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Remediation of Petroleum Impacted Soils in Fungal Compost Bioreactors
Abstract
The ability of the white rot fungus Phanerochaete chrysosporium to enhance the biotransformation of benzo(a)pyrene (B(a)P) in contaminated soils was evaluated in compost bioreactors. Radiolabelled114C and chemical mass balances were used to evaluate: 1) rate of disappearance of test compound; 2) mineralization; 3) formation of bound contaminant residue; and 4) treatment costs.
Mineralization of B(a)P was found to be insignificant over the duration of test period. Moreover, no radioactivity was recovered in volatile organic traps indicating that transformation of B(a)P resulted in chemicals intermediates that remained associated with the compost matrix.
Bound contaminant residue formation was found to be the major mechanism of B(a)P removal accounting for nearly 100% of the contaminant loss from the solvent extract (methylene chloride/acetone). A maximum rate of bound contaminant removal of 1.36 mg B(a)P/Kg soil-day was estimated in fungal inoculated system over the first thirty days of treatment. This was significantly different from the maximum rate of bound residue formation estimated in the noninoculated systems (0.83 mg B(a)P/Kg soil-day) over the same time period. After thirty days, the rate of bound residue formation decreased to near zero in the inoculated system while remaining constant in the noninoculated reactors. The decrease in bound residue formation coincided with decline in benzo(a)pyrene removal. Data suggest that fungal activity may have been reduced over time by nutrient limitation.
... Several studies have documented the ability of white-rot fungi to remediate soils contaminated with polycyclic aromatic hydrocarbons (PAHs) (Stroo et al. 1989;Qiu and McFarland 1991;McFarland et al. 1992;McFarland and Qiu 1995;Andersson and Henrysson 1996;Bogan et al. 1996a,b). However, most published work has focused only on disappearance of the PAH contaminants, with little attention to their actual fate. ...
... However, most published work has focused only on disappearance of the PAH contaminants, with little attention to their actual fate. Among those which have addressed pollutant fate, some authors showed significant accumulations of soluble PAH transformation products, such as ketones and quinones in the cases of fluorene, anthracene and benz[a]anthracene (Andersson and Henrysson 1996;Bogan et al. 1996a,b), while others reported incorporation of PAH (benzo[a]pyrene) into soil organic matter (Qiu and McFarland 1991;McFarland et al. 1992;McFarland and Qiu 1995). It should be noted, however, that these latter authors frequently observed more bound residue formation in indigenous microbial (i.e. ...
... It should be noted, however, that these latter authors frequently observed more bound residue formation in indigenous microbial (i.e. substrate-amended non-inoculated) soil cultures (McFarland et al. 1992;McFarland and Qiu 1995), and found white-rot fungi (specifically, Phanerochaete chrysosporium) in some of their 'non-inoculated' cultures (McFarland and Qiu 1995). Thus, the role of the fungi in the putative humification reported in these studies is very difficult to Correspondence to: Dr Bill W. Bogan, c/o Tienzyme, Inc., 123 Coal Alley, State College, PA 16801, USA (e-mail: wwbogan@gateway.net). ...
The white-rot fungus Pleurotus ostreatus catalysed some humification of anthracene, benzo[a]pyrene and fluoranthene in two polycyclic aromatic hydrocarbon (PAH)-contaminated soils, one from a former manufactured gas facility and one from an abandoned electric coking plant. However, the extent of humification of PAH observed in these experiments was considerably less than that previously reported for other pollutants, such as chlorophenols. Addition of surfactants and related amendments significantly enhanced PAH removal from both soils by P. ostreatus, although humification of PAH was not always enhanced under these conditions.
... In basidiomycetous fungi, PAH quinones are either accumulated as dead-end products (Andersson & Henrysson 1996) or are metabolized by one of several pathways catalyzed by extracellular, non-specific ligninolytic enzymes (Hammel et al. 1992). These reactions result in either complete degradation to CO 2 and H 2 O, or to the formation of bound residues through oxidative crosslinking to the humic fractions of soil (Bogan et al. 1999;Burgos et al. 1996;May et al. 1997;McFarland et al. 1992;Qiu and Mc-Figure 1. Pyrene metabolism by Penicillium janthinellum SFU403. ...
... pyrene and other PAH may be detoxified by microbial metabolism that renders them non-bioavailable to other organisms. This would be similar to extracellular humification of PAH metabolites mediated by fungal extracellular enzymes and chemical reactions in the soil (Bogan et al. 1999;Kastner et al. 1995;May et al. 1997;McFarland et al. 1992;Qiu & McFarland 1991). Further research is ongoing to determine the chemical nature of the bound metabolites. ...
We have previously shown that the filamentous fungus, Penicillium janthinellum SFU403 (SFU403) oxidizes pyrene to pyrene 1,6- and 1,8-quinones and that the level of pyrenequinones (PQs) subsequently declines suggesting that PQs are not terminal metabolites. The purpose of this study was to determine the fate of PQs in SFU403. First, we compared the fate of 14C-pyrene in SFU403 and a non-pyrene-oxidizing fungus, a Paecilomyces sp.. After 7 days of incubation, more than 80% of the radioactivity was cell-associated in both fungi; however, while 90% of the 14C could be extracted from the Paecilomyces sp. as unmetabolized pyrene, 65-80% of the bound radioactivity remained inextractable from SFU403. Further evidence that pyrene oxidation to PQs was required for irreversible binding was obtained by comparing the extent of 14C bound to SFU403 when it was grown for 21 days under conditions that resulted in differing amounts of 14C-pyrene oxidation. The results showed that approximately 40% of the inextractable products were bound residues derived from pyrene metabolites. The balance (60%) could be attributed to strong sorption of unreacted pyrene. We used electron paramagnetic resonance spectroscopy and oxygen consumption studies to demonstrate that both NADPH and glutathione can reduce PQs by one electron to their corresponding semiquinone anion radicals in vitro. These studies demonstrate that PQs are metabolized by SFU403 to bound residues, possibly via semiquinone intermediates.
... Composting has been shown to be effective in the decontamination of soils containing nitroaromatic compounds (Daun et al. 1998; Lenke et al. 1998; Williams & Mayler 1990), aliphatic compounds (Beaudin et al. 1996), chlorophenols (Semple & Fermor 1995; Valo & Salkinoja-Salonen 1986), herbicides (Dooley et al. 1995), pharmaceutical compounds (Rhodes & Peck 1995) and polycyclic aromatic hydrocarbons (PAH) (Joyce et al. 1998; McFarland et al. 1992; Potter et al. 1999 ). Composting appears to be particularly useful in the bioremediation of petroleum hydrocarbons, especially the PAH fraction. ...
... This may be due to sequestration of pyrene in the organic matrix during the lag phase, a process that has been demonstrated previously to render pyrene inaccessible to bacterial degradation (Bogan & Sullivan 2003). PAH degradation rates during composting can best be modeled by first-or zero-order kinetics, reaching a plateau where no more degradation occurs (Joyce et al. 1998; McFarland et al. 1992; Potter et al. 1999). During experiments using the 11-l batch composting reactor, a constant pyrene removal rate of 0.31 mg kg )1 day )1 was observed during the first month (Figure 3 ). ...
Experiments were conducted to determine the effects of composting or simple addition of compost to the mineralization of n-hexadecane, pyrene and benzo(a)pyrene in soil. Soil (contaminated or clean) was composted with maple leaves and alfalfa. Samples from different composting phases were spiked with radiolabeled and cold n-hexadecane, pyrene or benzo(a)pyrene, placed in aerated microcosms at different temperatures, and monitored for mineralization. It was determined that neither composting nor the addition of compost had any effect on n-alkane or benzo(a)pyrene mineralization. In contrast, the pyrene mineralization rate increased dramatically with the amount of time that soil had been composted. Highest pyrene mineralization rates and extents (more than 60% after 20 days) were obtained when pyrene was in contact with composted soil from the curing stage. Neither thermophiles (55 degrees C) nor fungi were responsible for pyrene mineralization.
... This can be done by washing the soil or using a vacuum extractor [23]. To treat soils and other materials contaminated with petroleum wastes, bioreactors have been used [28,29]. ...
Bioremediation is one of the most imminent technological approaches to meet hazardous waste problems, which transforms toxic chemicals into less toxic or nontoxic substances using bacteria or fungi. Instead of direct chemical or physical treatment, such biological transformation is more striking where microorganisms are used as efficient, cost-effective and non-disruptive tools for eliminating hazardous materials. Major destructive impacts of pollutants are perinatal, respiratory, cardiovascular and mental disorders, mortality, allergy, cancer etc. Remarkable results leading to destruction of contaminants can be obtained using genetically concocted microbes that produce many modified enzymes through ecological new technology. Microorganisms utilize metabolic degradation pathways in situ to degrade the foreign undesirable matter directly instead of simply relocating them to another medium to minimize interference of the restoration place. It is certain that for remediation of polluted sites, bioremediation will play a key role in paving the way to greener pastures. The aim of this review article is to provide appropriate information regarding research findings on bioremediation, its types and techniques of eliminating pollutants by microbial consortia. This will facilitate to understand the strategic role of bioremediation at different levels and to apply latest research and knowledge to remove toxicity and to develop strategies to manage the waste generatedin industries, which is a global alarm. Until now, not many microbial enzymes have been exploited and huge microbial diversity is yet to be explored.
... The degradation rate of benzo [a] pyrene was found to be double of the degradation rate in the culture without the fungi. After a month the degradation stopped, which is suggested to be due to nutrient limitation (McFarland et al. 1992). Also AI-Jawhari (2015) found that the maximum crude oil bioremediation was 95% by the pure culture of A. niger, after 28 days treatment. ...
Excessive use of petroleum hydrocarbons is causing many problems in the ecosystem. Practically speaking, injudicious use and inappropriate discharge of all forms of hydrocarbons compounds are harmful for the ecosystem. On the other hand, hydrocarbon components like polyaromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) and their biodegradation products are known for their carcinogenic behavior. The reason of persistence of carbon-based compounds (petroleum hydrocarbons) for a long time in the ecosystem depends on many factors such as the physical factors, type of soil, type of microbes in that particular environment, water and sediment of that area, and above all the chemical nature of the petroleum hydrocarbon. The degradation rate of any hydrocarbon product depends upon the chemical nature of the compound, influence of physical factors (here temperature plays a significant role), and accessibility of hydrocarbon as carbon source for microbes, especially the extracellular enzymes secreted by the microbes. The hydrocarbon compounds released in the soil sediments are easy to degrade compared to the aquatic system; since the diversity of microbes in soil and sediment is more, therefore, released hydrocarbon compounds are easily degraded into simple and nontoxic components. Filamentous fungi are a very important biodegrader, owing to their greater biomass compared to bacterial cell. The fungi have more surface area for biosorption and enzyme secretion for efficient biodegradation of petroleum hydrocarbons. In addition to fungi, other organisms such as bacteria and algae have also been employed as an efficient hydrocarbon biodegrader. The main problem with petroleum hydrocarbon biodegradation is that owing to the recalcitrant nature of petrochemicals, the process is complicated, and it also takes a long time for mineralization. Environmental factors also determine the fate of petroleum hydrocarbons in aquatic and terrestrial ecosystem and also rely on several climatic conditions such as temperature, light, aerobic and anaerobic conditions, pH, wind, availability of nitrogen compounds, presence of humic acids, and salinity. There are several methods and approaches used all over the globe to remove or biodegrade the unwanted hydrocarbons using physical and chemical means, but these approaches are not efficient, and moreover they are not cost-effective. The use of biological means by applying potential microbes for bioremediation is an efficient, eco-friendly, and cost-effective tactic without addition of any unwanted load on the environment.
... The contaminated soil requires pretreatment (e.g., excavation) or alternatively the contaminant can be stripped from the soil via soil washing or physical extraction (e.g., vacuum extraction) before being placed in a bioreactor (Vidali 2001). Bioreactors have been used to treat soil and other materials contaminated with petroleum residues (McFarland et al. 1992;Déziel et al. 1999). ...
With the rising population of the world and daily life demands supplied through industries and modern industrialized agricultural systems, the need for preservation of ecosystems is increasingly revealed. The repeated occurrence of the calamities such as wars, earthquakes, and tsunamis are additional reasons that necessitate further attention to the cleaning of the polluted and/disrupted ecosystems. One of the most economical and stable approaches to cope with this vital task is the use of the techniques developed through progresses in an interdisciplinary science, bioremediation. Bioremediation as a branch of environmental biotechnology takes advantage of various living organisms including bacteria, fungi, algae, and plants in order to remediate the contaminated ecosystems. Here in this introductory chapter, bioremediation and bioremediation techniques are introduced, and fungal bioremediation (mycoremediation) is paid in detail as the main introductory part to the remnant of the present book.
... Investigation of the magnitude of PAHs losses by volatilization also give seemingly contradicting results, with some studies showing that volatilization represents a negligible PAH loss pathway (Guerin, 2000;Kirchmann and Ewnetu, 1998), whereas others show that volatilization plays an important role in contaminant removal (Bossert and Bartha, 1984;Cousins and Jones, 1998). Similarly, when inoculating contaminated soil with organisms, some studies have found no differences between inoculated and non-inoculated systems (Ahtiainen et al., 2002;Canet et al., 2001;McFarland and Qiu, 1995;McFarland et al., 1992;Weissenfels et al., 1990), whereas other studies found a positive effect on PAH degradation (ŠaŠek et al., 2003). As degradation and mineralization of PAHs depend on many interacting factors, it is important to describe the process as completely and as detailed as possible. ...
This paper presents a comprehensive and critical review of research on different co-composting approaches to bioremediate hydrocarbon contaminated soil, organisms that have been found to degrade PAHs, and PAH breakdown products. Advantages and limitations of using certain groups of organisms and recommended areas of further research effort are identified. Studies investigating the use of composting techniques to treat contaminated soil are broad ranging and differ in many respects, which makes comparison of the different approaches very difficult. Many studies have investigated the use of specific bio-additives in the form of bacteria or fungi with the aim of accelerating contaminant removal; however, few have employed microbial consortia containing organisms from both kingdoms despite knowledge suggesting synergistic relationships exist between them in contaminant removal. Recommendations suggest that further studies should attempt to systemize the investigations of composting approaches to bio-remediate PAH-contaminated soil, to focus on harnessing the biodegradative capacity of both bacteria and fungi to create a cooperative environment for PAH degradation, and to further investigate the array of PAHs that can be lost during the composting process by either leaching or volatilization.
... Nevertheless, the best results have generally been obtained for the degradation of low molecular weight PAHs (2–4 rings), while those of high molecular weight show a refractory nature due probably to their hydrophobicity or their complex structure (Crawford et al., 1993; Boonchan et al., 2000). McFarland et al. (1992) explain the reduction of biodegradation by reduced bioavailability, the larger PAHs might be immobilized in micropores and/or bind differently , e.g. oxidative coupling reactions. ...
The level and fate of 16 polycyclic aromatic hydrocarbons (PAHs), targeted by the US Environmental Protection Agency (USEPA), has been studied over 90 days of composting of activated sludge with green
waste, under a semi-arid climate. The total PAH calculated from the sum of the amounts of the 16 PAHs
in the initial mixture of activated sludge and green waste, was lower than accepted European Union cutoff
limits by about 0.48 mg kg�1. The treatment by composting led to a decrease of all PAHs mainly in the
stabilization phase, but some differences could be observed between PAHs with three or fewer aromatic
rings (N 6 3) and those with four or more (NP4). The former (except phenanthrene) exhibited a continuous
decrease, while the latter PAHs with N of four or more and phenanthrene showed increases in the
intermediate stages (30–60 days). This indicates the high potential sorption mainly of PAH with high
molecular weight (NP4) plus phenanthrene, their tight adsorption makes them inaccessible for microbial
attack. The high molecular weight PAHs showed a greater reduction of their bioavailability than
those of low molecular weight. Naphthalene, with the lowest molecular weight, showed the smallest
decrease (about 67.8%) compared to other PAHs of higher molecular weight (decrease reaching 100%).
This is in agreement with the fact that the adsorption is less reversible with increased numbers of fused
aromatic rings or an increase of their hydrophobicity.
... Composting could also be used to increase degradation of pesticides (Fogarty and Tuovinen, 1991; Lemmon and Pylypiw, 1992; Michel et al., 1995 Michel et al., , 1997a Brown et al., 1997; Buyuksonmez et al., 2000), complex natural polymers, e.g. lignin (Lynch, 1987; Requena et al., 1996 Requena et al., , 1997 Chamuris et al., 2000; Tuomela et al., 2000), bioplastics (Mergaert et al., 1994aMergaert et al., ,1994b Mergaert and Swings, 1996; Kleeberg et al., 1998; Rick et al., 1998) and (polyaromatic) hydrocarbons (McFarland et al., 1992; Berger and Schwartz, 1994; Civilini, 1994; Riggle, 1995; Kästner et al., 1995; Silveira and Ganho, 1995; Civilini and Sebastianutto, 1996; Hupe et al., 1996; Sukesan and Watwood, 1998; Löser et al., 1999; Van Gestel et al., 2003). Among the various biological niches found during a composting process, there are likely some that facilitate the degradation of xenobiotic compounds. ...
Composting is a controlled self-heating, aerobic solid phase biodegradative process of organic materials. The process comprises mesophilic and thermophilic phases involving numerous microorganisms. In several successive steps, microbial communities degrade organic substrates into more stable, humified forms and inorganic products, gener-ating heat as a metabolic waste product. Due to the complexity of substrates and intermedi-ate products, microbial diversity and the succession of populations is a prerequisite to ensure complete biodegradation. Due to the dynamic process, both in time and space (microhabi-tats), which is reflected by constantly changing pH, humidity, oxygen partial pressure and temperature it is extremely difficult to detect, albeit isolate, all the microorganisms involved. Research on composts is also so difficult because the process can hardly be simulated in the laboratory since all major gas and temperature fluxes are to a large extent determined by the physical extension of the system. In this comprehensive survey of literature an inventory of the mesophilic and thermophilic bacteria, actinomycetes and fungi isolated during several phases of composting (including also self-heating organic materials) is presented.
... Existeix un factor crític que contribueix a la dificultat intrínseca d'eliminació d'aquests compostos: l'envelliment. A mesura que augmenta el temps de permanència dels HAPs en un sòl, disminueix la seva biodisponibilitat degut a la immobilització d'aquests compostos en els microporus i a la seva associació a la matriu del sòl, possiblement per reaccions oxidatives d'acoblament [Bollag, 1992; McFarland, 1992; Eggen, 1999]. Aquest procés s'anomena envelliment i s'explica per la gran afinitat dels HAPs per adherir-se a les partícules del sòl [Brenner, 2002]. ...
Un dels principals problemes de l'aplicació de tècniques de biorecuperació en sòls contaminats és el gran nombre de variables que intervenen en l'èxit del procés. Davant la dificultat d'establir fórmules generals d'actuació, cada projecte requereix una sèrie d'estudis previs (caracterització de la zona, assajos de tractabilitat) que permetin avaluar diferentscondicions en base a les quals poder realitzar el disseny de la tècnica a aplicar.Fins ara l'avaluació d'una tècnica de biorecuperació s'efectuava només en termes de grau de desaparició del contaminant; actualment, però, s'ha vist la importància de realitzar aquesta avaluació també en funció del grau de mineralització i dels metabòlits acumulats en el sòl.Així doncs l'objectiu principal d'aquest projecte és la posta a punt d'un sistema físic que permeti determinar el grau de mineralització d'un procés de biodegradació i d'un seguit deprotocols experimentals mitjançant els quals es puguin identificar i quantificar els compostosorgànics romanents en el sòl. Paral·lelament, es vol avaluar la influència de l'aplicació dedeterminades condicions (bioaugment i bioestimulació) en el cas concret de la biodegradació d'un HAP: el fenantrè.La successió d'experiments, basats en la mineralització d'una font de carboni fàcilmentassimilable pels microorganismes com la glucosa, ha permès obtenir el disseny definitiu delsistema físic. La seva eficàcia s'ha comprovat en la determinació de l'evolució de la mineralització durant la biodegradació de fenantrè. De les diferents condicions estudiades, cal destacar els resultats obtinguts en el cas del bioaugment: la inoculació de la soca Mycobacterium sp. AP1 no ha tingut cap efecte sobre el grau de mineralització del fenantrè.A continuació s'ha posat a punt un seguit de protocols experimentals per la identificació iquantificació de compostos orgànics en sòls. En base a les característiques del sòl i la rutametabòlica del fenantrè s'ha definit el protocol d'extracció; consisteix en dues extraccionsdiferenciades: una en medi neutre (pH≈7) i una en medi àcid (pH≈2). Seguidament, s'han duta terme els fraccionaments necessaris per condicionar els extractes de cara la seva posterior anàlisi per HPLC. Aquest procediment ha permès quantificar el fenantrè romanent en el sòl però no s'ha pogut identificar cap metabòlit provinent del procés de biodegradació. En el casque fossin presents en el sòl, la concentració dels metabòlits ha resultat ser massa baixa per la sensibilitat del mètode descrit en aquest treball.
... PAHs are very hydrophobic substances that have an ability to bind to organic matter in a soil (McFarland et al., 1992;Richnow et al., 1995), this results in a lowering of the bioavailability of these organic pollutants. For bioremediation purposes, one way to overcome this could be to use microorganisms that produce extracellular enzymes that can act outside the cell. ...
The capability of wood-rotting fungi (WRF) to colonise contaminated soil is an important fungal characteristic in the development of WRF-based soil bioremediation, it is also important to have methods that monitor the presence of the WRF in the soil. In this lab-scale study, it was shown that it was possible to re-capture, localise and identify a brown-rot fungus, Antrodia vaillantii, after it has been inoculated into, and grown in, a contaminated soil from a former gasworks site. The three-dimensional outgrowth of A. vaillantii was monitored by allowing it to grow into fungicide-treated wood baits, temporarily placed in the soil. After two weeks, the baits were withdrawn from the soil and surface sterilised with hydrogen peroxide to favour fungi growing inside baits, i.e., A. vaillantii. After subsequent plating of baits on selective agar medium the presence of A. vaillantii was confirmed with PCR/RFLP. A. vaillantii was found to be viable throughout the 54 days long study and exhibited a surface growth pattern similar to other well-known cord-forming basidiomycetes. Firstly, the upper part of the soil closest to the place of inoculation was colonised, however, over a period of time, the area of colonisation spread deeper into the soil. The detection method employed in the current study gave a conservative estimate of the fungal proliferation and did not require extensive sampling. Its use could be applicable in both applied research, such as soil bioremediation, and in pure microbial ecology studies.
... However, the use of their suggested two-phase model indicated that approximately 2.4 times higher removal rates might be found during the first three weeks of treatment as compared to the use of the one-phase model. The reduction in biodegradation over time in the kinetic study can be explained by reduced bioavailability of PAHs due to immobilisation in micropores or changes in binding forms (McFarland et al., 1992). Although data has been analysed using the one-phase and two-phase models, the variable nature of compost complicated the fitting of the second phase of the twophase model. ...
The biodegradation of 16 polycyclic aromatic hydrocarbons (PAHs), listed as priority pollutants by the USEPA, present in a coal-tar-contaminated soil from a former manufactured gas plant site was investigated using laboratory-scale in-vessel composting reactors to determine the suitability of this approach as a bioremediation technology. Preliminary investigations were conducted over 16 weeks to determine the optimum soil composting temperature (38, 55 and 70 degrees C). Three tests were performed; firstly, soil was composted with green-waste, with a moisture content of 60%. Secondly, microbial activity was HgCl2-inhibited in the soil green-waste mixture with a moisture content of 60%, to evaluate abiotic losses, while in the third experiment only soil was incubated at the three different temperatures. PAHs and microbial populations were monitored. PAHs were lost from all treatments with 38 degrees C being the optimum temperature for both PAH removal and microbial activity. Calculated activation energy values (E(a)) for total PAHs suggested that the main loss mechanism in the soil-green waste reactors was biological, whereas in the soil reactors it was chemical. Total PAH losses in the soil-green waste composting mixtures were by pseudo-first order kinetics at 38 degrees C (k = 0.013 day(-1), R2 = 0.95), 55 degrees C (k = 0.010 day(-1), R2 = 0.76) and at 70 degrees C (k = 0.009 day(-1), R2 = 0.73).
... First order constants of P PAH reached a maximum of about 0.014 day ÿ1 during optimal composting conditions at S:GW 0.8:1, MC 60% and T 38 C. The removal rates reported in this investigation are in agreement with those reported by McFarland and Qiu (1995) and Potter et al. (1999) during composting of PAH-contaminated wastes. The reduction in degradation over time in the kinetic study can be explained by reduced bioavailability of PAHs due to immobilisation in micropores or changes in binding forms (Beck et al., 1996;Ehlers and Luthy, 2003;McFarland et al., 1992). ...
In-vessel composting of polycyclic aromatic hydrocarbons (PAHs) present in contaminated soil from a manufactured gas plant site was investigated over 98 days using laboratory-scale in-vessel composting reactors. The composting reactors were operated at 18 different operational conditions using a 3-factor factorial design with three temperatures (T, 38 degrees C, 55 degrees C and 70 degrees C), four soil to green waste ratios (S:GW, 0.6:1, 0.7:1, 0.8:1 and 0.9:1 on a dry weight basis) and three moisture contents (MC, 40%, 60% and 80%). PAH losses followed first order kinetics reaching 0.015 day(-1) at optimal operational conditions. A factor analysis of the 18 different operational conditions under investigation indicated that the optimal operational conditions for degradation of PAHs occurred at MC 60%, S:GW 0.8:1 and T 38 degrees C. Thus, it is recommended to maintain operational conditions during in-vessel composting of PAH-solid waste close to these values.
... The rates of losses reported in this investigation are in agreement with those reported by McFarland and Qiu (1995) and Potter et al. (1999) during composting of PAH-contaminated wastes. The reduction in losses of PAHs over time in the kinetic study can be explained by reduced bioavailability of PAHs due to immobilisation in micropores or changes in binding forms (McFarland et al., 1992). To test whether bioavailability might be a limiting factor on the kinetics of in-vessel composting, relationships between the first-order constant of losses and the total organic carbon content following 98 days of con-tinuous treatment were sought. ...
In-vessel composting of an aged coal-tar contaminated soil from a manufactured gas plant site was investigated over 98days using laboratory-scale in-vessel composting reactors. The composting reactors were operated at 18 different operational conditions using a logistic three-factor factorial design with three temperatures (T=38, 55 and 70 degrees C), four soil to green waste ratios (S:GW; 0.6:1, 0.7:1, 0.8:1 and 0.9:1 on a dry weight basis) and three moisture contents (MC; 40%, 60% and 80%). Excitation-emission matrix (EEM) fluorescence spectroscopy was used to investigate organic matter dynamics in the composting mixture. The results of this investigation indicated that formation of humic substances can be monitored by fluorescence excitation-emission matrix, and provided evidence of progressive mineralization or humification of the composting mixture. Peak excitation wavelength shifts and peak fluorescence intensity can both be used as indicators to monitor the humification or maturation of compost. Finally, the fluorescence index can be applied to investigate the origin of humic substances and fulvic acids, and the humification or maturation of compost.
An infection caused by fungal, viral or bacterial pathogens that take
advantage of a host having a weak immune system is termed as an
opportunistic infection. Mostly these pathogens can only cause disease in
immunocompromised patients. HIV, leukopenia, malnutrition, ageing and
genetic predisposition are some of the examples. The pathogenic
microorganisms followed some steps for completing the process of infection.
These are exposure, adhesion, invasion, colonization, toxicity, and finally the
tissue damage.
Keywords: opportunistic, infection, immunocompromised, leukopenia
Waste asphalt shingle (WAS) has traditionally been disposed of by landfilling due to environmental concerns surrounding Polycyclic aromatic hydrocarbons in WAS, which may potentially leach out, causing environmental pollution. However, this disposal method has been less environmentally acceptable and less cost effective than in the past due to concern on land resources. This study evaluates the potential of degradation of WAS, therefore reducing the polycyclic aromatic hydrocarbons (PAHs) content, by exploiting microbial biodegradation. The white rot fungus Phanerochaete chrysosporium was tested for its potential to degrade waste asphalt shingle binder. The biodegradation process was analyzed and quantified by both Fourier-transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Results illustrate that P. chrysosporium can degrade WAS binder. GPC analysis indicates that the small asphaltic molecules were biodegraded preferentially by P. chrysosporium. The PAHs content of the WAS binder increased initially during fungal biodegradation, but subsequently decreased with the progression in biodegradation to a level lower than that of the original shingle binder. Results from this study could be used to develop solutions to the sustainable management of waste asphalt shingles.
Spent engine oil is derived from lubricating oil which has been used to lubricate various internal combustion engines and it is drained out for disposal during servicing of the engine. Spent engine oil causes great damage to soil and soil microflora when disposed indiscriminately. Thus, the bioremediation of spent engine oil contaminated soil was studied using indigenous degrading fungi isolated from hydrocarbon contaminated soils obtained from automobile mechanic workshops located at both Okpe and Uvwie Local Government Areas of Delta State, in the Niger Delta region of Nigeria. Three (3) fungi isolates with high engine oil biodegradability potential were used for the spent engine oil (SEO) bioremediation study. The fungi isolates used for the test were identified as, Aspergillus glaucus , Trichoderma polysporum and Talaromyces flavus using the API 20C method. The test microcosms were incubated for four weeks at 28 ± 2<sup>o</sup>C. Physicochemical parameters such as, Sulphate concentrations, Total petroleum hydrocarbon, Nitrate concentrations, Phosphate concentrations, Total organic carbon content, pH and Hydrocarbon utilizing fungi counts were monitored weekly using standard ASTM methods to assess the biodegradation of the spent engine oil. At the end of the test duration, Talaromyces flavus recorded the highest percentage spent engine oil biodegradation (69.66%) for the 5% SEO experimental set up. Similarly, Aspergillus glaucus recorded the highest percentage SEO biodegradation (66.16%) for the 10% experimental set up. Thus, Talaromyces flavus and Aspergillus glaucus could be used to effectively bioaugment the bioremediation process of spent engine oil contaminated soils to restore the soil to its original state within a short period of time.
The release of petroleum hydrocarbon products into the soil due to rapid industrialization and accidental spills poses a serious threat to soil as well as groundwater. These compounds are known as carcinogen and neurotic organic pollutants which cause serious risk to human health and ecosystem. The introduced of bioaugmentation is one of the promising strategy, inexpensive and clean in situ bioremediation due to noninvasive and the selected of hydrocarbon-degrading microorganisms added into the soil can accelerate the degradation capacity of organic pollutants together with indigenous microbial population in the soil. This technique produced a maximum biodegradative capacity of organic pollutants in the soil. To demonstrate the potential of bioaugmentation in soil contaminated with petroleum hydrocarbon, many researchers studied the parameters to determine the optimal degradation conditions. In this chapter, we reviewed the experimental findings and the process of bioaugmentation of hydrocarbon-polluted soil by several selected bacterial strains that were isolated from previous studies around the world.
It is known that the white rot fungus such as Phanerochaete chrysosporium have the ability to degrade polycyclic aromatic hydrocarbons. The simulative solid waste which containing garden soil, corncob and anthracene was prepared, then put it into composting reactor after inoculating well growth phanerochaete chrysosporium. The conditions of composting process were temperature 20°C, and aeration content 0.1m3/ h. After 42 days of treatment anthracene content reduced from 5800mg/kg to 1967.36mg/kg and 66.08% removal of enthracene was observed. The results indicated that P. chrysosporium could be applied effectively to the composting of hazardous waste.
Application of fungal technology (mycoremediation) for the cleanup of polluted soils holds promise since 1985 when the white rot fungus Phanerochaete chrysosporium was found to be able to metabolize a number of important environmental pollutants. This ability is generally attributed to the lignin-degrading enzymic system of the fungus. A similar degrading capability was later described with other white-rot fungal species. Most of the experiments were performed using liquid culture media. In soil conditions, where besides the fungus-degrading capability also other factors affect the process, our knowledge is rather limited. Many of the factors are similar to those generally influencing any soil bioremediation process (properties of the environmental matrix, bioavailability, temperature and other physical parameters, pollutant toxicity). Optimum performance of white rot fungal mycelium introduced into soil depends especially on its survival, colonization of the soil matrix and relation to autochthonous soil microflora. The development of fungal technology for decontamination of polluted soil has also been retarded by limited basic research knowledge; most of the results were obtained with the single fungal species Phanerochaete chrysosporium. However, the data were often generalized for all other white-rot fungal species without considering their physiological and ecological diversity. The goal of the presentation is the evaluation of the above aspects influencing the development of mycoremediation.
Environmental pollution and in particular contaminated waste due to polycyclic aromatic hydrocarbons (PAHs) are of current environmental concern. In an effort to find solutions, bioremediation techniques have shown promising results in the treatment of contaminated wastes. Composting approaches as a bioremediation technology to treat contaminated waste were first reported in the 1980s. This article provides a comprehensive review of research to date on the use of composting approaches for bioremediation of PAH-contaminated waste. It critically evaluates the existing research in an effort to assess the relative effectiveness of different composting approaches, determine optimal composting operation conditions, and identify the limitations and advantages of using composting approaches relative to other solutions, and recommends areas of further research effort.
This study investigated the effect of inoculation of white rot fungus, Pleurotus ostreatus, temperature and two pre-treatment methods on PAH degradation in aged creosote contaminated soil. It is shown that Pleurotus ostreatus has an overall positive effect on PAH degradation, and that temperature and soil pre-treatment affect this degradation. In general, adding bark and incubating at 22°C before inoculation with white rot fungi has a better effect on PAH degradation than no pre-treatment, or pre-treatment with fertilizer. At low temperature (8°C) fungal inoculation had best effect when fertilizer was not added, and significant effect on degradation on different groups of PAH compounds, except for the more easily degradable compounds, 3-ring PAHs and heterocyclic compounds was obtained. Pre-treatment with fertilizer stimulated microbial activity at low temperature and enhanced PAH degradation even without addition of fungi.
The use of lignin degrading fungi for decomposition of a wide variety of xenobiotics has become an area of intensive research. One distinct advantage of lignin degrading fungi over bacteria is that they do not require preconditioning to a particular pollutant prior to transformation. This degradative ability has been attributed to a nonspecific and nonstereoselective extracellular lignin-degrading enzymatic system (ligninase) which is induced by the fungi under nitrogen or carbon-limiting conditions (Reid, 1979). Ligninases (lignin-peroxidases) are responsible for the initial oxidative attack on lignin and other complex molecules via formation of a free radical thereby leading to depolymerization of complex molecular structures. Potential degradative ability of peroxidases may extend to include (1) sorbed contaminants, (2) high molecular-weight, hydrophobic contaminants, and (3) complex mixtures of chemicals typical of a contaminated site.
Principles of Composting
Application of Compost for the Detoxification of Toxic Organic Compounds
Degradation of Petroleum Products
Degradation of Halogenated Compounds
Degradation of Pesticides
Degradation of Explosives
The Fate of Organic Pollutants During Composting
To assess the "bioaccessible" pool of mycelia-bound polycyclic aromatic hydrocarbons (PAHs) and to quantify its biodegradation kinetics in soil, a soil-slurry system containing mycelial pellets of Phanerochaete chrysosporium as a separable biophase was set up. In sterilized and unsterilized soil-slurry, the distribution and dissipation of phenanthrene and pyrene in soil, fungal body of P. chrysosporium and water were independently quantified over the incubation periods. Biosorption and biodegradation contributions to bio-dissipation of dissolved- and sorbed-PAHs were identified. The biodegradation kinetics of PAHs by allochthonous P. chrysosporium and soil wild microorganisms was higher than those predicted by a coupled desorption-biodegradation model, suggesting both allochthonous and wild microorganisms could access sorbed-PAHs. The obvious hysteresis of PAHs in soil reduced their biodegradation, while the biosorbed-PAHs in P. chrysosporium body as an interim pool exhibited reversibly desorption and were almost exhausted via biodegradation. Both biosorption and direct biodegradation of PAHs in soil slurry were stimulated by allochthonous P. chrysosporium. After 90-day incubation, the respective biodegradation percentages for phenanthrene and pyrene were 63.8% and 51.9% in the unsterilized soil without allochthonous microorganisms, and then increased to 94.9% and 90.6% when amended with live P. chrysosporium. These indicate that allochthonous and wild microorganisms may synergistically attack sorbed-PAHs.
The need for aeration of microcosms duringmineralization of 14C-labeled compounds in highoxygen demand environments was assessed using activecompost-soil mixtures as the model system. Rapidmineralization of 14C-hexadecane occurred incontinuously aerated microcosms while nomineralization occurred in unaerated microcosms. Dailyflushing with air also yielded no mineralization.Mineralization of 14C-glucose was much lessdependent on aeration. The alkaline solution volumeand number of CO2 traps required for continuousaeration were calculated and tested experimentally.
The objective of this study was to investigate the degradation patterns of petroleum hydrocarbons during bioremediation of soils containing low levels of contaminants. The study was conducted in pilot-scale bioslurry reactors (70 l) under aerobic conditions. The reactors were equipped with a process-gas-recirculation system to ensure complete containment and eventually complete degradation of all contaminants. The concentrations of benzene, toluene, ethyl benzene, and xylenes (BTEX-compounds) and of naphthalene, anthracene, and phenanthrene were found to decrease rapidly. But, polyaromatic hydrocarbons (PAHs) containing >3 aromatic rings did not show significant biodegradation. Addition of rapidly metabolizing substrates such as sodium acetate and/or phenanthrene did not enhance the degradation of PAHs containing >3 aromatic rings. However, the augmented phenanthrene was rapidly metabolized.
The polycyclic aromatic hydrocarbons (PAH) are highly hazardous pollutants found in soil, sediments and air, and which are produced in the process of organic matter combustion. Some of them are acutely toxic, mutagenic or carcinogenic. The group of fungi which includes Aspergillus ochraceus, Cunninghamella elegans, Cunninghamella echinulata, Phanerochaete chrysosporium, Bjerkandera sp., Trametes versicolor and the yeast Saccharomyces cerevisiae have the ability to oxidize or transform polycyclic aromatic hydrocarbons and render them non-toxic.
Pleurotus ostreatus was applied to aged creosote-contaminated soil. The white rot fungus degraded benzo[a]pyrene most extensively the first month (28%) and further incubation had a less pronounced effect: degradation increased only an additional 4% to 32%. Removal of artificially added [14C]benzo[a]pyrene was higher than the originally aged benzo[a]pyrene; 40$ of the compound was removed after one month and 49% after 3 months of incubation. The mineralisation degree to 14CO2 was only 1%, but it was still significantly higher in comparison to unsterile control soil (0.1%) without rot fungus.
Degradation of polycyclic aromatic hydrocarbons in aged-creosote contaminated soil by applying spent mushroom compost, oyster mushroom, was studied in medium sized polyethylene columns. Two different commercial sources of inoculum were compared, and the effect of organizing soil and substrate in layers or mixing it together was investigated. Degradation of 3-ring compounds were similar for the two fungal inoculums. For the hard degradable PAHs (4- and 5-ring) there was a significant difference. The 4- and 5-ring PAHs were degraded better when soil and fungal substrate were homogenized rather than layered. Fish oil added to spent mushroom compost and mixed with creosote contaminated soil gave best degradation of PAHs. This treatment, incubated for 7 weeks at ambient temperature, resulted in the following removal: 86% of total 16 PAHs, 89% of 3-ring PAHs, 87% of 4-ring PAHs and 48% of 5-ring PAHs.
Four white-rot fungi (Phanerochaete chrysosporium IMI 232175, Pleurotus ostreatus from the University of Alberta Microfungus Collection IMI 341687, Coriolus versicolor IMI 210866 and Wye isolate #7) and all possible combinations of two or more of these fungi, were incubated in microcosms containing wheat straw and non-sterile coal-tar contaminated soil to determine their potential to degrade polycyclic aromatic hydrocarbons (PAHs). Biotic and abiotic controls were prepared similarly and PAH concentrations remaining in each microcosm were determined after 8, 16 and 32 weeks by GC-MS following extraction with dichloromethane. The greatest PAH losses were in the biotic control, compared to small or negligible differences in microcosms inoculated with one or more fungi. These results suggest that in the biotic control native microorganisms colonised the straw added as organic substrate and degraded PAH as an indirect consequence of their metabolism. By contrast, in other microcosms, colonisation of straw by the natural microflora was inhibited because the straw was previously inoculated with fungi. Soil cultures prepared at the end of the experiment showed that though introduced fungi were still alive, they were unable to thrive and degrade PAH in such a highly contaminated soil and remained in a metabolically inactive form.
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