Dilution versus pollution in watercourses affected by acid mine drainage: a graphic model for the Iberian Pyrite Belt (SW Spain)

The aim of this study was to chemically characterize the water quality impacts of the 88 acid mine drainage (AMD) generating mines in the Spanish sector of the Iberian Pyrite Belt (IPB). This was necessary because the Water Framework Directive of the European Union and the hydrological plans of the Tinto, Odiel, and Piedras river basins require that water quality be improved enough to allow at least some of the rivers in the IPB to sustain healthy fish populations by 2027. The results indicate a clear decrease in metals, arsenic, and sulfate concentrations and increased pH between the AMD-sources and the river channels.info:eu-repo/semantics/publishedVersio

Effects of aeration and organic loading rates on degradation of trichloroethylene in a methanogenic-methanotrophic coupled reactor

The effects of four aeration and four organic loading (OLR) rates on trichloroethylene (TCE) degradation in methanogenic-methanotrophic coupled reactors were studied using ethanol as the carbon source for the methanogens. Microcosm and PCR studies demonstrated that methanotrophs capable of mineralizing TCE and methanogens were present in the biomass throughout the study. The gene for the particulate form of methane monooxygenase (pMMO) was detected by PCR, but not that for the soluble form (sMMO). TCE mineralization by methanotrophs was therefore due primarily to pMMO activity. Low TCE concentrations were measured in effluent and off-gas samples in all cases. Volatilization losses were 0-5%. Dichloroethylene (DCE) was also observed, but vinyl chloride and ethylene were never detected. Changes in the aeration rate had no effect on TCE removal, but did influence DCE degradation. Reductive dechlorination of TCE to DCE was favored at low and no-aeration conditions, and DCE accumulation occurred due to slow DCE degradation. Low DCE levels were observed at the higher aeration rates, which indicated that conditions in these reactors were amenable to the aerobic co-metabolism of TCE and DCE. The OLR did have an effect on TCE removal. TCE and DCE removal were negatively affected when the OLR was increased. An OLR of 0.3 g COD lrx\u443day\u443 or lower with an aeration rate of 3 lO2 lrx\u443day\u443 and higher is the recommended operating condition of a coupled reactor for removal of TCE.NRC publication: Ye

A microcosm test for potential mineralization of chlorinated compounds under coupled aerobic/anaerobic conditions

In this study, the feasibility of using a mineralization test under coupled aerobic/anaerobic conditions was demonstrated. The coupling of anaerobic methanogenic and aerobic methanotrophic conditions in a microcosm required the presence of both a carbon source for anaerobic metabolism and oxygen for aerobic metabolism. These requirements were fulfilled by using a slow hydrolyzing organic matter along with intermittent addition of oxygen to the bottle headspace. Perchloroethylene (PCE) mineralization tests confirmed the effectiveness of the proposed methodology as well as PCE mineralization under coupled conditions.NRC publication: Ye

Microwave-assisted retting and optimization of the process through chemical composition analysis of the matrix

Pre-soaked flax stems were subjected to microwave assisted retting at different power levels and the effectiveness of microwave assisted retting was studied through the analysis of chemical compounds presented in the retted flax fibers processed from the stems. Response surface statistical design was used for this study with JMP\uae 10 software. Chemical analyses were performed by gravimetric methods to find out percentage of compounds. Cellulose, hemicellulose, lignin and pectin concentrations and the sugar content in the solution obtained after the treatment were subjected to analysis. Cellulose percentage in the fiber was increased significantly (p<0.0001) with the increase of microwave power at various soaking levels, which proved the release of cellulosic fiber with the application of microwave energy during retting. Hemicellulose, lignin and pectin concentrations decreased significantly after microwave-assisted retting which explained higher degree of retting after the treatment. This study noted change in chemical composition of the fibers, which can be used as a tool to estimate the effectiveness of microwave-assisted retting and the results could lead to optimization of the process. \ua9 2013 Elsevier B.V.Peer reviewed: YesNRC publication: Ye

Comparison of different means of providing oxygen to a biobarrier to be used for the degradation of MTBE

NRC publication: Ye

Bioremediation of a TCA-contaminated site : From microcosms to column to field studies

NRC publication: Ye

Biodegradation of fuel oxygenates by MTBE-degrading microorganisms

Methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) are widely used as additives to gasoline and are frequently detected in surface and ground waters. Rhodococcus ruber IFP 2007, isolated for its capacity to grow on ETBE owing to the presence of a cytochrome P450, is able to convert both ETBE and MTBE to tert-butyl alocohol (TBA). Mycobacterium austroafricanum IFP 2012 possesses a different oxidation system and is able to use MTBE as a carbon and energy source. The capacities of these strains to degrade fuel oxygenates have been investigated and compared. Their performances in lab-scale biofilters have been determined and the process is being optimized prior to its implementation in a pilot-scale biobarrier reactor.NRC publication: Ye