Efficient degradation of lube oil by a mixed bacterial consortium

A laboratory study was performed to assess the biodegradation of lube oil in bio-reactor with 304# stainless steel as a biofilm carrier. Among 164 oil degrading bacterial cultures isolated from oil contaminated soil samples, Commaonas acidovorans Px1, Bacillus sp. Px2, Pseudomonas sp. Px3 were selected to prepare a mixed consortium for the study based on the efficiency of lube oil utilization. The percentage of oil degraded by the mixed bacterial consortium decreased slightly from 99% to 97.2% as the concentration of lube oil was increased from 2000 to 10,000 mg/L. The degradation of TDOC (total dissolved organic carbon) showed a similar tendency compared with lube oil removal, which indicated that the intermediates in degradation process hardly accumulated. Selected mixed bacterial consortium showed their edge compared to activated sludge. Scanning electron microscopy (SEM) photos showed that biofilms on stainless steel were robust and with a dimensional framework constructed by EPS (extracellular polymeric substances), which could promote the biodegradation of hydrocarbons. The increase of biofilm followed first-order kinetics with rate of 0.216 μg glucose/(cm2·day) in logarithm phase. With analysis of Fourier transform infrared spectroscopy (FT-IR) and gas chromatography-mass spectrometry (GC-MS) combined with removal of lube oil and TDOC, mixed bacterial consortium could degrade benzene and its derivatives, aromatic ring organic matters with a percentage over 97%.     

Molecular characterization of bacterial community in aerobic granular sludge stressed by pentachlorophenol

To characterize the effects of pentachlorophenol (PCP) on the performance and microbial community of aerobic granular sludge in sequencing batch reactor (SBR), the web-based terminal restriction fragment length polymorphism (T-RFLP) and real-time PCR (RT- PCR) techniques were used to explore the bacterial community structure. When PCP increased from 0 to 50 mg/L, the COD removal rate changed little, while the ammonia removal rate dropped from 100% to 64.9%. The results of molecular characterization showed t...     

北京市大气细粒态气溶胶的化学成分研究

2000年6月在北京北郊中国科学院大气物理所气象塔观测场采集了大气中细粒态气溶胶样品.用质子诱导X射线荧光分析法(PIXE)对样品进行了分析,得到Al、Si、P、S、Cl、K等19种元素的浓度及其谱分布并对当前北京市大气气溶胶的来源、化学元素成分的变化进行了研究.结果表明,这19种元素中的许多元素的浓度与过去相比有不同幅度的降低,说明北京市对大气污染的防治是有效果的.     

冬季中国东海大气气溶胶中水溶性离子的组成与来源分析

运用离子色谱对2009年冬季中国东海大气气溶胶中水溶性离子Cl-、NO3-、SO42-、CH3SO3-（MSA）、Na＋、K＋、NH 4＋、Mg2＋、Ca2＋进行了测定,同时由SPSS（statistical package for social sciences）软件进行相关性分析探讨其来源.分析结果表明,气溶胶中二...     

关中盆地NO2和SO2对颗粒物污染的协同效应

基于WRF-Chem模式模拟了关中盆地2019年1月2—14日一次颗粒物污染事件,评估了NO_x和SO₂减排及其在颗粒物污染中的协同作用对PM_2.5污染的影响。敏感性实验结果表明：NO_x减排可使PM_2.5中硝酸盐含量下降,但大气中O₃浓度上升,大气氧化能力增强,其他二次组分上升,导致PM_2.5下降不明显;SO₂人为源减排可使硫酸盐质量浓度下降,但由于硫酸盐在PM_2.5中占比较低,当SO₂减排75%时,PM_2.5仅下降1.74%;当减排比例较高时,NO_x和SO₂同时减排更有利于颗粒物污染防治。PM_2.5质量浓度在NO_x和SO₂同时减排75%时比分开减排75%时多下降0.75%,主要是硫酸盐下降所致;对气溶胶含水量进行分析,发现NO_x<...     

兰州远郊区黑碳气溶胶浓度特征

利用兰州大学半干旱气候与环境观测站(SACOL)2007年1月1日至2009年8月28日黑碳气溶胶浓度和同期常规气象资料,分析了兰州远郊区黑碳气溶胶浓度特征.结果表明,该区黑碳气溶胶日平均浓度为1568ng/m3,低于东部地区区域本底站浓度,表明该地区污染较轻;黑碳浓度具有明显的季节变化,从春季到冬季平均浓度依次增大,分别为1234.74,1290.23,1669.06,2088.73ng/m3,日变化具有明显的双峰结构,最大值出现在09:00,最小值出现在17:00.黑碳浓度的变化特征与本地区的盛行风向、人类活动及天气过程有密切关系.沙尘气溶胶对黑碳浓度的影响取决沙尘过程的强度、沙尘携带的人为污染物的种类及数量、黑碳颗粒被其他气溶胶混合和包裹的程度.统计分析得出该地区大气黑碳气溶胶本底浓度约为1000ng/m3.     

餐厨垃圾废液制备高效解磷菌肥

从小麦土中筛选出2株高效解磷菌P1和P7,其解磷能力在10 d内达到117.57 mg·L-1和219.59 mg·L--1。经16S rDNA测序鉴定及构建系统进化树,鉴定P1为Enterobacter cloacae,P7为Kosakonia cowanii。通过正交实验及单因素实验,对解磷菌在餐厨废液中生长条件进行了优化。结果表明,Kosakonia cowanii生长条件影响程度的顺序依次为温度>pH>摇床转速>接种量,最优的培养条件为温度25 ℃,pH=7,摇床转速140 r·min-1,接种量1.0%。将筛选的解磷菌制备成解磷菌肥,并进行大蒜盆栽实验。结果表明,30 d后,土壤有效磷相比空白提升了16.32％,大蒜叶宽与叶数相比空白分别提升了63.16％和60.00％。     

Sensitivity of a molecular marker based positive matrix factorization model to the number of receptor observations

To investigate the impact of the number of observations on molecular marker-based positive matrix factorization (MM-PMF) source apportionment models, daily PM_2.5 samples were collected in East St. Louis, IL, from April 2002 through May 2003. The samples were analyzed for daily 24-h average concentrations of elemental and organic carbon, trace elements, and speciated particle-phase organic compounds. A total of 273 sets of observations were used in the model and consisted of all valid sets of observations from the year long data set minus one sixth of the measurements, which were collected every 6th day and were analyzed by different chemical analysis techniques. In addition to the base case of 273 samples, systematic subsets of the data set were analyzed by PMF. These subsets of data included 50% of the observations (135–138 days), 33% of the observations (90–92 days) and 20% of the observations (52–56 days). In addition, model runs were also examined that used 48-h, 72-h, 6-day, and weekly average concentrations as model inputs. All MM-PMF model runs were processed following the same procedures to explore the stability of the source attribution results. Consistent with previous MM-PMF results for East St. Louis, the main sources of organic aerosol were found to be mobile sources, secondary organic aerosols (SOAs), resuspended soil and biomass combustions, as well as an n-alkane dominated point source and other combustion sources. The MM-PMF model was reasonably stable when the number of observations in the input was reduced to ninety, or approximately 33% of observations present in the base case. In these cases, the key factors including resuspended soil, mobile and secondary factors, which accounted for more than 70% of the measured OC concentrations, were stable as defined by a relative standard deviation (RSD) of less than 30%. Similar results were obtained from the smaller data subsets, but resulted in larger uncertainties, with several of these factors yielding RSD of greater than 30%. The three factors with the largest OC contributions were more stable than the other minor factors, even when the number of observations was nominally 50 days. Secondary organic aerosol (SOA) was the most stable factor observed in the model runs. Since it is unclear if these results can be broadly applied to all MM-PMF models, additional studies of this nature are needed to assess the broader applicability of these conclusions. Until such studies are implemented, this paper provides a foundation to design future studies in sampling strategies for source apportionment using MM-PMF.     

用于气溶胶采样预分离的直流式旋风分离器

频繁的滤材堵塞是大气气溶胶采样器(流量大于500 m3/h)运行中常见的问题,安装预分离器是缓解这一问题的有效途径之一。研究了可用于这种气溶胶取样器预分离的旋风分离器,确定了使用轴流进气直流式的结构。在惯性分离理论的基础上,提出了切割粒径的计算方法。建立了流量为700～800 m3/h的预分离器性能测试装置和方法,并对3个旋风分离器性能进行了测试。实验结果表明:3个旋风分离器的切割粒径在12～14.5μm,与计算较好地符合;性能最佳的旋风分离器的切割粒径为14.5μm,10μm颗粒的透过率为73%,符合技术要求。     

Biodegradation of organochlorine pesticide endosulfan by bacterial strain Alcaligenes faecalis JBW4

The recently discovered endosulfan-degrading bacterial strain Alcaligenesfaecalis JBW4 was isolated from activated sludge. This strain is able to use endosulfan as a carbon and energy source. The optimal conditions for the growth of strain JBW4 and for biodegradation by this strain were identified, and the metabolic products of endosulfan degradation were studied in detail. The maximum level of endosulfan biodegradation by strain JBW4 was obtained using broth at an initial pH of 7.0, an incubation temperature of 40℃ and an endosulfan concentration of I00 mg/L. The concentration of endosulfan was determined by gas chromatography. Strain JBW4 was able to degrade 87.5% of α-endosulfan and 83.9% of β-endosulfan within 5 days. These degradation rates are much higher than the previously reported bacterial strains. Endosulfan diol and endosulfan lactone were the major metabolites detected by gas chromatography-mass spectrometry; endosulfan sulfate, which is a persistent and toxic metabolite, was not detected. These results suggested that A. faecalis JBW4 degrades endosulfan via a non-oxidative pathway. The biodegradation of endosulfan by A. faecalis is reported for the first time. Additionally, the present study indicates that strain JBW4 may have potential for the biodegradation of endosulfan residues.