• 상하수도학회지
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• 제20권3호
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• pp.431-441
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• 2006

This study investigated the physiological characteristics of biofilm microorganisms formed onto the different drinking water distribution pipe surfaces. The simulated drinking water distribution pipe system which had several PVC, STS 304, and GS coupons was operated at flow velocity of 0.08 m/sec (Re 1,950) and 0.28 m/sec (Re 7,300), respectively. At velocity of 0.08 m/sec, the number of viable heterotrophic bacteria in the biofilm over the 3 months of operation averaged $3.3{\times}10^4$, $8.7{\times}10^4$, and $7.2{\times}10^3CFU/cm^2$ for PVC, STS, and GS surfaces, respectively. The number of attached heterotrophic bacteria averaged $1.4{\times}10^3$, $5.6{\times}10^2$, and $6.5{\times}10^2CFU/cm^2$ on PVC, STS, and GS surfaces at the system with relatively high flow velocity of 0.28m/sec. The changes of physiological profile of biofilm-forming microorganisms were characterized by community-level assay that utilized the Biolog GN microplates. Biofilms that formed on different pipe surfaces displayed distinctive patterns of community-level physiological profile (CLPP), which reflected the metabolic preference for different carbon sources and/or the utilization of these carbon sources to varying degrees. The CLPP patterns have shown that the metabolic potential of a biofilm community was different depending on the pipe material. The effect of the pipe material was also characterized differently by operation condition such as flow rate. At flow velocity of 0.08 m/sec, the metabolic potential of biofilm microorganisms on GS surface showed lower levels than PVC and STS biofilms. For biofilms on pipe material surfaces exposed to water flowing at 0.28 m/sec, the metabolic potential was in order of PVC>GS>STS. Generally, the levels of the bacterial biofilm's metabolic potentials were shown to be notably higher on pipe surfaces exposed to water at 0.08 m/sec when compared to those on pipe surfaces exposed to water at 0.28 m/sec.

• 한국산학기술학회논문지
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• 제16권4호
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• pp.2971-2977
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• 2015

본 연구는 마이크로코즘에서 적조생물 Cochlodinium polykrikoides을 살조하기 위해 사용된 화학물질과 황토의 처리 후 미소생물그룹의 단주기 변화를 파악하였다. 황토 4g 과 10g에서 적조생물의 살조효과는 20%이하로 낮게 관찰된 반면, 화학물질(TD49)의 $0.8{\mu}M$ 에서는 대상생물이 85%이상 제어되었다. 미소생물그룹에서 박테리아는 모든 실험군에서 조사 1일 후 현저하게 증가하였고, 2일 후 가장 높게 관찰된 후 점차적으로 감소하는 경향을 관찰하였다. 대조적으로 종속영양편모충은 조사 3-5일 경과 후 현저하게 높게 증가하였다. TD49처리군에서 박테리아가 2일후 점차적으로 감소한 것은 포식자인 HNF의 증가로 기인된 것으로 파악되었다. 또한 피각을 형성하지 않는 섬모충 Uronema sp.,의 증가는 박테리아의 증가 후 2-3일의 시간차를 두고 반응하는 특색을 관찰하였다. 즉 이는 적조생물이 살조된 후 분해되는 과정에서 박테리아의 현저한 증식을 일으켰고, 이와 함께 포식자 HNF와 Uronema sp.는 일정의 시간차를 두고 높은 개체수를 유지 한 것으로 판단되었다. 이와 같은 경향은 살조물질 TD49처리군에서 두드려졌다. 특히. 사이즈가 큰 무각섬모충 Euplotes sp. 개체수는 HNF와 Uronema sp.의 현저한 증가 후 높게 관찰되는 특성을 보였다. 결과적으로 살조제 TD49물질은 미소생물그룹에 긍정적인 효과를 가져왔고, 이는 박테리아, HNFs 섬모충으로 이어지는 먹이망의 에너지 흐름이 효율적으로 작용하고 있다는 것을 시사할 수 있었다.

• 미생물학회지
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• 제36권2호
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• pp.130-135
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• 2000

순천만 갯벌의 3개 지점의 표층(5cm)과 심층(20 cm)토양의 물리화학적 요인과 종속영양세균의 분포, 섬유소 분해율과 체외효소의 활성을 측정하였다. 온도, 수분함량, 인산염 인 그리고 유기물함량은 각각 -1~$30^{\circ}C$, 42.1~53.1%, 0.0779~0.1961mg/g, 그리고 1.99~7.64%로 나타나었다. 섬유소 films의 분해율은 7.7%~100%/month 범위로 1~2월에 최저 그리고 8~9월에 최고의 분해율을 나타냈다. 종속영양세균의 분포는 $0.87{\times}10^6 ~ 3.6{\times}10^7 $CUFs/g dry soil의 범위에 속해Tdmu 심층의 경우 표층에 비해 낮았다. MUF-기질의 분해율로 측정한 phoshatase, $\alpha$-D-gluocosidase, $\beta$-D-glucosidase, cellobiohydrolase 활성의 변화는 각각 152.23~1779.80 nMi/hr 2.67~202.18 nM/hr, 5.03~258.26 nM/hr, 3.42~63.07 nM/hr으로 모두 하계에 상대적으로 높은 값을 나타내었다. 섬유소 분해는 수온상승이 주된 요인이었으며, 정점간, 깊이간 큰 차이는 나타나지 않았다. 체외효소의 활성은 온도 및 섬유소 분해율과 높은 양의 상관관계를 나타냈다. 종속영양세균의 분포는 섬유소 분해와 체외효소의 활성과 높은 상괸은 나타나지 않았다.

• 대한환경공학회지
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• 제31권3호
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• pp.232-239
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• 2009

본 연구는 도시 하수처리장의 미생물 군집 내 항생제 내성 세균의 특징과 하천으로의 항생제 내성 세균 노출의 계절적 변화의 특성을 평가하였다. 일반 종속영양세균 배양을 위한 R2A agar (R2A)와 대장균군을 선택하여 배양하는 MacConkey sorbitol agar (MSA)에 항생제를 첨가 하여 제작한 배지에 하수처리장 시료를 도말하여 배양한 결과 모든 시료에서 다제 항생제 내성 세균을 검출 해 낼 수 있었다. Ampicillin과 sulfathiazole의 내성률이 다른 나라에 비해 높게 측정 되었으며 시료내 유기물의 정도, 사용된 배지에 따라 내성률이 다름을 볼 수 있었다. R2A 배지에서 분리된 다제 항생제 내성 세균은 모두 기존에 알려진 병원성 세균과 그 염기서열이 유사한 것으로 볼 때 병원성 세균의 항생제 내성 정도가 일반 세균보다 높음을 본 연구 결과로 보일 수 있었다. 또한 본 연구에서는 하수처리장이 하천에 미치는 유해성을 계절별로 관찰하여 전체 미생물중 항생제 내성 세균의 비율은 수온과 비례한다는 결과를 얻었다. 이 결과는 지구 온난화가 미생물 유해성을 증가시킬 가능성을 시사한다.

• 한국환경보건학회지
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• 제39권6호
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• pp.513-521
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• 2013

Objectives: This study was performed in order to detect indicator bacteria in drinking spring water (DSW) samples in Seoul Metropolitan City, and to identify their genus through 16S rRNA sequencing and then assessing the genetic relation of their strains. Methods: For indicator bacteria detection and identification of total coliforms, we analyzed DSW between the spring and summer seasons. In particular, DSW samples were chosen from sites repeatedly found unsatisfactory in recent years. Results: Heterotrophic plate counts of DSW in the spring and summer season were investigated in the range of 0-550 and 0-800 CFU/mL, respectively. Total coliforms of these were 0-1,900 and 0-2,100 CFU/100mL, fecal coliforms were 0-600 and 0-550 CFU/100mL, and Escherichia coli were 0-7 and 0-326 MPN/100mL. The detection ratio of fecal pollution indicators and that of fecal coliforms increased to 58.6% in the summer from 12.5% in the spring and Escherichia coli increased to 51.4% from 4.7%. As a result of genetic analysis on the isolated bacteria, the genus of total coliforms was classified in the order of Enterobacter spp. 12.7%, Serratia spp. 7.3%, E. hermanii 6.4%, Rahnella spp. 5.5%, Hafnia spp. 4.5%, Escherichia coli 3.6%, Klebsiella spp. 3.6% in the spring season. In the summer season, it was classified in order of Klebsiella spp. 16.6%, Enterobacter spp. 13.0%, Escherichia coli 11.0%, Serratia spp. 8.6%, Raoultella spp. 7.0%, Kluyvera spp. 5.6% and Citrobacter spp. 3.0%. Conclusions: The increase of fecal pollution in summer indicates that special attention to drinking DSW is required.

• 한국물환경학회지
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• 제20권2호
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• pp.190-195
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• 2004

A new technology for advanced wastewater treatment was developed using a modified Rotating Biological Contactor (RBC) process, named as Rotating Activated Bacillus Contactor (RABC) process that utilizes Bacillus sp., the facultatively anaerobic or activated microaerophilic bacteria on multiple-stage reticular rotating carriers, as a predominant species. The RABC process for a municipal wastewater with relatively low concentrations of organics, nitrogen, and phosphorus showed stable and high removal efficiencies, less than $BOD_5$ 10 mg/L, T-N 15 mg/L, and T-P 1.5 mg/L in final effluent. The performance load of RABC process was shown to be $1.23kg{\cdot}BOD/m^2{\cdot}day$ for the first stage (average $0.31kg{\cdot}BOD/m^2{\cdot}day$ for the total stages) based on both removed BOD and converted disc area corresponding to the reticular one. The sludge produced in the RABC process is characterized by low generation rate (about $0.18kg{\cdot}MLSS/kg{\cdot}BOD$) and excellent settleability. The number ratio of Bacillus ($2.4{\times}10^6CFU/ml$) to heterotrophic bacteria ($3.6{\times}10^7CFU/ml$) inhabiting in the biofilms of the RABC process was 6.7 %, indicating that Bacillus sp. was a predominant species in the biofilms. The RABC process with reticular rotating carriers showed its excellent performance for the advanced wastewater treatment without any offensive odor problem due to organic overloading.

• 상하수도학회지
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• 제28권2호
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• pp.161-170
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• 2014

It is essential to decrease energy consumption and excess sludge to economically operate sewage treatment plant. This becomes more important along with a ban on sea dumping and exhaustion of resource. Therefore, many researchers have been study on energy consumption reduction and strategies for minimization of excess sludge production from the activated sludge process. The aeration cost account for a high proportion of maintenance cost because sufficient air is necessary to keep nitrifying bacteria activity of which the oxygen affinity is inferior to that of heterotrophic bacteria. Also, additional costs are incurred to stabilize excess sludge and decrease the volume of sludge. There were anoxic, aerobic, membrane, deairation and concentration zone in this MBR process. Continuous aeration was provided to prevent membrane fouling in membrane zone and intermittent aeration was provided in aerobic zone through ammonia sensor. So, there was the minimum oxygen to remove $NH_4-N$ below limited quantity that could be eliminated in membrane zone. As the result of this control, energy consumption of aeration system declined by between 10.4 % and 19.1 %. Besides, we could maintain high MLSS concentration in concentration zone and this induced the microorganisms to be in starved condition. Consequentially, the amount of excess sludge decrease by about 15 %.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1221-1228
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• 2005

Carbon electrode was applied to a wastewater treatment system as biofilm media. The spatial distribution of heterotrophic bacteria in aerobic wastewater biofilm grown on carbon electrode was investigated by scanning electron microscopy, atomic force microscopy, and biomass measurement. Five volts of electric oxidation and reduction potential were charged to the carbon anode and cathode of the bioelectrochemical system, respectively, but were not charged to electrodes of a conventional system. To correlate the biofilm architecture of bacterial populations with their activity, the bacterial treatment efficiency of organic carbons was measured in the bioelectrochemical system and compared with that in the conventional system. In the SEM image, the biofilm on the anodic medium of the bioelectrochemical system looked intact and active; however, that on the carbon medium of the conventional system appeared to be shrinking or damaging. In the AFM image, the thickness of biofilm formed on the carbon medium was about two times of those on the anodic medium. The bacterial treatment efficiency of organic carbons in the bioelectrochemical system was about 1.5 times higher than that in the conventional system. Some denitrifying bacteria can metabolically oxidize $H_{2}$, coupled to reduction of $NO_{3}^{-}\;to\;N_{2}$. $H_{2}$ was produced from the cathode in the bioelectrochemical system by electrolysis of water but was not so in the conventional system. The denitrification efficiency was less than $22\%$ in the conventional system and more than $77\%$ in the bioelectrochemical system. From these results, we found that the electrochemical coupling reactions between aerobic and anaerobic reactors may be a useful tool for improvement of wastewater treatment and denitrification efficiency, without special manipulations such as bacterial growth condition control, C/N ratio (the ratio of carbon to nitrogen) control, MLSS returning, or biofilm refreshing.

• 대한환경공학회지
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• 제29권9호
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• pp.997-1002
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• 2007

본 연구의 목적은 pilot scale ASBF(호기성 침지형 생물막) 반응기를 이용하여 용해성 유기물과 질소화합물의 제거실험을 하였으며, 고정생물막 내에서의 용해성 유기물과 질소화합물 제거를 통한 종속영양미생물 및 독립영양미생물의 동적관계를 이해하고 개선하고자 하였다. 또한, 침지형 생물막 표면에 질산화 박테리아의 성장을 촉진시키기 위해 특별하게 설계한 구조를 라군에 추가하여 폐수처리 효과의 강화 가능성을 조사하였다. 침지형 생물막에 공기 기포가 직접적으로 접촉할 수 있도록 하였으며, 특히 낮은 온도에서 ASBF 실험장치의 용해성 유기물과 암모니아성질소 제거효과를 살펴보기 위해 회분식으로 운전하였다. 본 연구의 ASBF 반응조는 향후 용해성 유기물과 질소화합물의 제거를 위해 기존 폐수처리장 뿐만 아니라 신설 폐수처리장에도 확대 적용될 수 있을 것으로 기대 된다.

• 한국환경보건학회지
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• 제37권2호
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• pp.124-132
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• 2011

Biofilm and aeration tank of pilot and full RABC (rotating activated Bacillus contactor) plant were analyzed to characterize and determine bacterial community structure in food wastewater treatment system at winter. Concentration of heterotrophic bacteria and Bacillus group was $10^7$ and $10^5$ CFU/ml, respectively, at biofilm of pilot-plant while others represented $10^6$ and $10^4$ CFU/ml, respectively. Five and eight phyla were detected at biofilm of pilot- and full-plant, respectively, by 16S rDNA sequencing. Biofilm of pilot-plant was dominated by ${\beta}$-Proteobacteria (38.8%), ${\gamma}$-Proteobacteria (22.4%), and Bacteroidetes (12.2%), and the most dominant genus was Zoogloeae genus (22.4%). Candidate division TM7 (12.5%) was only detected at biofilm of full-plant and it was dominated by Bacteroidetes (33.3%), ${\gamma}$-Proteobacteria (29.2%), and ${\beta}$-Proteobacteria (20.8%). Clostridium genus specific primer set enabled to detect the sequences of Clostridium genus. These suggested that anaerobic and aerobic bacteria were coexisted even from the initial period of biofilm formation and ${\beta}$-Proteobacteria, ${\gamma}$-Proteobacteria and Bacteroidetes were major phyla in biofilm of food wastewater treatment system at winter.