• 한국물환경학회지
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• 제25권5호
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• pp.674-681
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• 2009

Characteristics of organic matters (OM) in wastewater and the removal efficiencies were investigated using the influent and the effluent samples collected from 21 wastewater treatment plants. The OM characteristics investigated included biodegradability, humic content, specific UV absorbance (SUVA), the distribution percentage of refractory OM (R-OM), and synchronous fluorescence spectra. The types of wastewater (sewage, livestock waste/night soils, industrial waste) were easily distinguished by comparing the synchronous fluorescence spectra of the influent wastewater. The prominent peak of protein-like fluorescence (PLF) was observed for livestock waste/night soils whereas sewage exhibited a unique fluorescence peak at a wavelength of 370 nm. Irrespective of the wastewater types, the distribution percentage of R-OM increased from the influent to the effluent. Livestock waste/night soils showed the highest removal efficiency among all the three types of wastewater. There was no statistical difference of the removal efficiency between a traditional activated sludge and biological advanced treatment processes. Removal efficiency based on dissolved organic carbon DOC presented good correlations with the distribution percentage of R-OM and fulvic-like fluorescence (FLF) of the influent. The prediction for DOC removal efficiency was improved by using multiple regression analyses based on some selected OM characteristics and mixed liquid suspended solid (MLSS).

• 한국환경과학회지
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• 제11권8호
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• pp.819-827
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• 2002

Laboratory scale experiments were conducted to evaluate the performance of a biofilter for eliminating dimethyl sulfide(DMS). A commercial compost/pine bark nugget mixture served as the biofilter material for the experiments. The gas flow rate and DMS concentration entering the filter were varied to study their effect on the biofilter efficiency. The operating parameters, such as the residence time, inlet concentration, pH, water content, and temperature, were all monitored throughout the filter operation. The kinetic dependence of the DMS removal along the column length was also studied to obtain a quantitative description of the DMS elimination. High DMS removal efficiencies(>95％) were obtained using the compost filter material seeded with activated sludge. DMS pollutant loading rates of up to 5.2 and 5.5 g-DMS/m$^3$/hr were effectively handled by the upflow and downflow biofilter columns, respectively. The macrokinetics of the DMS removal were found to be fractional-order diffusion-limited over the 9 to 25 ppm range of inlet concentrations tested. The upflow column had an average macrokinetic coefficient(K$\_$f/) of 0.0789 $\pm$ 0.0178 ppm$\^$$\sfrac{1}{2}$//sec, while the downflow column had an average coefficient of 0.0935 $\pm$ 0.0200 ppm$\^$$\sfrac{1}{2}$//sec. Shorter residence times resulted in a lower mass transfer of the pollutant from the gas phase to the aqueous liquid phase, thereby decreasing the efficiency.

• 상하수도학회지
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• 제25권3호
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• pp.383-390
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• 2011

In this study, a process combined biofiltration with sulfur-utilizing autotrophic denitrification and membrane separation was proposed to examine the efficiency of nitrogen removal. As an experimental device, hollow-fiber module was installed in the center of reactor to generate the flux forward sulfur layer in the cylinder packed with granular sulfur. In addition, a simple module was installed in activated sludge aeration tank which inside and outside of sulfur-using denitrification module was covered with microfilter and the module was considered as an alternative of clarifier. The experiment for developing new MBR process was carried out for three years totally. As the results of first two-year experiment, successful nitrogen removal performance was revealed with lab-scale test and pliot scale plant using artificial wastewater and actual plating wastewater. In this year, pilot scale test using actual domestic wastewater was performed to prove field applicability. As the results, high-rate nitrogen removal performance was confirmed with about 0.19 kg ${NO_3}^--N/m^3$ day of rate. Also significant fouling and pressure increase were not found during the experiment. And, the production ratio of sulfate and the consumption ratio of alkalinity showed a slightly higher value about 311 mg ${SO_4}^{2-}/L$ and 369 mg $CaCO_3$/L, respectively. In conclusion, the developed MBR process can be utilized as an alternative for retrofiting existing wastewater plants as well as new construction of advanced sewage wastewater treatment plants, with cost-effective merit.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.847-853
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• 1999

A Pseudomonas sp. strain that is capable of utilizing dicarboxylic acids as a sole carbon source was isolated from activated sludge by using the enrichment culture technique. This organism accumulated polyhydroxyalkanoates (PHAs) with an unusual pattern of monomer units that depends on the carbon sources used. Polyhydroxybutyrate (PHB) homopolyester was synthesized from glucose or small $C_{-even}$ alkanoic acids, such as butyric acid and hexanoic acid. Accumulation of PHB homopolyester was also observed in the cells grown on $C_{-odd}$ dicarboxylic acids, such as heptanedioic acid and nonanedioic acid as the sole carbon sources. In contrast, a copolyester consisting of 6 mol% 3-hydroxybutyrate (3HB) and 94 mol% 3-hydroxyvalerate (3HV) was produced with a PHA content of as much as 36% of the cellular dry matter. This strain produced PHAs consisting both of the short-chain-length (SCL) and the medium-chain-length (MCL) 3-hydroxyacid units when heptanoic acid to undecanoic acid were fed as the sole carbon sources. Most interestingly, polyester consisting of significant amount of relevant fractions, 3HB, 3HV, and 3-hydroxyheptanoate (3HHp), was accumulated from heptanoic acid. According to solvent fractionation experiments, the polymer produced from heptanoic acid was a blend of poly(3HHp) and of a copolyester of 3HB, 3HV, and 3HHp units. The hexane soluble fractions contained only 3HHp units while the hexane-insoluble fractions contained 3HB and 3HV units with a small amount of 3HHp unit. The copolyester was an elastomer with unusual mechanical properties. The maximum elongation ratio of the copolyester was 460% with an ultimate strength of 10 MPa, which was very different from those of poly(3HB-co-3HV) copolyesters having similar compositions produced from other microorganisms.

• 한국습지학회지
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• 제13권1호
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• pp.117-127
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• 2011

본 연구의 목적은 하수처리장의 공간적 그리고 운전인자에 따른 테트라싸이클린 내성균(TRB) 및 테트라싸이클린 내성 유전자(TRG)들의 거동을 파악하는데 있다. 이를 위한 노력으로, 세 개의 실제 다른 하수처리장내에서 7개월 이상 각각의 반응조별로 시료를 채취하여 TRB 및 TRG가 분석되었다. 통계 기법은 주성분분석(PCA)을 통해 이들 간에 어떠한 일반적 관계식이 성립하는지 알아보려 노력하였다. 통계 분석결과, 활성슬러지내에 TRB 농도는 1차 침전 유입수에 있는 TRB 농도에 많은 영향을 받는 것을 알 수 있었다. 또한, 본 연구를 통해 TRB와 TRG의 내거동이 하수처리장 SRT 조건에 많이 영향을 받는 것을 알 수 있었다.

• KSBB Journal
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• 제19권3호
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• pp.236-240
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• 2004

Batch experiment에서 다양한 질소 농도에서 구해진 질소제거 속도와 비 생장속도 등의 데이터를 토대로 4.6일의 체류시간을 갖는 2단 처리 장치를 설계하였다. 그리고 continuous experiments에서는 3.5일의 체류시간을 갖는 2단의 처리 장치를 설계하였다. 두 가지 값에 차이는 있지만 실제 현장에서 폐수 처리 장치를 설계할 때 충분한 자료가 되리라고 판단한다. 따라서 위의 결과를 토대로 기존 시스템에 미세조류 시스템을 부가한다면 기존공정의 단점인 잉여질소 제거 장치로서 충분히 역할을 수행해 배출 기준치를 만족시키는 안전한 폐수처리장치가 되리라고 판단한다.

• 한국산학기술학회논문지
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• 제15권3호
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• pp.1795-1800
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• 2014

본 논문은 생물학적 활성오니 폐수처리공정의 열전달 모델식을 제시하여 공정의 온도를 예측하였다. 열전달 모델은 폐수처리공정에 들어오고 나가는 모든 열을 고려하였다. 공정에 들어오는 열은 태양 복사열과 포기조 impeller의 기계적 에너지의 변환열, 포기조 내의 생화학 반응열이다. 공정에서 나가는 열은 폐수 자체의 복사열, 포기작용에 의한 증발열과 포기조 표면으로 나가는 전도열, 바람에 의한 대류열, 포기조와 지표면과의 전도열을 고려하였다. 들어오고 나가는 모든 열은 기존의 열전달 경험식을 적용하였다. 적용된 경험식으로 폐수처리장 공정의 열전달 모델식을 제시하였다. 모델식으로 실제 폐수처리공정의 온도를 예측하였으며, 모델식 예측치와 실제값이 $1.0^{\circ}C$ 이내로 일치하였다.

• Journal of Microbiology and Biotechnology
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• 제23권12호
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• pp.1765-1773
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• 2013

The cathode reaction is one of the most seriously limiting factors in a microbial fuel cell (MFC). The critical dissolved oxygen (DO) concentration of a platinum-loaded graphite electrode was reported as 2.2 mg/l, about 10-fold higher than an aerobic bacterium. A series of MFCs were run with the cathode compartment inoculated with activated sludge (biotic) or not (abiotic) on platinum-loaded or bare graphite electrodes. At the beginning of the operation, the current values from MFCs with a biocathode and abiotic cathode were $2.3{\pm}0.1$ and $2.6{\pm}0.2mA$, respectively, at the air-saturated water supply in the cathode. The current from MFCs with an abiotic cathode did not change, but that of MFCs with a biotic cathode increased to 3.0 mA after 8 weeks. The coulomb efficiency was 59.6% in the MFCs with a biotic cathode, much higher than the value of 15.6% of the abiotic cathode. When the DO supply was reduced, the current from MFCs with an abiotic cathode decreased more sharply than in those with a biotic cathode. When the respiratory inhibitor azide was added to the catholyte, the current decreased in MFCs with a biotic cathode but did not change in MFCs with an abiotic cathode. The power density was higher in MFCs with a biotic cathode ($430W/m^3$ cathode compartment) than the abiotic cathode MFC ($257W/m^3$ cathode compartment). Electron microscopic observation revealed nanowire structures in biofilms that developed on both the anode and on the biocathode. These results show that an electron-consuming bacterial consortium can be used as a cathode catalyst to improve the cathode reaction.

• 환경생물
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• 제25권3호
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• pp.267-272
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• 2007

우리나라 20개 지역의 경작토, 쓰레기 매립토, 부엽토 및 활성오니토에서 채취한 40개 토양 시료로부터 Poly(butylene succinate-co-butylene adipate) (PBSA)를 분해하는 미생물을 $37^{\circ}C$에서 강화배양과 투명환시험법을 이용하여 PBSA를 분해하는 균주를 선발하였다. 선발한 세균은 16S rDNA 염기서열분석으로 동정한 결과 Streptomyces sp. PBSA-1로 밝혀졌으며 진균은 형태적, 배양적 특징을 통하여 Aspergillus fumigatus PBSA-2와 Aspergillus fumigatus PBSA-3으로 동정되었다. 변형 Sturm test를 이용하여 선발균의 PBSA분해활성을 측정한 결과 $37^{\circ}C$에서 40일 동안 Streptomyces sp. PBSA-1은 PBSA를 83% 분해하였으며, A. fumigatus PBSA-2와 A. fumigatus PBSA-3은 PBSA를 각각 65% 및 75%분해하는 것으로 나타나 이 균주들은 PBSA의 분해에 대하여 매우 높은 활성을 가지는 것으로 평가되었다.

• 한국물환경학회지
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• 제22권2호
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• pp.250-257
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• 2006

The objective of this study is to propose an alternative process for the small sewage treatment plants in rural communities. A biofilter has been used for biological wastewater treatment, which is becoming the alternative to the conventional activated sludge system. The proposed process used in this study, which is packed with floating media (i.e. expanded polystylene), has advantages of biofilter system and alternative flow system and they are incorporated into one process. Pilot and bench scale studies were performed using domestic wastewater. In the results of pilot plant study, it was observed that the stable effluent water quality was achieved and it met the present effluent criteria of suspended solid (SS), organic matters, T-N and T-P. In the study for determination of the cycle of backwashing, it was observed that the cycle of backwashing depended on BOD loading rates of influents. In the BOD loading rates of $0.5kg\;BOD/m^3{\cdot}day$ and $1.0kg\;BOD/m^3{\cdot}day$, the backwashing cycle of 28 hour and 16 hour were needed, respectively. The optimum backwashing time was 120~80 seconds at the media expansion rate of 50%. In the removal of SS, organic matters, T-N and T-P, SS removal was rather achieved by physical filtration than biological mechanism and the removal of organic matters except for SS, T-N and T-P were mainly rather achieved by biological mechanism than physical filtration. In bench-scale study, the effects of recirculation rate was investigated on removal of SS, TCOD, T-N and T-P. It was observed that the recirculation made removal efficiencies of SS, TCOD, T-N and T-P increased. Especially, in T-N removal, the increase of T-N removal efficiency of 40% was observed in the reicirculation rate of 1Q compared with 0Q.