• 한국물환경학회지
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• 제18권4호
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• pp.371-377
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• 2002

The purpose of this study is to develop effective operating process in order to achieve more suitable conditions of Anoxic-Oxic-Anoxic-Stripper(AOAS) SBR through real-time control. To improve the removal efficiency, glucose, methanol and synthetic food waste acid fermentant were added as an external carbon source, In the case of glucose and synthetic food waste acid fermentant, TN, TP were removed to average 86.9%, 73.0% respectively. Methanol was removed to average 64.6%, 55.4% respectively. The synthetic food waste acid fermentant proved to be the most efficient and allowed for the substitution of an external carbon source. The removal rate of $COD_{Cr}$, was approximately 90% at all cases. The results of the study that a correlation between ORP (Oxidation-Reduction Potential), pH and DO and nitrification or denitrification when an external carbon source is added and when it isn't was showed that ${\Delta}ORP$ is suitable parameter. ORP reacted properly to denitrification (${\Delta}ORP<-10$) and nitrification (${\Delta}ORP<0$). The use of real-time control saved anywhere between 61 and 67 minutes at the anoxic(1) stage and 26 to 52 minutes at the oxic(1) stage. When the time saved from the anoxic(1) and oxic(1) was added to the anoxic(2) stage for the removal efficiency of TN and TP increased from 0.7 to 13.9% and 12 to 35 % respectively.

• 한국환경과학회지
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• 제19권1호
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• pp.17-26
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• 2010

To understand the initial changes in the microbial activities of wetland soil after construction, dehydrogenase activity (DHA) and denitrification potential (DNP) of soil from 1 natural wetland and 2 newly constructed wetlands were monitored. Soil samples were collected from the Daepyung marsh as a natural wetland, a treatment wetland in the West Nakdong River, and an experimental wetland in the Pukyong National University, Busan. The results showed that the DHA of the natural wetland soil was 6.1 times higher than that of the experimental wetland and similar to that of the treatment wetland 6 months after wetland construction (fall). Few differences were observed in the DNP between the soil samples from the natural wetland and 2 constructed wetlands four months after wetland construction (summer). However, 6 months after the construction (fall), the DNP of the soil samples from the natural wetland was 12.9 times and 1.8 times higher than that of the experimental wetland and the treatment wetland, respectively. These results suggested that the presence of organic matter as a carbon source in the wetland soil affects the DHA of wetland soil. Seasonal variation of wetland environment, acclimation time under anaerobic or anoxic wetland conditions, and the presence of carbon source also affect the DNP of the wetland soil. The results imply that the newly constructed wetland requires some period of time for having the better contaminant removal performance through biogeochemical processes. Therefore, those microbial activities and related indicators could be considered for wetland management such as operation and performance monitoring of wetlands.

• Environmental Engineering Research
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• 제24권2호
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• pp.254-262
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• 2019

The impact of free cyanide ($CN^-$) and thiocyanate ($SCN^-$) on the $CN^-$ (CDO) and $SCN^-$ degraders (TDO) to nitrify and denitrify aerobically was evaluated under alkaline conditions. The CDO's were able to nitrify under cyanogenic conditions, achieving $NH_4{^+}-N$ removal rates above 1.66 mg $NH_4{^+}-N.L^{-1}.h^{-1}$, except when $CN^-$ and $SCN^-$ loading was 15 mg $CN^-/L$ and 50 mg $SCN^-.L^{-1}$, respectively, which slightly inhibited nitrification. The TDO's were able to achieve a nitrification rate of 1.59 mg $NH_4{^+}-N.L^{-1}.h^{-1}$ in the absence of both $CN^-$ and $SCN^-$, while the presence of $CN^-$ and $SCN^-$ was inhibitory, with a nitrification rates of 1.14 mg $NH_4{^+}-N.L^{-1}.h^{-1}$. The CDO's and TDO's were able to denitrify aerobically, with the CDO's obtaining $NO_3{^-}-N$ removal rates above 0.67 mg $NO_3{^-}-N.L^{-1}.h^{-1}$, irrespective of the tested $CN^-$ and $SCN^-$ concentration range. Denitrification by the TDO's was inhibited by $CN^-$, achieving a removal rate of 0.46 mg $NO_3{^-}-N.L^{-1}.h^{-1}$ and 0.22 mg $NO_3{^-}-N.L^{-1}.h^{-1}$ when $CN^-$ concentration was 10 and 15 mg $CN^-.L^{-1}$, respectively. However, when the CDO's and TDO's were co-cultured, the nitrification and aerobic denitrification removal rates were 1.78 mg $NH_4{^+}-N.L^{-1}.h^{-1}$ and 0.63 mg $NO_3{^-}-N.L^{-1}.h^{-1}$ irrespective of $CN^-$ and $SCN^-$ concentrations.

• 한국해양환경ㆍ에너지학회지
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• 제4권4호
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• pp.32-41
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• 2001

전라북도곰소만 조간대에서 조석에 따른 오염물질의 플럭스를 구한 결과, COD의 경우, 4월에는 창조와 낙조시 COD의 유출입량이 동일하였고, 8월에는 창조시 83.0 ton COD/hr가 유입되어 낙조 시에는 68.6 ton COD/hr이 유출되어 조사해역의 갯벌이 평균적으로 5.69g COD/$m^2/day$의 정화력이 있는 것으로 평가되었다. 한편, 총질소의 플럭스는 4월의 창조 시에 0.486 ton N/hr이 유입되어 낙조 시에 0.330 ton N/hr으로 유출되어 조사해역 갯벌의 질소 정화력은 0.062 g N/$m^2/day$으로 평가되었다. 8월에도 창조 시에 3.144 ton N/hr이 유입된 후 낙조 시에 2.011 ton N/hr이 유출되고 있어 조사 해역의 갯벌이 0.448g N/$m^2/day$의 정화능력이 있음을 알 수 있었다. 부유물질의 플럭스는 4월의 창조 시에 0.31 ton SS/hr가 유입되어 낙조 시에 0.26 ton SS/㎡/day의 정화력이 있는 것으로 평가되었다. 8월에도 창조 시에 1.63ton SS/hr가 유입되어 낙조 시에 1.34 ton SS/hr이 유출되고 있어 조사해역의 갯벌이 시간당 0.29 ton의 부유물질을 수용하여 0.12g SS/$m^2/day$의 정화력이 있는 것으로 평가되었다. 곰소만 갯벌에서의 탈질산화는 1999년 4월에 0.009∼1.720 m mole N₂/㎡/day(평균 0.702 m mole ${N_2}/m^2/day$), 8월에 0.033∼0.133 m mole ${N_2}/m^2/day$(평균 0.077 m mole ${N_2}/m^2/day$)였으며, 2000년 4월에는 0.000∼1.909 m mole ${N_2}/m^2/day$(평균 0.756 m mole ${N_2}/m^2/day$), 8월에는 0.000∼1.697 m mole N₂/㎡/day(평균 0.392 m mole ${N_2}/m^2/day$)으로 계절별로 지점별로 탈질산화의 차이가 나타났으며 4회 평균치는 0.482 m mole ${N_2}/m^2/day$으로 평가되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권4호
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• pp.30-38
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• 2010

This study was conducted to determine the potential applicability of slowly released molasses (SRM) to treat nitratecontaminated groundwater. SRM was made by dispersing molasses in hydroxy propyl methyl cellulose-silicamicrocrystalline cellulose matrix. Column test indicated that SRM could continuously release molasses with slowly decreasing release rates of $64.6mg-COD/L{\cdot}h$ up to 65 hrs, $12.1mg-COD/L{\cdot}h$ up to 215 hrs, and $4.4mg-COD/L{\cdot}h$up to 361 hrs. A batch test using an isolated indigenous heterotrophic denitrifier Pseudomonas sp. KY1 having nitrite reductase (nirK) and liquid molasses demonstrated that the bacterium decreased 100 mg-N/L of nitrate to less than 10 mg-N/L at the C/N ratio of 10/1 in 48 hours. In a Pseudomonas sp. KY1-attached Ottawa sand column which continuously received molasses from a SRM-containing reservoir, the bacterium successfully removed nitrate from 20 mg-N/L to 3 mg-N/L during the 361 hours of column operation. The results showed the possibility that SRM can be used as a reliable, longterm extra carbon source for indigenous heterotrophic denitrifiers.

• Journal of Microbiology and Biotechnology
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• 제30권11호
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• pp.1688-1696
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• 2020

Soil physical and chemical characteristics, soil potential denitrification rates (PDR), community composition and nirK-, nirS- and nosZ-encoding denitrifiers were studied by using MiSeq sequencing, quantitative polymerase chain reaction (qPCR), and terminal restriction fragment polymorphism (T-RFLP) technologies base on short-term (5-year) tillage field experiment. The experiment included four tillage treatments: conventional tillage with crop residue incorporation (CT), rotary tillage with crop residue incorporation (RT), no-tillage with crop residue retention (NT), and rotary tillage with crop residue removed as control (RTO). The results indicated that soil organic carbon, total nitrogen and NH₄⁺-N contents were increased with CT, RT and NT treatments. Compared with RTO treatment, the copies number of nirK, nirS and nosZ in paddy soil with CT, RT and NT treatments were significantly increased. The principal coordinate analysis indicated that tillage management and crop residue returning management were the most and the second important factors for the change of denitrifying bacteria community, respectively. Meanwhile, this study indicated that activity and community composition of denitrifiers with CT, RT and NT treatments were increased, compared with RTO treatment. This result showed that nirK, nirS and nosZ-type denitrifiers communities in crop residue applied soil had higher species diversity compared with crop residue removed soil, and denitrifying bacteria community composition were dominated by Gammaproteobacteria, Deltaproteobacteria, and Betaproteobacteria. Therefore, it is a beneficial practice to increase soil PDR level, abundance and community composition of nitrogen-functional soil microorganism by combined application of tillage with crop residue management.

• 한국미생물·생명공학회지
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• 제49권3호
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• pp.432-439
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• 2021

Microbial community plays important roles in the culture environment of mud crab Scylla serrata. One of the environmental management efforts for the cultivation of S.serrata is by stabilizing microorganisms involved in nitrogen cycle process. The availability of dissolved inorganic nitrogen in its culture environment under a recirculating system closely relates to the nitrogen cycle, which involves both anaerobic and aerobic bacterial activities. Anaerobically, there are two major nitrogen compound degradation processes, i.e., denitrification and dissimilatory nitrate reduction to ammonium (DNRA). This study aimed to identify denitrifying and DNRA bacteria isolated from the recirculating cultivation of S. serrata. The water samples were collected from anaerobic filters called close filter system, which is anaerobically conditioned with the addition of varying physical filter materials in the recirculating mud crab cultures. The results showed that three denitrifying bacterial isolates and seven DNRA bacterial isolates were successfully identified. The phylogenetic analysis based on 16S rRNA gene of the denitrifying bacteria revealed that HIB_7a had the closest similarity to Stenotrophomonas daejeonensis strain MJ03. Meanwhile, DNRA bacterial isolate of HIB_92 showed a 100% similarity to Bacillus sonorensis strain N3, Bacillus vallismortis strain VITS-17, Bacillus tequlensis strain TY5, Geobacillus sp. strain DB24, Bacillus subtilis strain A1, and Bacillus mojavensis strain SSRAI21. This study provides basic information denitrifying and DNRA bacterial isolates identity which might have the potential to be applied as probiotics in aquaculture systems in order to maintain optimal environmental conditions.

• 한국토양비료학회지
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• 제49권1호
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• pp.60-65
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• 2016

The main objective of this research was to estimate the total mass of nitrogen discharged from various sources in paddy field area of South Korea in 2010 and 2013. Input and output budgets for nitrogen were estimated by mass balance approach. The mass balance approach reduces the effect of flow variations, and the large scale approach minimizes local effects, resulting in easier and faster establishment of strategy for nonpoint pollution problems. Nitrogen inputs were chemical fertilizer, compost, atmospheric deposition, biological fixation, and agricultural water, while crop uptake, denitrification, volatilization, and infiltration were nitrogen outputs. The estimated total nitrogen inputs for paddy field in South Korea were $266,211ton\;yr^{-1}$, $260,729ton\;yr^{-1}$, while those of total nitrogen outputs were $168,463ton\;yr^{-1}$, $164,994ton\;yr^{-1}$ in 2010 and 2013, respectively. Annual amounts of potential nitrogen outflow from paddy field were $97,748ton\;yr^{-1}$, $95,735ton\;yr^{-1}$ in 2010 and 2013. Also, annual rate of potential nitrogen outflow were 36.7%, 36.7% in 2010 and 2013, respectively.

• 지질공학
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• 제12권4호
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• pp.471-484
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• 2002

금강 유역의 충적층(면적 $3,029\textrm{km}^2$)에는 총 81억톤에 이르는 지하수가 부존하는 것으로 알려져 있으나, 과도한 농업활동에 의해 질소계 비료의 사용량이 증가함(250 N kg/ha 이상)에 따라 질산염 오염이 증가하고 있다 본 연구에서는 금강 권역의 대표적인 충적층 분포 지역의 충적층 지하수를 대상으로 질산염의 오염 현황 및 거동 특성을 파악하고자 광역적인 수리지구화학 연구를 수행하였다. 채취된 지하수 시료(총 186개)는 대체적으로 높은 질산염 농도(평균 42.2 mg/L, 최대 295 mg/L)를 보여주어 심하게 오염되어 있음을 나타내었다. 특히, 채취된 시료의 약 29%는 먹는물 수질 기준(44 mg/L $NO_3$)을 초과하고 있다. 연구지역 내 지하수 중의 질산염의 분포는 충적 대수층의 지구화학적 환경에 따라 크게 좌우되고 있다. 특히, 충적층 지하수의 산화-환원 전위(Eh)의 감소는 질산염의 농도 및 철과 망간의 농도 감소와 뚜렷한 상관성을 나타내었다. 따라서, 충적 대수층 지질매체 자체의 퇴적 환경의 차이를 반영하는 것으로 판단되는 산화-환원 상태(redox state)의 변화는 충적층 지하수 내의 질소계 오염물질의 거동을 지배함은 물론 탈질(denitrification)에 의한 자연저감을 조절하고 있는 것으로 판단된다. 특히, 탄소가 풍부한 실트질 충적층의 존재는 혐기성 환경을 조성함으로써, 질산염 오염에 대하여 상당한 정도의 완충 능력을 지니게 하는 것으로 판단된다.

• 한국미생물·생명공학회지
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• 제31권2호
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• pp.197-200
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• 2003

In oil-contaminated environments, anaerobic biodegradation of toluene depended on the concentration and distribution of terminal electron acceptor as well as the physicochemical properties such as DO concentration, redox potential and pH. This study showed the anaerobic biodegradation of toluene in two different soils by using nitrate reduction, ferric iron reduction, sulfate reduction and methanogensis. Toluene degradation rates in the soil samples taken from rice filed and tidal mud flat by nitrate reduction were higher than those by other processes. Tho soil samples from the two fields were enriched for 130 days by providing toluene as a sole carbon source and nitrate or sulfate as a terminal electron acceptor. The toluene degradation rates in the enriched denitrifying consortia obtained from the rice field and tidal mud flat soil were 310.7 and 200.6 $\mu$mol$ L^{-1}$ / $d^{-1}$, respectively. The toluene (legradation rates in the enriched sulfate-reducing consortia from the fields ranged fi-om 149.1 to 86.1$\mu$mol $L^{-1}$ / $d^{-1}$ .