Bioelectrochemical Methane Conversion of Coal under Electrostatic Field

( Gyung-geun Oh ),( Young-chae Song ),( Dong-mei Piao ),( Dong-hoon Kim ),( Byung-uk Bae ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-

The methane conversion of coal to obtain clean energy is one of the reliable approaches to address recent environmental issues, including fine dust. We demonstrate that an electrostatic field greatly improves the biogenic methane conversion of coal in a bioelectrochemical batch reactor. For the experiment, the pairs of insulated electrodes were prepared by coating the surface of the titanium foil with a dielectric polymer and placed in three bioelectrochemical anaerobic reactors. The bioelectrochemical reactors were inoculated with anaerobic sludge after adding an anaerobic medium containing yeast extract and coal. The bulk solution in bioelectrochemical reactors was exposed to the electrostatic fields ranged from 0.67 V/cm to 3.33 V/cm by polarizing the insulated electrodes with an external voltage source, and the bioelectrochemical reactors were operated at mesophilic condition (35℃). Another anaerobic batch reactor without the insulated electrode pair was also prepared at the same procedure and used as the control. After the start-up, the methane production was started from the bioelectrochemical reactors without the lag phase. The cumulative methane production was gradually saturated to 176.3 mL in the bioelectrochemical reactor with the electrostatic field of 1.67 V/cm, which was higher than the reactor with 0.67 V/cm or 3.33 V/cm as well as the control. The exoelectrogenic and electrotrophic species in the bulk solution were confirmed by the electrochemical analysis (cyclic voltammetry and electrochemical impedance spectroscopy). This suggests that the electrostatic field of 1.67 V/cm significantly enhanced the biological direct interspecies electron transfer for the methane conversion of coal. Interestingly, after the cumulative methane production was saturated, the residual organic matter, the intermediates produced from the hydrolysis and acidogenic fermentation of coal, was still high in the bioelectrochemical reactors. This suggests that the intermediates have a self-inhibitory effect on methane conversion. The residual intermediates were further converted to methane by supplementing the anaerobic medium and anaerobic sludge. The total methane conversion of coal in the bioelectrochemical reactor exposed to the electrostatic field of 1.67 V/cm reached 168.5 mL/g lignite, which is the highest reported so far. An electric field established by polarizing insulated electrode greatly improves methane conversion of coal in the bioelectrochemical reactor.

Bioelectrochemical methane conversions of lignite at mesophilic- and thermophilic temperatures

Gyung-geun Oh,Yooung-Chae Song,Dong-Mei Piao,Byung-Uk Bae 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

유기물 부하변동에 대한 수평 혐기성 소화조의 완충 거동

오경근 ( Gyung-geun Oh ),송영채 ( Young-chae Song ),우정희 ( Jung-hui Woo ),김극태 ( Keug-tae Kim ),이채영 ( Chae-young Lee ),박정수 ( Jung-su Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2021 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2021 No.-

수평 혐기성 소화조(50L)의 유기물 부하율 변동에 대한 완충능력을 평가하기 위한 연구를 수행하였다. 음식 폐기물과 하수슬러지 열수탄화액 혼합물을 유입수로 사용하여 HRT 30일에서 정상상태로 운전 중인 수평 혐기성소화조의 유기물 부하율을 1일의 단기간 동안 1.5배 및 2배로 증가시킨 후 메탄발생량 및 소화조 내용물의 이화학적 특성 변화를 관찰하였다. 유기물 부하율을 1일간 2배로 증가시켰을 때 pH는 7.45에서 7.15로 감소하였으며, VFAs는 0.93 g COD/L에서 1.2 g COD/L로 증가하였다. 또한, 알칼리도는 9.14 g as CaCO₃/L에서 8.04 g as CaCO₃/L로 감소하였으며, COD 및 VS 제거율은 각각 45%, 51%까지 감소하였다. 그러나, COD 및 VS 제거율은 점차 회복되었으며 7-8일 이후 각각 67.4% 및 68.8%의 정상상태 값을 보였다. 그러나, 메탄발생량은 정상상태의 167%에 해당하는 1.29 L/L.d까지 증가하였으며, 바이오가스의 메탄함량은 64.3%로서 정상상태와 큰 차이가 없었다. 이 결과는 유기물 부하율의 단기간 2배 증가가 메탄생성에 악영향을 미칠 정도로 이화학적 성상변화가 나타나지 않는다는 것을 의미한다. 그러나, 관측된 이화학적 특성변화가 충격부하 이전의 정상상태 값으로 회복되는데 7-8일 정도 소요되었다. 유기물 부하율을 1일간 1.5배 증가시켰을 때 pH, 알칼리도는 소폭 감소하였다가 1일 이내에 정상상태로 회복되었으며, VFAs 농도는 큰 변화가 없었다. 또한, COD 및 VS 제거율은 정상상태와 큰 차이가 없었으며, 메탄생성량은 0.93 L/L.d로서 유기물 부하율 증가 이전보다 최대 124%까지 증가하였다. 음식폐기물과 하수슬러지 열수분해액의 혼합물을 처리하는 수평 혐기성 소화조는 유기물 부하율의 단기간 변동에 대응하는 완충력이 매우 큰 것으로 평가되었다.

석탄으로부터 메탄생성을 위한 생물전기화학 혐기성 소화조에서의 직접전자전달

오경근 ( Gyung-geun Oh ),송영채 ( Young-chae Song ),김동훈 ( Dong-hoon Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 추계학술발표논문집 Vol.2018 No.-

석탄에서 발생하는 바이오가스인 Coal-Bed Methane (CBM)은 지하에 매장된 석탄층에 존재하는 천연가스 원으로, 열적으로 생성되기도 하지만 혐기성 미생물에 의한 석탄에 함유된 유기물의 메탄전환 반응에 의하여 연속적으로 생성되기도 한다. 그러나 혐기성미생물을 이용한 CBM의 생성은 매우 느리며, 메탄의 생성 수율이 적다. 이는 석탄의 유기물 성분은 탄화과정에 생성된 리그닌 등의 소수성 고형물질로서 가수분해반응이 매우 느리게 진행된다. 또한, 가수분해 생성물들의 구성성분은 주로 미생물들이 이용하기 어려운 난분해성 방향족 화합물들이다. 생물전기화학 혐기성소화에서 메탄생성균과 전기활성미생물 사이의 직접전자전달이 메탄 발생에 큰 역할을 할 수 있다. 석탄의 생물학적 메탄 생성을 위한 촉진제로 이용된 효모 추출물은 미생물 생장을 위한 최상의 유기 질소 공급원으로 작용하는 것으로 알려져 있다. 본 연구는 유전물질을 코팅한 전극을 이용한 생물전기화학 혐기성소화 회분식 반응조에서 효모 추출물을 주입하여 석탄의 생물학적 메탄전환을 촉진하여 종간직접전자전달에 미치는 영향에 대하여 살펴보고자 하였다. 생물전기화학 혐기성 반응조 (Bio-Electro chemical Anaerobic Digetion)를 유전체를 코팅한 전극을 이용하여 준비하였으며, 전기장(Electric Field) 0.33V/cm, 0.66 V/cm 으로 형성시켜 10 g Coal/L를 주입하여 처리하는 동안 TCOD 농도, 메탄함량에 대한 미치는 영향을 평가하였다. 전극을 사용하지 않은 대조구에서는 1g 석탄에서 12.3ml의 메탄이 발생한 반면 전기장을 0.33 V/cm, 0.66 V/cm 형성시킨 반응조에서는 각 32.6 ml, 32.8 ml로 2배 이상 증가하였다. 이는 TCOD 분석 결과와 경향이 동일하게 나타났다. 전극을 사용하지 않은 곳에서 8.35 g TCOD/L이었으며, 전기장을 형성한 반응조에서는 각각 7.08 g TCOD/L, 7.23 g TCOD/L 로 분석되었다. 이는 난분해성 유기물인 석탄이 전기장을 이용한 생물전기화학 혐기성 소화에서 전기 활성미생물이 성장하여 직접종간전자전달 (Direct Interspecies Electron Transfer, DIET)에 의하여 분해가 촉진되어 메탄생성반응이 크게 향상되었다는 것을 의미한다. 사사: 본 논문은 2018년도 정부(미래창조과학부)의 재원으로 한국연구재단의 지원을 받아 수행된 연구입니다 (NRF-2017R1E1A1A01075325).

갈탄의 생물전기화학적 메탄전환에 대한 전자계의 영향

오경근(Gyung-geun Oh),송영채(Young-chae Song),박동매(Dong-mei Piao),김동훈(Dong-hoon Kim) 대한환경공학회 2020 대한환경공학회 학술발표논문집 Vol.2020 No.11

Mohs 미세도식 수술로 치로한 피부 점액성 에크린 암 1 예

오창근,장호선,김문범,권경술 대한피부과학회 2000 大韓皮膚科學會誌 Vol.38 No.8

Primary mucinous eccrine carcinoma(MEC) of the skin is a rare adnexal tumor, presumably of eccrine origin, which most commonly occurs in the head and neck regions. These tumors, although rarely metastatic, have a high incidence of local recurrence. We examined the case of a patient with primary MEC of the left lower lateral eyelid. The tumor was treated by Mohs surgery, fresh-tissue technique. There was no recurrence after 2 years of follow-up.

모낭성 피부병변 압출시 관찰되는 섬유성 물질의 성상에 관한 연구

박정흠,오창근,이성광,장호선,권경술,이채욱,서경형 대한피부과학회 2000 大韓皮膚科學會誌 Vol.38 No.9

Background: Comedo extractor is in general used for the management or diagnosis of the follicular cutaneous disorders such as acnc and folliculitis. During observing such extracted materials, we happened to discover the extraordinary thread-like fibrous materials. Objective: We tried to clarify the nature of these fibrous materials. Methods: The extracted materials from 20 patients with follicular cutanous disorders including 10 acne vulgaris and 10 pityrosporum folliculitis and 10 normal persons were investigated by pKOH, Masson trichrome for collagen fiber, Gomoris reticulum for reticulum fiber, acid orcein for elastic fiber, periodic acid-Schiff for fungal element and alcian blue for mucin. And we performed above mentioned special stainings in two biopsy specimens. Results .' Most of the extracted fibrous materials were reticulum fibers(95%) and some of them were elastic fibers(35%). And we observed the reticulum fibers and elastic fibers taken off from the pilosebaceous follicle on the histopathologic study Conclusion: The fibrous materials extracted from folliculor lesions were reticulum fibers or elastic fibers. And the observed presence of elastic fibers and reticulum fibers might result from tissue necrosis produced by leukocytes during the inflammatory phase of pilosebaceous follicles.

피부과 내원환자에서 간실질 효소와 B형 및 C형 바이러스성 간염 항체 유병률에 관한 연구

박정흠,오창근,장호선,김문범,권경술 대한피부과학회 2000 大韓皮膚科學會誌 Vol.38 No.9

Background: Recently, in dermatologic area, the number of skin biopsy for diagnosis and treatment has been increased and the dermatosurgery which should give patients satisfaction developed widely. As the frequency of direct contact with patients increases, we must recognize and prevent infectious diseases such as hepatitis B and C. Also, because drugs which may affect function of liver were used in many medical clinics and shops, we have more chance of evaluating liver function before the treatment. Objective: We investigated the prevalence and associated diseases of the patients with elevated transaminase (AST,ALT), positive of hepatitis B surface antigen and anti-HCV Ab. And we tried to study the causes of elevated transaminase. Method: All the 1704 outpatients who visited the dermatologic clinic of Pusan National University Hospital from March 1996 to February 1999 were enrolled. AST and ALT level were assessed by kinetic method and elevated group comprised the subjects with AST and ALT levels exceeding the upper limit of normal for our laboratories (AST $gt;40IU/L or ALT $gt;371U/L). HBsAg and anti-HCV Ab were tested by enzymeimmunoassay(EIA) and medical records were reviewed. Results: The prevalence of elevated transaminase was 13.6% and the peak age was the sixth decade. Most common associated disease categories were drug druption, eruption & urticaria. The prevalence of positive hepatitis B surface antigen was 9.7% and the peak age was the fourth decade (42.4%). Associated diseases of antigen positive patients were lichen planus, urticaria, cryoglobulinemia, etc. The prevalence of positive anti-HCV Ab was 3.4% and the sixth decade was the peak incidence of age distribution. The diseases such as urticaria, erythema nodosum, psoriasis, alopecia, and so on were investigated in the patients. Common suspected causes of elevated transaminase(AST, ALT) were hepatotoxic drug and viral hepatitis. Conclusion: Increased hepatic parenchymal enzyme was investigated in a high percentage of studied patients. Also, the prevalence of HBV and HCV infection in dermatologic patients were relatively higher than that of reported normal Korean people. Therefore dermatologists should recognize these facts and be careful in dermatologic procedure.

Influence of Water Electrolysis on Bioelectrochemical Methane Conversion of Coal

( Dong-mei Piao ),( Young-chae Song ),( Gyung-geun Oh ),( Dong-hoon Kim ),( Yong-tae Ahn ),( Yeo-myeong Yun ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-

The influence of water electrolysis on the biogenic methane conversion of coal was investigated in a bioelectrochemical anaerobic batch reactor. For the experiment, the pairs of ordinary electrodes (OE) consisting of anode and cathode were prepared with titanium foil and the surface of the OE surface was coated with a dielectric polymer to obtain a pair of insulated electrodes (IE). The pairs of OE or IE were placed in the bioelectrochemical anaerobic batch reactors, and polarized by applying voltage (0.5V, 1.0V, and 2.0V for the OEs, 2.0V for the IE) with an external voltage source. The bioelectrochemical anaerobic reactors were operated at 35oC after adding a medium containing yeast extract, coal (lignite, 2.5 g/L), and seeding with anaerobic sludge. The cumulative methane production in the OE reactor applied with the voltage of 2.0 V was gradually saturated to 162.9 mL without lag phase, which was higher 136 mL in the IE reactor. However, when the electrodes in the OE reactor were applied with a voltage (0.5V, 1.0V) lower than the voltage for water electrolysis, the cumulative methane production from coal was less than the blank. This indicates that the oxygen from the water electrolysis on the anode polarized with 2.0V was served as an electron acceptor to stimulate the ring-opening reaction of the high molecular coal hydrolysis products. However, the methane production from the OE and IE reactors was gradually decreased by the accumulation of the coal conversion intermediates. By supplementing the anaerobic medium containing yeast extract and anaerobic sludge, the cumulative methane production was abruptly increased again in the IE reactor, which was significantly higher than those of the OE reactors. The total methane yield of coal was 153.9 mL/g lignite in the IE reactor, significantly higher than 54.1 mL/g lignite in the OE reactor (2.0 V). This suggests that the coal could be effectively hydrolyzed and fermented under the electrostatic field in the IE reactor, and the methane conversion of coal via biological direct interspecies electron transfer could be stimulated by supplementing yeast extract and anaerobic sludge.

생물전기화학기술을 이용한 하수처리장 방류수 수질개선 가능성

송영채 ( Young Chae Song ),오경근 ( Gyung Geun Oh ) 한국물환경학회 2015 한국물환경학회지 Vol.31 No.4

The study on the improvement of discharge water quality from domestic wastewater treatment plant (DWTP) was performed in a filter type bioelectrochemical system. The COD removal efficiency for a synthetic discharge water was about 88%, and the effluent COD was less than 5mg/L. The nitrification efficiency of the bioelectrochemical system was over 97%, but a considerable amount of the nitrogen was remained as nitrate form in the effluent. The total nitrogen removal efficiency was only around 30%. There are no significant differences in the removal of COD and nitrogen at 0.6 and 0.8V of the applied voltages between anode and cathode. The removal of COD and nitrogen in the system were quite stable when the HRT ranged from 60 to 15 minutes, and at 10 minutes of HRT, the nitrification efficiency was slightly decreased. The performance of the bioelectrochemical system has quickly recovered from the shocks in the influent due to high concentration of COD and nitrogen. For the effluent that discharged from the DWTP, the removal efficiencies of COD and total nitrogen from the bioelectrochemical system were 50 and 30%, respectively. Thus the bioelectrochemical system was a feasible process for further polishing the effluent quality from DWTP.