改变Ag3VO4的晶体结构;与Ag3VO4和WO3相比,WO3/Ag3VO4的吸收带边发生了红移。实验结果表明:w(WO3)为3.5%时,WO3/Ag3VO4对罗丹明B的可见光催化降解效果最好;在光催化剂加入量0.8 g/L、初始罗丹明B质量浓度10 mg/L的条件下,于室温下光照180 min时的罗丹明B去除率达95.76%,TOC去除率达96.5%;WO3与Ag3VO4在能带间的耦合作用下形成异质结结构,很好地抑制了光生电子-空穴对的复合。