• 한국환경과학회지
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• 제4권5호
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• pp.123-123
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• 1995

The treatment performances of anaerobic-aerobic activated sludge process were investigated under various operation conditions. The treatment system proposed in this study gave a relatively stable performance against hourly change of the flow rate and showed a satisfactory removal of nitrogen and phosphorus compounds under experimental conditions. The recycle ratio of mixed liquor from aerobic to anaerobic region and peak coefficient primarily controlled the extent of nitrogen removal. The recycle ratio had the optimum values which were determined by the microbial activities of nitrification and denitrification. The behavior of the treatment unit could be simulated by using the kinetic equations and reactor models which considered the treatment units as complete mixing tanks.

• 한국물환경학회지
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• 제23권6호
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• pp.906-912
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• 2007

A lab-scale thermophilic aerobic digestion (TAD) system was operated at $64^{\circ}C$ with mixed primary and secondary sludges taken from a large wastewater treatment plant. The semi-continuously operated reactor at HRTs of 1, 3 and 6 days indicated that longer HRT could stabilize sludge organics and solids comparable to anaerobic digestion. It has been found that reduced HRT of 3 and 1 day produced the effluent with highly biodegradable soluble organics, indicating the possibility of energy recovery in TAD. No proof of biological nitrification was observed at thermophilic operating temperature of $64^{\circ}C$, while nitrogen removal seemed due to nitrogen exertion during the aerobic thermophilic cell synthesis as well as ammonia stripping.

• 한국막학회:학술대회논문집
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• 한국막학회 1993년도 춘계 총회 및 학술발표회
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• pp.41-41
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• 1993

Recently, the advanced membrane separation technology has even been applied to the post treatment to biological process of wastewater treatment, since the efficiency of biological treatment significantly depends on maintaining a high biomass concentration in the bioreator. Particularly, anaerobic microbes in the biological system have slower growth rates than aerobic microbes and thus it takes a long hydaulic retention time(HRT) to prevent biomass washout in the completely mixed anaerobic digester. The anaerobic sludge also has poor settleability owing to its diffusible and somewhat filamentous nature. Moreover, the residual gasification and consequent sludge rise in the clarifier compartment become a considerable problem, which proves that complete separation of biological solids is difficult.

• 자원리싸이클링
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• 제16권5호
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• pp.71-76
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• 2007

가정에서 분리 배출된 폐플라스틱은 일반적으로 수선별 등 분리선별 공정을 거친 후 종말품으로 회수되어, 현재 대부분이 매립이나 소각되고 있다. 혼합폐플라스틱 종말품의 경우 2006년 약 175만톤 발생된 것으로 예측되고 있으나, EPR실시 이후로 발생량은 2000년에 비해 2배 이상 크게 증가한 실정이다. 특히, 혼합폐플라스틱 종말품의 경우 PVC 함량(4 wt.% 이하)이 매우 높아 이들의 재활용에 커다란 제약이 되고 있다. 본 연구에서는 혼합폐플라스틱 종말품으로부터 풍력 및 습식 비중선별장치를 이용하여 폴리올리핀계 (PE, PP, PS) 플라스틱을 경량물로 회수하는 선별시스템을 개발하였다. 본 선별시스템은 풍력선별, 자력선별, 1단계 파쇄, 정량공급 및 습식 비중선별 공정으로 구성되어 있으며, 습식 비중선별 공정은 원심분리를 기본으로 혼합-세척-선별 및 탈수가 단일장치내에 집약된 특징이 있다. 또한, 본 연구에서는 연질 플라스틱의 분쇄 효율을 크게 개선한 파쇄기를 개발하였다. 개발된 습식 비중선별장치의 용량은 시간당 0.5 톤으로, 이를 이용하여 회수된 경량물의 PVC 함량은 0.3wt.% 이하이며, 경량 및 중량 회수물의 수분 함량도 각각 10% 이하를 달성하였다.

• 상하수도학회지
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• 제22권5호
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• pp.551-559
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• 2008

An experimental study was carried out to evaluate the potential of flotation process for the secondary clarifier of an activated sludge process. Flotation techniques, applied in this study, include electrofloation (EF) which generated fine bubbles smaller than $35{\mu}m$ in average and diffuser flotation (DF) which generated fine bubbles smaller than $55{\mu}m$ in average. The batch experiments were done with activated sludge displaying various characteristics. It was shown that the efficiency of solids/liquid separation was reduced as the diluted sludge volume index ($DSVI_{30}$) of activated sludge increased. The dependency, however, gradually decreased as the gas to solids (G/S) ratio increased. Thickening efficiency of EF was more than 2~10 times and DF process was more than 1.5~5 times as compared with gravity sedimentation (GS). Stable sludge blanket was maintained regardless of sludge settleability when the G/S ratio was 0.019 in the EF. On the other hand, Serious deterioration in the sludge blanket was observed in the DF depends on G/S ratio and sludge settleability. And For EF and DF, the suspended solids concentration of effluent was not nearly influenced on settleability of activated sludge and more clear than GS. A biological nutrient removal (BNR) process, combined with EF as a secondary clarifier was operated for three months. The mean MLSS (mixed liquid suspended solids) concentration in the reactor and mean solids concentration of return sludge were estimated to be 5,340 mg/L and 16,770 mg/L, respectively. The water quality of effluent was considerably stable and low value was accomplished, that was, standard suspended solids concentration $0.07{\pm}0.51mg/L$ and standard turbidity $1.44{\pm}0.56NTU$. The EF could be applicable for enhancement of efficiency of activated sludge system as well as improvement of the water quality of effluent.

• 미생물학회지
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• 제51권3호
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• pp.312-317
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• 2015

울릉도에서 7곳의 항구(천부항, 현포항, 태하항, 남양항, 사동항, 도동항, 저동항)와 1곳의 해변(구암)에서 표층해수를 채취하였다. 배양하지 않은 시료(uncultured samples)와 배양한 시료(cultured samples)에서 각각 미생물의 16S rDNA를 pyrosequencing하여 해양미생물의 분포를 조사하였다. 태하항과 사동항의 해수처럼 청정한 해수에서는 Alphaproteobacteria 분포율이 높았고, 남양항, 도동항, 저동항의 해수처럼 생활하수나 하천수의 유입이 많은 곳에서는 Gammaproteobacteria 분포율이 증가하였다. Marine broth로 배양한 시료(cultured samples)에서는 Alteromonas (천부항, 태하항, 구암해변, 남양항, 사동항), Shewanella (저동항), Vibrio (현포항, 도동항) 속이 우점으로 분포하였다. 본 연구결과는 항구로 유입되는 하천수나 생활하수가 해양미생물의 분포에 큰 변화를 초래한다는 것을 시사한다.

• 상하수도학회지
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• 제18권5호
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• pp.598-607
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• 2004

In this study, the effects of two pre-treatment processes were observed prior to membrane filtration: pre-coagulation and pre-ozonation. To compare the effect of two above-mentioned pre-treatments, we adopted the four schemes: first one is direct membrane filtration of river surface water, second one is membrane filtration after pre-coagulation, third one is membrane filtration after pre-ozonation and fourth one is membrane filtration after pre-coagulation and pre-ozonation. There are two exceptional characteristics in applied processes. One is the usage of the MF membrane which has high ozone resisting characteristic. Therefore, ozone resides in membrane module during filtration. The other is adoption of Jet Mixed Separator (JMS) as coagulation-sedimentation process. The change in transmembrane pressure and permeate water quality were also examined. As a result, considering the filtration performance efficiency and permeate water quality, the process composed of filtration with combination of both pre-coagulation and pre-ozonation was proved most effective. The improved efficiency was due to the reduction of loading rate of fouling inducing materials to membrane module by coagulation process as well as variable reactions, such as degradation, particle destabilization and coagulation, occurred by residual ozone in membrane module. The additional effect of pre-coagulation before pre-ozonation is suppression of AOC, one of the by-products induced by ozonation. Therefore, combination of pre-coagulation and pre-ozonation is the effective process to overcome the major de-merit of ozonation i.e. by-products formation.

• 한국미생물·생명공학회지
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• 제33권1호
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• pp.56-64
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• 2005

고도처리장의 효율적 운영을 위해 원생동물의 분포를 조사하고 수질자료의 예측을 위한 bioindicator의 가능성을 분석하였다. 원생동물 종류별 개체수 분포는 출현빈도가 높으면 개체수도 많은 편으로 관찰되었다. Aspidisca, Trachelophyllum, Vorticella, Cinetochiluum, Oikomonas, Epistylis의 출현빈도는 $95\%$이상이었다. 처리장의 원생동물 분포는 유입수의 성상과 운영조건 차이 등이 세균의 증식에 영향을 미치고 변화된 세균분포에 적합하게 원생동물 분포가 이루어진다고 판단된다. 미생물분포와 통계결과는 처리장마다 다르므로 여러 처리장보다는 단일처리장에 적용되는 지표개발이 처리장의 효율적 운영에 기여할 수 있다. 요인분석결과 요인적재량의 형태와 요인의 해석이 유사하였다. 고도처리공법이 유사하고, 유입수의 성상이 비슷하여 처리장운영에 관여하는 요인이 비슷하게 나타난 것으로 판단된다. 상관분석과 회귀방정식을 이용함으로 처리장 수질변화를 미리 예상할 수 있다. 처리장의 원생동물 분포, 유출수질, 운영조건 자료들이 충분히 확보되면 원생동물 분포를 가지고 운영현황 및 가까운 미래의 수질예측이 가능해진다. 수질예측이 가능함으로 운영조건의 조기변동으로 처리수질을 양호하게 유지할 수 있다.

• 유기물자원화
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• 제11권3호
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• pp.60-66
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• 2003

본 연구는 혐기성 소화를 이용한 음식물쓰레기와 하수슬러지 병합처리를 위한 음식물쓰레기 전처리 공정 방안을 모색하기 위하여 수행되었다. 음식물쓰레기 전처리 공정에 따른 음식물쓰레기 단위 공정별 성상 변화와 산발효조 적정 투여 기초조사 및 음식물쓰레기와 하수슬러지 혼합비 특성변화를 통한 산발효조의 효율 향상방안을 검토하였다. 연구결과, 음식물쓰레기의 구성성분은 대부분이 곡류와 채소류로 산발효 공정에서 유기산으로 전환될 가능성이 충분한 것으로 판단되며, 산발효조 투입시 TS의 적정한 범위를 위한 음식물쓰레기와 희석수의 비율은 1:5가 적합한 것으로 나타났다. 음식물쓰레기 분쇄 후 입도 분포 특성을 고려할 때 약 8mm 이하의 입자가 적합하며, 음식물쓰레기와 하수슬러지 슬러지의 혼합비는 3:7 이하가 적합한 것으로 나타났다.

• Environmental Engineering Research
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• 제19권1호
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• pp.75-81
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• 2014

Methanotrophic denitrification under a non-aerated condition (without external supply of oxygen or air) was investigated in a bioreactor coupled with a membrane diffuser. Batch experiment demonstrated that both methane consumption and nitrogen production rates were not high in the absence of oxygen, but most of the nitrate was reduced into $N_2$ with 88% recovery efficiency. The methane utilized for nitrate reduction was determined at 1.63 mmol $CH_4$/mmol $NO_3{^-}$-N, which was 2.6 times higher than the theoretical value. In spite of no oxygen supply, methanotrophic denitrification was well performed in the bioreactor, due to enhanced mass transfer of the methane by the membrane diffuser and utilization of oxygen remaining in the influent. The denitrification efficiency and specific denitrification rate were 47% and 1.69 mg $NO_3{^-}-N/g\;VSS{\cdot}hr$, respectively, which were slightly lower than for methanotrophic denitrification under an aerobic condition. The average concentration of total organic carbon in the effluent was as low as 2.45 mg/L, which indicates that it can be applicable as a post-denitrification method for the reclamation of secondary wastewater effluent. The dominant fatty acid methyl ester of mixed culture in the bioreactor was $C_{16:1{\omega}7c}$ and $C_{18:1{\omega}7c}$, which was predominantly found in type I and II methanotrophs, respectively. This study presents the potential of methanotrophic denitrification without externally excess oxygen supply as a post-denitrification option for various water treatment or reclamation.