Nitrate-consuming processes in a petroleum-contaminated aquifer quantified using push–pull tests combined with 15N isotope and acetylene-inhibition methods

2003 ◽  
Vol 66 (1-2) ◽  
pp. 59-77 ◽  
Author(s):  
A. Schürmann ◽  
M.H. Schroth ◽  
M. Saurer ◽  
S.M. Bernasconi ◽  
J. Zeyer
Keyword(s):  
Acetylene Inhibition ◽  
15N Isotope ◽  
Contaminated Aquifer ◽  
Pull Tests

Push-pull test evaluation of the in situ aerobic cometabolism of chlorinated ethenes by toluene-utilizing microorganisms

2005 ◽  
Vol 52 (7) ◽  
pp. 35-40 ◽  
Author(s):  
M.F. Azizian ◽  
J.D. Istok ◽  
L. Semprini
Keyword(s):  
Contaminated Aquifer ◽  
Chlorinated Aliphatic Hydrocarbons ◽  
Toluene Concentration ◽  
Aerobic Cometabolism ◽  
In Situ Conditions ◽  
Single Well ◽  
Reactive Solutes ◽  
Pull Tests ◽  
Intermediate Oxidation

Single-well, push-pull tests were conducted in a contaminated aquifer to evaluate the ability of toluene-oxidizing microorganisms to cometabolize chlorinated aliphatic hydrocarbons (CAHs), such as trichloroethene (TCE). Test solutions were injected into the aquifer using a standard monitoring well, and then were transported under natural-gradient conditions. Transport tests demonstrated similar transport characteristics of the conservative tracer and the reactive solutes. Biostimulation tests were then performed by injecting a test solution containing dissolved toluene substrate, hydrogen peroxide, bromide, and nitrate in order to increase the biomass of toluene-utilizing microorganisms. Decreases in toluene concentration and the production of o-cresol as an intermediate oxidation product indicated the simulation of toluene-utilizing microorganisms containing an ortho-monooxygenase enzyme. Transformation tests demonstrated that indigenous microorganisms had the capability to transform the surrogate compounds (e.g. isobutene) and both cis-dichloroethene (cis-DCE) and trans-dichloroethene (trans-DCE). Isobutene was transformed to isobutene oxide, indicating transformation by a toluene ortho-monooxygenase, and both cis-DCE and trans-DCE were transformed. In a final test, the utilization of toluene, and the transformation of isobutene, cis-DCE, and trans-DCE were all inhibited in the presence of 1-butyne, a known inhibitor of the toluene ortho-monooxygenase enzyme. The method assessed the activity of attached microorganisms under in situ conditions of bioremediation.

scholarly journals Activity and Diversity of Sulfate-Reducing Bacteria in a Petroleum Hydrocarbon-Contaminated Aquifer

2002 ◽  
Vol 68 (4) ◽  
pp. 1516-1523 ◽  
Author(s):  
Jutta Kleikemper ◽  
Martin H. Schroth ◽  
William V. Sigler ◽  
Martina Schmucki ◽  
Stefano M. Bernasconi ◽  
...  
Keyword(s):  
Carbon Source ◽  
Sulfate Reduction ◽  
Petroleum Hydrocarbon ◽  
Carbon Sources ◽  
Sulfate Reducing Bacteria ◽  
Rate Coefficients ◽  
Contaminated Aquifer ◽  
Sulfate Reducing ◽  
Pull Tests ◽  
Reducing Bacteria

ABSTRACT Microbial sulfate reduction is an important metabolic activity in petroleum hydrocarbon (PHC)-contaminated aquifers. We quantified carbon source-enhanced microbial SO4 2− reduction in a PHC-contaminated aquifer by using single-well push-pull tests and related the consumption of sulfate and added carbon sources to the presence of certain genera of sulfate-reducing bacteria (SRB). We also used molecular methods to assess suspended SRB diversity. In four consecutive tests, we injected anoxic test solutions (1,000 liters) containing bromide as a conservative tracer, sulfate, and either propionate, butyrate, lactate, or acetate as reactants into an existing monitoring well. After an initial incubation period, 1,000 liters of test solution-groundwater mixture was extracted from the same well. Average total test duration was 71 h. We measured concentrations of bromide, sulfate, and carbon sources in native groundwater as well as in injection and extraction phase samples and characterized the SRB population by using fluorescence in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE). Enhanced sulfate reduction concomitant with carbon source degradation was observed in all tests. Computed first-order rate coefficients ranged from 0.19 to 0.32 day−1 for sulfate reduction and from 0.13 to 0.60 day−1 for carbon source degradation. Sulfur isotope fractionation in unconsumed sulfate indicated that sulfate reduction was microbially mediated. Enhancement of sulfate reduction due to carbon source additions in all tests and variability of rate coefficients suggested the presence of specific SRB genera and a high diversity of SRB. We confirmed this by using FISH and DGGE. A large fraction of suspended bacteria hybridized with SRB-targeting probes SRB385 plus SRB385-Db (11 to 24% of total cells). FISH results showed that the activity of these bacteria was enhanced by addition of sulfate and carbon sources during push-pull tests. However, DGGE profiles indicated that the bacterial community structure of the dominant species did not change during the tests. Thus, the combination of push-pull tests with molecular methods provided valuable insights into microbial processes, activities, and diversity in the sulfate-reducing zone of a PHC-contaminated aquifer.

On-site and in situ bioremediation of wood-preservative contaminated groundwater

2000 ◽  
Vol 42 (5-6) ◽  
pp. 371-376 ◽  
Author(s):  
J.A. Puhakka ◽  
K.T. Järvinen ◽  
J.H. Langwaldt ◽  
E.S. Melin ◽  
M.K. Männistö ◽  
...  
Keyword(s):  
Iron Oxidation ◽  
Wood Preservative ◽  
Pilot Scale ◽  
High Rate ◽  
Contaminated Groundwater ◽  
Groundwater Temperature ◽  
In Situ Bioremediation ◽  
Contaminated Aquifer ◽  
Fluidized Bed Process

This paper reviews ten years of research on on-site and in situ bioremediation of chlorophenol contaminated groundwater. Laboratory experiments on the development of a high-rate, fluidized-bed process resulted in a full-scale, pump-and-treat application which has operated for several years. The system operates at ambient groundwater temperature of 7 to 9°C at 2.7 d hydraulic retention time and chlorophenol removal efficiencies of 98.5 to 99.9%. The microbial ecology studies of the contaminated aquifer revealed a diverse chlorophenol-degrading community. In situ biodegradation of chlorophenols is controlled by oxygen availability, only. Laboratory and pilot-scale experiments showed the potential for in situ aquifer bioremediation with iron oxidation and precipitation as a potential problem.

Remediation of PCE-contaminated aquifer by an in situ two-layer biobarrier: laboratory batch and column studies

2003 ◽  
Vol 37 (1) ◽  
pp. 27-38 ◽  
Author(s):  
C.M Kao ◽  
S.C Chen ◽  
J.Y Wang ◽  
Y.L Chen ◽  
S.Z Lee
Keyword(s):  
Column Studies ◽  
Contaminated Aquifer

scholarly journals Pull-out and Critical Embedment Length of Grouted Rebar Rock Bolts-Mechanisms When Approaching and Reaching the Ultimate Load

2021 ◽  
Author(s):  
Are Håvard Høien ◽  
Charlie C. Li ◽  
Ning Zhang
Keyword(s):  
Ultimate Load ◽  
Failure Mechanisms ◽  
Concrete Block ◽  
Rock Bolts ◽  
Rock Stratum ◽  
Pull Out ◽  
Deformation Length ◽  
Embedment Length ◽  
Pull Tests ◽  
Grouted Bolts

AbstractRock bolts are one of the main measures used to reinforce unstable blocks in a rock mass. The embedment length of fully grouted bolts in the stable and competent rock stratum behind the unstable rock blocks is an important parameter in determining overall bolt length. It is required that the bolt section in the stable stratum must be longer than the critical embedment length to ensure the bolt will not slip when loaded. Several series of pull tests were carried out on fully grouted rebar bolts to evaluate the pull-out mechanics of the bolts. Bolt specimens with different embedment lengths and water/cement ratios were installed in either a concrete block of one cubic meter or in steel cylinders. Load displacement was recorded during testing. For some of the bolts loaded beyond the yield load, permanent plastic steel deformation was also recorded. Based on the test results, three types of failure mechanisms were identified, corresponding to three loading conditions: (1) pull-out below the yield strength of the bolt steel; (2) pull-out between the yield and ultimate loads, that is, during strain hardening of the steel; and (3) steel failure at the ultimate load. For failure mechanisms 2 and 3, it was found that the critical embedment length of the bolt included three components: an elastic deformation length, a plastic deformation length and a completely debonded length due to the formation of a failure cone at the borehole collar.

scholarly journals Sources of Nitrogen for Winter Triticale (Triticosecale Wittm. ex A.Camus) Succeeding Pea (Pisum sativum L.)

Agronomy ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 527
Author(s):  
Andrzej Wysokinski ◽  
Izabela Lozak ◽  
Beata Kuziemska
Keyword(s):  
Root Nodule ◽  
Crop Residues ◽  
Spring Barley ◽  
Sandy Soils ◽  
High Availability ◽  
Atmospheric Nitrogen ◽  
15N Isotope ◽  
Carbon And Nitrogen ◽  
Winter Triticale ◽  
Pisum Sativum L

Atmospheric nitrogen biologically reduced in legumes root nodule and accumulated in their postharvest residues may be of great importance as a source of this macronutrient for succeeding crops. The aim of the study was to determine nitrogen uptake by winter triticale from pea postharvest residues, including N fixed from atmosphere, using in the study fertilizer enriched with the 15N isotope. Triticale was grown without nitrogen fertilization at sites where the forecrops had been two pea cultivars (multi-purpose and field pea) and, for comparison, spring barley. The triticale crop succeeding pea took up more nitrogen from the soil (59.1%) and less from the residues of the forecrop (41.1%). The corresponding values where the forecrop was barley were 92.1% and 7.9%. In the triticale, the percentage of nitrogen derived from the atmosphere, introduced into the soil with pea crop residues amounted to 23.8%. The amounts of nitrogen derived from all sources in the entire biomass of triticale plants grown after harvesting of pea were similar for both pea cultivars. The cereal took up more nitrogen from all sources, when the soil on which the experiment was conducted had higher content of carbon and nitrogen and a greater amount of N was introduced with the pea residues. Nitrogen from pea residues had high availability for winter triticale as a succeeding crop cultivated on sandy soils.

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