• 한국물환경학회지
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• 제22권2호
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• pp.300-307
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• 2006

The combined SHARON (Single reactor system for High ammonium Removal Over Nitrite)-ANAMMOX (Anaerobic ammonium oxidation) reactor were operated in mesophilic condition ($35^{\circ}C$). In this study, microbial granulation and characteristics of SHARON and ANAMMOX sludges were investigated using settling test, Scanning Electron Microscopy (SEM) and Fluorescence In Situ Hybridization (FISH). In SHARON reactor, Aerobic granulation with diameter of 1.5~2.5 mm was accomplished but aerobic granulation was weaker than anaerobic granular sludge. Initial seed sludge of ANAMMOX reactor was used as attached media for biofilm growth. ANAMMOX sludge was more compact and rounder rather than seed sludge. Though ANAMMOX sludge has high activity, it has lower settling ability than the seed granule. The color of ANAMMOX sludge was changed from dark to redish brown granular with diameter of 1~2 mm. In FISH of ANAMMOX sludge, high fraction of Candidatus B. stuttgartiensis which paid great role of nitrogen conversion was detected. Also, FISH results reveals that ANAMMOX bacteria inhabit at inner parts near surface, having advantages in utilization of substrates and protection from oxygen inhibition.

• 한국환경과학회지
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• 제1권2호
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• pp.125-136
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• 1992

Digestion of a municipal wastewater sludge by the anaerobic sequencing batch reactor (ASBR) was investigated to evaluate the performance of the ASBR process at a critical condition of high-solids-content fined. The reactors were operated at an HRT of 10 days with an equivalent loading rate of 0.8-1.5 gVS/L/d at 35$^{\circ}C$ The main conclusions drawn from this study were as follows: 1. Digestion of a municipal wastewater sludge was possible using the ASBR in spite of high concentration of settleable solids in the sludge. The ASBRS with 3- and 4-day cycle period showed almost identical high digestion performances. 2. No adverse effect on digestion stability was observed In the ASBRS in spite of withdrawal and replenishment of 30% or 40% of liquid contents. A conventional anaerobic digester could be easily converted to the ASBR without any stability problem. 3. Flotation thickening occurred in thicken step of the ASBRS throughout steady state, and floating bed volume at the end of thicken period occupied about 70% of the working volume of the reactor Efficiency of flotation thickening in the ASBRS could be comparable to that of additional gravity thickening of a completely mixed digester. 4. Solids were accumulated rapidly in the ASBR during start-up period. Solids concentrations in the ASBRS were 2.6 times higher than that in the completely mixed control reactor at steady state. Dehydrogenase activity had a strong correlation with the solids concentration. Dehydrogenase activity of the digested flu형e in the ASBR was 2.9 times higher than that of the flu형e in the control reactor, and about 25 times higher than that of the subnatant in the ASBR. 5. Remarkable increase in equivalent gas production of 52% was observed at the ASBRS compared with the control reactor in spite of similar quality of clarified effluent from the ASBRS and control reactor. The increase in gas production from the ASBRS was believed to be combined results of accumulation of microorganisms, higher driving force applied, and additional long-term degradation of organics continuously accumulated.

• Advances in environmental research
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• 제2권3호
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• pp.229-243
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• 2013

Coagulation-flocculation (CF) was tested coupled with an aerobic biofilter to reduce total petroleum hydrocarbon (TPHs) concentration and toxicity from petrochemical wastewater. The efficiency of the process was followed using turbidity and chemical oxygen demand (COD). The biofilter was packed with a basaltic waste (tezontle) and inoculated with a bacterial consortium. Toxicity test were carried out using Lactuca sativa var. capitata seeds. Best results for turbidity removal were obtained using alum. Considerable turbidity removal was obtained when using Opuntia spp. COD removal with alum was 25%, for Opuntia powder it was 36%. The application of the biofilter allowed the removal of 70% of the remaining TPHs after 30 days with a biodegradation rate (BDR) value 47 $mgL^{-1}d^{-1}$. COD removal was slightly higher with BDR value 63 $mgL^{-1}d^{-1}$. TPH kinetics allowed a degradation rate constant equal to $4.05{\times}10^{-2}d^{-1}$. COD removal showed similar trend with $k=4.23{\times}10^{-2}d^{-1}$. Toxicity reduction was also successfully achieved by the combined treatment process.

• Journal of Microbiology and Biotechnology
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• 제26권10호
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• pp.1746-1754
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• 2016

Recently, spherical beads entrapping quorum quenching (QQ) bacteria have been reported as effective moving QQ-media for biofouling control in MBRs for wastewater treatment owing to their combined effects of biological (i.e., quorum quenching) and physical washing. Taking into account both the mass transfer of signal molecules through the QQ-medium and collision efficiencies of the QQ-medium against the filtration membranes in a bioreactor, a cylindrical medium (QQ-cylinder) was developed as a new shape of moving QQ-medium. The QQ-cylinders were compared with previous QQ-beads in terms of the QQ activity and the physical washing effect under identical loading volumes of each medium in batch tests. It was found that the QQ activity of a QQ-medium was highly dependent on its specific surface area, regardless of the shape of the medium. In contrast, the physical washing effect of a QQ-medium was greatly affected by its geometric structure. The enhanced anti-biofouling property of the QQ-cylinders relative to QQ-beads was confirmed in a continuous laboratory-scale MBR with a flat-sheet membrane module.

• 한국물환경학회지
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• 제22권6호
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• pp.1075-1081
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• 2006

In this research, mortality rates of pathogen indicator microorganisms discharged from various point sources and diffuse sources in urban area were measured. Water samples were taken at domestic sewer, combined sewer overflow, effluent from a wastewater treatment plant, urban river, and sediment of an urban river. Mortality rates of indicator microorganisms in domestic sewer estimated by assuming the first order kinetics at $20^{\circ}C$ were as follows: total coliform = 0.092/day, fecal coliform = 0.185/day, E. coli = 0.252/day, and fecal streptococci = 0.281/day. Sensitivity of mortality rates of total coliform on temperature was estimated as $K_{temp}=K_{20}{\times}1.162^{(temp-20)}$ for the range of $10-20^{\circ}C$. Mortality rates due to sunlight were measured as 1.22-1.59/day while mortality rate due to settling for 40 min were estimated as $9.21{\times}10^3-20.0{\times}10^3/day$.

• 환경생물
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• 제38권4호
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• pp.678-690
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• 2020

본 연구는 점오염원인 하수종말처리장으로부터 배출되는 물의 수질을 분석하고 배출수의 영향을 받는 어류 중 지점들에서 공통적으로 출현하는 어종인 피라미(Z. platypus)를 선택하여 조직학적 변화를 참조하천 지점의 수질과 어류 조직을 비교·분석하였다. 2019년 6월 27~28일 하수종말처리장 4곳(대전, 전주, 청주, 익산)의 채집 결과, 참조하천에서 22종 450개체로 가장 많은 종 수 및 개체수가 확인되었다. 지점별로 5개체씩 2~3년생 피라미의 조직표본을 제작하여 아가미와 근육조직(피부조직)을 관찰한 결과, 참조하천을 제외한 나머지 지점의 조직은 병리적인 양상을 나타내었다. 수질분석 결과, 각 WTP에서는 배출수질 기준을 준수 혹은 더 좋은 수질로 방류하고 있었다. 그러나 하수종말처리수 배출수 및 방류수계 수질에서 오염도지표를 나타내는 항목인 BOD, COD, TP, TN, SS 값이 참조하천에 비해 높은 것으로 나타났다. 빈약한 어류상과 바이오마커로 이용된 종의 조직병리학적 상태는 참조하천에 비해 낮은 수질에서 기인한 것으로 추측되며, 따라서 원인이 되는 하수종말처리장 배출수 수질개선이 이루어져야 할 것으로 사료된다.

• 한국수자원학회논문집
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• 제47권5호
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• pp.483-490
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• 2014

활성슬러지 공정의 생물학적 반응조 및 2차 침전지 설계와 관련해서 정상상태 설계식(Ekama et al., 1986; WRC, 1984) 및 1-D flux theory 설계식(Ekama et al., 1997)을 사용하여 슬러지 농도에 따라 두 가지 공정을 일괄적으로 설계하였다. 또한, 슬러지 농도에 따른 생물학적 반응조 및 2차 침전지 크기 변화를 도식화하고, 유입수 성상이나 슬러지 침강성, 환경 및 운전조건 그리고 첨두유량이 각 공정의 크기결정에 미치는 영향을 평가하였다. 먼저유입수의 특성과 관련하여 난분해성 용해성 물질(fs,us)은 반응조 크기 결정에 큰 영향이 없었지만, 난분해성 입자성 물질(fs,up), 무기고형물(fi) 및 유기물 강도(Sti)의 영향은 크게 나타났다. 운전인자인 Sludge Retention Time (SRT)의 경우, 슬러지 생산량과 관련되므로 반응조 크기결정에 역시 큰 영향을 미쳤다. 2차 침전지의 설계요소인 Sludge Volume Index (SVI) 및 첨두유량이 커질수록 2차 침전지에 수리학적 부하가 커지게 되어, 2차 침전지가 크게 설계되어야 했다. 본 설계과정에서는, 온도 변화가 미치는 영향은 작게 나타났다. 대규모 처리장의 경우 반응조 및 2차 침전지 전체 크기 결정과 함께 1개조 크기의 상한선을 설정하여 개수를 산정하였다. 최종적으로 엔지니어는 여러 가지 슬러지 농도에 대하여 반응조 및 2차 침전조의 크기, 개수 및 현장조건을 고려한 건설비용을 반복적으로 계산하게 되면, 최소비용 설계와 함께 최적의 슬러지 농도를 결정하게 된다.

• Environmental Engineering Research
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• 제13권2호
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• pp.69-72
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• 2008

The movement of sediments in the stream crossing a large industrial complex to the mouth of Masan Bay was monitored for eight years. Sediment samples were seasonally collected in the period of $1992{\sim}1997$ and $2001{\sim}2002$. The heavy metal content of sediment was found to be higher at dry season with the peak on February and significantly decreased at rainy season. Metals content in stream sediments were rapidly decreased by large precipitation events in rainy season because the contaminants in the upstream sediments were transported to the dredged area of Masan Bay where is a typical enclosed bay in Korea. The increasing and decreasing tendency of heavy metals in sediment was repeatedly observed for six consecutive years. The heavy metals assessment of stream sediment provide us the information about the pollutant source, transport pattern and control strategy along the industrial complex. It was strongly suggested that the transportable stream sediments of an industrial area should be controlled as one of the important strategies to restore and manage the enclosed bay. Combined wastewaters have been collected and treated in a publicly owned treatment works (POTW) after industrial wastewater treatment at each location of industries since 1994. A field study was conducted to investigate the pollutant removal efficiency and performance of contact oxidation system installed and operated in two locations in the stream. The stream sediment quality was improved since then, and as a consequence the habitat of the estuary has been restored.

• 대한환경공학회지
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• 제28권6호
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• pp.654-660
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• 2006

본 연구에서는 대전천에 위치한 오정천지역의 소유역을 대상으로 CSOs 배출특성에 관한 모델링을 실시하였다. SWMM을 이용하여 대상유역에서 $2001{\sim}2004$년까지의 연간 유량, 수질, 및 부하량 변화에 대하여 모의를 실시하였다. 모의결과에 의하면, 강우에 의해 발생된 SS 유출부하량은 강우가 집중되는 $7{\sim}8$월에 가장 높게 나타났으나, 이때 강우의 증가에 비하여 부하량의 증가는 크지 않았는데 이는 강우가 잦은 $7{\sim}8$월에는 짧은 건기일수로 인하여 유출수의 SS농도가 낮아졌기 때문이다. $2001{\sim}2004$년 동안의 유량과 수질을 기초로 유출부하량을 산정한 결과 SS가 연간 하천에 미치는 부하량은 건기에 9.3%, 우기에 90.7%로 우기시에 미치는 영향이 매우 큰 것으로 나타났다. 우기시에 우수토실에서 월류를 통해 유출되는 CSOs는 38.4%, 차집관거로 차집 되어 하수처리장 방류구를 통해 방류되는 부분은 61.6%로 산정되었다.

• 대한환경공학회지
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• 제27권6호
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• pp.581-589
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• 2005

최근, 하 폐수 처리에 있어서 처리수의 보다 나은 수질과 엄격한 기준의 만족을 위해 기존의 공정외에 덧붙여 막분리 공정이 이용되고 있다. 그러나, 수처리 과정에서 막분리 공정의 사용은 막의 막힘 현상과 용존 유기오염물 제거의 어려움 등의 문제점이 있다. 본 연구에서는 막분리 공정에 응집제 alum과 PAC을 이용한 응집공정을 첨가하여 막 투과유속과 처리효율을 증가시켰다. 그리고 응집제 주입효과와 최적운전조건은 투과유속, 누적부피, 막의 총저항, 입자크기, 용존성 유기오염물, 용존성 알루미늄, 처리수의 수질을 분석하여 연구하였다. alum 응집에 비교해 PAC 응집은 큰 입자를 형성하여 여과 매체의 막힘현상을 줄이고 높은 투과유속과 누적 부피량을 보였다. 또한 PAC 응집에서 낮은 용존 유기오염물과 용존성 알루미늄은 투과유속 감소율을 낮추었다. $0.2\;{\mu}m$ 막 사용시 케이크여과의 모습을 보였으며, $0.45\;{\mu}m$ 막 사용시 순환운전으로 인한 플럭 깨짐 현상으로 공극보다 작은 플럭의 투과가 발생하여 투과유속이 계속 감소하고 막의 총저항이 증가하는 모습을 보였다. PAC과 alum 모두 약 $300{\pm}50\;mg/L$가 최적 응집주입량이었으며, PAC 응집과 $0.2\;{\mu}m$ 막 사용시 처리 효율이 가장 높고, $0.45\;{\mu}m$ 막 사용시 투과수량이 가장 많았다. 처리 효율은 탁도 99.8%, SS 99.9%, $BOD_5$ 94.4%, $COD_{Cr}$ 95.4%, T-N 54.3%, T-P 99.8%이었다.