• 상하수도학회지
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• 제14권1호
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• pp.62-75
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• 2000

Most of biological treatment to remove contaminants in municipal wastewater have been conducted by activated sludge process. But, the process have several probIems such as enormous site needed for construction of treatment facilities, unstable treatment due to limited ability to control load fluctuation, frequent sludge bulking and appearance of lots of surplus sludge. In this study, the experiments were performed through submerging biofilm of PEPP media in existing aeration tank with raw water from municipal wastewater treatment plant and then submerging PVDC and PEPP media, different from shape and chemical peculiarity in anoxic reactor. Throughout the experience, nutrient removal efficiency according to HRT, nitrogen phosphorous removal efficiency, behavior of nitrogen and dewatering efficiency have been compared and analysed with those of activated sludge process. As the results, BOD removal efficiency according to BOD volumetric load and F/M ratio was not found any differency in two processes, but was decreased below 90% as going along the condition of high load in activated sludge process. Kinetic coefficient was $K_{max}=1.162day^{-1}$, $K_s=53.77mg/L$, $Y=0.166mgVSS/mgBOD_{rem}$. and $K_d=0.019day^{-1}$. It was found that the removal efficiency, even though in aerobic condition, in biofilm process equipped anoxic reactor was higher than the one in activated sludge process within the range of 70~80%, and became better as HRT increased. Phosphorous removal efficiency was not found any differency in two processes. In biofilm process, treament efficiency even in conditions of high load was not decreased, because the biomass concentration could be maintained in high condition compared with activated sludge process. As HRT increased, suspended and attached biomass was increased and the other hand, F/M ratio was decreased as biomass' increasing. Biomass thickness was increased. from $10.43{\mu}m$ to $10.55{\mu}m$ as HRT increased and density of biomass within $40.79{\sim}41.16mg/cm^2$. The results also present that the dewatering efficiency of sludge generated in biofilm process was higher than in activated sludge process, and became better as HRT increased.

• 한국환경과학회지
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• 제6권6호
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• pp.671-678
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• 1997

This study was conducted to use oyster shell as media for biological wastewater treatment. The comparison between the removal efficiencies of the activated sludge and the submerged biofilm process with oyster shell media (5% of reactor volume) for domestic sewage treatment was made. The contaminant removal efficiencies of the submerged process were higher than that of the activated sludge process. And the removal efficiencies of the submerged biofilm process with oyster shell media of 10% and 18% were Investigated at various loading rate. The removal efficiencies of 10% were higher than that of the 18% during the experimental period. The effluent concentration from the sub- merged bloom process using oyster shell media was prediceted by the Stover-Kincannon model.

• 상하수도학회지
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• 제26권6호
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• pp.767-777
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• 2012

Annular Biofilm Reactor (ABR) equipped with coupons of three different pipe materials (STS 304, PVC, PE) was used to generate drinking water biofilm samples. The level of assimilable organic carbon (AOC) during the sample generation period was $37.3{\mu}g/L$, and this level did not seem to be low enough to limit the formation of biofilm in this study. Terminal-restriction fragment length polymorphism (T-RFLP) analyses determined T-RF profile as early as 3 h of exposure on PVC coupons. Average surface roughness ($R_a$) measured by atomic force microscopic analyses was 125.7 nm for PVC, and this value was higher than for STS (71.6 nm) and PE (74.0 nm). However, biofilm formation was faster on STS (6 h) than on PE (12 h), which indicated that surface roughness might not be the only factor that controlled the initiation of biofilm development. Upon detection of the T-RF peaks, richness (S) and diversity indices such as Shannon (H) and Simpson (1/D) demonstrated a rather slow increase until 48 h followed by rapid increase regardless of the pipe materials. Differences of microbial community structures among the biofilm samples were determined based on the cluster analysis using Jaccard coefficients (Sj). Biofilm communities could be divided into two distinct groups according to the exposure time regardless of the pipe materials. First group contained a young (< 48 h) biofilm samples (10 out of 11) but second group contained a mature (${\geq}$ 48 h) samples (11 out of 14). Results suggested that, due to the complexity of biofilm, the targeting of the first group of cluster was crucial for optimizing the management of drinking water distribution systems and controlling microbial growth.

• 한국환경보건학회지
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• 제23권1호
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• pp.43-49
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• 1997

This study was aimed to estimate removal efficiency(%) of BER(Biofilm-Electrode Reactor) and A.S(Activated Sludge) treatments. When were analyzed COD$_{Cr}$, NH$_3$-N and T-P by current density and reaction time, the results were as follows : 1) In BER treatment, the removal efficiency of COD$_{Cr}$ in domestic wastewater was 79-86% when current density was 2.39 mA/dm$2$(15mA)-3.98 mA/dm$^2$(25mA) and reaction time was 48 hr. 2) Removal efficiency of NH$_3$-N was 71-73% when current density was 2.39-3.98 mA/dm$^2$ and reaction time 48 hr. 3) When the reaction time was 48 hr removal efficiency(%) of BER treatment for COD$_{Cr}$, NH$_3$-N and T-P were more excellent than A.S. treatment. And then we prospect that was because activated microorganism colonies attached in biofilm on surface of electrode pannel. Therefore, In order to derive BER treatment efficiency(%) should establish optimum conditions of pH, temp., reaction time, current density and biochemical and electrochemical states.

• 상하수도학회지
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• 제21권5호
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• pp.521-529
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• 2007

Nutrient removal from synthetic wastewater was investigated using a MLE (Modified-Ludzack Ettinger) type MBBR (Moving Bed Biofilm Reactor), with different phenol ($C_6H_5OH$) concentrations, in order to determine the inhibition effects of phenol on biological nutrient removal and the biodegradation of phenolic wastewater. The wastewater was prepared by mixing a solution of molasses with known amounts of phenol and nutrients. The experiments were conducted in a lab-scale MLE type MBBR, operated with four different phenol concentrations (0, 67, 100 and 168mg/L) in the synthetic feed. Throughout the experiments, the ratio of the phenolic COD concentration to the total COD was varied from 0 to 1. Throughout batch test, the SNR (Specific Nitrification Rate) and SDNR (Specific Denitrification Rate) were significantly influenced by changes of the phenol concentration. Phenol was inhibitory to the nitrification/denitrification process, and showed greater inhibition with higher initial phenol concentrations. The SNR observed with 0, 67, 100 and 168mg phenol/L were very different like 10.12, 6.95, 1.51 and $0.35mg\;NH_{3^-}N/gMLVSS$ hr, respectively. Similarly, the SDNR observed at 0, 67, 100 and 168mg phenol/L were different like 0.322, 0.143, 0.049and 0.006mgN/gMLVSS day, respectively.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.457-460
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• 2000

Biofilm airlift 반응기를 이용한 선택적 질산화는 air가 2.5 L/min, $NH_4\;^+-N$ load가 $2.5\;kg-N/m^3/d$에서 약 90% 이상의 질소 제거율과 75-90%의 아질산성 질소의 축적이 일어났다. nitrite oxidizer가 낮은 DO의 영향으로 activity가 저해를 받아서 nitrite를 산화시키지 못하여 축적을 일으킨 것으로 보인다. 반응기 내부의 미생물의 양이 가장 많은 기간에 질소 제거율이 저하하고 nitrite ratio가 약간 감소됨을 보였다. 이는 많은 미생물의 양으로 용존산소가 감소되었기 때문이다. 미생물의 양에 따른 질소 부하의 증거로 F/M 비를 맞추어 그에 따른 질산화를 관찰하는 연구를 할 수 있을 것 같다.

• KSBB Journal
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• 제7권3호
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• pp.235-245
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• 1992

비표면적이 다른 media를 이용한 호기성 고정생물막공법에서 유기물부하율을 변화시키면서, 유출수의 성상과 활성슬러지의 설계인자가 호기성 고정생물막송법에 적용가능한지를 조사하였다. 유출수의 수질은 낮은 유기물부하율에서는 유출수의 농도가 비표면적에 따라 크게 변화하지 않았으나, 높은 부하율에서는 변화폭이 매우 크게 나타나으며, 비표면적별 유출수 농도를 보면 비표면적이 큰 경우가 유출수 농도가 낮았으며, 유입수농도가 클수록 유출수의 농도차이도 더 크게 나타났다. 동력학적 계수를 산출하기 위해 활성슬러지 공법의 모델을 고정생물막 공법에 적용시켜 본 결과 실험조건에서 실측 미생물 생산량과 계산된 미생물 생산량과의 차이는 COD를 기준으로 하였을 때가 더 잘 일치함을 알았다.

• 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.

• Journal of Microbiology and Biotechnology
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• 제25권11호
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• pp.1908-1919
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• 2015

This work investigated the potential of curcumin (CCM) and (-)-epigallocatechin gallate (EGCG) to inhibit N-acyl homoserine lactone (AHL)-mediated biofilm formation in gram-negative bacteria from membrane bioreactor (MBR) activated sludge. The minimum inhibitory concentrations (MICs) of CCM alone against all the tested bacteria were 200-350 μg/ml, whereas those for EGCG were 300-600 μg/ml. Biofilm formation at one-half MICs indicated that CCM and EGCG alone respectively inhibited 52-68% and 59-78% of biofilm formation among all the tested bacteria. However, their combination resulted in 95-99% of biofilm reduction. Quorum sensing inhibition (QSI) assay with known biosensor strains demonstrated that CCM inhibited the expression of C4 and C6 homoserine lactones (HSLs)-mediated phenotypes, whereas EGCG inhibited C4, C6, and C10 HSLs-based phenotypes. The Center for Disease Control biofilm reactor containing a multispecies culture of nine bacteria with one-half MIC of CCM (150 μg/ml) and EGCG (275 μg/ml) showed 17 and 14 μg/cm² of extracellular polymeric substances (EPS) on polyvinylidene fluoride membrane surface, whereas their combination (100 μg/ml of each) exhibited much lower EPS content (3 μg/cm²). Confocal laser scanning microscopy observations also illustrated that the combination of compounds tremendously reduced the biofilm thickness. The combined effect of CCM with EGCG clearly reveals for the first time the enhanced inhibition of AHL-mediated biofilm formation in bacteria from activated sludge. Thus, such combined natural QSI approach could be used for the inhibition of membrane biofouling in MBRs treating wastewaters.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1998년도 학술발표회 발표논문집
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• pp.508-512
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• 1998

Recently, biofilm reactors are considered as efficient wastewater treatment system in rural areas, because of characteristics of easy operation and economic feasibility. In order to select the most efficient media, an experimental apparatus with five different media was designed, installed and examined. The media used in this study were zeolite, artificial sponge gourd, absorbent biofilter, non-woven fabric and charcoal. With only one month investigation, all five media showed high removal efficiencies of BOD.