The industrial solvent trichloroethylene (TCE) is among the most ubiquitous chlorinated compounds found in groundwater pollution. TCE in environment can be removed by physical, chemical and biological procedures. The objective of this pilot-scale study was to apply an enhanced in situ bioremediation technology to remediate TCE-contaminated groundwater. Both aerobic and anaerobic remedial systems were evaluated at a TCE-spill site located in southern Taiwan. In the aerobic test zone, the effectiveness of air, nutrient, and sugarcane molasses injection to enhance the aerobic cometabolism on TCE degradation was evaluated. In the anaerobic test zone, the effectiveness of nutrient and sugarcane molasses injection to enhance the anaerobic reductive dechlorination on TCE degradation was also evaluated. Polymerase chain reaction was applied to analyze the gene variation in TCE-microbial degraders during the treatment process. Results from this study indicate that the aerobic TCE-degraders (type ¢º methanotrophs) and the gene of degradation enzymes (toluene monooxygenase, toluene dioxygenase, particulate methane monooxygenase) were detected after the treatment process in the aerobic test zone. Moreover, TCE concentration dropped from approximately 0.1 mg/L to below 0.05 mg/L in the aerobic test zone after six months of treatment. In the anaerobic treatment zone, Dehalococcoides (anaerobic TCE-degrader) and the gene of degradation enzyme (vcrA) were detected and a significant drop of TCE concentration was also observed. Results reveal that both the aerobic cometabolism and anaerobic dechlorination are feasible and applicable technologies to clean up TCE contaminated aquifers.

This study evaluates the effectiveness of molasses injection for reducing heavy metals and chlorinated solvents in a ground water plume at the Avco-Lycoming Superfund site in Williamsport, Pennsylvania. Molasses injection stimulates the respiration of microorganisms to make a more reducing environment. As the environment?s Redox potential decreases, the rate of chemical reduction increases. The concentrations of heavy metals and chlorinated solvents were monitored to evaluate the effectiveness of the molasses injection. The statistics revealed a decrease in the Oxidation-Reduction Potential in the groundwater and a reduction in hexavalent chromium and TCE concentrations in the groundwater. The Environmental Protection Agency views molasses injection as a viable technique for site remediation. Molasses injection is a form of facilitated natural attenuation. Molasses is injected into a plume to make the environment anaerobic. An anaerobic environment facilitates the microbes that breakdown trichloroethylene (TCE), trans-dichloroethylene (DCE), vinyl chloride (VC) and hexavalent chromium.

No description available.

Abstract The industrial solvents tetrachloroethylene (PCE) and trichloroethylene (TCE) are among the most ubiquitous chlorinated compounds found in groundwater contamination. One potential method for managing PCE/TCE contaminated sites is the intrinsic bioremediation. Recent regulations adopted by U.S. Environmental Protection Agency allow intrinsic bioremediation to be considered as an alternative during development of corrective action plans. In some remediation cases, enhanced bioremediation are performed to accelerate the contaminant biodegradation rate. The main objective of this study was to evaluate the potential of using intrinsic and enhanced bioremediation technologies to clean up PCE/TCE contaminated aquifers. PCE/TCE bioavailability was evaluated by laboratory microcosms under four reduction/oxidation (redox) conditions including aerobic cometabolism, methanogenesis, iron reduction, and reductive dechlorination. Acclimated bacteria, activated sludge, and aquifer sediments from a pentachlorophenol contaminated site were used as the inocula in this study. Methane, toluene, phenol, sludge cake, and cane molasses were used as the primary substrates (carbon sources) in the cometabolism and reductive dechlorination microcosms. Results from this study show that PCE and TCE can be significantly biodegraded under reductive dechlorination and aerobic cometabolism conditions, respectively. All five carbon sources evaluated in this study can be applied as the primary substrates by microbial consortia to enhance the aerobic cometabolism of TCE. The highest TCE degradation rate [Up to 100% of TCE removal (with an initial concentration of 3.6µM)] was observed in the microcosms with toluene enrichment bacteria as the microbial inocula and toluene as the primary substrate. Under reductive dechlorination conditions, both sludge cake and cane molasses could be used as the primary substrates by microbial consortia (from activated sludge and aquifer sediments) and enhanced the biodegradation of PCE. The highest PCE degradation rate [Up to 100% of PCE removal (with an initial concentration of 17µM)] was observed in the microcosms with anaerobic activated sludge as the microbial inocula and sludge cake as the primary substrate. Except for reductive dechlorination microcosms, no significant PCE removal was observed in the microcosms prepared under iron reduction conditions. Results from this feasibility study would be useful in designing a scale-up in situ (e.g., in situ biobarrier system) or on-site bioremediation system (e.g., bioslurry reactor) for field application. Moreover, the application of non-toxic organic waste to enhance PCE/TCE biodegradation has the potential to become an environmentally and economically acceptable technology for the bioremediation of chlorinated-solvent contaminated groundwater.

Microcosm studies were conducted beginning with three xylene isomers: ortho-xylene, meta-xylene and para-xylene; and continued with the four mononitroxylene (MNX) isomers, culminating with testing ten dinitroxylene (DNX) isomers. Soil samples were obtained from a historically contaminated site with high levels of dinitrotoluene (DNT), trinitrotoluene (TNT) and dinitroxylene (DNX) and used as the inoculum for microcosm tests. The microcosm method of different isomers was based on the previous work on biodegradation of nitrotoluene. As it was demonstrated previously that 2,4-DNT degrading bacteria were present at the site, it was hypothesized that these may be capable of transforming or cometabolizing some of DNX isomers. Thus, DNX cometabolism studies were conducted in the presence of 2,4-DNT degrading bacteria. The presence of xylene and 2,4-DNT degrading was confirmed in this thesis. Meanwhile, several MNX and DNX isomers showed degradability in microcosm studies. Cometabolism studies showed that four DNX isomers could be cometabolized by 2,4-DNT enrichment.

Submitted by Fabio Sobreira Campos da Costa (fabio.sobreira@ufpe.br) on 2017-05-04T13:51:09Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertaçãoSILVA2016.pdf: 1538144 bytes, checksum: 5e9ed18ffcbde4ab9a92d5f040477ab7 (MD5) / Made available in DSpace on 2017-05-04T13:51:09Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertaçãoSILVA2016.pdf: 1538144 bytes, checksum: 5e9ed18ffcbde4ab9a92d5f040477ab7 (MD5) Previous issue date: 2016-02-21 / FACEPE / O paclobutrazol (PBZ) é o regulador vegetal utilizado no manejo da produção da mangueira na maioria dos pomares sob as condições semiáridas do Nordeste. Apesar da sua eficiência na produtividade, estudos demonstram que o PBZ permanece ativo no solo por muito tempo e isso pode afetar o desenvolvimento das próximas colheitas, reduzindo o vigor vegetativo. A biodegradação do paclobutrazolem solo não saturado e com histórico de aplicação,foi avaliada durante 49 dias usando glicerol e resíduos industriais (glicerol do biodiesel, torta de amendoim e torta de gergelim) como fontes de adicionais de carbono. Os resíduos agroindustriais (torta de amendoime e torta de gergelim) além de carbono, também são fontes de nitrogênio. Foram realizados estudos cinéticos do consumo de PBZ, além da contagem dos micro-organismos totais, do perfil do pH e da fitotoxicidade no início e final dos experimentos. Adicionalmente, estudos investigativos acerca de produtos da biodegradação foram realizados, com análises de espectroscopia de infravermelho. A torta de amendoim foi o melhor resíduo agroindustrial, sendo usado nas quatro estratégias realizadas na próxima etapa. Nessas quatro estratégias de biodegradação foram realizados experimentos usando 100, 80, 50 e 20 % m/m do solo sem histórico com a adicão de 0, 20, 50 e 80 % m/m de solo com histórico, respectivamente. A adição de solo com histórico (50 ou 80% m/m) e a torta de amendoim favoreceram a biodegradação dosolo sem histórico, cuja biodegradação foi maior que 95%. O resíduoselecionado apresentou-se como uma adequada fonte de carbono e de nitrogênio, e, o solo com histórico um eficiente reservatório de micro-organismos capazes de degradar o PBZ. / Paclobutrazol (PBZ) is a growth regulator used in the management of mango production in most orchards in semi-arid conditions of the Northeast. Despite its efficiency in productivity, studies show that the PBZ remains active in the soil for a long time and this may affect the development of the next crop, reducing plant vigor. The biodegradation of paclobutrazol (PBZ) was evaluated during 49 days using glycerol and agro-industrial wastes (biodieselderived glycerol, peanut cake and sesame cake) as additional carbon sources and unsaturated soil with a history of PBZ application. Kinetic studies were performed of PBZ consumption beyond count of total microorganisms, pH profile and phytotoxicity at the beginning and end of the experiments. Additionally, investigative studies on the caracterization of biodegradation samples were performed with infrared spectroscopy analysis. Biodieselderived peanut cake was the best agro-industrial waste, andthis was used in the following four strategies. Four biodegradation strategies were performed using 100 %, 80 %, 50 % and 20 % of soil without history with the addition of 0 %, 20 %, 50 % and 80 % of soil with history, respectively. The addition of soil with history (50 or 80%) and the selected waste (peanut cake) favored biodegradation of soil without history, with rates about 95 %. The peanut cake waste proved to be an adequate source of carbon and nitrogen, and the soil with history, proved to be an efficient reservoir of microorganisms capable of biodegrading PBZ.

Contamination of soil with Polycyclic Aromatic Hydrocarbons (PAHs) is a serious environmental issue because some PAHs are toxic, carcinogenic and mutagenic. Bioremediation is a promising option to completely remove PAHs from the environment or convert them to less harmful compounds. One of the main challenges in bioremediation of PAHs in a conventional roller bioreactor is the limitation on mass transfer due to the strong hydrophobicity and low water solubility of these compounds. To address this challenge, a novel bead mill bioreactor (BMB) was developed by Riess et al. (2005) which demonstrated a significant improvement in the rates of mass transfer and biodegradation of PAHs. <p> In this study, to further improve mass transfer rates, baffles have been installed in both the conventional and bead mill bioreactors. Mass transfer rates of 1000 mg L-1 suspended naphthalene, 2-methylnaphthalene and 1,5-dimethylnaphthalene, three model compounds of PAHs, have been investigated in four bioreactors: conventional (control), baffled, BMB and baffled bead mill bioreactors. The baffled bioreactor provided mass transfer coefficients (KLa) that were up to 7 times higher than those of the control bioreactor. <p> Bioremediation of suspended naphthalene or 2-methylnaphthalene as a single substrate and their mixtures was studied using the bacterium <i>Pseudomonas putida </i>ATCC 17484. Both baffled and bead mill bioreactors provided maximum bioremediation rates that were 2 times higher than the control bioreactor. The maximum bioremediation rates of 2-methylnaphthalene were further increased in the presence of naphthalene by a factor of 1.5 to 2 compared to the single substrate. <p> Another rate-limiting step for bioremediation of PAH-contaminated soil is the strong sorption between the contaminant and soil. To find out the effect of sorption on the bioavailability of naphthalene, the appropriate sorption isotherms for three types of soils (sand, silt and clay) have been determined. It was observed that the sorption capacity of soils for naphthalene was proportional to the organic carbon content of the soils. The mass transfer of soil-bound naphthalene from the artificially prepared contaminated soils with short contamination history to the aqueous phase was studied in both the control and bead mill bioreactors. It was observed that the mass transfer was unexpectedly fast due to the increased interfacial surface area of naphthalene particles and the weak sorption between naphthalene and soils. It was concluded that artificially, naphthalene contaminated soils would likely not be any more difficult to bioremediate than pure naphthalene particles.

Contamination of soil with Polycyclic Aromatic Hydrocarbons (PAHs) is a serious environmental issue because some PAHs are toxic, carcinogenic and mutagenic. Bioremediation is a promising option to completely remove PAHs from the environment or convert them to less harmful compounds. One of the main challenges in bioremediation of PAHs in a conventional roller bioreactor is the limitation on mass transfer due to the strong hydrophobicity and low water solubility of these compounds. To address this challenge, a novel bead mill bioreactor (BMB) was developed by Riess et al. (2005) which demonstrated a significant improvement in the rates of mass transfer and biodegradation of PAHs. <p> In this study, to further improve mass transfer rates, baffles have been installed in both the conventional and bead mill bioreactors. Mass transfer rates of 1000 mg L-1 suspended naphthalene, 2-methylnaphthalene and 1,5-dimethylnaphthalene, three model compounds of PAHs, have been investigated in four bioreactors: conventional (control), baffled, BMB and baffled bead mill bioreactors. The baffled bioreactor provided mass transfer coefficients (KLa) that were up to 7 times higher than those of the control bioreactor. <p> Bioremediation of suspended naphthalene or 2-methylnaphthalene as a single substrate and their mixtures was studied using the bacterium <i>Pseudomonas putida </i>ATCC 17484. Both baffled and bead mill bioreactors provided maximum bioremediation rates that were 2 times higher than the control bioreactor. The maximum bioremediation rates of 2-methylnaphthalene were further increased in the presence of naphthalene by a factor of 1.5 to 2 compared to the single substrate. <p> Another rate-limiting step for bioremediation of PAH-contaminated soil is the strong sorption between the contaminant and soil. To find out the effect of sorption on the bioavailability of naphthalene, the appropriate sorption isotherms for three types of soils (sand, silt and clay) have been determined. It was observed that the sorption capacity of soils for naphthalene was proportional to the organic carbon content of the soils. The mass transfer of soil-bound naphthalene from the artificially prepared contaminated soils with short contamination history to the aqueous phase was studied in both the control and bead mill bioreactors. It was observed that the mass transfer was unexpectedly fast due to the increased interfacial surface area of naphthalene particles and the weak sorption between naphthalene and soils. It was concluded that artificially, naphthalene contaminated soils would likely not be any more difficult to bioremediate than pure naphthalene particles.

Contamination of groundwater supplies by gasoline and other petroleum-derived hydrocarbons released from underground or aboveground storage tanks is a serious and widespread environmental problem. Corrosion, ground movement, and poor sealing can cause leaks in tanks and associated piping. Petroleum hydrocarbons contain methyl tertiary-butyl ether (MTBE) (a fuel oxygenate), benzene, toluene, ethylbenzene, and xylene isomers (BTEX), the major components of gasoline, which are hazardous substances regulated by many nations. MTBE possesses all the characteristics of a persistent compound in the subsurface: high solubility, low volatility, low sediment sorption, and resistance to biodegradation. The objectives of this study were to (1) evaluate the biodegradibility of MTBE under aerobic conditions, and (2) assess the potential of using the aerobic bioremediation technique to clean up aquifers contaminated by MTBE. In this study, microcosms were constructed to determine the feasibility of biodegrading MTBE by intrinsic microbial consortia (aquifer sediments) under aerobic and aerobic cometabolic conditions. In the cometabolic microcosms, propane, ethanol, and BTEX were applied as the primary substracts to enhance the biodegradation of MTBE. The inocula used in this microcosm study were aquifer sediments collected from the contaminated-zones of a petroleum-hydrocarbon (including MTBE) contaminated site. Microcosms were constructed with nutrient medium (or site groundwater), sediments, and MTBE solution in 70-mL serum bottles sealed with Teflon-lined rubber septa. MTBE was analyzed using purge-and-trap instrument following gas chromatography (GC)/flame ionization detector (FID). Results show that the indigenous microorganisms were able to biodegrade MTBE under aerobic conditions using MTBE as the sole primary substrate. Microcosms with site groundwater as the medium solution show higher MTBE biodegradation rate. This indicates that site groundwater might contain some trace minerals or organics, which could enhance the MTBE biodegradation rate. Results show that the addition of BTEX would also enhance the MTBE removal. However, no significant MTBE biodegradation was observed in microcosms with propane and ethanol as the primary substrates. This reveals that the supplement of the second carbon source might inhibit the degradation of MTBE due to the preferential removal of some organics over MTBE. Results from the microcosm study suggest that aerobic biodegradation plays an important role on the MTBE removal. Intrinsic bioremediation is a feasible technology to remediate the studied MTBE-contaminated site.

Les micropolluants organiques (MPO) tels que les HAPs, PCBs et NP sont sous la surveillance étroite des différentes agences de santé et de l'environnement à cause de leurs effets toxiques, cancérigènes et perturbateurs endocriniens sur les organismes vivants. Dans l'environnement, ils se retrouvent dans le sol, les aquifères, les eaux usées, et en raison de leurs propriétés hydrophobes, ces MPO sont principalement associés aux compartiments matière organique dans les boues d'épuration et les sédiments de rivières. La digestion anaérobie, procédé de stabilisation des boues, présente un potentiel pour l'abattement de ces composés. Les deux principaux mécanismes qui régissent l'abattement dans ces conditions des MPO sont le cométabolisme et la biodisponibilité. Leur double influence est évaluée dans ce travail, avec un focus fort sur l'étude des interactions MPO-matrice, la détermination de la distribution des MPO dans les compartiments physiques de la matrice (libre, sorbé à la matière dissoute et colloïdale (DCM) et sorbé aux particules) et avec une caractérisation fonctionnelle, physique et chimique détaillée de la matrice. Pour cela, des réacteurs anaérobies continus et batch ont été mis en œuvre avec des boues de caractéristiques différentes. L'abattement des MPO varie considérablement en fonction des caractéristiques des boues s'expliquant soit par des variations du niveau de cométabolisme, soit par les différents niveaux de biodisponibilité ; ceci suggère qu'une caractérisation détaillée de la matrice boue pourrait aider à prévoir les niveaux d'abattement des MPO. Par ailleurs, les cinétiques en batch montrent que l'abattement des MPO est associé aux premières étapes de la digestion anaérobie, conjointement à leur transfert du compartiment des particules vers le compartiment aqueux. L'abattement des MPO s'observe simultanément dans les trois compartiments libre, sorbé à la DCM et sorbé aux particules. Il est aussi noté l'importance du compartiment DCM sur l'abattement des MPO de haut poids moléculaire. Les coefficients de partage KDOC et Kpart ont été calculés pour étudier les interactions MPO-matrice., Ces données couplées à celles de caractérisation fonctionnelle de la matrice par fluorescence 3D ont permis de construire un modèle explicatif et prédictif des interactions MPO-matrice à l'aide de la méthode de régression partielle des moindres carrés (PLS). Il a été constaté que le compartiment type acide humique a un rôle important dans les interactions MPO-matrice, principalement dans la phase aqueuse, et dans la phase particulaire, les protéines complexes régissent les interactions. Enfin, des modèles PLS explicatifs et prédictifs d'abattement total des MPO ont été construits. Il en ressort que l'abattement des MPO est favorisé par tous les paramètres du cométabolisme (abattement des divers compartiments matière) et par la concentration des MPO en phase aqueuse ce qui tenterait à confirmer que ce compartiment correspond au compartiment biodisponible. Le modèle prédictif basé sur les caractéristiques des boues initiales a identifié les concentrations initiales de MPO (libre, sorbé à la DCM et aux particules) comme les variables les plus importantes qui permettent de prédire l'abattement total des MPO. Cette étude contribue ainsi à mieux comprendre la répartition des MPO dans les matrices boue, et son implication dans le devenir des MPO, de prévoir cette répartition par une caractérisation fonctionnelle de la matrice et de proposer des stratégies pour optimiser l'abattement des MPO au cours de la digestion anaérobie. / Organic micropollutants (OPs) such as PAHs, NP and PCBs, are nowadays looked as environmental pollutants by environmental and health agencies because of their toxic, carcinogenic and endocrine disrupting effect on living organisms. Within the environment, they can deposit to soil, water bodies and sewage system and due to their hydrophobic properties, they are mainly associated with hydrophobic compartments such as organic matter in sewage sludge. Anaerobic digestion has been shown as a potential biological process for removing these compounds. The two main mechanisms that govern their anaerobic removals are the cometabolism and the bioavailability. In this work, cometabolism and bioavailability influences were evaluated focusing mainly on the study of the OP-organic matrix interactions, the determination of the OPs distribution among the physical compartments (free, sorbed to dissolved and colloidal matter (DCM) and sorbed to particles) combined with a detailed physical, chemical and functional matrix characterization. For this, continuous and batch anaerobic reactors were fed with different sludge samples. It was found that the OPs removals varied greatly as a function of sludge characteristics and that greater or lesser removal might be explained either by variations in cometabolism or by different levels of bioavailability, suggesting that a detailed characterization of the feed may help to predict the OPs removals. Additionally, batch kinetics demonstrated that OPs removals are coupled to the first step of the anaerobic digestion, jointly to the OPs transfer from the particules to the aqueous compartment. The OPs are simultaneously removed from the three physical compartments (free, DCM and particules). Moreover, it was highlighted the importance of the DCM fraction on the removal of the high molecular weight OPs. KDOC and Kpart partition coefficients were calculated to study the OP-organic matrix interactions coupled to a functional characterization by 3D fluorescence of the matrix in order to construct an explicative and predictive model of the OP-organic matrix interactions using partial least square regression (PLS). It was found that the humic acid-like compartment has a great role in the OP-organic matrix interactions mainly in the aqueous phase, and in the particulate phase, the complex proteins govern the interactions. Finally, explanatory and predictive PLS models of total OPs removals were constructed. It was concluded that OPs removals are favored by all cometabolic parameters (substrates removals) jointly to the aqueous OPs concentration which tends to confirm that this compartment corresponds to the bioavailable one. The predictive model based on the initial sludge characteristics, identified the initial OPs concentrations (free, DCM and particulate) as the most important variables that predict the total OPs removals. This study contributes to better understand the OPs distribution among the sludge compartments and its role in the fate and removal of the compounds, to predict this distribution through matter functional characterization and to propose strategies in order to optimize the OPs removals under anaerobic conditions.