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Alkyl benzene sulfonate removal in raw sewage stabilization lagoonsDendy, Bill B. January 1962 (has links)
No description available.
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Sesquioxides of soils effects on inorganic pH dependent cation exchange charge and on adsorption capacity for alkyl benzene sulfonate /Volk, Veril Van, Jackson, Marion LeRoy, January 1966 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1966. / Typescript. Vita. Includes facsimile of one published journal article and texts for two articles to be submitted to journals, all by the author and M.L. Jackson. Description based on print version record. Includes bibliographical references (leaves 116-128).
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Bioconversion of alkylbenzenes by Yarrowia lipolyticaLind, Aingy Chantel 03 1900 (has links)
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2009. / The abundance of alkane by-products formed in South Africa presents a
feedstock opportunity for the production of a wide range of commercially
important products, such as long-chain dioic acids and alcohols. These
compounds are formed as intermediates through the biological conversion of
alkanes, a route which is particularly attractive when compared with chemical
conversion due to its operation under milder process conditions. Furthermore,
advances in genetic manipulation, which enable the accumulation of a range
of metabolic intermediates, make the biological route remarkably flexible.
From the literature review Yarrowia lipolytica was identified as a promising
organism for use in studying alkane bioconversion because of its ability to
produce large quantities of fatty acids when grown on n-paraffins as a sole
carbon source.
The bioconversion of alkanes will not only depend on the genetic modification
but also on the process conditions to maximise growth and bioconversion.
The overall objective of this project was therefore to investigate the potential
of Y. lipolytica for alkane bioconversion by defining the conditions that
maximise both cell growth and bioconversion. The Y. lipolytica strains
supplied (TVN348, TVN493 and WT), however, were not yet modified to the
extent that accumulation of metabolic intermediates was possible. Use was
therefore made of a model system in which the alkane substrate was
substituted with an even chain alkylbenzene. Since Y. lipolytica is unable to
metabolise the benzene ring, the alkylbenzene is converted to the metabolic
intermediate, phenyl acetic acid (PAA), and the potential for bioconversion
assessed through measuring the accumulation of PAA. The specific
objectives of the project were therefore
1) to define and quantify the parameters for the establishment of an
effective model system in shake flasks with respect to trace elements,
buffering, added nitrogen, oxygen supply, glucose concentration,
alkylbenzene substrate and inducer requirements
2) to use the defined model system to identify the most promising strain
of Y. lipolytica TVN348, TVN493 and WT
3) to use the defined model system and selected strain for evaluation of
the influence of time of substrate addition and glucose concentration
on cell growth and bioconversion of Y. lipolytica under controlled
conditions in an instrumented bioreactor Furthermore, since poor reproducibility in cell growth and bioconversion had
been prevalent in previous studies, it was also aimed to identify and
statistically quantify the reproducibility between duplicate or triplicate samples
in each experiment and between sets of different experiments with respect to
PAA formation and cell concentrations.
Studies were conducted in shake flask cultures to define and quantify the
parameters for the model system. The parameters assessed included trace
elements, buffering, nitrogen concentration, oxygen supply, glucose
concentration, alkylbenzene substrate type and possible inducer
requirements. Trace elements, phosphate buffering and added nitrogen did
not significantly affect the cell growth of Y. lipolytica TVN348. The cell
concentration of Y. lipolytica TVN348 and TVN493 was increased by 65%
and 43% respectively for an increase in oxygen supply by decreasing the
working volume from 150ml to 50ml, while the cell concentration of Y.
lipolytica WT was increased by 41% when oxygen supply was increased by
switching from non-baffled to baffled flasks in 50ml cultures. Bioconversion
was also increased for an increase in oxygen supply: 2.4mM to 29.0mM PAA
(Y. lipolytica TVN348) and 1.2mM to 21.7mM PAA (Y. lipolytica TVN493) for a
decrease in working volume; 10.5mM to 46.6mM PAA (Y. lipolytica WT) when
switching from non-baffled to baffled flasks. These results indicated that
adequate oxygen supply is crucial to both growth and bioconversion, and that
further study should be conducted in 50ml working volumes. Cell
concentrations obtained in 1.6% (wt/v) and 3.2% (wt/v) glucose cultures
(3.95x108cells/ml and 4.03x108cells/ml respectively) indicated that cell growth
was neither enhanced nor inhibited by 3.2% (wt/v) glucose. Of the range of
substrates examined (propylbenzene, butylbenzene, sec-butylbenzene,
hexylbenzene, ethyltoluene and tert-butyltoluene for Y. lipolytica TVN348 and
TVN493; octylbenzene and decylbenzene for Y. lipolytica WT), hexylbenzene
was regarded as the best substrate for bioconversion (14.7mM and 14.1mM
PAA for TVN348 and TVN493 respectively; 42.6mM PAA for WT). Lastly, the
absence of a requirement for an additional inducer such as ethanol or oleic
acid was confirmed when PAA was formed from hexylbenzene in the culture
containing additional glucose (25.0mM). This suggested that when using
hexylbenzene as substrate, bioconversion was induced provided sufficient
glucose was available for cell maintenance.
Results from duplicate or triplicate flasks in each individual shake flask
experiment were reproducible and conclusions were based solely on results
which showed 95% confidence intervals. However, reproducibility problems
were experienced with results between different sets of experiments carried
out under the same conditions. The model system was therefore defined by: 1) no addition of trace elements,
additional buffering or added nitrogen, 2) cultures grown in 50ml volumes to
supply an adequate amount of oxygen crucial for growth and bioconversion,
3) 3.2% (wt/v) glucose and 4) addition of 1% (v/v) hexylbenzene at 24h with
no inducer requirements.
Use of the model system in shake flask cultures to identify the most promising
of the three strains of Y. lipolytica supplied demonstrated that there was no
significant difference in cell growth or bioconversion between these strains. Y.
lipolytica WT (which has no genetic modifications) was therefore used for
further investigation until an appropriate strain could be substituted when it
became available.
The growth and bioconversion of Y. lipolytica WT was further investigated
under controlled conditions in a bioreactor. The influence of time of substrate
addition (11h, 24h, 48h) and glucose concentration (3.2% and 6.4% (wt/v)) on
growth and bioconversion was examined.
When hexylbenzene was added at 48h, cell growth was increased
(8.90x108cells/ml) when compared to two of the triplicate cultures with
hexylbenzene addition at 24h (4.74x108cells/ml and 3.92x108cells/ml) and the
culture with hexylbenzene addition at 11h (2.82x108cells/ml). The third of the
triplicate cultures with hexylbenzene addition at 24h, on the other hand,
exhibited the strongest growth (2.23x109cells/ml). The poor reproducibility
between the triplicate cultures with hexylbenzene addition as 24h made it
difficult to determine whether hexylbenzene addition at 24h or 48h maximised
cell growth. Furthermore, the cell growth was not significantly improved when
the glucose concentration was increased from 3.2% (wt/v) to 6.4% (wt/v)
(7.47x108cells/ml for 6.4% glucose culture), however it was also not inhibited.
The highest amount of specific PAA formed by Y. lipolytica WT was found
when hexylbenzene was added at 11h (7.4x10-11mmol PAA/cell), however the
highest accumulated PAA was produced in the culture that exhibited the
strongest growth with hexylbenzene addition at 24h (41.4mM). This
suggested that the bioconversion of hexylbenzene was maximised when it
was added during the active growth phase. It is therefore recommended to
conduct fed-batch experiments in future to maintain the active growth phase.
Accumulated PAA was increased in 6.4% (wt/v) glucose culture (15.2mM
PAA) when compared with two of the 3.2% (wt/v) glucose cultures (5.4mM
and 4.3mM PAA). These results indicated that the increased glucose
concentration did not inhibit the bioconversion. Furthermore, PAA was formed
when 5% (wt/v) residual glucose was observed in the culture, suggesting that
the bioconversion of hexylbenzene was not inhibited at glucose concentrations as high as 5.0% (wt/v). If future work were to be conducted in
bioreactor culture where glucose is added in fed-batch operation, glucose
concentrations in cultures of up to 5% (wt/v) could be considered for initial
studies.
During bioconversion by Y. lipolytica, the PAA measured after hexylbenzene
exhaustion did not, however, correspond to 100% conversion. Further, poor
reproducibility was found in the bioreactor cultures. The disappearance of
hexylbenzene without a corresponding accumulation of PAA and poor
reproducibility was investigated by determining whether PAA was further
degraded or alternatively, whether other metabolic intermediates were being
formed and accumulated from the hexylbenzene. However, substitution of the
hexylbenzene with PAA as substrate confirmed that PAA could not be
metabolised. Further, NMR analyses of both the aqueous and organic phases
of the culture did not identify any additional metabolic intermediates. It is
recommended that additional analyses be conducted on the aqueous and
organic phases to further assess the possible accumulation of intermediates.
The development of the model system in shake flask cultures demonstrated
the importance of adequate oxygen supply for both cell growth and
bioconversion. It was also shown that no inducer was needed because
hexylbenzene acted as its own substrate inducer. Furthermore, comparison of
Y. lipolytica strains TVN348, TVN493 and WT under the defined conditions of
the model system revealed that the genetically modified strains (TVN348,
TVN493) did not exhibit enhanced bioconversion. Bioreactor cultures using
the model system under controlled conditions further showed that
bioconversion was not inhibited at a 5% (wt/v) residual glucose concentration
and suggested that bioconversion was maximised when hexylbenzene was
added during active growth phase. This informs on future work, suggesting
fed-batch operation in order to extend the active growth phase, where
glucose concentrations in the bioreactor of up to 5% (wt/v) can be considered.
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Risk assessment for Linear Alkylbenzene Sulfonates in Mediterranean coastal forest exposed to marine aerosols: a physiological perspectiveJalba, Adriana 09 February 2011 (has links)
The aim of this study was to understand the contribution of Linear Alkylbenzene Sulfonates (LAS) to the decline of Mediterranean coastal forest exposed to marine aerosols. LAS are a group of synthetic anionic surfactants widely used in the composition of household or industrial detergents and agrochemicals. This study was part of a large project (RISICO) aiming the assessment of the environmental impact of the LAS at multiple levels: biodegradation in the coastal waters, sorption – desorption processes in the sediments, toxicity to the aquatic life and toxicity to the coastal forest (by aerosolisation of the sea water).
Previous studies pointed out this group of surfactants as the main cause of the coastal forest decline. However, the quantification of this surfactant in the environmental samples (mainly sea water and foliar deposition) was done using non-specific analytical methods as methylene blue active substances (MBAS), leading to overestimation of the environmental concentrations of LAS.
The work hypothesis was that at actual environmental concentrations, the LAS does not play a key role in the foliar uptake of the sea salt deposited on the coastal vegetation by the marine aerosols, therefore the LAS may not be the main cause of the coastal forest decline.
The research involved both greenhouse experiments and field measurements. The experimental work was conducted on young Mediterranean trees (Laurus nobilis L., Quercus ilex L. and Pinus halepensis P. Mill.) and investigated the synergistic toxic effects of exposure to simulated marine aerosol contaminated with surfactants. An array of endpoints was used including photosynthetic activity, relative water content, foliar deposition and uptake of salt and LAS, and pigments analysis. The results of those experiments revealed that LAS itself did not have phytotoxic effects. Nevertheless, the surfactant was shown to enhance the foliar uptake of the salt in the tested species, especially in Pinus halepensis, confirming the conclusions of previous studies regarding the sensitivity of this species to polluted marine aerosols.
The field work was conducted in San Rossore National Park (Italy) and Porquerolles Island (France) and was focused on evaluating the health status of the Mediterranean forest (Quercus ilex L., Pinus halepensis Mill. and Pinus pinaster Aiton.) and also on quantification of LAS in coastal aerosols using highly specific analytical methods, like the mass spectrometry (MS). The frequencies and extent of injuries in the coastal trees were found to be correlated to the salt but not with the LAS content of the leaves. The concentrations of LAS in the Pinus and Quercus leaves were comparable in the two studied sites but the concentrations of salt were extremely high in San Rossore, suggesting that other factors may determine the excessive salt foliar uptake. The parallel MS and MBAS carried out in the same set of aerosol samples revealed that MBAS measurements were not relevant for LAS concentrations in the marine aerosols. Projecting the experimental results to the real LAS and salt exposure of the coastal forest, we concluded that LAS may play a marginal role in coastal vegetation decline.
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Risk assessment for linear alkylbenzene sulfonates in Mediterranean coastal forest exposed to marine aerosols: a physiological perspectiveJalba, Adriana 09 February 2011 (has links)
The aim of this study was to understand the contribution of Linear Alkylbenzene Sulfonates (LAS) to the decline of Mediterranean coastal forest exposed to marine aerosols. LAS are a group of synthetic anionic surfactants widely used in the composition of household or industrial detergents and agrochemicals. This study was part of a large project (RISICO) aiming the assessment of the environmental impact of the LAS at multiple levels: biodegradation in the coastal waters, sorption – desorption processes in the sediments, toxicity to the aquatic life and toxicity to the coastal forest (by aerosolisation of the sea water). <p>Previous studies pointed out this group of surfactants as the main cause of the coastal forest decline. However, the quantification of this surfactant in the environmental samples (mainly sea water and foliar deposition) was done using non-specific analytical methods as methylene blue active substances (MBAS), leading to overestimation of the environmental concentrations of LAS. <p>The work hypothesis was that at actual environmental concentrations, the LAS does not play a key role in the foliar uptake of the sea salt deposited on the coastal vegetation by the marine aerosols, therefore the LAS may not be the main cause of the coastal forest decline. <p>The research involved both greenhouse experiments and field measurements. The experimental work was conducted on young Mediterranean trees (Laurus nobilis L. Quercus ilex L. and Pinus halepensis P. Mill.) and investigated the synergistic toxic effects of exposure to simulated marine aerosol contaminated with surfactants. An array of endpoints was used including photosynthetic activity, relative water content, foliar deposition and uptake of salt and LAS, and pigments analysis. The results of those experiments revealed that LAS itself did not have phytotoxic effects. Nevertheless, the surfactant was shown to enhance the foliar uptake of the salt in the tested species, especially in Pinus halepensis, confirming the conclusions of previous studies regarding the sensitivity of this species to polluted marine aerosols. <p>The field work was conducted in San Rossore National Park (Italy) and Porquerolles Island (France) and was focused on evaluating the health status of the Mediterranean forest (Quercus ilex L. Pinus halepensis Mill. and Pinus pinaster Aiton.) and also on quantification of LAS in coastal aerosols using highly specific analytical methods, like the mass spectrometry (MS). The frequencies and extent of injuries in the coastal trees were found to be correlated to the salt but not with the LAS content of the leaves. The concentrations of LAS in the Pinus and Quercus leaves were comparable in the two studied sites but the concentrations of salt were extremely high in San Rossore, suggesting that other factors may determine the excessive salt foliar uptake. The parallel MS and MBAS carried out in the same set of aerosol samples revealed that MBAS measurements were not relevant for LAS concentrations in the marine aerosols. Projecting the experimental results to the real LAS and salt exposure of the coastal forest, we concluded that LAS may play a marginal role in coastal vegetation decline. <p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished
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Fate and transport of herbicides in soil in the presence of surfactants in irrigation waterNilufar, Fahmida. January 2005 (has links)
In many countries around the world, municipal sewage and industrial wastewaters are typically treated, or sometimes only partially treated, prior to their discharge into surface waters. A major anionic surfactant, Linear Alkyl benzene Sulfonate (LAS), and a degraded product of a non-ionic surfactant, Nonylphenol (NP), are frequently found in municipal wastewaters. When wastewater containing such surfactants and their degraded products is used for irrigation, it can have an effect on the sorption/desorption and movement of pesticides in soils. Therefore, a lysimeter study was conducted, in summer 2004, to assess the effect of LAS and NP on the movement of agricultural herbicides through a sandy loam soil. The degradation of the herbicides was studied in lysimeters over a ninety-day period. Irrigation water with a concentration of 12 mg L -1 of LAS and NP was used to assess their effect on the leaching of atrazine, metolachlor, and metribuzin. Moreover, a laboratory sorption experiment was undertaken to estimate the partition coefficients (kd) of the three herbicides with water containing the same concentrations of LAS and NP. Irrigation water containing low concentrations of surfactants (LAS and NP) did not increase leaching of the three herbicides. Therefore, these results would reduce the concerns regarding pesticide leaching through sandy soil brought on by LAS and NP in wastewaters for irrigation, which is becoming more important due to increasing water scarcity in the dry climate regions of the world. / Beside the lysimeter study, mathematical models can be used effectively and economically in a very short period of time for simulating herbicide concentrations into soil. PESTFADE, a one dimensional transient flow model, was used, in this study, to simulate the fate of the three herbicides in sandy soils. Another model, Artificial Neural Network (ANN), was also used over mathematical modeling due to its faster execution period and less input parameter requirements, for predicting the concentrations of the three herbicides in a sandy loam soil. The predicted concentrations, from both models were compared with the experimental results from the lysimeter study. Although slight overestimations and underestimations were observed, both models simulated herbicide concentrations in the soil profile satisfactorily.
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Fate and transport of herbicides in soil in the presence of surfactants in irrigation waterNilufar, Fahmida. January 2005 (has links)
No description available.
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