• Membrane and Water Treatment
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• 제15권1호
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• pp.1-9
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• 2024

Biological nutrient removal is gaining increasing attention in wastewater treatment plants; however, it is adversely affected by low temperatures. This study examined temperature effects on nutrient removal and morphological stability of the granular and denitrifying phosphorus accumulating organisms (PAO and DPAO, respectively) using sequencing batch reactors (SBRs) at 5, 10, and 20 ℃. Lab-scale SBRs were continuously operated using anaerobic-anoxic and anaerobic-oxic cycles to develop the PAO and DPAO granules for 230 d. Sludge granulation in the two SBRs was observed after approximately 200 d. The average removal efficiency of soluble chemical oxygen demand (SCOD) and PO₄^3--P remained >90% throughout, even when the temperature dropped to 5 ℃. The average removal efficiency of NO₃^--N remained >80% consistently in DPAO SBR. However, nitrification drastically decreased at 10 ℃. Hence, the removal efficiency of NH₄⁺-N was decreased from 99.1% to 54.5% in PAO SBR. Owing to the increased oxygen penetration depth at low temperatures, the influence on nitrification rates was limited. The granule in DPAO and PAO SBR was observed to be unstable and disintegrated at 10 ℃. In conclusion, morphological characteristics showed that changed conversion rates at low temperatures in aerobic granular sludge altered both nutrient removal efficiencies and granule formation.

• 대한환경공학회지
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• 제22권5호
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• pp.939-947
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• 2000

연속 회분식 반응기를 이용하여 생물학적 인 제거에 관한 미생물 분포 연구를 수행하였다. 탄소원으로 초산을 넣은 합성 폐수를 사용하였고 미생물 체류 시간과 수리학적 체류 시간은 각각 10일과 16시간으로 유지하였다. 인 방출과 흡수가 운전 시간이 경과됨에 따라 점점 빠르게 일어났으며 약 200일 경과 후 안정적인 인 제거가 유지되었다. 안정적인 생물학적 인 제거가 유지될 때의 미생물 분포를 조사하기 위하여 17개의 ribosomal RNA (rRNA) signature probe를 합성하여 슬러지로부터 분리한 전체 rRNA에 대하여 slot hybridization을 실시하였다. 분리한 전체 RNA에는 proteobacteria의 베타군 (beta subclass)에 속하는 rRNA가 가장 많이 함유되어 있음을 확인하였고 CTE probe와 관계된 rRNA가 다음으로 많이 분포하였다. 전통적으로 생물학적 인 제거를 담당하는 미생물로 여겨져 왔던 Acinetobacter, Aeromonas, Pseudomonas의 rRNA는 10% 미만으로 존재하고 있음이 확인되었다. 이러한 결과로부터 Rhodocyclus 그룹같은 proteobacteria의 베타군과 CTE에 속하는 미생물이 인 제거에 중요한 역할을 수행할 것으로 생각되었고 Acinetobacter, Aeromonas, Pseudomonas 등은 생물학적 인 제거에 있어서 과평가된 것으로 판단되었다.

• Journal of Microbiology and Biotechnology
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• 제28권4호
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• pp.652-662
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• 2018

Diarrhea is a global disease with a high morbidity and mortality rate in children. In this study, 25 fecal samples were collected from children under 5 years old. Seven samples had been taken from healthy children without diarrhea and marked as the healthy control group; eight samples had been sampled from children with diarrhea caused by dyspepsia and defined as the non-infectious group; and ten samples had been taken from children with diarrhea induced by intestinal infections and identified as the infectious group. We detected the microbial communities of samples by using high-throughput sequencing of 16S rRNA genes. The proportion of aerobic and facultative anaerobic microbes in samples of the infectious group was much higher than in the non-infectious group. In addition, the relative abundance of Enterococcus in the healthy control group was significantly higher than in the non-infectious group and infectious group. This can be used as a potential diagnostic biomarker for diarrhea.

• Journal of Microbiology and Biotechnology
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• 제16권10호
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• pp.1650-1655
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• 2006

Bacteria belonging to the genus Paenibacillus are facultatively anaerobic endospore formers and are attracting growing ecological and agricultural interest, yet their genome information is very limited. The present study surveyed the genomic features of P. polymyxa ATCC $842^T$ using pulse-field gel electrophoresis of restriction fragments and sample genome sequencing of 1,747 reads (approximately 17.5% coverage of the genome). Putative functions were assigned to more than 60% of the sequences. Functional classification of the sequences showed a similar pattern to that of B. subtilis. Sequence analysis suggests nitrogen fixation and antibiotic production by P. polymyxa ATCC $842^T$, which may explain its plant growth-promoting effects.

• 한국물환경학회지
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• 제22권3호
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• pp.566-571
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• 2006

A sequencing batch biofilm reactor (SBBR) operated with a cycle of anaerobic - aerobic - anoxic - aerobic has been evaluated for the nutrient removal characteristics. The sponge-like moving media was filled to about 10% of reactor volume. The sewage was the major substrate while external synthetic carbon substrate was added to the anoxic stage to enhance the nitrogen removal. The operational results indicated that maximum T-N and T-P removal efficiencies were 97% and 94%, respectively were achieved, while COD removal of 92%. The observations of significant nitrogen removal in the first aerobic stage indicated that nitrogen removal behaviour in this SBBR was different to conventional SBR. Although the reasons for aerobic nitrogen removal has speculated to either simultaneous nitrification and denitrification or anoxic denitrification inside of the media, further researches are required to confirm the observation. The specific oxygen uptake rate (SOUR) test with biofilm and suspended growth sludge indicated that biofilm in SBBR played a major role to remove substrates.

• 한국물환경학회지
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• 제27권6호
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• pp.754-759
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• 2011

A sequencing batch reactor (SBR) was operated under different pH conditions to better understand the influence of pH to granulation in enhanced biological phosphorus removal systems. Granules from the SBR were also investigated using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Considerable decreases in the amount of phosphorus released per substrate provided under anaerobic conditions and the content of biomass polyphosphate under aerobic conditions were observed when pH was changed from 7.5 to 7.0, followed by 6.5. Aerobic granulation was also observed at pH 7.0. A number of bacteria with the typical morphological traits of tetrad-forming organisms (TFOs) were observed at pH 7.0, including large members of cluster. Filamentous bacteria were also there in large numbers. The occurrence and growth of granules were further enhanced at pH 6.5. A SEM analysis showed that the aerobic granules had a compact microbial structure with shaperical shape and morphologically consisted of aggregates of small coccoid bacteria and filamentous bacteria encapsulated by extracellular polymeric substance. The main material ions identified by EDX moreover revealed that the structural materials for polyphosphate in the granules include phosphorus, potassium and calcium. Therefore, these results strongly suggested that PAOs are a dominant population in the microbial community of the aerobic granules.

• 한국물환경학회지
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• 제36권4호
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• pp.322-331
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• 2020

By introducing chemically enhanced primary treatment (CEPT) in the first stage of sewage treatment, organic matter in sewage can be effectively recovered. Because CEPT sludge contains a high biodegradable organic matter in volatile solids (VS), it is feasible to convert the collected CEPT sludge into energy through anaerobic digestion. This study examined the properties and biochemical methane potential (BMP) of the CEPT sludge obtained from a sewage treatment plant located in an ocean area. The CEPT sludge contains a VS content of 37,597 mg/L, which is higher than that of excessive sludge (ES), i.e., 33,352 mg-VS/L. In the methane generation reaction, the lag period was as short as 1 to 2 days. The BMP for the CEPT sludge was 0.57 ㎥-CH₄/kg-VS_removed which is better than that of ES, i.e., 0.36 ㎥-CH₄/kg-VS_removed. Unfortunately, the CEPT sludge showed a high salinity as 0.56~0.75% probably due to the saline sewage. Due to the salinity, repeated BMP testing in a sequencing batch reactor showed significantly low methane production rates and BMPs. Also, the ES showed a strongly reduced BMP when the salinity was adjusted from 0.20 to 0.70% by NaCl. The ES mixture with higher CEPT content showed a better BMP, which is suitable for co-digestion. Besides, anaerobic digestion for 100% CEPT sludge can be a considerable option instead of co-digestion.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1464-1472
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• 2014

The microbial community structures of two continuous stirred tank reactors digesting turkey manure with pine wood shavings as well as chicken and swine manure were investigated. The reactor fed with chicken/swine wastes displayed the highest organic acids concentration (up to 15.2 g/l) and ammonia concentration (up to 3.7 g/l ammonium nitrogen) and generated a higher biogas yield (up to $366ml/g_{VS}$) compared with the reactor supplied with turkey wastes (1.5-1.8 g/l of organic acids and 1.6-1.7 g/l of ammonium levels; biogas yield was up to $195ml/g_{VS}$). The microbial community diversity was assessed using both sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Additionally, methanogens were analyzed using methyl coenzyme M reductase alpha subunit (mcrA) genes. The bacterial community was dominated by members of unclassified Clostridiales with the prevalence of specific clostridial phylotypes in each reactor, indicating the effect of the substrate type on the community structure. Of the methanogenic archaea, methanogens of the genus Methanosarcina were found in high proportions in both reactors with specific methanosarcinas in each reactor, whereas the strict hydrogenotrophic methanogens of Methanoculleus sp. were found at significant levels only in the reactor fed with chicken/swine manure (based on the analyses of 16S rRNA gene). This suggests that among methanogenic archaea, Methanosarcina species which have different metabolic capabilities, including aceticlastic and hydrogenotrophic methanogenesis, were mainly involved in anaerobic digestion of turkey wastes.

• 한국토양비료학회지
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• 제42권5호
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• pp.341-347
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• 2009

본 연구는 밀기울과 쌀겨를 이용한 토양 혐기발효 처리가 토양 미생물상 변화에 미치는 영향을 구명하고자 수행하였다. 희석 평판법을 이용하여 토양 미생물상을 분석한 결과 쌀겨를 처리한 토양은 사상균이 크게 증가한 반면, 효모의 생장은 확인할 수 없었다. 반면 밀기울을 처리한 토양은 사상균의 생장이 크게 억제되었으며, 효모는 높은 밀도를 보였다. 인지질 지방산을 이용하여 토양 미생물상을 분석한 결과, 처리가 진행되는 20일 까지는 밀기울과 쌀겨를 처리구 모두 그람 음성균과 양성균의 변동이 미미하였으나, 처리가 종료되어 비닐을 제거한 이후에는 크게 상승하는 경향을 보였다. 각 처리별 미생물 군집구조를 분석한 결과, 밀기울과 쌀겨 처리는 미생물상에 큰 변화를 보였으며, 각각의 군집구조는 크게 달랐다.

• Animal Bioscience
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• 제36권9호
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• pp.1453-1464
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• 2023

Objective: This study investigated the changes in bacterial communities within decomposing swine microcosms, comparing soil with or without intact microbial communities, and under aerobic and anaerobic conditions. Methods: The experimental microcosms consisted of four conditions: UA, unsterilized soil-aerobic condition; SA, sterilized soil-aerobic condition; UAn, unsterilized soil-anaerobic condition; and San, sterilized soil-anaerobic condition. The microcosms were prepared by mixing 112.5 g of soil and 37.5 g of ground carcass, which were then placed in sterile containers. The carcass-soil mixture was sampled at day 0, 5, 10, 30, and 60 of decomposition, and the bacterial communities that formed during carcass decomposition were assessed using Illumina MiSeq sequencing of the 16S rRNA gene. Results: A total of 1,687 amplicon sequence variants representing 22 phyla and 805 genera were identified in the microcosms. The Chao1 and Shannon diversity indices varied in between microcosms at each period (p<0.05). Metagenomic analysis showed variation in the taxa composition across the burial microcosms during decomposition, with Firmicutes being the dominant phylum, followed by Proteobacteria. At the genus level, Bacillus and Clostridium were the main genera within Firmicutes. Functional prediction revealed that the most abundant Kyoto encyclopedia of genes and genomes metabolic functions were carbohydrate and amino acid metabolisms. Conclusion: This study demonstrated a higher bacteria diversity in UA and UAn microcosms than in SA and SAn microcosms. In addition, the taxonomic composition of the microbial community also exhibited changes, highlighting the impact of soil sterilization and oxygen on carcass decomposition. Furthermore, this study provided insights into the microbial communities associated with decomposing swine carcasses in microcosm.