Anaerobic removal of 2,4,6‐trinitrotoluene (TNT) under different electron accepting conditions: laboratory study

Changes in iso- and n-alkane distribution during biodegradation of crude oil under nitrate and sulphate reducing conditions

Anaerobic degradation of 2,4,6-trinitrotoluene (TNT) was studied under sulfate- and nitrate-reducing conditions using enrichment cultures developed from a TNT-contaminated soil from the Louisiana Army Ammunition Plant (LAAP) in Minden, Louisiana, USA. The soil samples were enriched using mineral salt media with either nitrate or sulfate as electron acceptors in the presence of TNT under strict anaerobic conditions. The enriched samples were experimented with TNT as either the sole source of carbon or nitrogen and also under co-metabolic conditions with molasses as co-substrate. The results revealed that TNT was removed under both electron acceptor conditions. However, the TNT degradation efficiency was significantly higher under sulfate-reducing conditions than the nitrate-reducing conditions. Under sulfate-reducing conditions, TNT removal was faster when molasses was used as co-substrate. The metabolic analysis showed that TNT was mineralized and the major end product was acetic acid, CO2, and ammonia. A soil slurry reactor with TNT-contaminated soil showed more than 90% of TNT removal within 60 days of incubation.

Anaerobic degradation of atrazine

Enhanced biodegradation of cyclotetramethylenetetranitramine (HMX) under mixed electron-acceptor condition

Anaerobic biodegradation of no. 2 diesel fuel in soil: a soil column study

Anaerobic biodegradation of no. 2 diesel fuel in soil: a soil column study

Biotransformation of explosives by anaerobic consortia in liquid culture and in soil slurry

Biotransformation of 17α-methyltestosterone in sediment under different electron acceptor conditions

Isolation and characterization of a sulfate-reducing bacterium that removed TNT (2,4,6-trinitrotoluene) under sulfate- and nitrate-reducing conditions

Anaerobic biodegradation of ethylthionocarbamate by the mixed bacteria under various electron acceptor conditions

The biodegradability of two surfactants, Triton X-100 and Rhamnolipid, was tested under aerobic, nitrate reducing, sulfate reducing, and anaerobic conditions in a respirometer. The results indicated that from a biodegradation standpoint, Rhamnolipid is superior to Triton X-100 since it is biodegradable under all conditions, whereas the Triton X-100 is partially biodegradable under aerobic conditions and nonbiodegradable under anaerobic, nitrate reducing, and sulfate reducing conditions.

Biokinetics of biodegradation of surfactants under aerobic, anoxic and anaerobic conditions

This study explored the removal of six pharmaceutically active compounds (PhACs) in lab-scale experiments with sediments under four redox conditions, namely aerobic, nitrate reducing, sulfate reducing, and methanogenic conditions using batch and column set-ups. Redox conditions were found to influence PhAC removal by sorption and biodegradation. The most optimal PhAC removal was observed at the outer ranges of the redox spectrum, i.e. either aerobic or deep anaerobic (sulfate reducing and methanogenic conditions), whereas nitrate reducing conditions were found least effective for PhACs biodegradation and sorption. For instance, sorption coefficient Kd values for metoprolol in column experiments were 90, 65, 42 and 11 L/kg for sulfate reducing, methanogenic, aerobic and nitrate reducing conditions, respectively. For the same conditions Kd values for propranolol were 101, 94, 55 and 55 L/kg, respectively. As expected, biodegradation efficiencies were highest under aerobic conditions, showing >99% removal of caffeine and naproxen, but no removal for propranolol and carbamazepine. The adaptive capacity of sediment was demonstrated by pre-exposure to PhACs leading to improved PhAC biodegradation. The results of this study indicate the necessity to combine diverse redox conditions, including aerobic conditions, for maximizing PhAC removal by sorption and biodegradation. Furthermore, our findings stress the need for additional treatment measures as recalcitrant PhACs are not effectively removed under any redox condition.

Pharmaceutical biodegradation under three anaerobic redox conditions evaluated by chemical and toxicological analyses

The biotransformation of trichloroethylene (TCE) under various electron acceptor conditions was investigated by using enrichment cultures developed from the anaerobic digester sludge of Thibodaux sewage treatment plant. The results indicated that TCE was biotransformed under sulfate reducing, methanogenic, nitrate reducing, iron reducing, and fermenting conditions. However, the rates of TCE removal varied among the conditions studied. The fastest removal of TCE (100% removal in 9 days) was observed under mixed electron acceptor conditions, followed in order by methanogenic, fermenting, iron reducing, sulfate reducing, and nitrate reducing conditions. Under mixed electron acceptor conditions, the TCE was converted to ethene, which was further metabolized. Under sulfate and nitrate reducing conditions, the major metabolites produced from TCE metabolism were cis and trans dichloroethylene (DCE). Under methanogenic, iron reducing, and fermenting conditions, cis and trans DCE and ethene were produced from TCE metabolism. This study showed evidence for TCE metabolism in a mixed microbial population system similar to any contaminated field sites, where heterogeneous microbial population exists.