Abstract:Nitroglycerin or glycerol trinitrate (GTN) is an energetic and toxic substance with a wide range of military and pharmaceutical applications. Studies conducted with activated sludge showed that GTN is amenable to aerobic degradation only in the presence of a primary carbon source, such as glucose.Kinetic experiments indicated that GTN is an inhibitory substrate whose presence during biodegradation, reduces substantially the microbial yield and the apparent maximum specific growth rate coefficient of primary su… Show more
“…Although the addition of calcium sulfate produced similar mineralization extents after 24 days, longer incubations (42 days) revealed that controlled-release nitrate has a greater enhancement of the anaerobic biodegradation (Figure C). This observation can be explained for two reasons: (a) controlled-release of nitrate benefits facultative microbes or nitrate reducers, which have the pathways to use higher free energy nitrate and (b) nitrocellulose provides not only the electron acceptors but also carbon and nitrogen sources (which could eventually become limiting in a closed system) and thus helps improve the biodegradation activity of sulfate reducers as well ( , ). 2 Effect of different added electron acceptors on the extent of anaerobic biodegradation ( 14 CO 2 recovery) as a function of depth intervals for n = 2.…”
Section: Resultsmentioning
confidence: 99%
“…The initial extraction of 1 g of nitrocellulose in 100 mL of water provides 0.29 mM nitrate in solution ( , ). Under anaerobic conditions, nitrocellulose can be degraded to nitrate, nitrite, sugar, H + , and NH 4 + that can be used by bacteria as electron acceptors and carbon sources ( , ). 1 Molecular structure of nitrocellulose (C n H 7/6 n O 11/6 n N 1/2 n , cellulose nitrate).…”
Experimental measurements demonstrated that rates of in situ microbial anaerobic biodegradation of phenanthrene in undisturbed marine sediments were enhanced when controlled-release electron acceptors (i.e., nitrate and sulfate (for comparison)) were employed. The experimental method used whole and interval cores injected with radiolabeled 14C-phenanthrene, which were incubated, sacrificed, and processed for 14CO2 recovery to determine degradation rates. Nitrocellulose and CaSO4 were formulated to release the electron acceptors into the sediments at rates consistent with bacterial utilization (i.e., that avoided inhibition observed previously at high soluble nitrate (although not sulfate) concentrations). The controlled-release of both compounds, measured in collateral experiments, enhanced the natural anaerobic phenanthrene biodegradation rates by factors up to 2-3. Biodegradation via sulfate reduction was most rapid in the early stages (24 days) of experiments, consistent with reports that many marine bacteria in submerged sediments are sulfate reducers. In comparison, in longer experiments (after 42 days), the anaerobic biodegradation rates were observed at least as high with the addition of nitrocellulose (over 40% of added phenanthrene recovered as 14CO2). Both nitrate and sulfate reduction was observed during anaerobic incubation, although the presence of nitrate seemed to reduce the sulfate reduction. The studied forms of the controlled-release nitrate and sulfate may provide capping amendments to decontaminate marine harbor sediments.
“…Although the addition of calcium sulfate produced similar mineralization extents after 24 days, longer incubations (42 days) revealed that controlled-release nitrate has a greater enhancement of the anaerobic biodegradation (Figure C). This observation can be explained for two reasons: (a) controlled-release of nitrate benefits facultative microbes or nitrate reducers, which have the pathways to use higher free energy nitrate and (b) nitrocellulose provides not only the electron acceptors but also carbon and nitrogen sources (which could eventually become limiting in a closed system) and thus helps improve the biodegradation activity of sulfate reducers as well ( , ). 2 Effect of different added electron acceptors on the extent of anaerobic biodegradation ( 14 CO 2 recovery) as a function of depth intervals for n = 2.…”
Section: Resultsmentioning
confidence: 99%
“…The initial extraction of 1 g of nitrocellulose in 100 mL of water provides 0.29 mM nitrate in solution ( , ). Under anaerobic conditions, nitrocellulose can be degraded to nitrate, nitrite, sugar, H + , and NH 4 + that can be used by bacteria as electron acceptors and carbon sources ( , ). 1 Molecular structure of nitrocellulose (C n H 7/6 n O 11/6 n N 1/2 n , cellulose nitrate).…”
Experimental measurements demonstrated that rates of in situ microbial anaerobic biodegradation of phenanthrene in undisturbed marine sediments were enhanced when controlled-release electron acceptors (i.e., nitrate and sulfate (for comparison)) were employed. The experimental method used whole and interval cores injected with radiolabeled 14C-phenanthrene, which were incubated, sacrificed, and processed for 14CO2 recovery to determine degradation rates. Nitrocellulose and CaSO4 were formulated to release the electron acceptors into the sediments at rates consistent with bacterial utilization (i.e., that avoided inhibition observed previously at high soluble nitrate (although not sulfate) concentrations). The controlled-release of both compounds, measured in collateral experiments, enhanced the natural anaerobic phenanthrene biodegradation rates by factors up to 2-3. Biodegradation via sulfate reduction was most rapid in the early stages (24 days) of experiments, consistent with reports that many marine bacteria in submerged sediments are sulfate reducers. In comparison, in longer experiments (after 42 days), the anaerobic biodegradation rates were observed at least as high with the addition of nitrocellulose (over 40% of added phenanthrene recovered as 14CO2). Both nitrate and sulfate reduction was observed during anaerobic incubation, although the presence of nitrate seemed to reduce the sulfate reduction. The studied forms of the controlled-release nitrate and sulfate may provide capping amendments to decontaminate marine harbor sediments.
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