Neal Adrian - Academia.edu (original) (raw)
Papers by Neal Adrian
Springer eBooks, 1988
Alachlor is a pre-emergence chloroacylanilide herbicide in widespread use, marketed as Lasso. In ... more Alachlor is a pre-emergence chloroacylanilide herbicide in widespread use, marketed as Lasso. In South Dakota, chemical spills amounting to nearly 9,000 gallons of pesticides and their solvents have been reported for the past two growing seasons. A large portion of this material has been alachlor; since many spills are not reported, its presence in the environment in high levels may be substantially greater than this.
Water Science and Technology, May 1, 2003
Biodegradation of the energetic compound 2,4,6-trinitrotoluene (TNT) and its intermediate 2,4,6-t... more Biodegradation of the energetic compound 2,4,6-trinitrotoluene (TNT) and its intermediate 2,4,6-triaminotoluene (TAT) was investigated in this study. From previous investigations, a relationship between the biological utilization of ethanol as co-substrate for the reduction of TNT under anaerobic conditions was proposed using an anaerobic fluidized-bed reactor (AFBR). In this study, the theoretical co-substrate requirement for reduction of TNT to TAT was further investigated through the systematic lowering of the ethanol loading to the reactor. Near complete reduction to TAT was observed up to a critical ethanol loading point, as well as the production of methane from the limited excess available ethanol. Once ethanol deficient loading conditions were established, the increased presence of incompletely reduced degradation intermediates, such as 2,4-diamino-6-nitrotoluene, and even TNT, was observed. The cessation of methanogenesis confirmed that no excess ethanol was available. Degradation of the TAT intermediate in the reactor effluent was investigated using two second-stage reactors under oxidizing conditions. The first was an aerobic activated sludge reactor, and the second was a denitrifying fluidized-bed reactor (DenFBR). The aerobic reactor was successful in lowering the chemical oxygen demand (COD), but complete removal of TAT was not accomplished. Because of TAT polymerization and auto-oxidation under aerobic conditions, it was difficult to confirm to what extent of TAT removal was biological. In the DenFBR, incompletely reduced TNT intermediates were not successfully degraded, but strong evidence existed for the degradation of TAT. This is the first known report of second stage degradation of TAT under denitrifying conditions.
Abstract : Pinkwater, a hazardous wastewater containing 2,4,6-trinitrotoluene (TNT), is produced ... more Abstract : Pinkwater, a hazardous wastewater containing 2,4,6-trinitrotoluene (TNT), is produced during munition production or demilitarization operations. Anaerobic bioreactors are under investigation as an alternative to activated carbon for treating pinkwater. This research studied the microbial community structure of an anaerobic bioreactor treating a synthetic feed containing ethanol and TNT. Samples from the reactor were taken weekly, ribonucleic acid (RNA) was extracted and membrane hybridizations were performed using ologonucleotide probes specific for the domains Bacteria and Archaea. The bacterial and archaeal ribosomal RNA (rRNA) were similar between the two reactors, but, after doubling the TNT loading, the archaeal rRNA decreased and the bacterial rRNA increased. In response to the increased TNT loading, the alpha-Proteobacteria increased to 60 percent of the bacterial rRNA, but remained unchanged in the control reactor. In the control reactor, the Methanosarcinales accounted for about 80 percent of the archaeal rRNA, while, in the +TNT reactor, they decreased from about 50 percent to 20 percent after increasing the TNT loading. The Methanomicrobiales accounted for about 80 percent of the Archaea, while they were barely detectable in the control reactor. The findings indicate that TNT significantly affects the bacterial and archaeal community structure. Several strategies are suggested for assessing and optimizing anaerobic bioreactors treating pinkwater.
Water Science and Technology, 2001
In this study, an anaerobic fluidized bed reactor (AFBR) was used to treat a synthetically produc... more In this study, an anaerobic fluidized bed reactor (AFBR) was used to treat a synthetically produced pink water waste stream containing trinitrotoluene (TNT). The synthesized waste consisted of 95 mg/l-TNT, the main contaminant in pink water, which was to be co-metabolized with 560-mg/l ethanol. Granular activated carbon was used as the attachment medium for biological growth. TNT was reduced to a variety of compounds, mainly 2,4,6-triaminotoluene (2,4,6-TAT), 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT), 2,6-diamino-4-nitrotoluene (2,6-DA-4-NT), 2-amino-4,6-dinitrotoluene (2-A-4,6-DNT), and 4-amino-2,6dinitrotoluene (4-A-2,6-DNT). These conversions resulted through the oxidation of ethanol to carbon dioxide under anoxic conditions, or reduction to methane under methanogenic conditions. The anaerobic reactor was charged with 1.0 kg of 16×20 U.S. Mesh Granular Activated Carbon (GAC) and was pre-loaded with 200g of TNT prior to the addition of the mixed seed culture. During the first three weeks of operation, ethanol was completely degraded and no methane was produced. Effluent inorganic carbon revealed stoichiometric conversion of the feed ethanol to dissolved inorganic carbon with accumulation of carbon dioxide in the headspace of the reactor. GAC extraction showed incremental reduction of the nitro groups to amino groups, with 2,4,6-TAT as the final product. After three weeks, the oxygen from the nitro groups was depleted and methane production commenced. The reproducibility of this phenomenon was confirmed by repeating the experiment in the same manner using an identical AFBR. Furthermore, serum bottle tests were conducted using TNT loading ratios of 0.2, 0.4, 0.8, 1.0 g-TNT/g-GAC as well as experiments in the absence of GAC. Similar behavior to that of the columns was observed, with degradation rates varying according to the particular condition. GAC greatly enhanced the degradation rates and the higher TNT loading resulted in slower degradation rates of ethanol.
Archives of Environmental Contamination and Toxicology, Feb 1, 1986
A streptomycete bacterium was isolated from a field soil sample previously treated with the insec... more A streptomycete bacterium was isolated from a field soil sample previously treated with the insecticide isofenphos and found to be capable of growing on several commercial carbamate and organophosphate insecticides. These included carbofuran, cloethocarb, ...
Proceedings of the Water Environment Federation, 2001
Two anaerobic fluidized-bed reactors (AFBRs), the first with sand and the second with granular ac... more Two anaerobic fluidized-bed reactors (AFBRs), the first with sand and the second with granular activated carbon (GAC) were utilized in the biodegradation of 2,4,6trinitrotoluene (TNT) with ethanol as co-substrate. The ethanol loading was systematically lowered beyond the critical point, and the degradation phenomena observed. The point at which the production of methane ceased corresponded well to the theoretical point at which no excess ethanol was available to the system. The complete reduction of TNT to 2,4,6-triaminotoluene (TAT) was observed up to the critical ethanol loading point. A third AFBR with GAC as the attachment medium was utilized under identical operating conditions. In addition to TNT, it received the energetic compounds hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7tetrazocine (HMX). In this reactor too the theoretical ethanol requirement corresponded well to the point at which methane production ceased, and the point up until which complete TNT reduction was observed. Through the operation of laboratory scale reactors, these observations are important practical verifications of the assumed TNT reduction mechanisms. Improved biodegradation was observed on the GAC medium AFBRs compared to the sand medium AFBR. Interestingly, the GAC medium AFBR receiving RDX and HMX was able to degrade the aromatics to a lower concentration than the GAC medium AFBR receiving only TNT. It is possible that the presence of these two energetic compounds may be stimulating some biological degradation process. The activated sludge reactors lowered the effluent DOC further, but were unable to remove TAT completely. Through batch tests with GAC, TNT and varying concentrations of ethanol some inhibition of the methanogens was observed in the presence of TNT. Sufficient ethanol was available to completely transform TNT to TAT, but the higher the presence of excess ethanol the more complete removal of TAT was observed.
Proceedings of the Water Environment Federation, 2000
Two anaerobic fluidized bed reactors (AFBRs) were used to study the biological degradation of org... more Two anaerobic fluidized bed reactors (AFBRs) were used to study the biological degradation of organic energetic compounds. During the first half of the study, the synthetically produced wastewater contained 95 mg/L of the compound 2,4,6-trinitrotoluene (TNT), which was cometabolized with 560 mg/L ethanol. During the second half of the study, the TNT was replaced with 16 mg/L hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 1.1 mg/L octahydro-1,3,5,7tetranitro-1,3,5,7-tetrazocine (HMX). Granular activated carbon (GAC) was selected as attachment medium for the first AFBR, which was preloaded with 200 g of TNT, before addition of the seed culture. During the first three weeks of operation, the ethanol was completely degraded, although no methane production was observed. Analysis of the effluent inorganic carbon content, however, indicated equivalent conversion of the ethanol to dissolved inorganic carbon, with accumulation of carbon dioxide in the reactor headspace. Once the oxygen from the nitro groups of the preloaded TNT was depleted, methane production started. The TNT degradation intermediates which were observed were 2,4,6-triaminotoluene (TAT), 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT), 2,6-diamino-4-nitrotoluene (2,6-DA-4-NT), 2-amino-4,6dinitrotoluene (2-A-4,6-DNT), and 4-amino-2,6-dinitrotoluene (4-A-2,6-DNT). After operating for a period of 200 days, no TAT, or any other intermediates, was observed in the AFBR effluent for a period of 60 days, at which point the AFBR was disrupted for the extraction of GAC. From this point onward, TAT was again constantly observed. It is possible that TAT was being degraded anaerobically during this period, although the phenomenon did not repeat itself. Less complete degradation of TNT, RDX and HMX was consistently observed on the sand attachment medium AFBR than on the GAC-AFBR. This could be attributed to the superior microbial attachment properties of the GAC, or to catalytic properties of the GAC surface. A secondary activated sludge treatment step followed both AFBRs, which aerobically degraded all residual TNT, RDX, HMX and intermediates.
Journal of Hazardous Materials, 2002
Pinkwater is generated during the handling and demilitarization of conventional explosives. This ... more Pinkwater is generated during the handling and demilitarization of conventional explosives. This listed hazardous waste contains dissolved trinitrotoluene (TNT) and cyclo trimethylene trinitramine (RDX), as well as some by-products. It represents the largest quantity of hazardous waste generated by the operations support command, and its treatment produces a by-product hazardous waste--spent granular activated carbon (GAC). Anaerobic treatment in a fluidized bed reactor (FBR) containing GAC is an emerging technology for organic compounds resistant to aerobic biological treatment. Bench scale batch studies using an anaerobic consortium of bacteria fed ethanol as the sole electron donor demonstrated the transformation of TNT to triaminotoluene (TAT), which then degrades to undetectable end products. RDX is sequentially degraded to nitroso-, dinitroso-, trinitroso- and hydroxylaminodinitroso-RDX before the triazine ring is presumably cleaved, forming methanol and formaldehyde as major end products. The bacterial members of the anaerobic consortia are typically found in sludge digesters at municipal or industrial wastewater treatment plants. The results of a pilot scale evaluation of this process that was conducted at McAlester Army Ammunition Plant (MCAAP, OK) over a 1 year period are reported in this paper. The pilot test experienced wide fluctuations in influent concentrations, representative of true field conditions. The FBR was a 20 in. (51 cm) diameter column with an overall height of 15 ft (4.9 m) and a bed of GAC occupying 11 ft (3.4m). Water was recirculated through the column continuously at 30 gpm (114 l/min) to keep the GAC fluidized, and pinkwater for treatment was pumped into the recirculation line. Several flowrates were evaluated to determine the proper mass loading rate (mass of TNT and RDX per reactor volume per time, kg/m(3) per day) which the reactor could handle while meeting the discharge limitations. Based on the tests performed, a 1 gpm (3.785 l/min) rate in the 188 gal (710 l) volume of the fluidized GAC bed was determined to consistently meet the discharge requirements. This information was used to develop a cost estimate for a system capable of treating the total effluent currently produced at MCAAP. The cost of installing and operating this system was compared to the cost of GAC adsorption for MCAAP at current pinkwater generation rates. The GAC-FBR system had an annual operating cost of approximately US$ 19K, compared to US$ 71 K annually for GAC adsorption. When including the amortization of the capital equipment required for the GAC-FBR, the payback period for installation of this new process was estimated at 3.7 years.
Water Research, 2003
(HMX), and 2,4,6-trinitrotoluene (TNT) by a methanogenic mixed culture was investigated. Microcos... more (HMX), and 2,4,6-trinitrotoluene (TNT) by a methanogenic mixed culture was investigated. Microcosms containing a basal medium and the mixed culture were amended with ethanol, propylene glycol (PG), butyrate or hydrogen gas as the electron donor and a mixture of TNT (50 µM), RDX (25 µM), and HMX (8 µM). After 29 days, TNT and RDX were completely transformed to unidentified end products in the bottles amended with ethanol, hydrogen, or PG, while 53%, 40%, and 22% of the HMX was transformed, respectively. There was no loss ofRDX or HMX in the electron donor unamended control bottles. The ethanol and PG were transformed to near stoichiometric amounts of acetate and propionate, suggesting the immediate electron donor supporting the transformation of the H 2 or electron donors that produce H 2 may be a useful strategy for enhancing the anaerobic biodegradation of explosives in contaminated groundwater and soils. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.
This study examined the biodegradation of RDX in wastewater from an industrial wastewater treatme... more This study examined the biodegradation of RDX in wastewater from an industrial wastewater treatment plant at the Holston Army Ammunition Plant in Kingsport, TN. Serum bottles containing 100 ml of a basal salts medium amended with 10 percent (v/v) sludge from the anoxic filter at the plant were amended with RDX and incubated under methanogenic conditions. Biodegradation intermediates corresponding to
Environmental Toxicology and Chemistry, 2001
The metabolic fate of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a mixed culture incubated ... more The metabolic fate of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a mixed culture incubated under methanogenic conditions was studied. Analysis by high-performance liquid chromatography (HPLC) confirmed the loss of RDX and the formation of mono-, di-, and trinitroso-RDX as transient biodegradation intermediates. An additional peak observed in the HPLC chromatograms was identified by liquid chromatography-mass spectrometry as hydroxylamino-dinitroso-1,3,5-triazine. This is the first report identifying hydroxylamino-dinitroso-1,3,5-triazine as a transient intermediate produced during the anaerobic biodegradation of RDX.
Applied and environmental microbiology, 1990
We studied the metabolic fate of bromacil in anaerobic aquifer slurries held under denitrifying, ... more We studied the metabolic fate of bromacil in anaerobic aquifer slurries held under denitrifying, sulfate-reducing, or methanogenic conditions. Liquid chromatograhy-mass spectrometry of the slurries confirmed that bromacil was debrominated under methanogenic conditions but was not degraded under the other incubation conditions. This finding extends the range of aryl reductive dehalogenation reactions to include nitrogen heterocyclic compounds.
Applied and environmental microbiology, 1994
Accurate predictions of carbon and energy cycling rates in the environment depend on sampling fre... more Accurate predictions of carbon and energy cycling rates in the environment depend on sampling frequencies and on the spatial variability associated with biological activities. We examined the variability associated with anaerobic biodegradation rates at two sites in an alluvial sand aquifer polluted by municipal landfill leachate. In situ rates of methane production were measured for almost a year, using anaerobic wells installed at two sites. Methane production ranged from 0 to 560 mumol . m . day at one site (A), while a range of 0 to 120,000 mumol . m . day was measured at site B. The mean and standard deviations associated with methane production at site A were 17 and 57 mumol . m . day, respectively. The comparable summary statistics for site B were 2,000 and 9,900 mumol . m . day. The coefficients of variation at sites A and B were 340 and 490%, respectively. Despite these differences, the two sites had similar seasonal trends, with the maximal rate of methane production occur...
Abstract: The US Army generates large volumes of explosives-contaminated wastewater during muniti... more Abstract: The US Army generates large volumes of explosives-contaminated wastewater during munitions production and demilitarization operations. Contaminants such as 2, 4, 6-trinitrotoluene (TNT) and hexahydro-l, 3, 5-trinitro-l, 3, 5-triazine (RDX) are ...
... The USACERL principal investigator was Bernard A. Donahue. Part ... observed. The formation o... more ... The USACERL principal investigator was Bernard A. Donahue. Part ... observed. The formation of C02 was observed from radiolabeled HMX during composting experiments although no intermediates were identified (Doyle et al. 1986). ...
The contents of this report are not to be used for advertising, publication or promotional purpos... more The contents of this report are not to be used for advertising, publication or promotional purposes. Citation of trade names does not constitute ar official endorsement or approval of the use of such commercial products. The findings of this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents.
Springer eBooks, 1988
Alachlor is a pre-emergence chloroacylanilide herbicide in widespread use, marketed as Lasso. In ... more Alachlor is a pre-emergence chloroacylanilide herbicide in widespread use, marketed as Lasso. In South Dakota, chemical spills amounting to nearly 9,000 gallons of pesticides and their solvents have been reported for the past two growing seasons. A large portion of this material has been alachlor; since many spills are not reported, its presence in the environment in high levels may be substantially greater than this.
Water Science and Technology, May 1, 2003
Biodegradation of the energetic compound 2,4,6-trinitrotoluene (TNT) and its intermediate 2,4,6-t... more Biodegradation of the energetic compound 2,4,6-trinitrotoluene (TNT) and its intermediate 2,4,6-triaminotoluene (TAT) was investigated in this study. From previous investigations, a relationship between the biological utilization of ethanol as co-substrate for the reduction of TNT under anaerobic conditions was proposed using an anaerobic fluidized-bed reactor (AFBR). In this study, the theoretical co-substrate requirement for reduction of TNT to TAT was further investigated through the systematic lowering of the ethanol loading to the reactor. Near complete reduction to TAT was observed up to a critical ethanol loading point, as well as the production of methane from the limited excess available ethanol. Once ethanol deficient loading conditions were established, the increased presence of incompletely reduced degradation intermediates, such as 2,4-diamino-6-nitrotoluene, and even TNT, was observed. The cessation of methanogenesis confirmed that no excess ethanol was available. Degradation of the TAT intermediate in the reactor effluent was investigated using two second-stage reactors under oxidizing conditions. The first was an aerobic activated sludge reactor, and the second was a denitrifying fluidized-bed reactor (DenFBR). The aerobic reactor was successful in lowering the chemical oxygen demand (COD), but complete removal of TAT was not accomplished. Because of TAT polymerization and auto-oxidation under aerobic conditions, it was difficult to confirm to what extent of TAT removal was biological. In the DenFBR, incompletely reduced TNT intermediates were not successfully degraded, but strong evidence existed for the degradation of TAT. This is the first known report of second stage degradation of TAT under denitrifying conditions.
Abstract : Pinkwater, a hazardous wastewater containing 2,4,6-trinitrotoluene (TNT), is produced ... more Abstract : Pinkwater, a hazardous wastewater containing 2,4,6-trinitrotoluene (TNT), is produced during munition production or demilitarization operations. Anaerobic bioreactors are under investigation as an alternative to activated carbon for treating pinkwater. This research studied the microbial community structure of an anaerobic bioreactor treating a synthetic feed containing ethanol and TNT. Samples from the reactor were taken weekly, ribonucleic acid (RNA) was extracted and membrane hybridizations were performed using ologonucleotide probes specific for the domains Bacteria and Archaea. The bacterial and archaeal ribosomal RNA (rRNA) were similar between the two reactors, but, after doubling the TNT loading, the archaeal rRNA decreased and the bacterial rRNA increased. In response to the increased TNT loading, the alpha-Proteobacteria increased to 60 percent of the bacterial rRNA, but remained unchanged in the control reactor. In the control reactor, the Methanosarcinales accounted for about 80 percent of the archaeal rRNA, while, in the +TNT reactor, they decreased from about 50 percent to 20 percent after increasing the TNT loading. The Methanomicrobiales accounted for about 80 percent of the Archaea, while they were barely detectable in the control reactor. The findings indicate that TNT significantly affects the bacterial and archaeal community structure. Several strategies are suggested for assessing and optimizing anaerobic bioreactors treating pinkwater.
Water Science and Technology, 2001
In this study, an anaerobic fluidized bed reactor (AFBR) was used to treat a synthetically produc... more In this study, an anaerobic fluidized bed reactor (AFBR) was used to treat a synthetically produced pink water waste stream containing trinitrotoluene (TNT). The synthesized waste consisted of 95 mg/l-TNT, the main contaminant in pink water, which was to be co-metabolized with 560-mg/l ethanol. Granular activated carbon was used as the attachment medium for biological growth. TNT was reduced to a variety of compounds, mainly 2,4,6-triaminotoluene (2,4,6-TAT), 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT), 2,6-diamino-4-nitrotoluene (2,6-DA-4-NT), 2-amino-4,6-dinitrotoluene (2-A-4,6-DNT), and 4-amino-2,6dinitrotoluene (4-A-2,6-DNT). These conversions resulted through the oxidation of ethanol to carbon dioxide under anoxic conditions, or reduction to methane under methanogenic conditions. The anaerobic reactor was charged with 1.0 kg of 16×20 U.S. Mesh Granular Activated Carbon (GAC) and was pre-loaded with 200g of TNT prior to the addition of the mixed seed culture. During the first three weeks of operation, ethanol was completely degraded and no methane was produced. Effluent inorganic carbon revealed stoichiometric conversion of the feed ethanol to dissolved inorganic carbon with accumulation of carbon dioxide in the headspace of the reactor. GAC extraction showed incremental reduction of the nitro groups to amino groups, with 2,4,6-TAT as the final product. After three weeks, the oxygen from the nitro groups was depleted and methane production commenced. The reproducibility of this phenomenon was confirmed by repeating the experiment in the same manner using an identical AFBR. Furthermore, serum bottle tests were conducted using TNT loading ratios of 0.2, 0.4, 0.8, 1.0 g-TNT/g-GAC as well as experiments in the absence of GAC. Similar behavior to that of the columns was observed, with degradation rates varying according to the particular condition. GAC greatly enhanced the degradation rates and the higher TNT loading resulted in slower degradation rates of ethanol.
Archives of Environmental Contamination and Toxicology, Feb 1, 1986
A streptomycete bacterium was isolated from a field soil sample previously treated with the insec... more A streptomycete bacterium was isolated from a field soil sample previously treated with the insecticide isofenphos and found to be capable of growing on several commercial carbamate and organophosphate insecticides. These included carbofuran, cloethocarb, ...
Proceedings of the Water Environment Federation, 2001
Two anaerobic fluidized-bed reactors (AFBRs), the first with sand and the second with granular ac... more Two anaerobic fluidized-bed reactors (AFBRs), the first with sand and the second with granular activated carbon (GAC) were utilized in the biodegradation of 2,4,6trinitrotoluene (TNT) with ethanol as co-substrate. The ethanol loading was systematically lowered beyond the critical point, and the degradation phenomena observed. The point at which the production of methane ceased corresponded well to the theoretical point at which no excess ethanol was available to the system. The complete reduction of TNT to 2,4,6-triaminotoluene (TAT) was observed up to the critical ethanol loading point. A third AFBR with GAC as the attachment medium was utilized under identical operating conditions. In addition to TNT, it received the energetic compounds hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7tetrazocine (HMX). In this reactor too the theoretical ethanol requirement corresponded well to the point at which methane production ceased, and the point up until which complete TNT reduction was observed. Through the operation of laboratory scale reactors, these observations are important practical verifications of the assumed TNT reduction mechanisms. Improved biodegradation was observed on the GAC medium AFBRs compared to the sand medium AFBR. Interestingly, the GAC medium AFBR receiving RDX and HMX was able to degrade the aromatics to a lower concentration than the GAC medium AFBR receiving only TNT. It is possible that the presence of these two energetic compounds may be stimulating some biological degradation process. The activated sludge reactors lowered the effluent DOC further, but were unable to remove TAT completely. Through batch tests with GAC, TNT and varying concentrations of ethanol some inhibition of the methanogens was observed in the presence of TNT. Sufficient ethanol was available to completely transform TNT to TAT, but the higher the presence of excess ethanol the more complete removal of TAT was observed.
Proceedings of the Water Environment Federation, 2000
Two anaerobic fluidized bed reactors (AFBRs) were used to study the biological degradation of org... more Two anaerobic fluidized bed reactors (AFBRs) were used to study the biological degradation of organic energetic compounds. During the first half of the study, the synthetically produced wastewater contained 95 mg/L of the compound 2,4,6-trinitrotoluene (TNT), which was cometabolized with 560 mg/L ethanol. During the second half of the study, the TNT was replaced with 16 mg/L hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and 1.1 mg/L octahydro-1,3,5,7tetranitro-1,3,5,7-tetrazocine (HMX). Granular activated carbon (GAC) was selected as attachment medium for the first AFBR, which was preloaded with 200 g of TNT, before addition of the seed culture. During the first three weeks of operation, the ethanol was completely degraded, although no methane production was observed. Analysis of the effluent inorganic carbon content, however, indicated equivalent conversion of the ethanol to dissolved inorganic carbon, with accumulation of carbon dioxide in the reactor headspace. Once the oxygen from the nitro groups of the preloaded TNT was depleted, methane production started. The TNT degradation intermediates which were observed were 2,4,6-triaminotoluene (TAT), 2,4-diamino-6-nitrotoluene (2,4-DA-6-NT), 2,6-diamino-4-nitrotoluene (2,6-DA-4-NT), 2-amino-4,6dinitrotoluene (2-A-4,6-DNT), and 4-amino-2,6-dinitrotoluene (4-A-2,6-DNT). After operating for a period of 200 days, no TAT, or any other intermediates, was observed in the AFBR effluent for a period of 60 days, at which point the AFBR was disrupted for the extraction of GAC. From this point onward, TAT was again constantly observed. It is possible that TAT was being degraded anaerobically during this period, although the phenomenon did not repeat itself. Less complete degradation of TNT, RDX and HMX was consistently observed on the sand attachment medium AFBR than on the GAC-AFBR. This could be attributed to the superior microbial attachment properties of the GAC, or to catalytic properties of the GAC surface. A secondary activated sludge treatment step followed both AFBRs, which aerobically degraded all residual TNT, RDX, HMX and intermediates.
Journal of Hazardous Materials, 2002
Pinkwater is generated during the handling and demilitarization of conventional explosives. This ... more Pinkwater is generated during the handling and demilitarization of conventional explosives. This listed hazardous waste contains dissolved trinitrotoluene (TNT) and cyclo trimethylene trinitramine (RDX), as well as some by-products. It represents the largest quantity of hazardous waste generated by the operations support command, and its treatment produces a by-product hazardous waste--spent granular activated carbon (GAC). Anaerobic treatment in a fluidized bed reactor (FBR) containing GAC is an emerging technology for organic compounds resistant to aerobic biological treatment. Bench scale batch studies using an anaerobic consortium of bacteria fed ethanol as the sole electron donor demonstrated the transformation of TNT to triaminotoluene (TAT), which then degrades to undetectable end products. RDX is sequentially degraded to nitroso-, dinitroso-, trinitroso- and hydroxylaminodinitroso-RDX before the triazine ring is presumably cleaved, forming methanol and formaldehyde as major end products. The bacterial members of the anaerobic consortia are typically found in sludge digesters at municipal or industrial wastewater treatment plants. The results of a pilot scale evaluation of this process that was conducted at McAlester Army Ammunition Plant (MCAAP, OK) over a 1 year period are reported in this paper. The pilot test experienced wide fluctuations in influent concentrations, representative of true field conditions. The FBR was a 20 in. (51 cm) diameter column with an overall height of 15 ft (4.9 m) and a bed of GAC occupying 11 ft (3.4m). Water was recirculated through the column continuously at 30 gpm (114 l/min) to keep the GAC fluidized, and pinkwater for treatment was pumped into the recirculation line. Several flowrates were evaluated to determine the proper mass loading rate (mass of TNT and RDX per reactor volume per time, kg/m(3) per day) which the reactor could handle while meeting the discharge limitations. Based on the tests performed, a 1 gpm (3.785 l/min) rate in the 188 gal (710 l) volume of the fluidized GAC bed was determined to consistently meet the discharge requirements. This information was used to develop a cost estimate for a system capable of treating the total effluent currently produced at MCAAP. The cost of installing and operating this system was compared to the cost of GAC adsorption for MCAAP at current pinkwater generation rates. The GAC-FBR system had an annual operating cost of approximately US$ 19K, compared to US$ 71 K annually for GAC adsorption. When including the amortization of the capital equipment required for the GAC-FBR, the payback period for installation of this new process was estimated at 3.7 years.
Water Research, 2003
(HMX), and 2,4,6-trinitrotoluene (TNT) by a methanogenic mixed culture was investigated. Microcos... more (HMX), and 2,4,6-trinitrotoluene (TNT) by a methanogenic mixed culture was investigated. Microcosms containing a basal medium and the mixed culture were amended with ethanol, propylene glycol (PG), butyrate or hydrogen gas as the electron donor and a mixture of TNT (50 µM), RDX (25 µM), and HMX (8 µM). After 29 days, TNT and RDX were completely transformed to unidentified end products in the bottles amended with ethanol, hydrogen, or PG, while 53%, 40%, and 22% of the HMX was transformed, respectively. There was no loss ofRDX or HMX in the electron donor unamended control bottles. The ethanol and PG were transformed to near stoichiometric amounts of acetate and propionate, suggesting the immediate electron donor supporting the transformation of the H 2 or electron donors that produce H 2 may be a useful strategy for enhancing the anaerobic biodegradation of explosives in contaminated groundwater and soils. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.
This study examined the biodegradation of RDX in wastewater from an industrial wastewater treatme... more This study examined the biodegradation of RDX in wastewater from an industrial wastewater treatment plant at the Holston Army Ammunition Plant in Kingsport, TN. Serum bottles containing 100 ml of a basal salts medium amended with 10 percent (v/v) sludge from the anoxic filter at the plant were amended with RDX and incubated under methanogenic conditions. Biodegradation intermediates corresponding to
Environmental Toxicology and Chemistry, 2001
The metabolic fate of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a mixed culture incubated ... more The metabolic fate of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in a mixed culture incubated under methanogenic conditions was studied. Analysis by high-performance liquid chromatography (HPLC) confirmed the loss of RDX and the formation of mono-, di-, and trinitroso-RDX as transient biodegradation intermediates. An additional peak observed in the HPLC chromatograms was identified by liquid chromatography-mass spectrometry as hydroxylamino-dinitroso-1,3,5-triazine. This is the first report identifying hydroxylamino-dinitroso-1,3,5-triazine as a transient intermediate produced during the anaerobic biodegradation of RDX.
Applied and environmental microbiology, 1990
We studied the metabolic fate of bromacil in anaerobic aquifer slurries held under denitrifying, ... more We studied the metabolic fate of bromacil in anaerobic aquifer slurries held under denitrifying, sulfate-reducing, or methanogenic conditions. Liquid chromatograhy-mass spectrometry of the slurries confirmed that bromacil was debrominated under methanogenic conditions but was not degraded under the other incubation conditions. This finding extends the range of aryl reductive dehalogenation reactions to include nitrogen heterocyclic compounds.
Applied and environmental microbiology, 1994
Accurate predictions of carbon and energy cycling rates in the environment depend on sampling fre... more Accurate predictions of carbon and energy cycling rates in the environment depend on sampling frequencies and on the spatial variability associated with biological activities. We examined the variability associated with anaerobic biodegradation rates at two sites in an alluvial sand aquifer polluted by municipal landfill leachate. In situ rates of methane production were measured for almost a year, using anaerobic wells installed at two sites. Methane production ranged from 0 to 560 mumol . m . day at one site (A), while a range of 0 to 120,000 mumol . m . day was measured at site B. The mean and standard deviations associated with methane production at site A were 17 and 57 mumol . m . day, respectively. The comparable summary statistics for site B were 2,000 and 9,900 mumol . m . day. The coefficients of variation at sites A and B were 340 and 490%, respectively. Despite these differences, the two sites had similar seasonal trends, with the maximal rate of methane production occur...
Abstract: The US Army generates large volumes of explosives-contaminated wastewater during muniti... more Abstract: The US Army generates large volumes of explosives-contaminated wastewater during munitions production and demilitarization operations. Contaminants such as 2, 4, 6-trinitrotoluene (TNT) and hexahydro-l, 3, 5-trinitro-l, 3, 5-triazine (RDX) are ...
... The USACERL principal investigator was Bernard A. Donahue. Part ... observed. The formation o... more ... The USACERL principal investigator was Bernard A. Donahue. Part ... observed. The formation of C02 was observed from radiolabeled HMX during composting experiments although no intermediates were identified (Doyle et al. 1986). ...
The contents of this report are not to be used for advertising, publication or promotional purpos... more The contents of this report are not to be used for advertising, publication or promotional purposes. Citation of trade names does not constitute ar official endorsement or approval of the use of such commercial products. The findings of this report are not to be construed as an official Department of the Army position, unless so designated by other authorized documents.