Effect of surfactant on the estimation by solid phase microextraction of bioavailable pyrene in soil samples

This study was focused on the effect of the presence of surfactant on the bioremediation efficacy and sensitivity of solid phase microextraction (SPME) in the pyrene-contaminated soil. Soils with 1.3 and 7.6% soil organic matter (SOM) were tested for biodegradation by microorganisms and extracted by aqueous solutions of the matrix used for SPME. For the biodegradation test, the presence of Triton X-100 at 5× CMC (critical micelle concentration) significantly enhanced pyrene removal for soil with lower SOM content (1.3%). However, this removal was insignificant for soil with higher SOM content (7.6%). The results may suggest that 5× CMC was not sufficient to improve significantly pyrene desorption for soil with higher SOM content. For the bioavailability test, in the absence of Triton X-100, SPME estimation of bioavailability in soils with indigenous or seeded microorganisms had an error range within 15%. However, with addition of Triton X-100, SPME estimations showed a significant decline (41 and 77%), in relation to their predicted values, for soil samples with SOM of 1.3 and 7.6%, respectively. The main reason for this underestimation is that micelle formation from the application of surfactant impacted the concentration of dissolved pyrene, rather than competitive site occupation between pyrene and surfactant molecules for SPME fiber. Thus, if soil samples contain surfactant, SPME would significantly underestimate bioavailability and risk level of PAH-contaminated sites.     

Yeast and bacteria cell hydrophobicity and hydrocarbon biodegradation in the presence of natural surfactants: rhamnolipides and saponins

This study concerns the relation between hydrocarbon biodegradation in the presence of natural surfactants and cell hydrophobicity resulting from the use of these surfactants. The relative capabilities of two bacterial strains (Pseudomonas aeruginosa and Bacillus subtilis) and two yeast strains (Candida maltosa, Yarrowia lipolytica) were investigated. The selected microorganisms were tested separately and in combination in order to achieve the optimal degrading performance. The surface cell hydrophobicity of microorganisms and the degree of hydrocarbon biodegradation were measured. The microbial adhesion to the hydrocarbon (MATH) test was used to denote the surface cell hydrophobicity of the microbial species. The results indicate the correlation between the modification of the surface cell and the degree of hydrocarbon biodegradation; however results for bacteria differ from that obtained for yeast strains. Saponins, as the surfactant, was more effective than rhamnolipides during hydrocarbon biodegradation, though the concentration of this surfactant has no significant influence on the surface cell hydrophobicity.     

Naphthalene,phenanthrene and surfactant biodegradation

The impact of surfactants on naphthalene and phenanthrene biodegradation and vice versa after surfactant flushing were evaluated using two anionic surfactants: sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS); and two nonionic surfactants: POE (20) sorbitan monooleate (T-maz-80) and octylphenol poly(ethyleneoxy) ethanol (CA-620). Naphthalene and phenanthrene biodegradation varied differently in the presence of different surfactants. Naphthalene biodegradation was not impacted by the presence of SDS. In the presence of T-maz-80 and CA-620, naphthalene biodegradation occurred at a lower rate (0.14 d^-1 for T-maz-80 and 0.19 d^-1 for CA-620) as compared to un-amended control (0.29 d^-1). Naphthalene biodegradation was inhibited by the presence of SDBS. In the presence of SDS, phenanthrene biodegradation occurred at a lower rate (0.10 d^-1 as compared to un-amended control of 0.17 d^-1) and the presence of SDBS, CA-620 and T-maz-80 inhibited phenanthrene biodegradation. The surfactants also responded differently to the presence of naphthalene and phenanthrene. In the presence of naphthalene, SDS biodegradation was inhibited; SDBS and T-maz-80 depleted at a lower rate (0.41d^-1 and 0.12 d^-1 as compared to 0.48 d^-1 and 0.22 d^-1). In the absence of naphthalene, CA-620 was not degradable, while in the presence of naphthalene, CA-620 began to degrade at a comparatively low rate (0.12 d^-1). In the presence of phenanthrene, SDS biodegradation occurred at a lower rate (1.2 d^-1 as compared to 1.68 d^-1) and a similar trend was observed for T-maz-80. The depletion of SDBS and CA-620 did not change significantly. The choice of SDS for naphthalene-contaminated sites would not adversely affect the natural attenuation of naphthalene, in addition, naphthalene was preferentially utilized to SDS by naphthalene-acclimated microorganisms. Therefore, SDS was the best choice. T-maz-80 was also found to be usable in naphthalene-contaminated sites. For phenanthrene contaminated sites, SDS was the only choice.     

A bioactive foam reactor for the removal of volatile organic compounds: system performance and model development

A bioactive foam reactor (BFR), a novel bioreactor operated using surfactant foams and suspended microorganisms for the treatment of gaseous toluene, was investigated to characterize its performance with respect to the mass transfer and biodegradation rates. The BFR system consisted of two reactors in series; a foam column for toluene mass transfer using fine bubbles and a cell reservoir where suspended microorganisms actively biodegraded toluene. In this study, a series of short-term experiments demonstrated that the BFR could achieve stable removal performance and a high elimination capacity (EC) for toluene at 100.3 g/m³/h. A numerical model, combining mass balance equations for the mass transfer and subsequent biodegradation, resulted in reasonable agreement with the experimental findings. At an inlet toluene concentration of 100 ppm_v, the toluene concentration in the liquid phase remained extremely low, indicating that the microbial activity was not hindered in the BFR system. However, the experimental and model prediction results showed that the actual mass of toluene transferred into the liquid phase was not closely balanced with the amount of toluene biodegraded in the BFR used in this study. Consequently, methods, such as increasing the effective volume of the foam column or the mass transfer coefficient, need to be implemented to achieve higher toluene EC and better BFR performance.     

涕灭威及其复合污染对斑马鱼胚胎DNA的影响

研究了一种毒性很高的氨基甲酸酯类杀虫剂--涕灭威和广泛使用的阴离子表面活性剂十二烷基苯磺酸钠(SDBS)组成的复合污染体系对斑马鱼胚胎DNA的影响．结果表明,涕灭威对斑马鱼胚胎DNA的损伤随浓度增大而加重,但低浓度涕灭威在短时间内造成的DNA单链断裂是可以修复的,高浓度则导致难以修复的双链断裂．一定浓度(20mg·L^-1)的SDBS在复合污染体系中能减弱涕灭威的毒性．     

Gaseous CAH removal by biofiltration in presence and absence of a nonionic surfactant

The objectives of this study were to investigate the biodegradation of gaseous trichloroethylene (TCE) and tetrachloroethylene (PCE) in an activated carbon biofilter inoculated with phenol-oxidizing microorganisms and to study the effect of surfactant concentration below its critical micelle concentration (CMC) on the removal efficiency of TCE or PCE. For the enhanced biofiltration, a biodegradable nonionic surfactant was added to biofilters. The investigation was conducted using two specially built stainless steel biofilters, one for TCE and the other for PCE.

The removal efficiency of gaseous TCE was 100% at a residence time of 7?min and its average inlet concentration of 85?ppm. For gaseous PCE, 100% removal efficiency was obtained at residence times of 4–7?min and its average concentrations of 47–84?ppm. It was found that adsorption by GAC and absorption by influent nutrient solution were a minor or negligible mechanism for TCE and PCE removal in the activated carbon biofilters. The TCE and PCE activated carbon biofilter performances were observed to be a little enhanced but not significantly, when the surfactant was introduced at concentrations of 5–50?mg/l. Surfactant concentrations of 5–15?mg/l were found to be an optimal dosage in the biofilter operation for avoiding significant residual in the effluent from biofilters.

     

Modification of cell surface properties of <Emphasis Type="Italic">Pseudomonas alcaligenes</Emphasis> S22 during hydrocarbon biodegradation

Biodegradation of water insoluble hydrocarbons can be significantly increased by the addition of natural surfactants one. Very promising option is the use of saponins. The obtained results indicated that in this system, after 21 days, 92% biodegradation of diesel oil could be achieved using Pseudomonas alcaligenes. No positive effect on the biodegradation process was observed using synthetic surfactant Triton X-100. The kind of carbon source influences the cell surface properties of microorganisms. Modification of the surface cell could be observed by control of the sedimentation profile. This analytical method is a new approach in microbiological analysis.     

Application of biological activated carbon as a low pH biofilter medium for gas mixture treatment

Packing material is a crucial component of a bioreactor as it is the microbial population's habitat. This study assessed potential improvements to current biofiltration processes by investigating use of a novel support medium. Biological activated carbon (BAC) with microorganisms growing on granular activated carbon can produce a novel medium in which both adsorption and biodegradation contribute to pollutants removal. Investigation of carbon characteristics demonstrated that BAC was an ideal packing medium for biofiltration. The application of the novel packing medium for gas mixture treatment was evaluated in a low pH biofilter. Results demonstrated that BAC biofilter obtained high removal efficiency for both H(2)S and toluene. The removal mechanisms of BAC were investigated after the biofilter operation and it demonstrated that the performance of the BAC system was mainly controlled by the additive contributions of two removal mechanisms - adsorption and biodegradation. This study also indicated the potential for simultaneous treatment of hydrogen sulfide and toluene at low pH condition.     

表面活性剂TW-80对土壤中多环芳烃生物降解的影响

以表面活性剂TW80为供试物,进行了为期150d的实验研究,并分别在30、60和150d间隔采样监测PAHs降解率。结果表明,30d后,土壤中PAHs的降解率达90%,比对照提高约30%.60d后,浓度为10000mg·kg^-1表面活性剂的土壤和对照中,PAHs降解率从65.1%和60%迅速提高到93.8%和79.2%.其它处理中,PAHs的平均降解率仅比30d的结果提高4%.150d后,所有处理中PAHs的降解率均达到90%以上。可以认为,表面活性剂能提高PAHs的生物可利用性,加快PAHs的降解速率,从而减少污染暴露时间。但表面活性剂浓度过高可抑制微生物活性。研究还发现,TW80土壤中含有优势真菌。经鉴定为常见青霉、蠕形青霉、淡紫青霉和顶孢头孢霉。它们是土壤PAHs迅速降解的动因.     

Co-degradation with glucose of four surfactants,CTAB, Triton X-100, SDS and Rhamnolipid,in liquid culture media and compost matrix

Strengthened biodegradation is one of the key means to treat surfactant pollution in environment, and microorganism and surfactant have significant effects on degradation. In this paper, co-degradation of CTAB, Triton X-100, SDS and rhamnolipid with glucose by Pseudomonas aeruginosa, Bacillus subtilis and compost microorganisms in liquid culture media, as well as the degradation of rhamnolipid in compost were investigated. The results showed that CTAB was recalcitrant to degrade by the three microorganisms and it also inhibited microorganisms from utilizing readily degradable carbon source. Non-ionic surfactant Triton X-100 could also hardly be degraded, but it was not toxic to microorganisms and would not inhibit the growth of the microorganisms. Anion surfactant SDS had no toxicity to microorganisms and could be co-degraded as carbon source with glucose. Biosurfactant rhamnolipid was a kind of particular surfactant, which had no toxicity and could be degraded by Bacillus subtilis and compost microorganisms, while it could not be utilized by its producing bacterium Pseudomonas aeruginosa. Among these three bacteria, the compost consortium had the strongest degradation capacity on the tested surfactants due to their microorganisms’ diversity. In compost matrix rhamnolipid could be degraded during composting, but not preferentially utilized.     

Effect of type of granular activated carbon on DOC biodegradation in biological activated carbon filters

The purpose of this paper is to clarify the effect of the two different GAC types (steam activated or chemically activated) on DOC biodegradation in biological activated carbon (BAC) columns. For this purpose, raw water taken from a surface reservoir was fed to continuous-flow lab-scale biofiltration columns which were run for more than 18,000 bed volumes. The effect of pre-ozonation on DOC removal was also evaluated. Experimental results showed that biological activity inside the BAC columns extended the service life and the choice of filter material was crucial in BAC systems. The DOC biodegradation was higher in thermally activated carbon columns compared to the chemically activated one. The ability of GAC to better adsorb and retain organic compounds increased the chance of biodegradation. Contrary to expectations, pre-ozonation did not significantly enhance DOC biodegradation. Despite the high increase in biodegradable dissolved organic carbon (BDOC) upon ozonation, overall DOC biodegradation efficiencies did not differ from raw water. Overall, the DOC biodegradation in columns was higher than in most of the studies. This observation was primarily attributed to the low specific ultraviolet absorption (SUVA) values in raw water indicating a high biodegradability.     

Effect of adsorbents on degradation of toxic organic compounds by coimmobilized systems

The use of coimmobilized systems for treatment of toxic organic compounds has been proposed. The proposed approach combines the use of adsorbents and laboratory identified microorganisms immobilized in a protective permeable barrier to achieve a greater degree of control over the remediation process. This study was launched to understand the effect of adsorbents and changes in adsorption on the degradation of toxic compounds by coimmobilized systems. The specific case studied involved the degradation of pentachlorophenol (PCP) by Arthrobacter (ATCC 33790) coimmobilized with powdered activated carbon within calcium alginate capsules.The design parameters studied included adsorbent content and type as well as the effect of solution pH and surfactant concentration on adsorption and biodegradation. It was found that the equilibrium adsorption behavior of PCP was strongly influenced by solution pH and surfactant concentration. A mathematical model was developed that combined the physical processes of mass transfer and adsorption with biological degradation of PCP. The model was used to predict the effect of various parameters on the degradation of PCP. Based on model predictions, the degradation of PCP. Based on model predictions, the degradation of PCP was strongly dependent on variations in adsorbent capacity and affinity for this contaminant.     

Biodegradation of polyalcohol ethoxylate by a wastewater microbial consortium

Polyalcohol ethoxylate (PAE), an anionic surfactant, is the primary component in most laundry and dish wash detergents and is therefore highly loaded in domestic wastewater. Its biodegradation results in the formation of several metabolites and the fate of these metabolites through wastewater treatment plants, graywater recycling processes, and in the environment must be clearly understood. Biodegradation pathways for PAE were investigated in this project with a municipal wastewater microbial consortium. A microtiter-based oxygen sensor system was utilized to determine the preferential use of potential biodegradation products. Results show that while polyethylene glycols (PEGs) were readily degraded by PAE acclimated microorganisms, most of the carboxylic acids tested were not degraded. Biodegradation of PEGs suggests that hydrophobe–hydrophile scission was the dominant pathway for PAE biodegradation in this wastewater community. Ethylene glycol (EG) and diethylene glycol (DEG) were not utilized by microbial populations capable of degrading higher molecular weight EGs. It is possible that EG and DEG may accumulate. The microtiter-based oxygen sensor system was successfully utilized to elucidate information on PAE biodegradation pathways and could be applied to study biodegradation pathways for other important contaminants.     

Quantifying the biodegradation of phenanthrene by Pseudomonas stutzeri P16 in the presence of a nonionic surfactant.

The low water solubility of polycyclic aromatic hydrocarbons is believed to limit their availability to microorganisms, which is a potential problem for bioremediation of polycyclic aromatic hydrocarbon-contaminated sites. Surfactants have been suggested to enhance the bioavailability of hydrophobic compounds, but both negative and positive effects of surfactants on biodegradation have been reported in the literature. Earlier, we presented mechanistic models of the effects of surfactants on phenanthrene dissolution and on the biodegradation kinetics of phenanthrene solubilized in surfactant micelles. In this study, we combined the biodegradation and dissolution models to quantify the influence of the surfactant Tergitol NP-10 on biodegradation of solid-phase phenanthrene by Pseudomonas stutzeri P16. Although micellized phenanthrene does not appear to be available directly to the bacterium, the ability of the surfactant to increase the phenanthrene dissolution rate resulted in an overall increase in bacterial growth rate in the presence of the surfactant. Experimental observations could be predicted well by the derived model with measured biokinetic and dissolution parameters. The proposed model therefore can serve as a base case for understanding the physical-chemical effects of surfactants on nonaqueous hydrocarbon bioavailability.     

Surfactant-Enhanced Biodegradation of a PAH in Soil Slurry Reactors

This study focuses on finding operational regimes for surfactant-enhanced biodegradation. Biodegradation of phenanthrene as a model poly cyclic aromatic hydrocarbon (PAH) was studied in soil slurry reactors in the presence and absence of a Triton N-101 surfactant solution. Results showed that the presence of surfactant slowed the initial biodegradation rate of phenanthrene, but increased the total mass of phenanthrene degraded over a four day period by 30%. A mathematical model was developed which simulates the biodegradation of low solubility hydrocarbons in the presence of soils and surfactants by accounting for the hydrocarbon bioavailability in different phases of the system. The model was able to simulate the experimental results using parameters and rate coefficients that were obtained through independent experiments.

The model was used to investigate the effect of different operating conditions on the overall biodegradation of phenanthrene. Simulation results showed that there is a system-specific optimum surfactant concentration range, beyond which bioremediation is hindered. The results also indicate that for a given system, the optimal surfactant concentration can be determined from simple sorption and solubility equilibrium experiments. Finally, a metric is presented for determining the potential effectiveness of surfactant-enhanced bioremediation based on the Monod and bioavailability parameters for a given system.     

十二烷基苯磺酸钠对引发内置物感染表皮葡萄球菌生物被膜的作用

【背景】随着医用内置物的广泛使用,由表皮葡萄球菌生物被膜导致的医院获得性感染不断增多,目前鲜见关于表面活性剂针对表皮葡萄球菌生物被膜作用的报道。【目的】通过研究阴离子型表面活性剂十二烷基苯磺酸钠(sodium dodecyl benzene sulfonate,SDBS)分别对ATCC 35984 (产膜表皮葡萄球菌标准株)生物被膜的清除、生物被膜内细菌代谢和形成生物被膜的关键物质多糖胞间黏附素(polysaccharide intercellular adhesion,PIA)产生的影响,为临床使用SDBS防治由表皮葡萄球菌生物被膜引起的相关感染提供可靠的理论及实践依据。【方法】利用XTT减低法,评价SDBS对ATCC 35984已形成生物被膜的清除效率及对生物被膜内细菌代谢的影响;激光共聚焦显微镜观察SDBS对生物被膜作用的效果;采用刚果红培养基观察SDBS对PIA产生的影响。【结果】浓度为256、128、64、32、16 mg/L的SDBS在作用6、12、24 h时,对ATCC 35984的生物被膜均有显著的清除效率(P<0.01);浓度为32 mg/L时对生物被膜内细菌的...     

Sorption isotherms and kinetics in the primary biodegradation of anionic surfactants by immobilized bacteria: I. Pseudomonas C12B

The surfactant-degrading biocatalyst Pseudomonas C12B was immobilized by covalent linking on silanized inorganic supports and by physical entrapment of cells within reticulated polyurethane foam. Both immobilized biocatalysts have been shown to be appropriate for the effective primary biodegradation of the anionic surfactants sodium dodecyl sulphate (SDS), dodecylbenzene sulphonic acid (DBS), dioctyl sulphosuccinate (DOSS) and dihexyl sulphosuccinate (DHSS). The overall surfactant removal from water by cells entrapped in reticulated polyurethane foam exhibits a biphasic process, a rapid sorption step of the surfactant onto the cell-loaded support and the intrinsic primary biodegradation slower step, both acting cooperatively. The optimization of variables for the adsorption and the biodegradation processes (flow rate, particle size, substrate concentration) have been studied. Sorption isotherms for the surfactants on reticulated polyurethane foam have been established as type II of the Brunauer, Deming, Deming and Teller (BDDT) classification. The kinetics of the primary biodegradation of SDS by cells covalent linked on sepiolite treated with 3-aminopropyl triethoxysilane (APTS) were found to be first-order. In this case, surfactant adsorption does not exist.     

Treatment of raw and ozonated oil sands process-affected water under decoupled denitrifying anoxic and nitrifying aerobic conditions: a comparative study

Batch experiments were performed to evaluate biodegradation of raw and ozonated oil sands process-affected water (OSPW) under denitrifying anoxic and nitrifying aerobic conditions for 33 days. The results showed both the anoxic and aerobic conditions are effective in degrading OSPW classical and oxidized naphthenic acids (NAs) with the aerobic conditions demonstrating higher removal efficiency. The reactors under nitrifying aerobic condition reduced the total classical NAs of raw OSPW by 69.1 %, with better efficiency for species of higher hydrophobicity. Compared with conventional aerobic reactor, nitrifying aerobic condition substantially shortened the NA degradation half-life to 16 days. The mild-dose ozonation remarkably accelerated the subsequent aerobic biodegradation of classical NAs within the first 14 days, especially for those with long carbon chains. Moreover, the ozone pretreatment enhanced the biological removal of OSPW classical NAs by leaving a considerably lower final residual concentration of 10.4 mg/L under anoxic conditions, and 5.7 mg/L under aerobic conditions. The combination of ozonation and nitrifying aerobic biodegradation removed total classical NAs by 76.5 % and total oxy-NAs (O3–O6) by 23.6 %. 454 Pyrosequencing revealed that microbial species capable of degrading recalcitrant hydrocarbons were dominant in all reactors. The most abundant genus in the raw and ozonated anoxic reactors was Thauera (~56 % in the raw OSPW anoxic reactor, and ~65 % in the ozonated OSPW anoxic reactor); whereas Rhodanobacter (~40 %) and Pseudomonas (~40 %) dominated the raw and ozonated aerobic reactors, respectively. Therefore, the combination of mild-dose ozone pretreatment and subsequent biological process could be a competent choice for OSPW treatment.     

Monitoring of petroleum hydrocarbon degradative potential of indigenous microorganisms in ozonated soil

This study was performed to investigate the petroleum hydrocarbon (PH) degradative potential of indigenous microorganisms in ozonated soil to better develop combined pre-ozonation/bioremediation technology. Diesel-contaminated soils were ozonated for 0–900min. PH and microbial concentrations in the soils decreased with increased ozonation time. The greatest reduction of total PH (TPH, 47.6%) and aromatics (11.3%) was observed in 900-min ozonated soil. The number of total viable heterotrophic bacteria decreased by three orders of magnitude in the soil. Ozonated soils were incubated for 9weeks for bioremediation. The number of microorganisms in the soils increased during the incubation period, as monitored by culture- and nonculture-based methods. The soils showed additional PH-removal during incubation, supporting the presence of PH-degraders in the soils. The highest removal (25.4%) of TPH was observed during the incubation of 180-min ozonated soil during the incubation while a negligible removal was shown in 900-min ozonated soil. This negligible removal could be explained by the existence of relatively few or undetected PH-degraders in 900-min ozonated soil. After a 9-week incubation of the ozonated soils, 180-min ozonated soil showed the lowest TPH concentration, suggesting that appropriate ozonation and indigenous microorganisms survived ozonation could enhance remediation of PH-contaminated soil. Microbial community composition in 9-week incubated soils revealed a slight difference between 900-min ozonated and unozonated soils, as analyzed by whole cell hybridization. Taken together, this study provided insight into indigenous microbial potential to degrade PH in ozonated soils.     

Influence of chemical surfactants on the biodegradation of crude oil by a mixed bacterial culture.

The effects of surfactant physicochemical properties, such as the hydrophile-lipophile balance (HLB) and molecular structure, on the biodegradation of 2% w/v Bow River crude oil by a mixed-bacterial culture were examined. Viable counts increased 4.6-fold and total petroleum hydrocarbon (TPH) biodegradation increased 57% in the presence of Igepal CO-630, a nonylphenol ethoxylate (HLB 13, 0.625 g/L). Only the nonylphenol ethoxylate with an HLB value of 13 substantially enhanced biodegradation. The surfactants from other chemical classes with HLB values of 13 (0.625 g/L) had no effect or were inhibitory. TPH biodegradation enhancement by Igepal CO-630 occurred at concentrations above the critical micelle concentration. When the effect of surfactant on individual oil fractions was examined, the biodegradation enhancement for the saturate and aromatic fractions was the same. In all cases, biodegradation resulted in increased resin and asphaltene concentrations. Optimal surfactant concentrations for TPH biodegradation reduced resin and asphaltene formation. Chemical surfactants have the potential to improve crude oil biodegradation in complex microbial systems, and surfactant selection should consider factors such as molecular structure, HLB, and surfactant concentration.