Tributyl phosphate (TBP) is widely used as a solvent and plasticizer with a special use as a solvent for the extraction of uranium and plutonium from other radionuclides in nuclear fuel reprocessing. Although the biodegradation of alkyl phosphates by microorganisms has been noted in the literature, biodegradation of TBP is little-documented. The proposed products of the degradation are potentially useful; the liberated 1-butanol as a biomass growth substrate and the co-released inorganic phosphate moiety as a ligand that can precipitate with heavy metals to retain these as biominerals on the biomass. Microorganisms growing on TBP were isolated from industrially contaminated sites and from laboratory enrichment cultures. A mixed culture, containing Pseudomonas spp., supported the deposition of heavy metal (uranyl) phosphate and the removal of the latter from solution (biodecontamination). This general biocatalytic approach has been reported previously; these new isolates show potential for the simultaneous treatment of two classes of waste: the breakdown of one waste (TBP) could be harnessed to the treatment of another class of waste (heavy metals) This approach would represent a considerable advance over established bioprocesses for metal removal, where the cost of the addition of exogenous organophosphate substrate (phosphate donor for the metal precipitation reaction) may ultimately limit their use.

HighlightsRemediation of high pH Cr(VI) contamination related to COPR and its groundwater.Extensive characterization of COPR and its related groundwater.Cr(VI) reduction to Cr(III) by biogenic nano-magnetite and nano-zero valent iron.Critical assessment of reactivity and passivation using spectroscopy and imaging.Stabilization of the COPR Cr(VI) source by addition of nanoparticles.

A mixed culture utilizing EDTA as the sole carbon source was isolated from a mixed inoculum of water from the River Mersey (United Kingdom) and sludge from an industrial effluent treatment plant. Fourteen component organisms were isolated from the culture, including representatives of the genera Methylobacterium,Variovorax, Enterobacter,Aureobacterium, and Bacillus. The mixed culture biodegraded metal-EDTA complexes slowly; the biodegradability was in the order Fe>Cu>Co>Ni>Cd. By incorporation of inorganic phosphate into the medium as a precipitant ligand, heavy metals were removed in parallel to EDTA degradation. The mixed culture also utilized a number of possible EDTA degradation intermediates as carbon sources.

The use of citrate as a chelating agent in decontamination operations is of environmental concern as it can mobilize toxic heavy metals if discharged into the environment. Many heavy metalcitrate complexes are recalcitrant to biodegradation. Citrate-utilizing strains of Pseudomonas aeruginosa and Pseudomonas putida were isolated from a mixed culture which had been maintained with EDTA as the carbon source for 2 years. Citrate (5 mM) was used as the sole carbon source in medium supplemented with 5 mM Cd, Zn, Cu, Fe, Co, or Ni. Removal of the metals from the medium was promoted by the incorporation of inorganic phosphate as a precipitant, with formation of nickel and cobalt phosphates con®rmed by X-ray powder diffraction analysis. The potential of P putida to biodegrade citrate in a nickel±citrate secondary waste was illustrated using a ®ll-and-draw reactor supplied with ef¯uent from a bioinorganic ion exchange column that had been used previously to concentrate nickel from aqueous solution.

Following a thorough site investigation, a biological Sequential Reactive Barrier (SEREBAR), designed to remove Polycyclic Aromatic Hydrocarbons (PAHs) and BTEX compounds, was installed at a Former Manufactured Gas Plant (FMGP) site. The novel design of the barrier comprises, in series, an interceptor and six reactive chambers. The first four chambers (2 nonaerated-2 aerated) were filled with sand to encourage microbial colonization. Sorbant Granular Activated Carbon (GAC) was present in the final two chambers in order to remove any recalcitrant compounds. The SEREBAR has been in continuous operation for 2 years at different operational flow rates (ranging from 320 L/d to 4000 L/d, with corresponding residence times in each chamber of 19 days and 1.5 days, respectively). Under low flow rate conditions (320−520 L/d) the majority of contaminant removal (>93%) occurred biotically within the interceptor and the aerated chambers. Under high flow rates (1000−4000 L/d) and following the installation of a new interceptor to prevent passive aeration, the majority of contaminant removal (>80%) again occurred biotically within the aerated chambers. The sorption zone (GAC) proved to be an effective polishing step, removing any remaining contaminants to acceptable concentrations before discharge down-gradient of the SEREBAR (overall removals >95%).