• 유기물자원화
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• 제17권4호
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• pp.112-121
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• 2009

겨울과 여름의 평균 기온차가 무려 $32^{\circ}C$에 이르는 우리나라에서 외부환경의 영향을 감소시킬 수 있는 유기성 폐자원의 지하혐기조 효율에 관한 연구는 매우 중요하다. 돈슬러리의 지하혐기소화조의 설계인자를 구명(究明)하기 위하여 수원소재 서울대 부속목장에 $20m^3$의 용량 소화조 pilot plant를 설계, 제작하여 유기물부하율(OLR) $23.6kgVS/m^3$/일을 인입하여 종온($31{\sim}37^{\circ}C$)으로 약 40일간 운전하였다. 평균 $CH_4$ 생성율은 $5.78{\sim}8.62m^3$/일로 분석되었으며, 바이오가스의 주(主)구성가스는 $CH_4$과 $CO_2$ 로서 각각 67.5%, 19.6%로 나타났다. 바이오가스 생성율은 $733L/kg\;VS_{added}$, $CH_4$ 생성량은 $495L/kg\;VS_{added}$ 분석되었다. 돈슬러리의 혐기소화공정 후 돈슬러리의 생화학적 요인, 즉, TS, VS, TSS, $BOD_5$, $TCOD_{cr}$, $SCOD_{cr}$, $NH_3-N$, available P과 병원성 미생물, 즉, fecal coliforms and Salmonella는 각각 68%, 74%, 79%, 86%, 89%, 81%, 55%, 79% 감소되었으며, 미생물은 98%, 100% 사멸되었다. 본 연구에서 변형 UGAD는 돈슬러리의 바이오가스 생성과 생화학적 요인의 농도저감효과가 높은 것으로 관찰되어 산업화를 위하여 향후 심도있는 연구가 필요하다.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제1권2호
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• pp.125-136
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• 1997

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 feed. 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 sludge in the ASBR was 2.9 times higher than that of the sludge 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.

• 상하수도학회지
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• 제28권4호
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• pp.411-417
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• 2014

The performance of the new aerobic digestion system combined with inorganic sludge separation unit and sludge solubilization unit, CaviTec II, is evaluated. Anaerobic digester effluent sludge is used for feed sludge of CaviTec II system. By addition of CaviTec II, the amount of cake generated is reduced by 27%, and the soluble nitrogen is reduced by 92%.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.266-269
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• 2005

반응조의 유입수 CODcr농도를 $75000{\sim}95000mg/L$로 운전하였을 경우 유출수 CODcr농도는 $14000{\sim}19000mg/L$로서, 제거율은 $75{\sim}85%$로 나타났다. 고온소화$(45{\pm}2^{\circ}C)$로 운전한 결과 유입수 pH는 $4.2{\sim}4.5,$ 유출수의 pH는 $6.8{\sim}7.2$를 유지하였다. TS(총고형물질)와 VS(휘발성고형물질)의 유입수를 단계적으로 각각 $2.94{\sim}5.09%$와 $2.98{\sim}5.01%$로 유지할 경우, 유출수는 단계적으로 각각 $0.65{\sim}1.1%$와 $0.6{\sim}0.8%$였다. 유출수의 TS, VS의 제거율은 각각 78, 85%이었다. $CH_4$발생량은 0.28 $m^3-CH_4/kg-VS$이었다.

• 환경위생공학
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• 제23권4호
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• pp.73-82
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• 2008

In this study, a dry single-phase anaerobic digestion process (Dranco system) was investigated to evaluate the optimum operational conditions. Several factors such as injection rate of organic waste, biogas production, $CH_4$ content in the biogas, pH of the sludge, $NH_3$-N and VFA concentration were investigated based on the operation of the digestion process for 2 months (short term) and 8 months (long-term). The operation results showed that a small quantity of food waste should be injected every week and that a 10% increase of the microorganism injection rate should be needed. However, normal operation was conducted after 11 weeks based on the designed quantity. The $CH_4$ content in the biogas was high at the beginning and the end of the food injection. However, it was low during week days. When the biogas production was high, the $CH_4$ concentration was low. The biogas production increased with an increase of the injection rate. $100m^3$/ton of biogas was produced from normal operation of the digestion process based on the designed quantity. The pH values of the digestion tank based on short-term operation ranged from 8 to 8.5. However, the pH values ranged from 7.45 to 8.15 after 4 weeks of long-term operation. The $NH_3$-N concentration of short-term operation ranged from 4,500 to 5,500 ppm and it gradually decreased to 2,000ppm after normal operation was commenced. For long-term operation, it was 5,000ppm initially and 3,800ppm after normal operation was commenced. The VFA concentration of sludge was less than 900ppm and 2,500ppm for short and long-term operations, respectively, after normal operation. Overall, the differences between sludge pH, $NH_3$-N and VFA concentrations may be due to the different types of microorganisms and the digestion ability of the microorganisms which exist in the accumulation of non digested organics. Moreover, it may be also caused by the type of food waste. Further investigation is needed to confirm these relationships.

• 태양에너지
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• 제18권3호
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• pp.197-203
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• 1998

A 5 ton/day pilot scale two-phase anaerobic digester was constructed and tasted to treat Korean food wastes in Anyang city. The process was developed based on 3 years of lab-scale experimental results on am optimim treatment method for the recovery of biogas and humus. Problems related to food waste are ever Increasing quantity among municipal solid wastes(MSW) and high moisture and salt contents. Thus our food waste produces large amounts of leachate and bed odor in landfill sites which are being exhausted. The easily degradable presorted food waste was efficiently treated in the two-phase anaerobic digestion process. The waste contained in plastic bags was shredded and then screened for the removal of inert material such as fabrics and plastics, and subsequently put into the two-stage reactors. Heavy and light inerts such as bones, shells, spoons and plastic pieces were again removed by gravity differences. The residual organic component was effectively hydrolyzed and acidified in the first reactor with 5 days space time at pH of about 6.5. The second, methanization reactor part of which is filled with anaerobic fillters, converted the acids into methane with pH between 7.4 to 7.8. The space time for the second reactor was 15 days. The effluent from the second reactor was recycled to the first reactor to provide alkalinities. The process showed stable steady state operation with the maximum organic rate of 7.9 $kgVS/m^3day$ and the volatile solid reduction efficiency of about 70%. The total of 3.6 tons presorted MSW containing 2.9 tons of food organic was treated to produce about $230m^3$ of biogas with 70% of methane and 80kg humus. This process is extended to full scale treating 15 tons of food waste a day in Euiwang city and the produced biogas is utilized for the heating/cooling of adjacent buildings.

• 상하수도학회지
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• 제10권2호
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• pp.104-116
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• 1996

Anaerobic digestion is generally used for the treatment of volatile organic solids such as manure and sludge from waste water treatment plants. However, the reaction rate of anaerobic process is slow, and thus it requires a large reactor volume. To minimize such a disadvantage, physical and chemical pre-treatment is generally considered. Another method to reduce the reactor size is to adopt different reactor system other than CSTR. In this paper, the effects of heat pre-treatment and reactor configurations on the anaerobic treatability of volatile solids was studied. Carrot, kale, primary sludge, and waste activated sludge was chosen as the test materials, and the BMP method was used to evaluate the maximum methane production and first order rate constants from each sample. After the heat treatment at $130^{\circ}C$ for 30min., the measured increase in SCOD per gram VS was up to 394 mg/L for the waste activated sludge. However, the methane production potential per gram VS was increased for only primary and waste activated sludge by 17-23%, remaining the same for carrot and kale. The overall methane production process for the tested solids can be described by first order reactions. The increased in reaction constant after heat pre-treatment was also more significant for the primary and waste activated sludge than that for carrot and kale. therefore, the heat pre-treatment appeared to be effective for the solids with high protein contents rather than for the solids with high carbohydrate contents. Among the four reactor systems studied, CSTR, PFR, CSTR followed by PFR, and PFR with recycle, CSTR followed by PFR appeared to be the best choice considering methane conversion rate and the operational stability.

• 한국환경보건학회지
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• 제22권2호
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• pp.96-103
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• 1996

The objectives of this study were to examine the biodegradation of phenol using the anaerobic fluidized bed reactor(AFBR). Mixed microorganisms were selected from the anaerobic digestion tank, and could be adapted to high concentration of phenol by increasing the phenol concentration 600-3600 mg/l step by step. The results were summarized as follows: 1. The average removal efficiency of phenol was 90%, decreased by increasing concentration of phenol, and then a shock range was 1200~2400 ppm. 2. The production rate of biogas in overall limits was proportional to the concentration of influent phenol. 3. At steady state, compositions of gases were $CH_4$ 55~60%, $C0_2$ 34~43%, respectively. These were similar to that of the theoretical estimates. 4. The production rates of biogas and methane per the molarity of phenol removed were linearly increased, 56.45 l gas/mol-phenol and 29.20 l $CH_4/mol$-phenol. Using this biogas, the recoverable energy was 269.1 kcal/mol phenol. It was 120.2 kcal/g-COD, transforming into the chemical oxygen demand. 5. The bulk of microorganisms existed in suspended section of fluidized bed with type of biofilm and its concentration was 340 mg/g-media. In conclusion, the anaerobic treatment of pure phenol was possible and its removal efficiency, introducing the AFBR, was successful. Also toxic organic compound such as phenol was biodegradable and was recoverable as resource of energy.

• 상하수도학회지
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• 제34권4호
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• pp.259-266
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• 2020

In this study, a pilot-scale (3 ㎥/day) membrane distillation (MD) process was operated to treat digestate produced from anaerobic digestion of livestock wastewater. In order to evaluate the performance and energy cost of MD process, it was compared with the pilot scale (10 ㎥/day) reverse osmosis (RO) process, expected competitive process, under same feed condition. As results, MD process shows stable permeate flux (average 10.1 L/㎡/hr) until 150 hours, whereas permeate flux of RO process was decreased from 5.3 to 1.5 L/㎡/hr within 24 hours. In the case of removal of COD, TN, and TP, MD process shows a high removal rate (98.7, 93.7, and 99% respectively) stably until 150 hours. However, in the case of RO process, removal rate was decreased from 91.6 to 69.5% in COD and from 93.7 to 76.0% in TP during 100 hours of operation. Removal rate of TN in RO process was fluctuated in the range of 34.5-62.9% (average 44.6%) during the operation. As a result of energy cost analysis, MD process using waste heat for heating the feed shows 18% lower cost compare with RO process. Thus, overall efficiency of the MD process is higher then that of the RO process in terms of permeate flux, removal rate of salts, and operating cost (in the case of using waste heat) in treating the anaerobic digestate of livestock wastewater.

• Asian-Australasian Journal of Animal Sciences
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• 제26권1호
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• pp.122-127
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• 2013

The hypochlorite ion ($OCl^-$) is a widely used disinfecting agent in pig rearing in Korea, but its residual effect on $CH_4$ production from pig slurry is unclear. The objective of this study was to investigate the inhibition effects of residual $OCl^-$ on $CH_4$ production during the initial anaerobic digestion stage of pig slurry. Three organic concentrations (9.9, 26.2 and 43.7 g/L) of volatile solids (VS) were tested with the addition of 52.3 mg/L $OCl^-$, ten times of the typical concentration used in Korea, or without $OCl^-$ (Control) in anaerobic batch culture. The culture was run under mesophilic ($38^{\circ}C$) conditions for 20 d. At the lowest organic concentration with $OCl^-$, the VS degradation was 10.3% lower (p<0.05) than Control, while at the higher organic concentration with $OCl^-$, it did not differ from Control. $CH_4$ yields were higher in the control treatments than their $OCl^-$ counterpart cultures, and $CH_4$ yields of Control and $OCl^-$ treatments at the organic concentrations of 9.9, 26.2 and 43.7 g/L differed in the probability level (p) of 0.31, 0.04, and 0.06, respectively. Additionally, $CH_4$ concentration increased steeply and reached 70.0% within 4 d in the absence $OCl^-$, but a gradual increase up to 60.0% was observed in 6 d in the $OCl^-$ treated cultures. The $R_m$ (the maximum specific $CH_4$ production rate) and ${\lambda}$ (lag phase time) of 9.9 g/L with $OCl^-$ were 8.1 ml/d and 25.6 d, while the $R_m$ was increased to 15.1 ml/d, and ${\lambda}$ was reduced to 11.4 d in PS-III (higher organic concentration) with $OCl^-$. The results suggest that a prolonged fermentation time was necessary for the methanogens to overcome the initial $OCl^-$ inhibitory effect, and an anaerobic reactor operated with high organic loadings was more advantageous to mitigate the inhibitory effect of residual hypochlorite ion.