Current Search:   Biodegradation (x)

View All Items

  • CSV Spreadsheet
(1 - 5 of 5)
DEGRADATION OF HALOGENATED ALIPHATIC COMPOUNDS IN SEQUENTIAL ANAEROBIC/AEROBIC METHANOGENIC AND HOMOACETOGENIC ENVIRONMENTS
Title
DEGRADATION OF HALOGENATED ALIPHATIC COMPOUNDS IN SEQUENTIAL ANAEROBIC/AEROBIC METHANOGENIC AND HOMOACETOGENIC ENVIRONMENTS.
Creator
Hoxworth, Scott, Randall, Andrew, University of Central Florida
Abstract / Description
The objective of this study was to utilize an alternating anaerobic/aerobic sequence to biologically transform perchloroethylene to non-hazardous end products such as ethylene, CO2 and H2 using a single microbial consortia in a methanogenic and/or a homoacetogenic environment followed by a aerobic methanotrophic environment. Reductive dechlorination of PCE and TCE to cDCE and VC in an anaerobic environment is typically carried out by methanogens, sulfidogens, or homoacetogens but often (e.g....
Show moreThe objective of this study was to utilize an alternating anaerobic/aerobic sequence to biologically transform perchloroethylene to non-hazardous end products such as ethylene, CO2 and H2 using a single microbial consortia in a methanogenic and/or a homoacetogenic environment followed by a aerobic methanotrophic environment. Reductive dechlorination of PCE and TCE to cDCE and VC in an anaerobic environment is typically carried out by methanogens, sulfidogens, or homoacetogens but often (e.g. in-situ) leads to an accumulation of daughter compounds (cDCE, VC) which are more toxic than their parent compounds (PCE, TCE). Furthermore, PCE is resistant to degradation in aerobic environments while VC and cDCE are readily oxidized co-metabolically by aerobic methanotrophic bacteria, among others. In order to achieve complete mineralization of chlorinated solvents using a biotic system, an anaerobic/aerobic treatment strategy was investigated. This strategy has been accomplished successfully at a lab scale with anaerobic and aerobic reactors in series, and in-situ anaerobic zones with downgradient aerobic zones have been proposed in the field. In contrast, the focus of this research was to expose single mixed microbial consortia to sequential anaerobic/aerobic treatments in order to determine if reductive dechlorination could be sustained following aerobic phases of treatment. If possible this would imply that the anaerobic and aerobic zones (in-situ) or reactors (ex-situ) would not necessarily have to be spatially separated. In pure or dilute cultures where soil material is not present strict anaerobes would typically not resume metabolic activity if exposed to frequent aerobic phases of treatment. However in aquifer material or reactors with large floc/granules it might be possible due to the protection of anaerobic micro-environments as a result of diffusion limitations. Microcosms contained in sealed 120-mL serum bottles were used to generate experimental data including autoclaved abiotic controls with mercuric chloride. Inocula for these microcosms come from a several sources, including anaerobic digester sludge, soils, and contaminated aquifers. Once an experimental microcosm showed signs of reductive dechlorination, an aerobic treatment was implemented. The anaerobic phase of the microcosm was interrupted with a short duration aerobic phase. Headspace air or hydrogen peroxide addition was used to supply oxygen. Analytical data from the experiments indicated that anaerobic reductive dechlorination was readily accomplished during anaerobic phase experiments as PCE was sequentially dechlorinated to TCE and then to cDCE as reported in previous research reported by others in the literature. Additionally, a few mixed consortia microcosms showed evidence of further reductive dechlorination to VC and ethylene. During the sequential environment experiments, analytical data also indicated that reductive dechlorination also resumed after an aerobic sequence utilizing hydrogen peroxide as an oxidizer in the microcosm. No conclusive evidence was observed to indicate that aerobic degradation of cDCE during any of the aerobic phase treatments. This was probably due to the inocula not containing methanotrophs.
Show less
Date Issued
2004
Identifier
CFE0000282, ucf:46238
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000282
MODELING MICROBIOLOGICAL AND CHEMICAL PROCESSES IN MUNICIPAL SOLID WASTE BIOREACTOR: DEVELOPMENT AND APPLICATIONS OF A THREE-PHASE NUMERICAL MODEL BIOKEMOD-3P
Title
MODELING MICROBIOLOGICAL AND CHEMICAL PROCESSES IN MUNICIPAL SOLID WASTE BIOREACTOR: DEVELOPMENT AND APPLICATIONS OF A THREE-PHASE NUMERICAL MODEL BIOKEMOD-3P.
Creator
Gawande, Nitin, Reinhart, Debra, University of Central Florida
Abstract / Description
The numerical computer models that simulate municipal solid waste (MSW) bioreactor landfills have mainly two components – a biodegradation process module and a multi-phase flow module. The biodegradation model describes the chemical and microbiological processes of solid waste biodegradation. The models available to date include predefined solid waste biodegradation reactions and participating species. In a bioreactor landfill several processes, such as anaerobic and aerobic...
Show moreThe numerical computer models that simulate municipal solid waste (MSW) bioreactor landfills have mainly two components – a biodegradation process module and a multi-phase flow module. The biodegradation model describes the chemical and microbiological processes of solid waste biodegradation. The models available to date include predefined solid waste biodegradation reactions and participating species. In a bioreactor landfill several processes, such as anaerobic and aerobic biodegradation, nitrogen and sulfate cycling, precipitation and dissolution of metals, and adsorption and gasification of various anthropogenic organic compounds, occur simultaneously. These processes may involve reactions of several species and the available biochemical models for solid waste biodegradation do not provide users with the flexibility to selectively simulate these processes. This research work includes the development of a generalized biochemical process model, BIOKEMOD-3P, which can accommodate a large number of species and process reactions. This model is able to simulate bioreactor landfill processes in a completely mixed condition; when coupled with a multi-phase model it will be able to simulate a full-scale bioreactor landfill. This generalized biochemical model can simulate laboratory and pilot-scale operations which are important to determine biochemical parameters important for simulation of full-scale operations. To illustrate application of BIOKEMOD-3P, two sets of laboratory MSW bioreactors were simulated in this research work. The first demonstrated simulation of data from anaerobic biodegradation of MSW in experimental bioreactors. In another application, simultaneous nitrification and denitrification processes in MSW bioreactors were simulated. The results from these simulations generated information about various modeling parameters that would help implement these processes in a full-scale bioreactor landfill operation.
Show less
Date Issued
2009
Identifier
CFE0002659, ucf:48227
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002659
CHEMICAL AND BIOLOGICAL TREATMENT OF MATURE LANDFILLLEACHATE
Title
CHEMICAL AND BIOLOGICAL TREATMENT OF MATURE LANDFILLLEACHATE.
Creator
Batarseh, Eyad, Reinhart, Debra, University of Central Florida
Abstract / Description
This dissertation is about treatment of the nonbiodegradable organic content of landfill leachate by chemical oxidation combined with biological treatment. It is divided into three parts. In the first part, ferrate was compared to Fenton's reagent for the purpose of removing non-biodegradable organic compounds from mature leachate. Oxidation conditions (time, pH, and dose) were optimized to yield maximum organic removal using two leachate samples from 20 and 12-year old solid waste cells....
Show moreThis dissertation is about treatment of the nonbiodegradable organic content of landfill leachate by chemical oxidation combined with biological treatment. It is divided into three parts. In the first part, ferrate was compared to Fenton's reagent for the purpose of removing non-biodegradable organic compounds from mature leachate. Oxidation conditions (time, pH, and dose) were optimized to yield maximum organic removal using two leachate samples from 20 and 12-year old solid waste cells. Results from this research demonstrated that ferrate and Fenton's reagent had similar optimum pH ranges (3-5), but different organic removal capacities, ranging from 54 to 79 % of initial leachate organic contents. An advantage of ferrate was that it was relatively effective over a wide pH range (Fenton's reagent lost its reactivity outside optimum pH range). Advantages associated with Fenton's reagent include a higher organic removal capacity, production of more oxidized organic compounds (measured as chemical oxygen demand/dissolved organic carbon), and production of more biodegradable byproducts (measured as 5-day biochemical oxygen demand/chemical oxygen demand). Finally, both treatments were found to oxidize larger molecules (>1000 dalton) and produce smaller molecules, as indicated by an increase in smaller molecule contribution to organic carbon. In part two, effects of Fenton's reagent treatment on biodegradability of three landfill leachates collected from a Florida landfill were evaluated using biochemical oxygen demand (BOD), biochemical methane potential (BMP), and tertamethylammonium hydroxide (TMAH) thermochemolysis gas chromatography/mass spectrometry (GC/MS). The hypothesis was that Fenton's reagent will remove refractory compounds that inhibit biodegradation and will produce smaller, more biodegradable organic molecules which will result in an increase in BOD and BMP values. Both BOD and BMP results demonstrated that Fenton's reagent treatment did not convert mature leachate to biodegradable leachate, as indicated by a low BOD5 expressed as C /dissolved organic carbon (DOC) ratio of almost 0.15 in treated samples and a low net methane production / theoretical methane potential (less than 0.15). Ultimate BOD only slightly increased. However the first-order BOD reaction rate increased by more than five fold, suggesting that Fenton's reagent removed refractory and inhibitory compounds. BMP results demonstrated that the ratio of CO2/CH4 produced during anaerobic biodegradation did not increase in treated leachate (compared to untreated), indicating that small biodegradable organic acids produced by oxidation were removed by coagulation promoted by Fenton's reagent. Finally, the TMAH thermochemolysis results showed that several of the refractory and inhibitory compounds were detected fewer times in treated samples and that carboxylic acids did not appear in treated samples. In the third part of this dissertation the application of flushing/Fenton's reagent oxidation to produce sustainable solid waste cells was evaluated. A treatment similar to pump and treat process utilizing Fenton's reagent on-site treated leachate combined with in-situ aeration was proposed. Treated leachate would be recycled to the landfill cell flushes releasable nonbiodegradable carbon from the cell and oxidizes it externally. This technique was demonstrated to have treatment cost and time benefits over other alternatives for producing completely stable solid waste cells such as anaerobic flushing and biological and/or mechanical pretreatment of solid waste (used in the EU).
Show less
Date Issued
2006
Identifier
CFE0001276, ucf:46912
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001276
The effect of glycerol on readily biodegradable chemical oxygen demand (RBCOD) in a wastewater stream
Title
The effect of glycerol on readily biodegradable chemical oxygen demand (RBCOD) in a wastewater stream.
Creator
Rawut, Rojina, Sadmani, A H M Anwar, Lee, Woo Hyoung, Duranceau, Steven, University of Central Florida
Abstract / Description
This study evaluated the short-term effects of glycerol addition on readily biodegradable (RB) chemical oxygen demand (COD) in a carbon limited wastewater influent. The presence of an RB fraction provides with a suitable substrate for microorganisms to produce volatile fatty acids (VFA). The oxygen utilization rate (OUR) has been used to evaluate the oxygen consumption for RB substrate in wastewater. Wastewater with low organic content contains limited RB substrate, and thus, additional...
Show moreThis study evaluated the short-term effects of glycerol addition on readily biodegradable (RB) chemical oxygen demand (COD) in a carbon limited wastewater influent. The presence of an RB fraction provides with a suitable substrate for microorganisms to produce volatile fatty acids (VFA). The oxygen utilization rate (OUR) has been used to evaluate the oxygen consumption for RB substrate in wastewater. Wastewater with low organic content contains limited RB substrate, and thus, additional carbon source is required to improve biological treatment capability. Acetate, propionate, methanol, and glycerol are the commonly available carbon sources for biological treatment process. However, the cost of acetate and propionate are relatively high, and it is not economical to use these carbon sources in the wastewater plant. The use of methanol as a carbon source inherently poses safety issues in field applications due to its toxic and flammable properties. On the other hand, crude glycerol is the byproduct of biodiesel, which is an excellent carbon source alternative. However, crude glycerol contains impurities and requires a certain degree of purification to enhance the performance. The samples for the study were collected from the Iron Bridge Wastewater Reclamation Facility (Oviedo, FL) designed for treating municipal wastewater. The total COD (TCOD) of the sample influent was in the range of 237 to 408 mg COD/L, and RBCOD value was between 38 and 80.5 mg COD/L, containing up to 10 mg COD/L of VFA. This study also demonstrates the relationship between the glycerol concentration and OURs during the diauxic growth phase from the addition of glycerol. The growth was due to the existence of RB substrate and availability of glycerol for the microorganisms. TCOD increased from 284 to 378 mg COD/L and from 284 mg COD/L to 323 mg COD/L by spiking approximately 30 and 15 mL of glycerol stock solution (6.67 g/L), respectively. RBCOD increased from 45 to 89 mg COD/L and 55 mg COD/ L by spiking 30 mL and 15 ml glycerol stock solution, respectively. The initial influent heterotrophic active biomass (ZBH) increased from 5.4 to 15.8 mg VSS/L (8 to 23.4 mg COD/L) due to the addition of glycerol, indicating that the glycerol may be an adequate carbon source. The COD of wastewater with limited VFA (e.g., 10 mg COD/L) increased up to 2,502 mg COD/L where propionic acid (2,468 mg COD/L) exists as the primary end product with a small quantity of acetic acid (34 mg COD/L). Propionic acid was the main VFA component fermented from the glycerol addition. Glycerol addition led to increased RBCOD accompanied by high VFA production. This research investigated the short-term effect of glycerol addition on existing RBCOD in wastewater. It is recommended to explore the effect of increased RBCOD by the addition of glycerol to the effluent N and P for future study.
Show less
Date Issued
2016
Identifier
CFE0006543, ucf:51324
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006543
Evaluation of The Biodegradability and Toxicity of PCA and mPCA
Title
Evaluation of The Biodegradability and Toxicity of PCA and mPCA.
Creator
Rueda, Juan, Randall, Andrew, Duranceau, Steven, Yestrebsky, Cherie, University of Central Florida
Abstract / Description
The main types of hypergolic propellants used at Kennedy Space Center (KSC) are hydrazine (HZ) and monomethylhydrazine (MMH). HZ and MMH are classified as hazardous materials and they are also known to be potentially carcinogenic to humans; therefore, handling these substances and their waste is strictly regulated. The wastes streams from HZ and MMH have been estimated to be the main hazardous wastes streams at KSC. Currently at KSC these wastes are first neutralized using citric acid and...
Show moreThe main types of hypergolic propellants used at Kennedy Space Center (KSC) are hydrazine (HZ) and monomethylhydrazine (MMH). HZ and MMH are classified as hazardous materials and they are also known to be potentially carcinogenic to humans; therefore, handling these substances and their waste is strictly regulated. The wastes streams from HZ and MMH have been estimated to be the main hazardous wastes streams at KSC. Currently at KSC these wastes are first neutralized using citric acid and then they are transported on public roads for incineration as hazardous materials. A new method using alpha ketoglutaric acid (AKGA) was proposed to treat HZ and MMH wastes. From the reaction of AKGA with HZ and MMH two stable products are formed, 1,4,5,6-tetrahydro-6-oxo-3-pyridazinecarboxylic acid (PCA) and l-methyl-1,4,5,6-tetrahydro-6-oxo-3-pyridazinecarboxylic acid (mPCA), respectively.The cost of purchasing AKGA is greater than the cost of purchasing citric acid; thus, AKGA can only become a cost effective alternative for the treatment of HZ and MMH wastes if the products of the reactions (PCA and mPCA) can be safely disposed of into the sewage system without affecting the treatment efficiency and effluent quality of the wastewater treatment plant (WWTP). In this research mPCA and PCA were analyzed for acute toxicity using fish and crustaceans as well as their effect on the wastewater treatment efficiency and viability using AS microbes, and their biodegradability by AS organisms. Acute toxicity on fish and crustaceans was investigated according to the methods for acute toxicity by USEPA (USEPA Method EPA-821-R-02-012) using Ceriodaphnia dubia (96 hours) and Pimephales promelas (96 hours) as the test organisms. The effect of mPCA and PCA in the treatment efficiency and viability were estimated from respiration inhibition tests (USEPA Method OCSPP 850.3300) and heterotrophic plate counts (HPCs). Lastly, the biodegradability of mPCA and PCA was assessed using the Closed Bottle Test (USEPA Method OPPTS 835.3110). For mPCA, the 96 hours LC50 for C. dubia was estimated at 0.77 (&)#177; 0.06 g/L (with a 95% confidence level) and the NOEC was estimated at 0.5 g/L. For P. promelas, the LC50 was above 1.5 g/L but it was noticed that mPCA had an effect on their behavior. Abnormal behavior observed included loss of equilibrium and curved spine. The NOEC on the fish was estimated at 0.75 g/L. PCA did not exhibit a significant mortality on fish or crustaceans. The LC50 of PCA in P. promelas and C. dubia was (>) 1.5 g/L and the NOEC was 1.5 g/L for both organisms. An Inhibitory effect on the heterotrophic respiration of activated sludge organisms was not observed after exposing them for 180-min to PCA and mPCA at concentrations of up to 1.5 g/L compared to the blank controls. Overall the impact of PCA and mPCA on total respiration rates was small, and only observed at 1,500 mg/L if at all. The difference was apparently caused by inhibition of nitrification rather than heterotrophic inhibition. However due to the variability observed in the measurements of the replicates, it is not possible to firmly conclude that PCA or mPCA at 1,500 mg/L was inhibitory to nitrification.Based on the results from the HPCs, mPCA and PCA did not affect the viability of heterotrophic organisms at 750 mg/L. In the BOD-like closed bottle test using a diluted activated sludge mixed liquor sample, the AS microorganisms were capable of biodegrading up to 67% of a 2 mg/L concentration of PCA (with respect to its theoretical oxygen demand, or ThOD) in 28 days. No biodegradation was observed in the samples containing 2 and 5 mg/L of mPCA after 28 days of incubation using a diluted activated sludge mixed liquor sample as inoculum.The results of this study show that mPCA is more toxic than PCA to Ceriodaphnia dubia and Pimephales promelas. However neither mPCA nor PCA had an effect on the heterotrophic respiration of an AS mixed liquor sample at 1.5 g/L and there was probably no significant inhibition of the nitrification respiration. Samples of PCA and mPCA at 2 and 5 mg/L could not be completely degraded (with respect to their total theoretical oxygen demand) by dilute AS biomass during a 28 day incubation period. mPCA did not show significant degradation in the two different biodegradation tests performed.
Show less
Date Issued
2013
Identifier
CFE0004744, ucf:49779
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004744