• Environmental Engineering Research
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• 제10권5호
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• pp.257-263
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• 2005

A batch and a continuous type experiments were conducted to test the conditions for simultaneous phosphorus release and uptake, and denitrification, taking place in one process. The bacteria able to denitrify as well as to remove phosphorus were evaluated for the application to biological nutrient removal(BNR) process. In the batch-type experiment, simultaneous reactions of phosphorus release and uptake, and also denitrification were observed under anoxic condition with high organic and nitrate loading. However the rate and the degree of P release were lower than that occurred under anaerobic condition. BNR processes composed of anaerobic-anoxic-oxic(AXO), anoxic-anaerobic-oxic(XAO) and anoxic-oxic(XO) were operated in continuous condition. The anoxic reactors in each process received nitrate loading. In the AXO process, P release in anaerobic reactor and the luxury uptake in oxic reactor proceeded actively regardless to nitrate loading. However in XAO and XO processes, P release and luxury uptake occurred only with the nitrate loading less than $0.07\;kg{NO_3}^--N$/kgMLSS-d. With higher nitrate load, P release increased and the luxury uptake decreased. Therefore, it appeared that the application of denitrifying phosphorus-removing bacteria (DPB) to BNR process must first resolve the problem with decrease of luxury uptake of phosphorus in oxic reactor.

• 한국환경농학회:학술대회논문집
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• 한국환경농학회 2011년도 30주년 정기총회 및 국제심포지엄
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• pp.293-293
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• 2011

• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1155-1160
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• 2012

Sulfur-utilizing autotrophic denitrification relies on an inorganic carbon source to reduce the nitrate by producing sulfuric acid as an end product and can be used for the treatment of wastewaters containing high levels of nitrates. In this study, sulfur-denitrifying bacteria were used in anoxic batch tests with sulfur as the electron donor and nitrate as the electron acceptor. Various medium components were tested under different conditions. Sulfur denitrification can drop the medium pH by producing acid, thus stopping the process half way. To control this mechanism, a 2:1 ratio of sulfur to oyster shell powder was used. Oyster shell powder addition to a sulfur-denitrifying reactor completely removed the nitrate. Using 50, 100, and 200 g of sulfur particles, reaction rate constants of 5.33, 6.29, and $7.96mg^{1/2}/l^{1/2}{\cdot}h$ were obtained, respectively; and using 200 g of sulfur particles showed the highest nitrate removal rates. For different sulfur particle sizes ranging from small (0.85-2.0 mm), medium (2.0-4.0 mm), and large (4.0-4.75 mm), reaction rate constants of 31.56, 10.88, and $6.23mg^{1/2}/l^{1/2}{\cdot}h$ were calculated. The fastest nitrate removal rate was observed for the smallest particle size. Addition of chemical oxygen demand (COD), methanol as the external carbon source, with the autotrophic denitrification in sufficiently alkaline conditions, created a balance between heterotrophic denitrification (which raises the pH) and sulfur-utilizing autotrophic denitrification, which lowers the pH.

• KSBB Journal
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• 제14권5호
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• pp.616-620
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• 1999

Winogradsky column을 이용하여 10개의 탈질 박테리아를 분리하였다. 그 중 가장 성능이 우수한 탈질 박테리아를 Pseudomonas CW4로 명하였다. Pseudomonas CW4는 무산소 조건에서 배양하였고, Pseudomonas CW4의 최적 생육조건을 온도, pH. 교반속도, 탄소원 농도 및 질산성질소 농도에 변화를 주어 측정하였다. 최적 생육 온도 3$0^{\circ}C$, 최적 pH 범위는 6~8이었다. 교반속도와 탄소원 농도에 대한 영향은 아주 작았다. 그리고 질산성 질소의 초기농도 142.5 mg/L 에서 15 시간만에 100% 탈질을 나타내었다.

• 한국산림과학회지
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• 제84권2호
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• pp.178-185
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• 1995

여천공단의 대기오염이 산림생태계에 미치는 영향을 파악하기 위하여 공단의 남단에 위치한 남해화학주변과 그 지역에서 2km, 4km, 6km, 8km 및 10km 떨어진 지점을 선정하여 산림토양의 화학적 특성, 탈질균 및 황산환원균 동태와 지의류 출현도를 비교하였다. 여천공단 주변지역의 토양은 적황색 산림토양군(R Y)에 속하는 토양이었으나 같은 산림토양군에 속하는 토양에 비해 pH가 매우 낮았다. 산림토양의 pH가 낮음으로 인해 C/N비가 15~25의 범주에 있음에도 불구하고 유기물의 분해 등 무기화에 관여하는 미생물의 활력이 낮아서 유기물함량이나 전질소함량은 상대적으로 높았다. 공단 인접지역에서 4km 지점에 이르는 곳까지의 토양 화학특성이 6km 이후 지역에 비해 대기오염 피해도가 심하게 나타났으나 탈질균 및 황산환원균의 분포량 차이에 따른 피해도 구분은 어려웠다. 한편, 지의류는 산림토양에 반영된 대기오염도의 차이에 비해 확연한 결과를 나타냈으며, 특히 엽상지의류는 바위에 붙어 사는 지의류에 비해서 더 민감한 반응을 나타냄을 확인할 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제10권3호
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• pp.410-414
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• 2000

The effect of the COD/N ratio on denitrification characteristics was evaluated for the development of a denitrification process. Activated sludge, acclimated to an anoxic condition, was used as the denitrifier consortium (mixture of denitrifying organisms) for enhanced nitrogen removal in a recirculating aquarium system. Synthetic wastewater containing nitrate was used as the influent solution and glucose was used as the carbon source for denitrification. The COD/N ratio varied within a range of 1.5-7.2. The denitrification efficiency was higher than 97% even at a COD/N ratio of 1.5. Under a theoretical COD/N ratio of 3.0, nitrite was detected, however, the amount was less than 1% of the total influent nitrogen. The number of both nitrate-reducing bacteria and denitrifying bacteria reached $3.5{\times}10^5/ml$ with a COD/N ratio of 1.5 after 45 days of operation.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권1호
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• pp.32-37
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• 2006

In this study, we have purified and characterized the membrane bound nitrate reductase obtained from the denitrifying bacteria, Ochrobactrum anthropi SY509, which was isolated from soil samples. O. anthropi SY509 can grow in minimal medium using nitrate as a nitrogen source. We achieved an overall purification rate of 15-fold from the protein extracted from the membrane fraction, with a recovery of approximately 12% of activity. The enzyme exhibited its highest level of activity at pH 5.5, and the activity was increased up to $70^{\circ}C$. Periplasmic and cytochromic proteins, including nitrite and nitrous oxide reductase, were excluded during centrifugation and were verified using enzyme essay. Reduced methyl viologen was determined to be the most efficient electron donor among a variety of anionic and cationic dyestuffs, which could be also used as an electron donor with dimethyl dithionite. The effects of purification and storage conditions on the stability of enzyme were also investigated. The activity of the membranebound nitrate reductase was stably maintained for over 2 weeks in solution. To maintain the stability of enzyme, the cell was disrupted using sonication at low temperatures, and enzyme was extracted by hot water without any surfactant. The purified enzyme was stored in solution with no salt to prevent any significant losses in activity levels.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 총회 및 춘계학술발표회
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• pp.368-371
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• 2003

Leaking underground storage tanks are a major source of groundwater contamination by petroleum hydrocarbons. Bioremediation of aromatic hydrocarbons in groundwater and sediments is often limited by dissolved oxygen. Aerobic bioremediation has been highly effective in the remediation of many fuel releases, but Many aromatic hydrocarbons degrade very slowly under anaerobic conditions. Nitrate is a good alternative electron acceptor to oxygen and denitrifying bacteria are commonly found in the subsurface and in association with contaminated aquifer materials. Because nitrate is less expensive and more soluble than oxygen. it may be more economical to restore fuel-contaminated aquifers using nitrate rather than oxygen. This study show that biodegradation of BTEX and MTBE is enhanced by the nitrate-amended microcosms under aerobic/anaerobic conditons. Although aromatic hydrocarbons degrade very slowly under anaerobic conditions. Biodegradaton was observed for all of the test compounds.

• 한국물환경학회지
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• 제39권1호
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• pp.61-75
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• 2023

Denitrifying bacteria convert nitrate to nitrogen gas using an external carbon source as an electron donor. The external carbon source affects the denitrification performance and bacterial community structure. Although methanol is a cheap and effective external carbon source, the addition of diverse carbon sources may improve the total nitrogen removal rate and biomass characteristics, such as settleability. In this study, denitrifying reactions were performed using solely methanol and mixed carbon sources of methanol, glucose, and acetate in a sequencing batch reactor. The denitrifying reactor using methanol resulted in a total nitrogen removal rate of 0.39 ± 0.025 kg-N/m³-day while the suspended biomass transformed into dark brown granules. Methyloversatilis discipulorum had the highest predominance at 43.84%. The individual denitrifying biomasses, which were separately enriched with methanol, glucose, and acetate, showed the same total nitrogen removal performance of 0.39 ± 0.016 kg-N/m³-day. However, the addition of mixed carbon sources showed an improved total nitrogen removal rate of 0.42 ± 0.043 kg-N/m³-day, with the domination of Candidatus Saccaribacteria at 25.61%. The denitrifying granules turned pale yellow color. Influent COD/NO₃^--N ratios of 3.5, 5, and 7.5 exhibited COD/NO₃^--N consumptions of 4.3 ± 0.4, 4.4 ± 0.8, and 5.2 ± 0.7, and the consistent predominance of Candidatus Saccharibacteria.

• Journal of Microbiology and Biotechnology
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• 제24권6호
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• pp.843-853
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• 2014

In the context of artificial groundwater recharge, a reactive soil column at pilot-scale (4.5 m depth and 3 m in diameter) fed by treated wastewater was designed to evaluate soil filtration ability. Here, as a part of this project, the impact of treated wastewater filtration on soil bacterial communities and the soil's biological ability for wastewater treatment as well as the relevance of the use of multi-bioindicators were studied as a function of depth and time. Biomass; bacterial 16S rRNA gene diversity fingerprints; potential nitrifying, denitrifying, and sulfate-reducing activities; and functional gene (amo, nir, nar, and dsr) detection were analyzed to highlight the real and potential microbial activity and diversity within the soil column. These bioindicators show that topsoil (0 to 20 cm depth) was the more active and the more impacted by treated wastewater filtration. Nitrification was the main activity in the pilot. No sulfate-reducing activity or dsr genes were detected during the first 6 months of wastewater application. Denitrification was also absent, but genes of denitrifying bacteria were detected, suggesting that the denitrifying process may occur rapidly if adequate chemical conditions are favored within the soil column. Results also underline that a dry period (20 days without any wastewater supply) significantly impacted soil bacterial diversity, leading to a decrease of enzyme activities and biomass. Finally, our work shows that treated wastewater filtration leads to a modification of the bacterial genetic and functional structures in topsoil.