• Journal of Microbiology and Biotechnology
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• 제12권5호
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• pp.849-853
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• 2002

Metal ions have an adverse effect on anaerobic digestion. In an acetate degradation test of upflow of anaerobic sludge blanket granules with $Cu^{2+}$, not all of the acetate that disappeared was stoichiometrically converted to methane. In the presence of 400 mg/g-VSS (volatile suspended solids) $Cu^{2+}$, only 26% of the acetate consumed was converted to methane. To study acetate conversion by other anaerobic microorganisms, sulfate and nitrate reductions were investigated in the presence of $Cu^{2+}$ Sulfate and nitrate reductions exhibited more resistance to $Cu^{2+}$than methanogenesis, and the granules reduced 2.2 mM and 5.4 mM of nitrate and sulfate, respectively, in the presence of 400 mg/g-VSS copper ion. However, the acetate degraded by sulfate and nitrate reductions was only 24% of the missing acetate that could have been stoichiometrically converted to $CO_2$. Accordingly, 76% of the acetate consumed appeared to have been converted to other unknown compounds.

• Journal of Microbiology and Biotechnology
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• 제30권7호
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• pp.1005-1012
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• 2020

Acid mine drainage (AMD) has been a serious environmental issue that threatens soil and aquatic ecosystems. In this study, an acid-tolerant sulfate-reducing bacterium, strain S4, was isolated from the mud of an AMD storage pond in Vietnam via enrichment in anoxic mineral medium at pH 5. Comparative analyses of sequences of the 16S rRNA gene and dsrB gene involved in sulfate reduction revealed that the isolate belonged to the genus Desulfovibrio, and is most closely related to Desulfovibrio oxamicus (with 99% homology in 16S rDNA sequence and 98% homology in dsrB gene sequence). Denaturing gradient gel electrophoresis (DGGE) analyses of dsrB gene showed that strain S4 represented one of the two most abundant groups developed in the enrichment culture. Notably, strain S4 was capable of reducing sulfate in low pH environments (from 2 and above), and resistance to extremely high concentration of heavy metals (Fe 3,000 mg/l, Zn 100 mg/l, Cu 100 mg/l). In a batch incubation experiment in synthetic AMD with pH 3.5, strain S4 showed strong effects in facilitating growth of a neutrophilic, metal sensitive Desulfovibrio sp. strain SR4H, which was not capable of growing alone in such an environment. Thus, it is postulated that under extreme conditions such as an AMD environment, acid- and metal-tolerant sulfate-reducing bacteria (SRB)-like strain S4 would facilitate the growth of other widely distributed SRB by starting to reduce sulfate at low pH, thus increasing pH and lowering the metal concentration in the environment. Owing to such unique physiological characteristics, strain S4 shows great potential for application in sustainable remediation of AMD.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.508-513
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• 2001

Recently, ground granulated blast-furnace slag (GGBFS) has been increasingly used as additive for concrete. Many researchers reported that concrete using GGBFS had a better resistance under severe environments, such as marine or sulfate-rich soils, than Portland type cement concrete. The aim, therefore, of this study is to evaluate on the effectiveness of concrete using GGBFS when the concrete exposes to sulfate-rich environment. The detailed items for experiments show 2 series consisted of sulfate immersion test with mortar and sulfate diffusion test with concrete. The sulfate immersion test was performed for 400 days and contained reduction of compressive strength, length change and XRD analysis. For sulfate diffusion test, sulfate ions diffusivity was calculated on tile consideration of electrochemical theory by the diffusion cell test. As the results of this study, it was found that the concrete using GGBFS as additive was superior to portland type cement concrete. Consequently, the use of concrete with GGBFS for recycling may expect the durable and economical benefits.

• Computers and Concrete
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• 제29권 5호
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• pp.335-346
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• 2022

Geopolymers are an important alternative material supporting recycling, sustainability, and waste management. Durability properties are among the most critical parameters to be investigated; in this study, the durability of manufactured geopolymer samples under the attack of 10% magnesium sulfate and 10% sodium sulfate solution was investigated. 180 cycles of freezing and thawing were also tested. The experimentally obtained results investigate the durability of geopolymer mortar prepared with fly ash (class F) and alkali activator. Three different quarry dust wastes replaced the river sand aggregate: limestone, marble, and basalt powder as fine filler aggregate in three different replacement ratios of 25%, 50%, and 75% to produce ten series of geopolymer composites. The geopolymer samples' visual appearance, weight changes, UPV, and strength properties were studied for up to 12 months at different time intervals of exposure to sulfate solutions to investigate sulfate resistance. In addition, Scanning Electron Microscopy (SEM), EDS, and XRD were used to study the microstructure of the samples. It was beneficial to include quarry waste as a filler aggregate in durability and mechanical properties. The compact matrix was demonstrated by microstructural analysis of the manufactured specimens. The geopolymer mortars immersed in sodium sulfate showed less strength reduction and deterioration than magnesium sulfate, indicating that magnesium sulfate is more aggressive than sodium sulfate. Therefore, it is concluded that using waste dust interrogation with partial replacement of river sand with fly ash-based geopolymers has satisfactory results in terms of durability properties of freeze-thaw and sulfate resistance.

• 한국물환경학회지
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• 제20권5호
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• pp.480-487
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• 2004

This study was conducted to find the effect of electron acceptors on the formation of granular sludge by using four different types of electron acceptors. The phosphorous uptake, denitrification, and sulfate reduction in anoxic modes were simultaneously occured because of the presence of the polyphosphate accumultating organism(PAO) that utilize nitrate and sulfate as an electron acceptor in the anoxic zone. Denitrirying phosphorous removal bacteria(DPB) was enriched under anaerobic/anoxic/aerobic condition with a nitrate as an electron acceptor, and desulfating phosphorous removal bacteria(DSPB) was enriched under anaerobic/anoxic/aerobic condition with a sulfate as an electron acceptor. Polyphosphate accumulating organism(PAO) were enriched in the anaerobic/aerobic SBR. PAO took up acetate faster than DPB and DSPB during the aerobic phase. The sludge with nitrate and sulfate as an electron acceptors grew as a granules which possessed high activity and good settleability. In the anaerobic/aerobic modes, typical floccular growth was observed. In the result of bench-scale experiment, simultaneous reactions of phosphorus uptake, denitrification and sulfate reduction were observed under anoxic condition with nitrate and sulfate as an electron acceptors. These results demonstrated that the anaerobic/anoxic modes with nitrate and sulfate as an electron acceptors played an important role in the formation of the sludge granulation.

• 한국건축시공학회지
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• 제19권1호
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• pp.1-7
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• 2019

본 연구에서는 전력구 콘크리트 구조물에서 발생하는 균열저감을 위해 알파형 반수석고를 치환한 콘크리트의 역학적 특성을 평가하였다. 알파형 반수석고의 치환율은 0, 6, 9, 12, 15%로 설정하여, 응결시간, 압축강도, 건조수축을 측정하였으며, 미세구조 및 결정구조의 분석을 실시하였다. 실험 결과, 알파형 반수석고의 치환율이 증가할수록 응결시간이 단축되었으며, 압축강도가 저하되는 경향을 확인하였다. 한편, 알파형 반수석고를 15% 치환할 경우 보통포틀랜드시멘트 콘크리트에 비해 건조수축이 약 60% 저감되는 효과가 나타났다. 따라서, 전력구 콘크리트 구조물에 알파형 반수석고를 치환한 콘크리트를 적용할 경우 균열저감 성능이 향상될 것으로 판단되며, 압축강도의 개선은 필요할 것으로 판단된다.

• Clinical and Experimental Pediatrics
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• 제56권4호
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• pp.159-164
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• 2013

Purpose: Indoxyl sulfate and p-cresyl sulfate are important protein-bound uremic retention solutes whose levels can be partially reduced by renal replacement therapy. These solutes originate from intestinal bacterial protein fermentation and are associated with cardiovascular outcomes and chronic kidney disease progression. The aims of this study were to investigate the levels of indoxyl sulfate and p-cresyl sulfate as well as the effect of probiotics on reducing the levels of uremic toxins in pediatric patients on dialysis. Methods: We enrolled 20 pediatric patients undergoing chronic dialysis; 16 patients completed the study. The patients underwent a 12-week regimen of VSL#3, a high-concentration probiotic preparation, and the serum levels of indoxyl sulfate and p-cresyl sulfate were measured before treatment and at 4, 8, and 12 weeks after the regimen by using fluorescence liquid chromatography. To assess the normal range of indoxyl sulfate and p-cresyl sulfate we enrolled the 16 children with normal glomerular filtration rate who had visited an outpatient clinic for asymptomatic microscopic hematuria that had been detected by a school screening in August 2011. Results: The baseline serum levels of indoxyl sulfate and p-cresyl sulfate in the patients on chronic dialysis were significantly higher than those in the children with microscopic hematuria. The baseline serum levels of p-cresyl sulfate in the peritoneal dialysis group were significantly higher than those in the hemodialysis group. There were no significant changes in the levels of these uremic solutes after 12-week VSL#3 treatment in the patients on chronic dialysis. Conclusion: The levels of the uremic toxins p-cresyl sulfate and indoxyl sulfate are highly elevated in pediatric patients on dialysis, but there was no significant effect by probiotics on the reduction of uremic toxins in pediatric dialysis patients. Therefore, studies for other medical intervention to reduce uremic toxins are also necessary in pediatric patients on dialysis.

• 한국세라믹학회지
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• 제45권7호
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• pp.375-379
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• 2008

Redox behavior was observed in alkali alkaline earth silicate PDP (Plasma Display Panel) glass melts doped with sulfate and sulfide by square wave voltammetry (SWV). According to voltammograms produced at a temperature range of 1100 to $1400^{\circ}C$ and frequency range of 5 to 1000 Hz, both melts showed the same behavior in which there is one reduction peak at low frequency but another peak at an increase of frequency. Based on the frequency dependence of the peak current, self diffusivity of $S^{4+}$ was determined. Based on the temperature dependence of the peak potential, standard enthalpy (${\Delta}H^0$) and standard entropy (${\Delta}S^0$) for the reduction of $S^{4+}$ to $S^0$ were calculated.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.90-93
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• 2003

Sampling of waters from each stage of treatment system, SAPS (Successive Alkalinity Producing System), and spring water near the Hanchang coal mine of Kangwon. Province were carried out periodically and analyzed to evaluate the source and possible path of groundwater contamination by acid mine drainage(AMD). Chemical and sulfur isotope compositions showed that spring water was affected by seepage from mine tailings, and seepage of stonewall, a part of treatment system, was affected by both seepage from mine tailings and mine adit drainage. Through the treatment system no appreciable decrease of sulfur content was identified. And almost similar sulfur isotope compositions of water from each stage of the treatment system may suggest incomplete or very poor sulfate reduction by sulfate reducing bacteria.

• 한국안전학회지
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• 제4권1호
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• pp.71-74
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• 1989

The $\alpha$-Fe$_2$O$_3$ gas sensor, prepared by the precipitation of Fe(OH)$_3$ from a solution of iron(III) sulfate and tin (IV) chloride, was composed of fine particles and was superior in sensitivity to other $\alpha$-Fe$_2$O$_3$. The gas sensitivity was found to depend on the amounts of remaining sulfate ion the microstructure and a small amount of iron(II) species generated through the reduction of $\alpha$-Fe$_2$O$_3$. The sensing mechanism of $\alpha$-Fe$_2$O$_3$gas sensor was confirmed to be due to the reduction of $\alpha$-Fe$_2$O$_3$ to the low resistive Fe$_3$-xO$_4$ by combustible gas and to depend on the crystral structure.