Publications by authors named "Langwaldt J"

The role of biodegradation in the attenuation of natural organic matter (NOM) was investigated in long-term experiments that simulate artificial ground water recharge (AGR) for drinking water production. Lake water containing 5.8 mg L(-1) total organic carbon (TOC) was continuously fed into an 18.

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This study evaluated the removal of natural organic matter (NOM) and structural changes in the microbial community during infiltration of humic lake water at three artificial groundwater recharge (AGR) sites in Finland. The three sites were at waterworks in Hämeenlinna, Jyväskylä and Tuusula, sites A, B and C, respectively. Site A used groundwater recharge by both basin and sprinkling infiltration, site B used only sprinkling infiltration, and site C used only basin infiltration.

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This study describes the removal of polycyclic aromatic hydrocarbons (PAHs) from creosote oil contaminated soil by modified Fenton's reaction in laboratory-scale column experiments and subsequent aerobic biodegradation of PAHs by indigenous bacteria during incubation of the soil. The effect of hydrogen peroxide addition for 4 and 10 days and saturation of soil with H(2)O(2) on was studied. In both experiments the H(2)O(2) dosage was 0.

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The aim of this study was to characterize the labile part of dissolved organic carbon (DOC) present in groundwater by identification of natural organic carbon substrates and to assess their microbial utilization during aeration of the groundwater. The studied chlorophenol (CP) contaminated groundwater contained 60-2650 micromoll(-1) of DOC of which up to 98.0% were CPs; 1.

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On-site biological treatment has been used for groundwater cleanup from industrial and agricultural chemicals. The pump-and-treat efficiency is controlled by retardation of contaminants by sorption onto the saturated subsurface solids and by the presence of non-aqueous-phase liquids in the aquifer. On-site bioreactors have been widely used for treatment of contaminants such as petroleum hydrocarbons, monoaromatic hydrocarbons, chlorinated aliphatics and aromatics.

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Kinetics of simultaneous iron and polychlorophenol (CP) oxidation by groundwater enriched cultures were studied in laboratory and during actual remediation in order to reveal the fate and effects of iron on aerobic on-site bioremediation of boreal groundwater. 2,4,6-tri- (TCP), 2,3,4,6-tetra- (TeCP) and pentachlorophenol (PCP) were degraded in fluidized-bed bioreactor (FBR) by over 99%, over 99%, and over 96%, respectively. The oxygen consumption rate for CP-biodegradation was 1.

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Kinetics of simultaneous iron and 2,4,6-trichlorophenol (TCP) oxidation by groundwater enriched cultures were studied in order to reveal the competition for oxygen in aerobic in situ bioremediation of boreal groundwater. Chemical iron oxidation at near neutral pH in synthetic groundwater depended by the first order on the concentrations of ferrous iron and dissolved oxygen and by the second order on pH. The chemical iron oxidation rate constant was on average 2.

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Air-lift percolator experiments simulated in situ subsurface degradation of 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol, in mixtures and individually, by indigenous microorganisms from a chlorophenol-contaminated aquifer. Inoculation with a chlorophenol(CP)-degrading gram-positive isolate from the CP-contaminated groundwater did not significantly increase CP degradation rates. Feed concentrations of up to 55 mg CP l-1 were degraded.

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