• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2003년도 생물공학의 동향(XII)
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• pp.128-131
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• 2003

The effect of microwave irradiation on waste activated sludge was investigated in order to improve solubilization. a different levels of microwave irradiation time were varied within a range from 1 min to 15 min. When WAS was pretreated at 1, 3, 5, 7, and 15 min, the SCOD concentration increased according to microwave irradiation time. A simple batch procedure was used to measure the VFA potential, i.e. the amount of VFA that can be formed through digestion of organic constituent in sludge. At equilibrium point, TVFA in the case of 1, 3, 5, 7 and 15 min microwaved sludges was 8%, 122%, 243%, 279% and 232% higher than that in the case of raw sludge, respectively.

• 유기물자원화
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• 제17권1호
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• pp.96-102
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• 2009

본 연구에서는 혐기성 소화 성능 향상을 위해 초음파 및 알칼리 전처리에 의한 폐활성 슬러지의 가용화 효과를 조사하였다. 초음파 및 알칼리 전처리는 세포벽의 파괴로 인하여 모세관 흡입 시간을 증가시킬 뿐만 아니라 상등액의 용존성 화학적 산소요구량, 단백질 및 탁도 농도를 증가키는 것으로 나타났다. 알칼리와 초음파 전처리를 병행한 슬러지 가용화가 초음파 전처리만을 수행한 경우에 비해 용존성 화학적 산소요구량과 단백질 증가가 높은 것으로 나타났다. 알칼리와 초음파 전처리를 동시에 수행한 경우 폐활성 슬러지의 고형물 농도 증가에 따라 가용화 효율이 감소하는 것으로 조사되었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.398-401
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• 2000

A device to measure the temperature difference between the supernatant and the sediment blanket in the course of SV30 measurement in processing of activated sludge process. The temperature elevation in the sludge sediment represent the metabolic heat production by the microorganisms and can be an indicator for the capability of waste treatment. The utilities of the device for the analysis of activated sludge process were demonstrated in this report.

• 한국콘텐츠학회논문지
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• 제9권10호
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• pp.444-450
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• 2009

본 연구는 폐 활성슬러지를 이용하여 $Pb^2+$와 $Cr^2+$의 생체흡착속도 및 평형을 도출하였으며, 가압부상법이 이용하여 A/S 비에 따른 폐슬러지의 분리효율을 비교하였다. 흡착량 및 접촉시간은 흡착평형과 동역학 모델식을 이용하여 모사하였다. 폐 활성슬러지상에서 $Pb^2+$와 $Cr^2+$의 흡착평형은 Langmuir와 Redlich-Peterson식에 의해 잘 예측될 수 있었다. 흡착속도는 유사 1차 반응식보다는 유사 2차 반응식에 의해 더 잘 예측되었다. 가압부상법을 이용한 폐 활성슬러지의 분리효율은 90%이상 유지하는 것이 가능하였다.

• 한국물환경학회지
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• 제23권6호
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• pp.927-933
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• 2007

Waste activated sludge (WAS) was thermally pretreated to enhance hydrolysis and ultimately methane yield. Batch and semi-continuous anaerobic digestion were conducted to evaluate the performance of methane fermentation of the hydrolyzed sludge and to investigate the kinetics of sludge fermentation. Thermal pretreatment remarkably enhanced digestion performances particularly the methane fermentation with three times more methane production than before the pretreatment. Gas production and kinetic parameters in the semi-continuous anaerobic digestion were estimated using Chen Hashimoto model. The model simulation fitted well the experimental results and the model was shown to be suitable for evaluating the effects of disintegration of WAS in anaerobic digestion. Three parameters ($B_o$, K, and ${\mu}_m$) determined by model simulation were $0.0807L-CH_4/g-VS$, 0.453 and $0.154d^{-1}$ for control sludge, and $0.253L-CH_4/g-VS$, 0.835 and $0.218d^{-1}$ for thermally pretreated sludge, respectively.

• 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.

• Journal of Microbiology and Biotechnology
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• 제11권4호
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• pp.570-576
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• 2001

Thermophilic aerobic bacteria were applied in the degradation of industrial waste activated sludge (WAS) on a laboratory scale expreiment. The performance of digestion was estimated by measuring the reduction of total suspended solids (TSS), dissolved organic carbon (DOC), and total organic carbon (TOC). Among three strains of Bacillus stearothermophilus and three strains of Thermus species, B. stearothemophilus ATCC 31197 showed the best overall efficiency level for the degradation of industrial WAS, which was collected from a wastewater treatment plant in an oil refinery factory. Industrial WAS coul be successfully detraded in a batch digestion with ATCC 31197. The stability of the digestion process with ATCC 31197 was successfully verified by semi-continuous (fill-and-draw) digestion experiment. From the results of this study, it was shown that the thermophilic aerobic digestion process with ATCC 31197 could efficiently be applied to the degradation of industrial WAS.

• 상하수도학회지
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• 제21권5호
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• pp.551-558
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• 2007

From the view point of biological wastewater treatment, C/N ratio is one of the most important factor in biological nutrient removal process. However, municipal sewage in Korea is characterized by extremely low content of carbon source and relatively higher portion of N source. Accordingly, it is necessary to dose external carbon source in order to obtain higher degree of carbon source within the process. In this study, the effects of pH pretreatment as an alternative plan for increasing carbon source on the cell disruption and COD solubility of waste activated sludge were conducted under well defined experimental conditions. During 5 hours, the value of COD solubilization rate ($S_R$) at pH 11.5 is approximately 4.4 times higher than the value of $S_R$ at pH 9.5. It is expected that the level of SCOD increased due to the result from cell disruption. However, VSS/TSS ratio was not significantly changed after 5 hours. As Alkalinity changes gradually from less than 15, 30 and 60 meq NaOH/L, average RBCOD/SCOD fraction showed 34, 36 and 45%,respectively.

• 상하수도학회지
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• 제33권4호
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• pp.291-297
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• 2019

Phosphorus is a vital resource for sustaining agriculture and nutrition, but a limited non-renewable resource. Thus, the recovery of phosphorus from waste activated sludge(WAS) was attempted by microwave heating and magnesium ammonium phosphorus(MAP) crystallization. Polyphosphate-accumulating organisms(PAOs) in WAS release phosphate from the cell when they are exposed to high temperature environments. Microwave heating caused phosphorus and ammonia to release from WAS. The amount was increased with increasing temperature, showing that 88.5% of polyphosphate present in the cells were released in the form of phosphate at $80^{\circ}C$. A similar result was also observed in the release of ammonia. On the other hand, both phosphorus and ammonia were crystallized with magnesium, and then was harvested as MAP. Phosphorus recovery rate reached almost 97.8%, but the ammonia was about 13.4%. These results cleary indicate that phosphorus could be recovered from WAS using a physiological trait of PAOs. Heavy metal analyses also show that the MAP crystal is useful and safe as a phosphorus fertilizer.

• 상하수도학회지
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• 제22권2호
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• pp.179-182
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• 2008

The KIDEA process, occurred in single reactor, is operated by three consequential steps, i.e., aerobic, settling, and discharge while introducing wastewater into the bottom of reactor continuously. It could accomplish biological oxidation (BOD), nitrification, denitrification (T-N), phosphate removal (T-P), and solid separation (SS) through the operational mode mentioned. Especially, this system has removed the T-P by wasting certain amount of sludge at the end of aeration phase during 5~10 minutes and not returned the activated sludge into the reactor, that is, no RAS (Return Activated Sludge). All running mode and instrumentation were controlled by the PLC equipment automatically. In this study, therefore, we have evaluated T-P removal efficiency and moisture content (MC) performance under the different excess sludge wasting mode. T-P track study and MC with TS concentration were analyzed during aerobic and settling phase. It has revealed that there was no significant difference of released T-P concentration between the first case which waste the sludge at the end of aerobic phase (0.2mg/L) and the second case which waste the sludge at 40 min of settling phase (0.25mg/L). Also, dewatering duration and MC have decreased 1.7% when TS concentration was increased from 0.31% to 0.5% during aerobic condition. Hence, it has concluded the system performance was less influenced by the operation time change of PLC program.