• 한국물환경학회지
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• 제21권5호
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• pp.490-495
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• 2005

Since there are very limited numbers of thermophilic anaerobic digesters being operated, it is often difficult to start up a new one using sludge from an existing reactor as a seed. However, for obvious reasons it seems few attempts have been made to compare the start-up performance of thermophilic anaerobic digestion using different sources of seed sludges. The purpose of this study was to evaluate the start-up performance of anaerobic digestion using aerobic Waste Activated Sludge (WAS) from a plant and mesophilic Anaerobic Digested Sludge (ADS) as the seed source at both mesophilic ($35^{\circ}C$) and thermophilic ($55^{\circ}C$) temperatures. In this study, two experiments were conducted. First, thermophilic anaerobic reactors were seeded with WAS (VSS = 4,400 mg/L) and ADS (VSS = 14,500 mg/L) to investigate start-up performance with a feed of acetate as well as propionate. The results show that WAS started to produce $CH_4$ soon after acetate feeding without a lag time, while ADS had a lag time of 10 days. When the feed was changed to propionate, WAS removed propionate down to below the detection limit of 10 mg/L, while ADS removed little propionate and produced little $CH_4$. Second, in order to further compare the methanogenic activity of WAS and ADS, both mesophilic and thermophilic reactors were operated. WAS acclimated to anaerobic conditions shortly and after acclimating it produced more $CH_4$ than ADS. WAS at mesophilic temperature biodegraded acetate at the same rate as for thermophilic. However WAS at mesophilic temperature biodegraded propionate at a much faster rate than at thermophilic. WAS as the seed source of anaerobic digestion resulted in much better performance than ADS at both mesophilic and thermophilic temperatures for both acetate and propionate metabolism.

• 상하수도학회지
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• 제18권4호
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• pp.515-521
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• 2004

Anaerobic digestion has many advantages over the more conventional aerobic treatment processes such as low levels of excess sludge production, low space (area) requirements, and the production of valuable biogas. The purpose of this study was to evaluate the effect of organic loading rate of anaerobic digestion on thermophilic($55^{\circ}C$) and mesophilic($35^{\circ}C$) conditions. Fluorescent in situ hybridization (FISH) method was also used to study the microbial community in the reactors. The stabilizing time in mesophilic anaerobic reactors was shorter as approximately 20 days than 40 days in the thermophilic anaerobic reactors. The amount of methane production rate in anaerobic reactors was independent of the concentrations of supplied substrates and the amount of methanogens. When the microbial diversity in the mesophilic and thermophilic reactors, which had been treated with acetate-based artificial wastewater, were compared, it was found that methanogenesis was carried out by microbial consortia consisting of bacteria and archaea such as methanogens. To investigate the activity of bacterial and archaeal populations in all anaerobic reactors, the amount of acetate was measured. Archaea were predominant in all reactors. Interestingly, Methanothrix-like methanogens appeared in mesophilic anaerobic reactors with high feed substrate concentrations, whereas it was not observed in thermophilic anaerobic reactors.

• Environmental Engineering Research
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• 제16권2호
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• pp.103-109
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• 2011

This work experimentally determined the effect of thermal and microwave pretreatments on the anaerobic digestion of mixtures of municipal primary and secondary sludges in semi-continuous mesophilic digesters at hydraulic retention times (HRT) of 20, 15, 10, 7, and 5 days. The ratio of soluble chemical oxygen demand (COD) to total COD in thermally pretreated and microwaved sludges at $80^{\circ}C$ was 2.7 and 3.2 times higher than that of raw sludge, respectively. The volatile solids (VS) and COD removal efficiencies in all three digesters fed with raw (control), thermally pretreated (TM), and microwaved (MW) sludges decreased as the HRT was reduced. The highest relative improvement in VS removal compared to the control occurred at the HRT of 5 days in the TM and MW (29 and 41% higher than the control, respectively). At this HRT, improvement in the COD removal efficiencies in the TM and MW compared to the control was 28 and 53%, respectively. Improvements in biogas production compared with the control increased in both the TM and MW as the HRT was reduced to 5 days. The relative improvement in daily biogas production compared to the control from the TM and MW was 33 and 53% higher than the control at the HRT of 5 days, respectively. The results show that microwave pretreatment is more effective than thermal pretreatment in increasing the solubilization degree and mesophilic anaerobic biodegradability of sewage sludge.

• 한국물환경학회지
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• 제21권1호
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• pp.34-39
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• 2005

The performance of elutriated acid fermentation with slurry-type piggery waste was investigated, especially to evaluate the effects of temperature and pre-treatment. In the first phase, the acid elutriation reactor with piggery waste after centrifugation operated at both mesophilic and thermophilic conditions to evaluate the effect of temperature. Solubilization yield($gVFAs/gSCOD_{prod.}$) and acidification rate($gVFAs/gSCOD_{prod.}$) in the thermophilic digestion were 0.45 and 0.55, which were higher than those of the mesophilic digestion, 0.25 and 0.45. In addition, the acid elutriation reactor at thermophilic temperature is more effective in removing e-coli. In the second phase, the acid elutriation reactor was fed with piggery waste before centrifugation. With piggery wastes before centrifugation, the solubilization yield and the acidificaton rate were 0.40 and 0.80, respectively, which were higher than the rates using piggery waste after centrifugation at both mesophilic and thermophilic conditions. The higher sludge volume reduction of 80% benefits sludge management. Furthermore, economical advantages can be achieved by removing the pre-treatment process, such as centrifugation. Consequently, the treatment with piggery waste before centrifugation proved to be effective. Also, the optimum temperature condition was estimated at mesophilic or thermophilic conditions, considering solubilization yields and acidification rates, though the system should be heated.

• 공업화학
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• 제23권1호
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• pp.28-34
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• 2012

본 연구에서는 UASB 반응조를 이용하여 음폐수 탈리액을 원료로 하여 중온소화($35{\pm}0.5^{\circ}C$)와 고온소화($55{\pm}0.5^{\circ}C$)법을 통한 운전을 실시하였다. 20일 동안은 중온소화로 운전을 하면서 5일 간격으로 유출수 재순환 비를 단계적으로 변화시켰다. 고온소화 역시 중온소화와 마찬가지 조건으로 운전을 실시하였다. 실험결과 중온소화 시 유기물제거율은 90% 이상, 메탄수율은 약 66~70%로 나타났다. 고온소화 시 유기물제거율은 80% 이상, 메탄수율은 약 62~68%로 나타났다. 또한, 유출수 반송을 3Q 이상으로 반송하여 운전할 경우 경제적이며 안정적인 운전을 할 수 있었다.

• 한국환경과학회지
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• 제31권12호
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• pp.1051-1059
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• 2022

This study investigated microbial communities and their diversity in a full-scale mesophilic anaerobic digester treating sewage sludge. Influent sewage sludge and anaerobic digester samples collected from a wastewater treatment plant in Busan were analyzed using high-throughput sequencing. It was found that the microbial community structure and diversity in the anaerobic digester could be affected by inoculation effect with influent sewage sludge. Nevertheless, distinct microbial communities were identified as the dominant microbial communities in the anaerobic digester. Twelve genera were identified as abundant bacterial communities, which included several groups of syntrophic bacteria communities, such as Candidatus Cloacimonas, Cloacimonadaceae W5, Smithella, which are (potential) syntrophic-propionate-oxidizing bacteria and Mesotoga and Thermovigra, which are (potential) syntrophic-acetate-oxidizing bacteria. Lentimicrobium, the most abundant genus in the anaerobic digester, may contribute to the decomposition of carbohydrates and the production of volatile fatty acids during the anaerobic digestion of sewage sludge. Of the methanogens identified, Methanollinea, Candidatus Methanofastidiosum, Methanospirillum, and Methanoculleus were the dominant hydrogenotrophic methanogens, and Methanosaeta was the dominant aceticlastic methanogens. The findings may be used as a reference for developing microbial indicators to evaluate the process stability and process efficiency of the anaerobic digestion of sewage sludge.

• 유기물자원화
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• 제21권3호
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• pp.43-52
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• 2013

본 연구에서는 유입 슬러지에 다양한 전처리 방법을 적용하여 전처리 방법이 중온혐기-고온호기 복합 슬러지 처리 공정의 슬러지 소화효율과 메탄가스 생성량에 미치는 영향을 비교 검증하였다. 실험실 규모의 슬러지 소화장치를 제작하여 서로 다른 유입 슬러지 전처리방법을 적용하여 4단계로 실험을 진행하였다. 1단계에서는 전처리를 하지 않은 슬러지를 공급하였고, 2, 3, 4단계에서는 각각 열처리, 열-알칼리처리, 장기 알칼리 처리(7일)를 거친 유입 슬러지를 공급하였다. 실험 결과, 1단계에서 4단계까지 진행되는 동안 총COD 제거율은 44%에서 76%까지 증가하였으며, 메탄 생성량 또한 101mL/L/day에서 165, 256mL/L/day까지 크게 증가하였다. 한편, 4단계에서는 7일간의 장기 알칼리 처리를 하였음에도 불구하고 3단계에 비해 총COD 제거율과 메탄 생성량이 증가하지 않았다. 결론적으로, 유입 슬러지의 전처리를 통해 복합 슬러지 처리 공정의 슬러지 제거 효율과 메탄생성량을 크게 증가시킬 수 있었으며, 여러 가지 전처리 방법 중 열-알칼리 처리법이 가장 효율적임을 실험결과를 통해 알 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제26권1호
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• pp.110-119
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• 2016

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 highthroughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

• 한국환경과학회지
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• 제15권9호
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• pp.897-905
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• 2006

This study has been conducted to investigate biodegradation characteristics and optimum mixing ratio for co-digestion with thermophilic acid-fermented food waste and sewage sludge using batch anaerobic digester. As the basis operating conditions for anaerobic digestion, the reaction temperature was controlled $35{\pm}1^{\circ}C$ and stirrer was set 70rpm. Thermophilic acid-fermented food waste and sewage sludge were mixed at the ratio of 10:0, 7:3, 5:5, 3:7, 0:10 and 5;5(food waste : sewage sludge) as the influent substrates. In results of co-digestion according to mixing ratio of thermophilic fermented food wastes and sewage sludge in batch mesophilic anaerobic digestion reactor, $385mL\;CH_4/g\;VS_{added}$ of methane production rate at 1:1 mixing ratio was more than that of any other mixing ratios. Compared with $293mL\;CH_4/g\;VS_{added}$ of methane production rate at 1:1 mixing ratio of food wastes and sewage sludge, pretreatment of food wastes by thermophilic acid fermentation was more effective in co-digestion with sewage sludge.

• 대한토목학회논문집
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• 제8권4호
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• pp.59-67
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• 1988

혐기성소화(嫌氣性消化)에 미치는 온도(溫度)의 영향(影響)을 가장 효과적으로 파악할 수 있는 체류시간(滯留時間) 5일(日)에서 인공(人工)슬러지를 대상으로 $35{\sim}55^{\circ}C$의 소화실험(消化實驗)을 행하였다. 소화온도증가(消化溫度增加)에 따라 메탄발효(醱酵)의 저해(沮害)가 감소하여, 중온(中溫) 및 중간영역(中間領域)의 온도(溫度)에서는 잔발효(酸醱酵)가 우세하였으나 $55^{\circ}C$에서는 활발한 메탄발효(醱酵)가 이루어졌다. 온도(溫度)의 변화(變化)는 미생물활성(微生物活性)뿐 아니라 슬러지의 물리(物理), 화학적(化學的) 특성(特性)에도 영향(影響)을 미친다고 추정된다. 또한 유입(流入) 슬러지의 희석(稀釋)에 의하여 소화저해(消化沮害)가 크게 감소하여 모든 온도(溫度)에서 활발한 메탄발효(醱酵)가 가능하였다. 소화효율(消化效率)은 수리학적(水理學的) 부하량외(負荷量外)에 유기물부하량(有機物負荷量)에도 지배받음을 알 수 있었다. 소화효율(消化效率)의 급격한 저해(沮害)가 발생된다고 보고된 $40{\sim}45^{\circ}C$에서도 뚜렷한 저해(沮害)는 없었다. 한편 소화온도증가(消化溫度增加)에 따라 소화(消化)슬러지의 침강특성(沈降特性)도 향상되었다.