摘要:

Amendment of Cr(VI)-contaminated soil (approx. 200 mg/kg) with various treatments resulted in greater CO2evolution and Cr(VI) reduction with organic amendments relative to controls receiving no organics, indicating bacterial reduction of Cr(VI) under anaerobic conditions. Isolation of Cr(VI)-reducing, indigenous bacteria, representative of the dominant soil population, further indicated Cr(VI) reduction by indigenous bacteria. Although desorption of Cr(VI) was evident with some treatments, its reduction was not affected.

ISSN:1088-9868    

DOI:10.1080/10889869891214169

出版商:TAYLOR & FRANCIS    

年代:1998

数据来源: Taylor

摘要:

Innovative in situ treatment technologies show promise as efficient methods for remediating the nation's waste sites. Unfortunately, due to various barriers, some innovative technologies that have been demonstrated at full scale are never transferred for commercial application. The National Research Council (NRC) has recently presented recommendations on how to overcome these barriers (NRC, 1997). User-friendly screening software, which specifically addresses each of the NRC recommendations, is presented for use by site managers to determine the appropriateness of an innovative remediation technology, in situ aerobic cometabolic bioremediation, to clean up a contaminated site with specified hydrogeologic and contaminant characteristics. The software estimates the performance and cost of the technology at the site. Software, such as the one presented, can be used to aid in the transfer and implementation of innovative remediation technologies.

ISSN:1088-9868    

DOI:10.1080/10889869891214178

出版商:TAYLOR & FRANCIS    

年代:1998

数据来源: Taylor

摘要:

A strain ofClostridium bifermentansisolated from a munitions-supplemented anaerobic digester is known to degrade 2,4,6-trinitrotoluene (TNT) in rich media such as Brain Heart Infusion (BHI) broth. In order to make this biodegradation process commercially feasible, a new growth medium was developed. Corn steep liquor and molasses were selected as possible nitrogen and carbon sources. A medium containing 2.4% corn steep liquor and 0.4% molasses was chosen based on the value for maximum specific growth rate. The values of µmand Ksfrom continuous runs were of 0.029 min−1and 0.488 g/L, respectively. To reduce the overhead cost for maintaining an anoxic environment for this obligatory anaerobic bacterium, the threshold oxygen level under which the bacterium can survive was determined. The degradation of TNT was then carried out in a batch bioreactor, and in a continuously stirred tank bioreactor. The solubility of TNT was enhanced by using the surfactant, Tween 80, and the optimal concentration of Tween 80 was determined to be 2.5%. This concentration of Tween 80 increased TNT solubility by 100% while the effect on growth rate was minimal. Degradation of TNT was then carried out in a continuously stirred tank bioreactor and was found to follow Michaelis-Menten-type kinetics. Degradation of TNT was found to be possible under limited oxygen presence, but at a reduced degradation rate.

ISSN:1088-9868    

DOI:10.1080/10889869891214187

出版商:TAYLOR & FRANCIS    

年代:1998

数据来源: Taylor

摘要:

Soil column and serum bottle microcosm experiments were conducted to investigate the potential for in situ anaerobic bioremediation of trichloroethy lene (TCE) and dichloromethane (DCM) at the Pinellas site near Largo, Florida. Soil columns with continuous groundwater recycle were used to evaluate treatment with complex nutrients (casamino acids, methanol, lactate, sulfate); benzoate and sulfate; and methanol. The complex nutrients drove microbial dechlorination of TCE to ethene, whereas the benzoate/sulfate and methanol supported microbial dechlorination of TCE only tocis-1,2-dichloroethylene (cDCE). Microbial sulfate depletion in the benzoate/sulfate column allowed further dechlorination ofcDCE to vinyl chloride. Serum bottle microcosms were used to investigate TCE dechlorination and DCM biodegradation in Pinellas soil slurries bioaugmented with liquid from the soil columns possessing TCE-dechlorinating activity and DCM biodegradation by indigenous microorganisms. Bioaugmented soil microcosms showed immediate TCE dechlorination in the microcosms with methanol or complex nutrients, but no dechlorination in the benzoate/sulfate microcosm. DCM biodegradation by indigenous microorganisms occurred in soil microcosms amended with either benzoate/sulfate or methanol, but not with complex nutrients. Bioaugmentation stimulated DCM biodegradation in both complex nutrient and methanol-amended microcosms, but appeared to inhibit DCM biodegradation in benzoate/sulfate-amended microcosms. TCE dechlorination occurred before DCM biodegradation in bioaugmented microcosms when both compounds were present.

ISSN:1088-9868    

DOI:10.1080/10889869891214196

出版商:TAYLOR & FRANCIS    

年代:1998

数据来源: Taylor

摘要:

Two decades after the manufacture and use of polychlorinated biphenyls (PCBs) were banned, PCB contamination remains widespread in the environment. Technologies available for PCB remediation are limited and often impractical for soils with dispersed PCB contamination. In this study, two remediation processes have been integrated for use on PCB-contaminated soils. This remediation strategy links in situ surfactant washing of PCBs from soil with aerobic biodegradation of the resulting surfactant-PCB solution by two field application vectors (F A Vs),Pseudomonas putidaIFL5::TnPCB andRalstonia eutrophaB30F4::TnPCB, which utilize surfac-tants as growth substrates and cometabolize PCBs. A bench-scale demonstration of this process was performed using PCB-contaminated soils from an electric power substation site. In a 2-day recycling wash using a 1% (wt/vol) surfactant solution, greater than 70% of the PCBs were removed from the soil. In the biodegradation phase, greater than 90% of the surfactant and 35% of the PCBs were biodegraded in 12 days. The residual PCBs were partitioned onto a solid carrier resulting in greater than 90% removal of PCBs from the bioreactor effluent and a 50-fold reduction in the amount of PCB-contaminated material.

ISSN:1088-9868    

DOI:10.1080/10889869891214204

出版商:TAYLOR & FRANCIS    

年代:1998

数据来源: Taylor

摘要:

The fate of 2,4,6-trinitrotoluene (TNT) and TNT transformation products in two aerobic enrichment cultures was investigated. Contaminant fate was assessed through analysis of TNT and its oxygen-stable aminated derivatives using capillary electrophoresis and by tracking the distribution of14C-labeled products in either the dissolved, mineralized, or biomass fractions. TNT transformation products were generated by reduction with Fe(0), reduction by S2−, and transformation byClostridium acetobutylicumand byEichornia crassipies(water hyacinth). Enrichment cultures varied in the growth substrate and nitrogen source supplied. The dextrose-fed mixed culture (DMC) was enriched on dextrose with yeast extract providing nitrogen for growth, whereas the anthranilic acid-fed mixed culture (AMC) received anthranilic acid as its source of both energy and nitrogen. Each culture transformed TNT, but their product distributions varied. The DMC exhibited higher levels of biomass association, whereas the AMC produced higher levels of aminated nitrotoluenes and unidentified water-soluble products. Neither mineralized TNT to a significant degree. TNT disappearance was observed in all transformation systems, along with the formation of water-soluble products; however, formation of aminated nitrotoluenes was observed only in the sulfide systems. Neither aerobic culture was capable of mineralizing the TNT transformation products introduced, regardless of the transformation method used to prepare them. The distribution of products between the aqueous phase and the biomass did vary between cultures and was affected by the transformation system used.

ISSN:1088-9868    

DOI:10.1080/10889869891214213

出版商:TAYLOR & FRANCIS    

年代:1998

数据来源: Taylor