降解菌对堆肥中多环芳烃降解作用的研究

通过在堆肥中加人经过驯化的降解菌这种土壤有机污染生物修复技术，对堆肥中多环芳烃的浓度变化进行监测，从而了解降解菌对堆肥中多环芳烃的降解作用。实验结果表明，降解菌的加人能明显地提高多环芳烃的降解率，本次实验中，菲、芴的去除率提高了25％左右，芘的去除率提高了约45％。     

固废拆解场污染土壤中多环芳烃降解菌的筛选鉴定与降解特性

以腐植酸(HA)溶液为吸附剂、从受多环芳烃污染的土壤中分离出来的降解菌制成为生物修复剂,以多环芳烃(PAHs)萘、菲、芘、荧蒽、苯并蒽、苯并芘为土壤污染物,对PAHs污染土壤进行修复实验。目的是筛选与分离吸附于HA的PAHs降解菌,研究HA与降解菌的协同效应对PAHs的降解效率的影响。用经过HA吸附的PAHs富集分离培养出1株高效降解菌株,命名为Tzyx3,鉴定其为解脂耶氏酵母菌(Yarrowia lipolytica)。15 d后,土壤中萘、菲、芘、荧蒽、苯并蒽、苯并芘的降解率分别为90.7%、91.0%、74.7%、86.9%、84.7%和74.7%,表明Tzyx3和HA在PAHs污染土壤中存在协作关系,Tzyx3能够直接利用HA对土壤中的多环芳烃进行降解。     

木糖氧化无色杆菌及混合菌群对多环芳烃的降解特性

采用木糖氧化无色杆菌及混合菌降解水中多环芳烃。考察了木糖氧化无色杆菌的降解广谱性及其对多环芳烃混合底物的降解,特别考察了混合菌对具有弱致癌性的■(Chrysene)的降解特性。结果表明,木糖氧化无色杆菌具有较宽的降解谱,对多环芳烃混合底物具有良好降解特性。当蒽、菲、芘和■4种PAHs共存时,木糖氧化无色杆菌对蒽、菲、芘和■的降解效率分别达83%、66%、85%和80%。与单一木糖氧化无色杆菌相比,混合菌对的降解效率较高。尖镰孢菌与木糖氧化无色杆菌、茄镰孢菌与木糖氧化无色杆菌和3株菌同时共存时,■的降解效率分别达87%、88%和86%。     

添加乙醇碳源对驯化菌种降解油制气废水的影响

进行了添加乙醇作为碳源强化油制气废水生物降解的研究,并利用GC／MS分析对油制气废水中芳烃类化合物的降解进行了初步研究。研究表明,共代谢基质乙醇的加入,可使菌种S-2、Y-3、XH-3、M-3对COD、氨氮、可萃取有机物等指标的去除率分别提高17．6％～25．6％、34．9％～42．8％、10．4％～14．2％;但在所采用的时间范围内,酚类化合物的去除率降低;芳烃类化合物的去除率提高15．4％～21．2％。除了维持无共代谢条件下对芳环数≤3的芳烃类化合物的良好降解能力外,对芳环数为4～6的化合物降解能力也有所提高。     

高效联苯降解菌的筛选及其特性

焦化废水属高浓度难降解工业有机废水,其中所含的多环芳烃属难降解有机物,且对环境产生毒害作用。为探索生物强化技术去除焦化废水中多环芳烃类化合物,采用选择性培养和多级富集的方法,以联苯为模型化合物,并作为惟一碳源,从焦化厂废水和污泥中分离和筛选得到6株联苯降解菌。通过逐渐提高底物浓度的方法驯化菌株后,从中筛选出降解效率最高的联苯降解菌株WIS-01,在此基础上进行菌属鉴定、细菌生长情况及联苯降解性能的研究。实验结果表明,3 d内菌株WIS-01对联苯的降解率可达99%以上,可耐受联苯的最高质量浓度为2 g/L。通过形态学、生理生化鉴定和16S rDNA序列比对分析,确定菌株WIS-01属于假单胞菌属,同源性达95%,命名为Pseudomonas sp.WIS-01。     

含油污泥中石油降解菌的分离及其降解特性

从渤海油田含油污泥中分离出3株石油烃降解菌,通过16S rRNA基因序列鉴定RS1、RS2和RS3分别为棒状杆菌、短杆菌和假单胞菌。经单因素实验确定,3株细菌对石油的最适降解条件分别为37℃、盐度3%、pH 8;32℃、盐度1%、pH 8;42℃、盐度1%、pH 6。降解实验结果表明,3株细菌30 d内对含油污泥中总石油烃的降解率分别为39.69%、31.13%和53.29%,而混合菌的降解效果明显高于单一菌株,降解率为58.08%;不同菌株对原油中不同组分的降解能力不同,其中,RS1对饱和烃的降解率最高,达20.74%,RS3对芳香烃的降解率最高,达到8.08%;GC-MS分析表明,混合菌对nC12~n-C34等正构烷烃均有明显降解,且对萘、苊、屈和苯并[b]荧蒽等多环芳烃的降解能力较强。     

菌源对多环芳烃降解菌的筛选及降解性能的影响

高效降解菌的筛选对利用生物修复技术有效去除环境中的多环芳烃具有重要意义。分别以石油污染土壤和焦化废水活性污泥为菌源,分离出芘降解菌和混合PAHs(菲、荧蒽和芘)降解菌共14株并对其降解性能进行对比研究。结果表明,筛选得到的菌株分别属于9个菌属,其中2种菌源共有的菌属为Mycobacterium sp.、Ralstonia sp.和Shinella sp.。芘和PAHs的高效降解菌(CP16和CM32)均属于分支杆菌属(Mycobacterium),来源于焦化废水活性污泥;菌株CP16对芘(50mg/L)的7 d降解率为74.99%,CM32对PAHs(菲50 mg/L、荧蒽和芘各10 mg/L)的7 d降解率为100%。因此,以焦化废水活性污泥为菌源更有利于获得高效的多环芳烃降解菌。     

添加剂对堆肥降解多环芳烃的影响

为了研究多环芳烃(PAHs)污染土壤堆肥修复的加速机制,在人工控温的堆肥装置中以芘、菲和芴为研究对象,采用室内模拟实验的方式研究了添加硫酸钙、过磷酸钙、草炭、竹炭、十二烷基硫酸钠(K12)和十二烷基苯磺酸钠(SD-BS)等对锯末高温堆肥降解污染土壤PAHs的影响。研究结果表明,生物堆肥可以有效的去除土壤中PAHs,堆肥7周后所有处理下芘、菲和芴的降解率基本达到80%以上。不同添加剂处理下芘、菲和芴降解率不同,尤其是添加草炭和竹炭处理中芴和菲在第4周的时候就取得90%以上的降解率,芘在第6周也取得80%以上的降解率,而且氮素的损失率也分别下降了42.6%和36.09%,比其他处理的PAHs降解率和保氮效果都要好。分析其原因,一方面可能是添加不同添加剂对堆肥过程中pH值、有机质(SOM)、总氮(TN)和过氧化氢酶(CAT)都有一定的影响,提高了土壤微生物的活性;另一方面可能是由于草炭和竹炭对氨有良好的吸附性,具有良好的保氮效果,同时也能改善了微生物和目标化合物的接触方式,从而提高了PAHs的降解率。     

多环芳烃降解菌的筛选及其在焦化场地污染土壤修复中的应用

经过富集、分离和纯化,从沈阳某焦化厂多环芳烃(PAHs)污染土壤中获得7株菌株B1~B7。通过初步降解实验和血平板实验,发现B4、B5、B7在15d时对PAHs总降解率均高于40%,为高效PAHs降解菌,B2为高效表面活性剂产生菌。将B4、B5、B7分别与B2等质量混合后对PAHs进行降解,发现添加B2可提高PAHs总降解率,B4+B2对PAHs的总降解率最大,在9d时平均值达到45.9%。经形态观察和16SrRNA基因序列比对,鉴定B2和B4分别归为假单胞菌属(Pseudomonas sp.)和芽孢杆菌属(Bacillus sp.)。接种B4+B2进行微生物修复实验,结果表明,接种B4+B2对PAHs污染土壤的微生物修复有明显的强化作用,在60d时PAHs总降解率达到48.1%;接种B4+B2对中环(4、5环)PAHs降解率的提高尤为明显,7种中环PAHs的平均降解率比不接种菌株的对照组提高29.6百分点。     

微生物降解多环芳烃有机污染物分子遗传学研究进展

多环芳烃是环境中广泛存在的一类难降解危险性致癌污染物 ,微生物酶在降解转化多环芳烃的过程及其归趋中起着重要作用。本文就微生物降解多环芳烃代谢途径的多样性和分子遗传学机制的研究进展进行了综述     

Sequential UV-biological degradation of polycyclic aromatic hydrocarbons in two-phases partitioning bioreactors

A method based on UV-irradiation in organic solvent followed by transfer of the remaining pollutants into silicone oil for subsequent biodegradation in a biphasic system inoculated with a phenanthrene degrading Pseudomonas sp. was tested for the treatment of various mixtures of PAHs. Acetone was first selected as the most suitable solvent compared to methanol, acetonitrile and silicone oil for the removal of pyrene and phenanthrene. The sequential treatment was then applied to the treatment of a mixture of fluorene, phenanthrene, anthracene, fluoranthrene, pyrene, benzo(a)anthracene and benzo(a)pyrene in acetone. These compounds were photodegraded in the following order of initial removal rates (mg l(-1) d(-1)): benzo(a)pyrene (7.8) > anthracene (5.0) > benzo(a)anthracene (2.5) > fluoranthrene (1.8) > pyrene (1.5) > phenanthrene (1.2) > fluorene (0.2). UV-treatment allowed complete removal of, anthracene, benzo(a)anthracene and benzo(a)pyrene and removals of 63% of pyrene and 37% of fluorene after 434 h or irradiation. The subsequent biological treatment removed the remaining phenanthrene and fluorene by 100% and 90%, respectively, after 790 h of cultivation. Although less efficient due to the presence of interfering compounds, the UV-biological treatment of a soil extract allowed a 63% removal of the seven PAHs named above. Microbial growth did not occur when the pollutants were directly supplied to the microorganism showing that biphasic systems reduced the toxicity effects cause by mixtures of PAHs at high concentrations. This study demonstrates the potential of selective UV treatment of high molecular weight PAHs followed by biological treatment of the low molecular weight species in biphasic systems.     

Removal of PAHs from water using an immature coal (leonardite)

It has been studied an immature coal (leonardite) as an adsorbent for removing PAHs [fluorene, pyrene, benzo(k)fluoranthene, benzo(a)pyrene and benzo(g,h,i)perylene] from water. To determine the efficiency of leonardite as an adsorbent of PAHs, factors such as pH, contact time and equilibrium sorption were evaluated in a series of batch experiments. There were no significant differences in the removal percentages for the various pH values studied, except for fluorene. The adsorption of fluorene was higher at lower pH values. The equilibrium time was reached at 24h. At this time, more than 82% of the pyrene, benzo(k)fluoranthene, benzo(a)pyrene and benzo(g,h,i)perylene had been removed. During the first 2h, the adsorption rate increased rapidly. After that time, however, there was a minor decrease. Equilibrium data were fitted to Freundlich models to determine the water-leonardite partitioning coefficient. Physical adsorption caused by the aromatic nature of the compounds was the main mechanism that governed the removal process. The polarity of the humic substances in leonardite may also have influenced the adsorption capacity.     

Contamination of polycyclic aromatic hydrocarbons (PAHs) in microlayer and subsurface waters along Alexandria coast,Egypt

The residues of seven polycyclic aromatic hydrocarbons (PAHs) pollutants in microlayer and subsurface seawater samples collected from Alexandria coast, Egypt, were analyzed by gas chromatography–electron-impact mass spectrometry-selected ion monitoring mode (GC–MS-SIM). The pollutants studied were, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene and benzo[a]pyrene. Total PAH levels in microlayer ranged from 103 to 523 ng/l, while it ranged in subsurface samples from 13 to 120 ng/l. The Western Harbor location recorded the highest level of PAHs pollutant over all the other location for both subsurface and microlayer waters. The two major PAHs in microlayer water at the Western Harbor were fluorene and phenanthrene, making up 27% and 20% of the total PAHs, while the two major PAHs in subsurface water at the Eastern Harbor were phenanthrene and fluoranthene recording up 21% each of the total PAHs. The total PAH levels were generally in the nano-gram per liter for microlayer and subsurface seawater samples. The dominant PAHs in both subsurface and microlayer samples were fluoranthene, pyrene and benzo[a]pyrene. The microlayer enrichment factor at Alexandria’s Mediterranean coast was ranged from 29 for fluorene to 3 for phenanthrene and benzo[a]pyrene which showed PAHs concentration in the microlayer with an average of five times more than the total PAH in the subsurface samples.     

Removal of polycyclic aromatic hydrocarbons from soil: a comparison between bioremoval and supercritical fluids extraction

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic substances which are resistant to environmental degradation due to their highly hydrophobic nature. Soils contaminated with PAHs pose potential risks to human and ecological health, therefore concern over their adverse effects have resulted in extensive studies on their removal from contaminated soils. The main purpose of this study was to compare experimental results of PAHs removal, from a natural certified soil polluted with PAHs, by biological methods (using bioaugmentation and biostimulation in a solid-state culture) with those from supercritical fluid extraction (SFE), using supercritical ethane as solvent. The comparison of results between the two methods showed that maximal removal of naphthalene, acenaphthene, fluorene, and chrysene was performed using bioremediation; however, for the rest of the PAHs considered (fluoranthene, pyrene, and benz(a)anthracene) SFE resulted more efficient. Although bioremediation achieved higher removal ratios for certain hydrocarbons and takes advantage of the increased rate of natural biological processes, it takes longer time (i.e. 36 d vs. half an hour) than SFE and it is best for 2-3 PAHs rings.     

Organic micropollutants’ distribution within sludge organic matter fractions explains their dynamic during sewage sludge anaerobic digestion followed by composting

The simultaneous fate of organic matter and 4 endocrine disruptors (3 polycyclic aromatic hydrocarbons (PAHs) (fluoranthene, benzo(b)fluoranthene, and benzo(a)pyrene) and nonylphenols (NP)) was studied during the anaerobic digestion followed by composting of sludge at lab-scale. Sludge organic matter was characterized, thanks to chemical fractionation and 3D fluorescence deciphering its accessibility and biodegradability. Total chemical oxygen demand (COD) removal was 41% and 56% during anaerobic digestion and composting, respectively. 3D fluorescence highlighted the quality changes of organic matter. During continuous anaerobic digestion, organic micropollutants’ removal was 22?±?14%, 6?±?5%, 18?±?9%, and 0% for fluoranthene, benzo(b)fluoranthene, benzo(a)pyrene, and nonylphenols, respectively. Discontinuous composting allowed to go further on the organic micropollutants’ removal as 34?±?8%, 31?±?20%, 38?±?10%, and 52?±?6% of fluoranthene, benzo(b)fluoranthene, benzo(a)pyrene, and nonylphenols were dissipated, respectively. Moreover, the accessibility of PAH and NP expressed by their presence in the various sludge organic matter fractions and its evolution during both treatments was linked to both the quality evolution of the organic matter and the physicochemical properties of the PAH and NP; the presence in most accessible fractions explained the amount of PAH and NP dissipated.

     

采油废水中多环芳烃的生态风险评价

先利用C-18固相萃取小柱富集大港油田港东联合处理站污水处理站的采油废水中16种多环芳烃(PAHs,即萘、苊烯、苊、芴、菲、蒽、荧蒽、芘、、苯并[a]蒽、苯并[b]荧蒽、苯并[k]荧蒽、苯并[a]芘、茚并[1,2,3-cd]芘、二苯并[a,h]蒽和苯并[g,h,i]苝),再用气相色谱/质谱(GC/MS)分析测定其浓度,以评价PAHs的去除率和生态风险。结果表明:(1)采油废水经处理后,COD、石油类去除率分别达到82.27%、91.06%;外排水COD、石油类达到《污水综合排放标准》(GB 8978—1996)一级标准要求,优于中国采油废水处理的一般水平。(2)采油废水主要以2、3环的PAHs为主,约占总量的93%以上。(3)苯并[a]芘超过《地表水环境质量标准》(GB 3838—2002)中限值。(4)处理前的采油废水中蒽、菲和苯并[a]芘具有一定的生态风险;处理后的外排水中萘、蒽、菲、荧蒽、苯并[a]芘的暴露浓度(PEC)/预测无效应浓度(PNEC)均小于1,目前尚未对环境造成威胁。但是8种PAHs(苊烯和苯并类PAHs除外)总和表现出较大的毒性,需要引起重视。     

Bioconcentration of polycyclic aromatic hydrocarbons by the freshwater oligochaete Lumbriculus variegatus

Tissue residues of the PAHs, anthracene, fluorene, fluoranthene and pyrene were determined in Lumbriculus variegatus at four time intervals during both a 96-h exposure period to monitor uptake, and a 96-h clean water period to assess depuration. Mean BCFs were 2390, 1210, 452 and 1920 for fluoranthene, anthracene, fluorene and pyrene, respectively. BCFs were positively correlated with the octanol/water partition coefficient values of the four PAHs. Depuration occurred most rapidly for fluorene, followed by anthracene and fluoranthene. No apparent depuration of pyrene was observed during the 96-h depuration period. Because of rapid depuration of some PAHs, it appears that the 24 h clean water gut clearance period recommended in conjunction with sediment bioaccumulation tests with L. variegatus has potential to result in an under-estimation of bioaccumulation of some chemicals.     

Binding of polycyclic aromatic hydrocarbons by humic acids formed during composting

Binding of two model polycyclic aromatic hydrocarbons (PAHs), phenanthrene and pyrene, by humic acids (HAs) isolated from an organic substrate at different stages of composting and a soil was investigated using a batch fluorescence quenching method and the modified Freundlich model. With respect to soil HA, the organic substrate HA fractions were characterized by larger binding affinities for both phenanthrene and pyrene. Further, isotherm deviation from linearity was larger for soil HA than for organic substrate HAs, indicating a larger heterogeneity of binding sites in the former. The composting process decreased the binding affinity and increased the heterogeneity of binding sites of HAs. The changes undergone by the HA fraction during composting may be expected to contribute to facilitate microbial accessibility to PAHs. The results obtained also suggest that bioremediation of PAH-contaminated soils with matured compost, rather than with fresh organic amendments, may result in faster and more effective cleanup.     

Treatment of PAHs in contaminated soil by extraction with aqueous DNA followed by biodegradation with a pure culture of Sphingomonas sp

The biodegradation of polycyclic aromatic hydrocarbons (PAHs) in aqueous deoxyribonucleic acid (DNA) solution from contaminated soil washing was investigated. Initial data with a model effluent consisting of anthracene, phenanthrene, pyrene and benzo[a]pyrene that were individually dissolved in 1% aqueous DNA solution confirmed their positive degradation by Sphingomonas sp. at around 10(8)CFU mL(-1) initial cell loading. For anthracene and phenanthrene, complete removal was achieved within 1h treatment. Degradation of pyrene and benzo[a]pyrene took a relatively longer time of a few days and weeks, respectively. DNA-dissolved PAHs were also degraded relatively faster than PAH crystals in aqueous medium to suggest that the binding of the PAHs in the polymer does not pose serious constraint to bacterial uptake. The DNA was stable against the PAH-degrading bacteria. Parallel experiments with actual DNA solutions obtained during pyrene extraction from an artificially spiked soil also showed similar results. Close to 100% pyrene degradation was achieved after 1d treatment. With its chemical stability, the cell-treated DNA was re-used up to four cycles without a considerable decline in extraction performance.     

The effect of temperature on the rate of disappearance of polycyclic aromatic hydrocarbons from soils

The effect of temperature on the range and rate of disappearance of four polycyclic aromatic hydrocarbons (PAHs; fluorene, anthracene, pyrene and chrysene) added as a mixture of pure compounds to two different soils (light loam and loamy sand) was investigated over 180 days in a laboratory experiment. An increase in temperature from 10 to 25 degrees C enhanced the losses of all four PAHs from both soils. The effect of temperature on the rate of PAH disappearance depended on the physico-chemical properties of the compound and of the soil. The long half-lives at lower temperatures as obtained in the laboratory tests may suggest high persistence of higher molecular weight PAHs under some field conditions.