• Journal of Environmental Science International
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• v.13 no.7
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• pp.675-680
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• 2004

This study was conducted to remove organics and nutrients using 2 stage intermittent aeration reactor. First reactor, using suspended microbial growth in intermittent aeration instead of anaerobic reactor in the typical BNR process, used minimum carbon source to release P, and it was possible to reduce ammonia loading going to second reactor. In the second reactor, using moving media intermittent aeration, it was effective to reduce nitrate in non-aeration time by attached microorganisms having long retention time. In aeration time, nitrification and P uptake were taken place simultaneously. From the experiment, two major results were as follows. First, the removal of organics was more than 90%, and optimum aeration/non-aeration time ratio for organic removal was corresponded with aeration/non-aeration time ratio for nitrogen removal. Second, in the first reactor, optimum aeration/non-aeration time ratio was 15/75 (min.) because it was necessary to maintain 75 min. of non-aeration time to suppress of impediment of return nitrate and to lead release of phosphate. In the second reactor, optimum aeration/non-aeration time ratio was 45/90 (min.).

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.307-312
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• 2011

The potential of algal-bacterial culture was investigated for advanced treatment of animal wastewater. Fed-batch experiments were carried out to examine treatability of nitrogen and phosphorus in different microbial consortium: Chlorella vulgaris, activated sludge, three microalgae strains (Scenedesmus, Microcystis, Chlorella) and Bacillus consortium, and three microalgae strains and sludge consortium. Single culture of C. vugaris showed the better efficiency for nitrogen removal but was not good at organic matter and phosphorus removal compared with activated sludge. Three microalgae and Bacillus consortium was best culture among the culture and consortium for pollutants removal tested in this experiment. Effect of $CO_2$ addition was studied by using three microalgae and Bacillus consortium. $CO_2$ addition enhanced T-P removal efficiency up to 60%. However, removal efficiencies of T-N and ammonia nitrogen reduced on the contrary.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.30 no.1
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• pp.43-51
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• 2024

The addition of oxygen scavengers to food products helps to reduce oxygen exposure, thereby mitigating deterioration, including changes in taste, odor, and color, as well as inhibiting microbial growth. Despite the advantages of the existing non-metallic oxygen removal materials in terms of safety for the human body and suitability for use in microwave ovens, their utilization has been limited due to their slow reaction initiation speed. Therefore, in the current study, sodium metabisulfite was impregnated into various porous media, including halloysite nanoclay, activated carbon, montmorillonite, and silica gel. The oxygen scavenger, produced by impregnating silica gel with sodium metabisulfite, demonstrated a 425% improvement in the initial oxygen removal rate compared to pure sodium metabisulfite. Additionally, sachets containing an oxygen-removing composition with an enhanced oxygen removal rate effectively decreased the oxygen concentration to less than 0.5% on the third day of storage in apple packaging, without elevating carbon dioxide levels. Moreover, it proved effective in preventing the browning of the apple surface. Therefore, the SM/SG oxygen-removal composition can be effectively applied to active food packaging by controlling the oxygen concentration within the packaging.

• Journal of Life Science
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• v.21 no.10
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• pp.1473-1480
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• 2011

Perchlorate ($ClO_4^-$) is a contaminant found in surface water and soil/ground water. Microbial removal of perchlorate is the method of choice since microorganisms can reduce perchlorate into harmless end-products. Such microorganisms require an electron donor to reduce perchlorate. Conventional perchlorate-removal techniques employ heterotrophic perchlorate-reducing bacteria that use organic compounds as electron donors to reduce perchlorate. Since continuous removal of perchlorate requires a continuous supply of organic compounds, heterotrophic perchlorate removal is an expensive process. Feasibility of autotrophic perchlorate-removal using elemental sulfur granules and activated sludge was examined in this study. Granular sulfur is relatively inexpensive and activated sludge is easily available from wastewater treatment plants. Batch tests showed that activated sludge microorganisms could successfully degrade perchlorate in the presence of granular sulfur as an electron donor. Perchlorate biodegradation was confirmed by molar yield of $Cl^-$ as the perchlorate was degraded. Scanning electron microscope revealed that rod-shaped microorganisms on the surface of sulfur particles were used for the autotrophic perchlorate-removal, suggesting that sulfur particles could serve as supporting media for the formation of biofilm as well. DGGE analyses revealed that microbial profile of the inoculum (activated sludge) was different from that of the biofilm sample obtained from enrichment culture that used sulfur particles for $ClO_4^-$-degradation.

• Journal of Korean Society on Water Environment
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• v.23 no.3
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• pp.397-402
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• 2007

Anammox reactor seeded with sewage sludge from RBC reactor and anaerobic granule from full-scale UASB reactor treating distillery wastewater was operated. Mixed granule and suspended sludge in the ammonium oxidizing process were taken and analyzed to investigate microbial community structure by molecular methods such as gene cloning and phylogenetic tree analysis after 250 days of continuous cultivation. The average nitrogen removal rate showed $0.9kg\;N/m^3-day$ after 250 days of continuous operation, then the maximum nitrogen removal rate showd $1.9kg\;N/m^3-day$ when $2.1kg\;N/m^3-day$ of nitrogen loading rate was applied. As results of gene cloning and phylogenetic tree analysis, Three kinds of phylum were found to be Proteobacteria, Acidobacteria and Planctomycetes (anammox bacteria) in mixed granule. Five kinds of phylum were found to be Proteobacteria, Chlorobi, Planctomycetes, Nitrospirae and Verrucomicrobia in suspended sludge. We found planctomycete KSU-1 and putative new anammox bacteria in the reactor. Microbial structure represented different consortia depending on the types of sludge in the anammox reactor.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.6
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• pp.889-896
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• 2012

In this study, simulation results of nitrogen and phosphorus removals and microbial activities for an $A_2O$ process in wastewater treatment plant are presented by using Activated Sludge Models (ASMs). Simulations were performed using pre-calibrated model and layout implemented in GPS-X simulation software. The models were used to investigate variations of SRT, water temperature, DO and C/N ratio effect on nutrients removal and microbial activity. According to the simulated results, the successful nitrification required SRT higher than 10.3 days, whereas increase of $NO_3$-N loading in the anaerobic reactor caused phosphorus release by PAOs; the effluent $NH_4$-N showed rapid change between $12^{\circ}C$(21.7 mg/L) and $13^{\circ}C$(3.2 mg/L); the effluent phosphorus was increased up to 1.9 mg/L at water temperature of $25^{\circ}C$; the DO increase was positive for heterotrophs and autotrophs growths but negative for PAOs growth; the PAOs showed low activity when C/N ratio was lower than 2.5. The experimental results indicated that the calibrated models can assure the prediction quality of the ASMs and can be used to optimize the $A_2O$ process.

• Journal of Soil and Groundwater Environment
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• v.20 no.5
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• pp.47-51
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• 2015

Biocatalytic degradation of total petroleum hydrocarbons (TPHs) in contaminated soil by hemoglobin and hydrogen peroxide is an effective soil remediation method. This study used a laboratory soil reactor experiment to evaluate the effectiveness of a nonspecific biocatalytic reaction with hemoglobin and H₂O₂ for treating TPH-contaminated soil. We also quantified changes in the soil microbial community using real-time PCR analysis during the experimental treatment. The results show that the measured rate constant for the reaction with added hemoglobin was 0.051/day, about 3.5 times higher than the constant for the reaction with only H₂O₂ (0.014/day). After four weeks of treatment, 76% of the initial soil TPH concentration was removed with hemoglobin and hydrogen peroxide treatment. The removal of initial soil TPH concentration was 26% when only hydrogen peroxide was used. The soil microbial community, based on 16S rRNA gene copy number, was higher (7.1 × 10⁶ copy number/g of bacteria, and 7.4 × 10⁵ copy number/g of Archaea, respectively) in the hemoglobin catalyzed treatment. Our results show that TPH treatment in contaminated soil using hemoglobin catalyzed oxidation led to the enhanced removal effectiveness and was non-toxic to the native soil microbial community in the initial soil.

• Microbiology and Biotechnology Letters
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• v.32 no.4
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• pp.328-333
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• 2004

To treat a waste gas containing a high strength H2S, the two-stages microbial desulfurization process that conof a bioreactor immobilized with Acidithiobacillusferrooxidans and a chemical absorption scrubber has was proposed. After 4 times repeat of batch cultures, the immobilized bioreactor has been stabilized and the rate of iron oxidation reached 0.89 kg . $m^{-3}{\cdot}m^{-1}$ at steady state. The two-stages microbial desulfurization prowas able to be operated for a long term over 54 days. The removal efficiencies of H2S were 97-99% at a space velocity of 70 h-I and a inlet concentration of 37,000 ppmv. The maximum elimination capacity of H2S was approximately 3.3 kg S . $m^{-3}{\cdot}m^{-1}$. In the bioractor, the concentrations of the $Fe^{3+}$ and the immobilzed cell were constantly maintained during the desulfurization.

• Journal of Microbiology and Biotechnology
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• v.26 no.8
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• pp.1409-1419
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• 2016

The effect of pH on propionate degradation in an upflow anaerobic sludge blanket (UASB) reactor containing propionate as a sole carbon source was studied. Under influent propionate of 2,000 mg/l and 35℃, propionate removal at pH 7.5-6.8 was above 93.6%. Propionate conversion was significantly inhibited with stepwise pH decrease from pH 6.8 to 6.5, 6.0, 5.5, 5.0, 4.5, and then to 4.0. After long-term operation, the propionate removal at pH 6.5-4.5 maintained an efficiency of 88.5%-70.1%, whereas propionate was hardly decomposed at pH 4.0. Microbial composition analysis showed that propionate-oxidizing bacteria from the genera Pelotomaculum and Smithella likely existed in this system. They were significantly reduced at pH ≤5.5. The methanogens in this UASB reactor belonged to four genera: Methanobacterium, Methanospirillum, Methanofollis, and Methanosaeta. Most detectable hydrogenotrophic methanogens were able to grow at low pH conditions (pH 6.0-4.0), but the acetotrophic methanogens were reduced as pH decreased. These results indicated that propionate-oxidizing bacteria and acetotrophic methanogens were more sensitive to low pH (5.5-4.0) than hydrogenotrophic methanogens.

• Economic and Environmental Geology
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• v.42 no.5
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• pp.471-477
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• 2009

An experimental removal of dissolved uranium (U) exsiting as uranyl ion (${UO_2}^{2+}$) was carried out using Shewanella p., iron-reducing bacterium. By the microbial reductive reaction, initial U concentration ($50{\mu}M$) was constantly decreased, and most U were removed from solution after 2 weeks. Major mechanism that U was removed from the solution was adsorption, precipitation and mineralization on the microbe surface. Under the transmission electron microscopy, the U adsorbed on the microbe was observed as being crystallized and eventually enlarged to several ${\mu}m$ sizes of minerals by combining with individual microbes and organic exudates. It seems that such U growth and mineralization on the microbial surface could affect the U behavior in a radioactive waste disposal site. Thus, the biogechemical reaction of metal-reducing bacteria observed in this experiment could give an affirmative measure that the microbial activity may retard U movement in subsurface environment.