Papers by Keyword: Sulfate-Reducing Bacteria (SRB)

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Authors: Stoyan N. Groudev, Irena Spasova, Marina Nicolova, Plamen S. Georgiev
Abstract: Experimental plots consisting of acidic and alkaline soils heavily contaminated with radionuclides (mainly U and Ra) and non-ferrous metals (mainly Cu, Zn, Cd, Pb) were treated in situ under real field conditions using the activity of the indigenous soil microflora. This activity was enhanced by suitable changes of some essential environmental factors such as pH and water, oxygen and nutrient contents of the soil. The treatment was connected with solubilization and removal of contaminants from the top soil layers (horizon A) due to the joint action of the soil microorganisms and leach solutions used to irrigate the soils (mainly acidophilic chemolothotrophic bacteria and diluted sulphuric acid in the acidic soil, and various heterotrophs and bicarbonate and soluble organics in the alkaline soil). The dissolved contaminants were removed from the soil profile through the drainage soil effluents or were transferred to the deeply located soil subhorizon B2 where they were precipitated as the relevant insoluble forms (uranium as uraninite, and the non-ferrous metals as the relevant sulphides) as a result of the activity of the sulphate-reducing bacteria inhabiting this soil subhorizon.
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Authors: Pavlina Kousi, E. Remoudaki, Artin Hatzikioseyian, Marios Tsezos
Abstract: An upflow fixed-bed sulphate-reducing reactor has been set up and monitored for the treatment of metal-bearing wastewater. Zinc has been chosen as the target metal to be sequestered from influent water stream at initial concentrations ranging from 50 to 400 mg/l and initial pH values ranging from 3 to 5. Main operating parameters of the reactor, such as the composition and content of electron donor, electron acceptor, sulphate and metal removal capacity, have been monitored during ten months of continuous operation. The results obtained have shown that the reactor has a considerable capacity of completely reducing sulphates for initial concentrations up to 7,200 mg/l, completely removing soluble zinc for initial concentrations up to 400 mg/l and completely removing Total Organic Carbon (TOC), for initial concentrations up to 1,500 mg/l.
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Authors: Hong Xu Bao, Xi Ping Ma, Jian Wang, Kui Jing, Zhi Hui Chen, Ai Jie Wang
Abstract: The objective of this study is to investigate the microbial community and its characteristics changes aroused by the ratios of COD/SO42- in the acidogenic-phase reactor of two-phase anaerobic process. A continuous-flow lab-scale test was conducted in an acidogenic sulfate-reducing reactor with molasses wastewater as sole organic carbon source and sodium sulfate as the electron acceptor. The experimental results showed that Acetic-acid Type Microbial Metabolism resulted in the formation of An Acetic-acid Type Climax Community. The change of the COD/SO42- ratio caused an ecological succession from a stable climax community at moderate and high COD/SO42- ratios to a sub-stable climax community at a lower COD/SO42- ratio. But Acetic-acid Type Microbial Metabolism kept unchanged during this course, which indicated the stability of Acetic-acid Type Climax Community. The Acetic-acid Type Microbial Metabolism and Acetic-acid Type Climax Community were of typical characteristics in the acidogenic sulfate-reducing reactor.
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Authors: Anke Wolthoorn, Simon Kuitert, Henk Dijkman, Jacco L. Huisman
Abstract: In a bench scale trial biological sulfate reduction was applied to convert anglesite (PbSO4) to galena (PbS). Anglesite is a main constituent of waste fractions such as the residue from an indirect leaching process or in lead paste from spent car batteries. The goal of this study was to develop a technology to decrease the lead (Pb) emissions by converting PbSO4 from a waste fraction into PbS, which can be recovered from the waste fraction using a flotation process or an electrochemical process. The conversion of anglesite to galena is based on the biological sulfate reduction process and a metal precipitation process. First sulfate is biologically reduced to sulfide. Secondly, the Pb2+ from the PbSO4 reacts chemically with the sulfide resulting from the first reaction. A bench-scale reactor was started up using sulfate- and sulfur-containing influent. The reactor was seeded with biocatalyst from several full-scale reactors. Anglesite-containing residue was added batch-wise when the formation of sulfide started. The residue contained mainly PbSO4 (51.7%), sulfate (SO4 2-, 19.9%) and elemental sulfur (S0, 15.1%). Galena precipitates in the bioreactor due to the near-neutral pH at which sulfate reduction is carried out. During the experiment a surplus of sulfide relative to Pb was maintained to prevent the formation of PbCO3 and the accompanying pH decrease that would unavoidable result in the inhibition of the biocatalyst. Both sulfate and sulfur present in the residue were biologically reduced. The formation of PbS was confirmed by the increased Pb:O ratio of the sludge (1:0.03) relative to the Pb:O ratio of the residue (1:0.3). A potential large-scale application is proposed.
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Authors: Qing Fen Li, Chun Hui Li, Ping Long, Li Li Xue
Abstract: The microbiological influenced corrosion (MIC) behaviors of the ship plate steel directly exposed in different medias (the sterile seawater, the ferrous bacteria solution and the sulfate-reducing bacteria solution) were investigated with electrochemical impedance spectroscopy (EIS), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Corrosion potential, electrochemical impedance and micrographs of specimens under different experimental conditions were obtained. Results show that the FB and SRB in the marine environment affect the corrosion behavior of the ship plate steel greatly. The corrosion process in FB and SRB environment was controlled by both bacteria and corrosion products. The mechanism of MIC is discussed.
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Authors: F. Battaglia-Brunet, Dominique H.R. Morin, S. Coulon, Catherine Joulian
Abstract: A process for the precipitation of trivalent arsenic sulphide in sulphate-reducing condition at low pH would be very attractive due to the high arsenic content (60%) in the final precipitate. A bacterial consortium able to reduce sulphate at pH 4.5 served to inoculate column bioreactors that were continuously fed with As(V) or As(III), glycerol and/or hydrogen, at pH values between 2 and 5. The diversity, functionality and evolution of the consortium colonizing the bioreactors were characterized by means of biomolecular tools, in relation with operating parameters (pH, As, sulphide, acetate). The highest As removal rate obtained during these experiments was close to 3 mg.l-1.h-1 using As(V) as the initial arsenic form, while precipitation rates were improved using As(III). When glycerol was replaced by hydrogen in a bioreactor containing a mature biofilm, sulphate-reducing activity increased roughly. Organisms related to Desulfosporosinus were the only sulphate-reducing bacterium (SRB) detected in the bioreactor. arrA genes, involved in As(V) dissimilatory reduction, were also detected and suggested that As(V) was reduced by a Desulfosporosinus-like organism. Molecular fingerprints evidenced an evolution of the bacterial population structure according to changes in operating conditions.
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Authors: Oyekanmi O. Oyekola, Robert P. van Hille, Susan T.L. Harrison
Abstract: This study investigated the influence of culture conditions on the dominant metabolic pathways and resultant reaction stoichiometry, using chemostat cultures. The kinetic properties (max and Ks) under conditions dominated by either lactate oxidation or lactate fermentation were determined. These properties were used to simulate the competition between lactate fermentation and oxidation. Sulphate reduction and lactate utilisation were determined across residence times of 1 to 5 d and feed sulphate concentrations of 1.0 to 10.0 g l-1. Assuming lactate limitation, results revealed a lower maximal growth rate max of 0.2 h-1 and a higher affinity for lactate characterised by Ks of 0.6 g l-1 for the lactate oxidisers (SRB) than the lactate fermenters. The latter were characterised by a max of 0.3 h-1 and Ks of 3.3 g l-1. Modelling of the competition between lactate fermenters and lactate oxidisers illustrated that lactate oxidisers compete more effectively for lactate under conditions of low lactate concentration (≤5 g l-1) and high sulphide concentration (0.5 g l-1). On the other hand lactate fermenters outcompete the oxidisers under conditions of higher lactate concentration (>5 g l-1). Findings from this study show that in order to optimise BSR system, an understanding of the impact of physicochemical conditions on the metabolic dominance is critical.
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Authors: Fu Shao Li, Mao Zhong An, Dong Xia Duan
Abstract: Corrosion behaviors of low nickel alloy high strength steel (LNAHSS) was studied by electrochemical impedance spectroscopy and scanning electron microscopy when the coupons of LNAHSS were exposed to the seawater culture media. As the results, LNAHSS was uniformly corroded in the fresh sterilized culture medium in a mode of active dissolution; in the culture medium with sulfate-reducing bacteria (SRB), LNAHSS was protected by the iron sulfides layer to some extent in the early stage of exposure, but severely localized corrosion subsequently occurred resulting from the localized breakdown of iron sulfides layer. So, in risks estimation, special precautions should be taken when LNAHSS serves in the environments containing SRB as the localized area can become the tress raiser.
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Authors: Da Cheng Wang, Cai Fu Qian, Sheng Xian Cao, Yang Liu, Jia Wei Sun
Abstract: The formation of fouling in stainless steel tube was simulated in the existence of both sulfate-reducing bacteria and iron bacteria under the experimental conditions of the water temperature 30±0.2°C and velocity of 0.4m/s with the dynamic simulation apparatus of shell-and-tube circulating cooling water. The paper studied the relation between water quality parameters and formation of fouling, such as Fe2+ concentration, CODcr and the total number of bacteria. The experimental results showed that: the main reason of the fouling resistance increase was the presence of sulfate-reducing bacteria and iron bacteria. The interaction between iron bacteria and sulfate-reducing bacteria accelerated the formation of biofouling. The influence of each parameter codetermined the formation of microbial fouling.
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Authors: Da Cheng Wang, Cai Fu Qian, Sheng Xian Cao, Yang Liu, Jia Wei Sun
Abstract: This study, conducted with the dynamic simulation equipment under constant conditions of water temperature 30°C and flow rate 0.4 m.s-1, is intended to simulate dynamically the fouling process on stainless steel tube heat exchanger of three types of fouling microorganisms, iron bacteria (IB), sulfate-reducing bacteria (SRB) and slime forming bacteria (HB), which are isolated from the slime in the bottom of circulating cooling tower. This experiment was tested through the on-line monitoring of fouling resistant and analysis of the characteristics of heat transfer ,the results indicate that induction period for the formation of biofouling in the stainless steel tube by slime-forming bacteria is 56 h, Iron bacteria is 25h, and sulfate-reducing bacteria is 22h. Among these bacteria, the greatest impact on the heat transfer is taken by the iron bacteria, and the sulfate-reducing bacteria are next.
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