一株高效脱硫菌的分离鉴定和脱硫特性研究

从污水净化厂二沉池回流污泥中分离到一株硫杆菌菌株dj-5,该菌株是一种兼性厌氧菌,通过生理生化特性鉴定,并结合16S rDNA序列分析及鉴定,该菌株可以确定为脱氮硫杆菌（Thiobacillus denitrificans）。该菌株的生长曲线表明菌体生长迅速,延滞期约为8 h,然后细菌进入对数生长期,这一阶段持续时间大约20～24 h,稳定期较短,细菌很快进入衰亡期。通过脱硫工艺实验考察了pH值、温度和搅拌速度对脱硫率和菌体生长的影响,结果表明,在进气量180 L/h、pH=6～8、温度为25～35℃和搅拌速度为270 r/min时,该菌株能正常生长,对进气浓度高达2 500 mg/m³的硫化氢脱除率在91%以上。     

硫化油生产过程的活性反应危害识别与评估

利用差示扫描量热仪（DSC）、反应量热仪（RC1和快速筛选仪（RSD）等仪器设备,对硫化油合成过程的热特征和压力特征进行系统研究,发现该反应为微吸热的过程,但仍应严格控制工艺参数,如压力、温度等。防止反应器中混入水等低沸点物质,导致容器超压。反应器内避免混入空气、硝酸等禁忌物料,防止因活性反应而引发灾害性燃爆事故。     

Vertical distribution of acid-volatile sulfide and simultaneously extracted metals in mangrove sediments from the Jiulong River Estuary,Fujian, China

Background Acid-volatile sulfide (AVS) is operationally defined as sulfides in sediment, which are soluble in cold acid, and is reported as the most active part of the total sulfur in aquatic sediments. It is a key partitioning phase controlling the activities of divalent cationic heavy metals in sediment. Methods In order to examine this in mangrove environments, six sites were selected along the Jiulong River Estuary in Fujian, China, which had previously been reported to be polluted by heavy metals. Sediments were sampled from 0–60 cm depth at each site, and the spatial distribution of AVS and SEM (simultaneously extracted metals: copper, cadmium, zinc, and lead) were determined. Results and Discussion The results indicate that the AVS concentrations had a spatial variation, ranging from 0.24 to 16.10 μmol g⁻¹ sediment dry weight. The AVS concentration in the surface layer is lower than that of the deeper sediment, with peak values in the 15–30 cm horizon. There was no correlation between the AVS value and organic matter content or total dissolved salts, but a significant positive correlation of AVS with surface sediment (0–5 cm) moisture content was found. This indicates that water logged sediments tend to have a high AVS value. The amount of SEM was within the range of 0.33–2.80 μmol g⁻¹ sediment dry weight and decreased with sediment depth. Conclusions There was a marked variation in AVS and SEM among different sites studied. AVS concentrations were generally lower in the surface sediments, while SEM concentrations slightly decreased with the depth. Higher concentrations of SEM found in the upper layers of the sediments confirm the earlier suggestions that this study area may suffer from increasing heavy metal pollution. Recommendations and Perspectives When monitoring environmental impacts by using AVS, the micro and large-scale spatial variation as well as vertical distribution need to be estimated to avoid misleading results. Both AVS and SEM concentrations in different sediment layers should be taken into account in assessing the potential impact of heavy metals on the biotic environment.     

Synergistic increase in cell lethality by dieldrin and H2O2 in rat thymocytes: Effect of dieldrin on the cells exposed to oxidative stress

Dieldrin, one of persistent pesticides, is highly resistant to biotic and abiotic degradation. It is accumulated in organisms. Recent studies suggest that dieldrin exerts a potent cytotoxic action on cells exposed to oxidative stress. In this study, the effect of dieldrin on rat thymocytes exposed to hydrogen peroxide (H₂O₂)-induced oxidative stress was examined. Dieldrin at 5 μM and H₂O₂ at 300 μM slightly increased cell lethality from a control value of 5.4 ± 0.5% (mean ± standard deviation of four experiments) to 7.8 ± 1.3% and 9.0 ± 0.3%, respectively. Simultaneous application of dieldrin and H₂O₂ significantly increased cell lethality to 46.2 ± 1.8%. The synergistic increase in cell lethality was dependent on dieldrin concentration (0.3–5 μM) but not on H₂O₂ concentration (30–300 μM). Dieldrin accelerated H₂O₂-induced cell death, which was estimated with the help of annexin V-FITC and propidium iodide. Presence of either dieldrin or H₂O₂ decreased the cellular content of nonprotein thiol and increased intracellular Zn²⁺ concentration. The combination of dieldrin and H₂O₂ further pronounced these effects. TPEN, a chelator of intracellular Zn²⁺, significantly attenuated the synergistic increase in cell lethality induced by dieldrin and H₂O₂. It is, therefore, suggested that dieldrin augments the cytotoxicity of H₂O₂ in a Zn²⁺-dependent manner.     

活性炭纤维生物挂膜脱除硫化氢

生物脱硫法作为一种高效、高实用性的除硫新技术而受到越来越多的关注。以活性炭纤维为微生物载体,通过活性污泥上清液挂膜驯化,考察硫化氢进气量、喷淋量、pH值和硫酸根离子浓度等条件对脱硫效率的影响。研究结果表明,在室温下,硫化氢负荷为90 g/(m3.h),进气浓度控制在3 g/m3,进气量为60 L/h,喷淋量为250～650 L/(m3.d),pH为2～5的条件下,生物活性炭纤维对硫化氢的去除率可保持在98%以上。     

磷酸根和硫离子在纳米铁表面的竞争吸附

通过纳米铁对磷酸根和硫离子的单吸附和竞争吸附的研究,从吸附动力学和吸附等温线两个方面分析并验证了其吸附特性和模式。分析表明,相对于磷酸根,纳米铁对硫离子的吸附能力更强,在竞争条件下居优势地位。采用准一级和准二级吸附动力学方程对实验数据进行模拟分析,结果表明,纳米铁对磷酸根和硫离子的吸附符合二级动力学方程。吸附等温线分析采用Freundlich和Langmuir吸附等温线方程模拟分析,分析结果表明,纳米铁颗粒对磷酸根的吸附符合Freundlich吸附模式,而对硫离子的吸附符合Langmuir吸附模式。     

热镀锌厂酸洗废水和锌灰中回收硫化锌

从热镀锌厂的酸洗废水和锌灰中回收硫化锌,采用X射线能谱仪(EDS),X射线衍射仪(XRD),傅里叶红外光谱仪(FTIR)和场发射透射电镜(FETEM)表征样品ZnS性质,电感耦合等离子发射体(ICP-OES)分析上清液性质,并研究该反应动力学过程。EDS和ICP分析表明,样品ZnS纯度达到85.45%,其上清液含有高浓度铁,含量为2 g/L,可用于制备复合亚铁絮凝剂,而其他重金属离子浓度均低于电镀废水排放标准。XRD分析表明,样品ZnS是立方晶型,调节pH和采用滴加方式能有效改善样品ZnS的晶型。采用Scherrer公式计算晶体粒径,结果表明,晶粒大小在3~6 nm之间。FTIR分析表明,样品ZnS呈现良好的红外透明性,且温度、pH和滴加方式对样品的红外透光性基本没有影响。FETEM结合XRD图表明,该纳米晶呈片状,近似为球形,呈多层叠加,分散性不明显,有团聚现象。动力学实验表明,逆一级动力学方程适合描述硫化沉淀的反应动力学过程,活化能为39.04 kJ/mol,沉淀过程受化学反应和扩散联合控制。     

Degradation of fipronil under laboratory conditions in a tropical soil from sirinhaém pernambuco,Brazil

The objective of this research was to assess the degradation of fipronil [5-amino-1-(2,6-dichloro-α,α,α -trifluoro-p-tolyl)-4-trifluoromethylsulfinylpyrazole-3-carbonitrile] in soils from sugar cane fields in Northeastern Brazil. Degradation experiments were carried out under laboratory conditions (controlled temperature and in the dark), where sterile and non-sterile soils (Ustoxs) were incubated [under moisture content of 55% of the water holding capacity (WHC)] and analyzed for fipronil disappearance and metabolite formation. Microbial communities present in the soil degrade fipronil. However, biodegradation seems to be dependent on the bioavailability of the fipronil and the half-life according to the zero-order model. Fipronil degradation rate appeared to be biphasic. Degradation fipronil ranged from 83 days (initial concentration = 978 ng g^{? 1}; short-term experiment) to 200 days (initial concentration = 689 ng g^{? 1}; long-term experiment). This an initial slower rate followed by a faster rate after 90 days of incubation may lead to shorter half-life than that calculated with the zero-order model. The sulfone derivative (an oxidation product) was the predominant metabolite, but the sulfide (a reduction product) and amide (a hydrolysis product) derivatives were also formed under non-sterile conditions after 120 days of incubation. The metabolites underwent further biodegradation, particularly the sulfone derivative. Bioavailability appears to affect fipronil degradation in soils with an effective capacity to adsorb fipronil (such as Ustoxs), while redox potential was important for the formation of metabolites. Despite the fine texture, more aerobic sites were present, thus favoring the formation of the sulfone metabolite over that of the sulfide metabolite. Therefore, microaggregation of Ustoxs, with high clay content, played a very important role in determining the types of metabolites formed.     

两段生物滤池处理城市污水厂恶臭气体中试研究

采用两段式生物滤池工艺处理山东某城市污水处理厂格栅间和污泥浓缩池散发的恶臭气体,研究了反应器的运行效果、污染物去除特性和微生物特性。该污水处理厂格栅间和污泥浓缩池逸散气体的主要成分为硫化氢、氨以及由甲硫醇、二甲胺、甲醇、丙酮、乙酸、丁酸和苯乙烯等物质组成的挥发性有机化合物。应用两段式生物滤池能够有效地去除这些污染物质,...