• 한국물환경학회지
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• 제29권4호
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• pp.459-465
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• 2013

A sequencing batch reactor was operated under different pH conditions to see the influence of pH to microbial community in enhanced biological phosphorus removal (EBPR) systems. Long term influences of different steady-state pH conditions on the microbial community composition were evaluated by polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and fluorescence in situ hybridization (FISH). The shift in populations from polyphosphate-accumulating organisms (PAOs) to Alphaproteobacteria was observed when pH was changed from 7.5 to 7.0. Alphaproteobacteria with the typical morphological traits of tetrad-forming organisms (TFOs) eventually became dominant members. The alphaproteobacterial TFOs were the phenotype expected for glycogen-accumulating organisms (GAOs), which accumulate large amount of glycogen into the cell. The results strongly suggested that low operational pH condition encourages the appearance of the GAOs in EBPR process, significantly reducing the EBPR capacity.

• 미생물학회지
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• 제38권2호
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• pp.113-118
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• 2002

혐기-무산소조건으로 구성된 회분식 반응조에서 질산염을 이용하여 인(P)도 동시에 제거될 수 있는 가능성을 알아보기 위해서 인의 제거 양상을 혐기-호기조건의 반응조와 비교하여 조사하였고, 질산염과 인을 동시에 제거하는 미생물분포를 분석하였다. 그 결과 비교적 낮은 농도의 유기물이 적용되었을 때(평균 CODcr=130mg/ι)두 반응조 모두 인이 효과적으로 제거되었으며 반응조내의 최종 인의 농도를 1 mg P/L. 이하로 유지하였다. 특히, 질산염을 전자수용체로 이용한 혐기-무산소조건의 반응조는 기존의 영양소제거 시스템과 비교하여 5-7 mg (P+N)/ι의 영양소를 추가적으로 제거하여 유기물의 효과적 인 이용이 가능한 것으로 판명되었다. 혐기-무산조 조건의 방응조내 미생물 분포를 조사 한 결과 질소원을 제거하는 미생물군(denitrifying bacteria)과 인을 제거하는 미생물군(polyphosphate accumulating bacteria)이 함께 존재하고 있음이 밝혀졌고, 이들 중 $\beta$-proteobacteria에 속하는 Zoogloea ramigera와 Rhodocyclus에 포함되는Alcaligenes defragrans 등은 탈질능력 이 있으면서 anoxic상태에서 인을 동시에 축적할 수 있는 탈질-탈인균주(denitrifying phosphate accumulating organisms; dPAO)로 조사되었다.

• 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.

• 한국폐기물자원순환학회지
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• 제35권8호
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• pp.701-708
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• 2018

Chemical batch tests were conducted to investigate the amount of nutrients that were released from the wasted activated sludge during microwave heating. For this study, three types of activated sludge were obtained from $A_2/O$, MLE and oxidation ditch (OD) processes. Polyphosphate-accumulating organisms in the activated sludge have a unique trait: they releases phosphate from the cell when they are exposed to high temperatures. The sludge obtained from the $A_2/O$ process released the largest amount of phosphate, followed by those from the MLE and OD processes. The release of phosphate increased with increasing polyphosphate content in the sludge under strongly alkaline or acidic conditions. Furthermore, ammonia and heavy metals were released with phosphorous. The largest amount of ammonia was observed from the sludge obtained from the MLE process. The release of heavy metals strongly depends on the pH conditions. Therefore, the chemical analysis results strongly suggest that both phosphorus and ammonia react with $Mg^{2+}$ or $Ca^{2+}$ to form metal complexes such as magnesium ammonium phosphate or hydroxyapatite under alkaline conditions.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 춘계학술발표대회
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• pp.105-108
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• 2000

Enhanced biological phosphorus removal (EBPR) is not always successfully achieved by anaerobic/aerobic operation. It has been reported that the EBPR deterioration was caused by the outgrowth of glycogen-accumulating organisms (GAO) over polyphosphate-accumulating organisms (PAO). It was found that pHcould be a tool which might induce the success of EBPR in a sequencing batch reactor (SBR) supplied with acetate. When the pH of anaerobic phase was controlled at 7.0, the operation resulted in failure of EBPR. However, when the pH of anaerobic phase increased up to 8.4, complete EBPR was achieved. We explained the mechanism of pH effect on the competition between GAO and PAO with experimental results and previously proposed biochemical models.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.77-80
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• 2000

Various analytical methods such as electron microscopy, quinone analysis, and 16S rDNA sequencing studies were used to investigate the microbial communities and to identify the microorganisms responsible for enhanced biological phosphorus removal (EBPR) in an anaerobic/aerobic sequencing batch reactor (SBR) fed with acetate. Electron photomicrographs showed that oval-shaped microorganisms of about $0.7\;{\sim}\;1\;{\mu}m$ in diameter dominated the microbial sludge. These microorganisms contained polyphosphate granules and glycogen inclusions, which suggests that they are a kind of phosphorus accumulating organism. Quinone and 16S rRNA sequence analyses showed that the members of Proteobacteria beta subclass were the most abundant species, which were affiliated with the Rhodocyclus-likes group. Phylogenetic analysis revealed that the two dominating clones of the beta subclass were most distantly related to Propionivibrio dicarboxylicus DSM 5885 and Rhodocyclus tenuis DSM 109 with about 95% and 96% sequence similarity, respectively. Therefore, it was concluded that the oval-shaped organisms related to the Rhodocyclus-likes group are likely to be responsible for biological phosphorus removal in SBR operation supplied with acetate.

• Journal of Microbiology and Biotechnology
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• 제12권6호
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• pp.929-935
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• 2002

The 5-stage biological nutrient removal (BNR) process with step feed system showed a very stable organic carbon and nutrient removal efficiency ($87\%\;COD\,;79\%\;nitrogen,\;and\;87\%$ phosphorus) for an operation period of 2 years. In each stage at the pilot plant, microbial communities, which are important in removing nitrogen and phosphorus, were investigated using fluorescence in-situ hybridization (FISH) and 165 rDNA characterization. All tanks of 5-stage sludge had a similar composition of bacterial communities. The totat cell numbers of each reactor were found to be around $2.36-2.83{\times}10^9$ cells/ml. About $56.5-62.0\%$ of total 4,6-diamidino-2-phenylindol (DAPI) cells were hybridized to the bacterial-specific probe EUB388. Members of ${\beta}$-proteobacteria were the most abundant proteobacterial group, accounting for up to $20.6-26.7\%$. The high G+C Gram-positive bacterial group and Cytophaga-Flexibacter cluster counts were also found to be relatively high. The beta subclass proteobacteria did not accumulate a large amount of polyphosphate. The proportion of phosphorus-accumulating organisms (PAOs) in the total population of the sludge was almost $50\%$ in anoxic-1 tank. The high G+C Gram-positive bacteria and Cytophaga-Flexibacter cluster indicate a key role of denitrifying phosphorus-accumulating organisms (dPAOs). Both groups might be correlated with some other subclass of proteobacteria for enhancing nitrogen and phosphorus removal in this process.

• 한국물환경학회지
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• 제33권4호
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• pp.387-393
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• 2017

A chemical batch tests were conducted to evaluate if microwave heating enhances phosphorous release from waste activated sludge (WAS) at pH 2.5, 5, 7, 9 and 11. Polyphosphate-accumulating organisms have a unique physiological feature, which releases intracellular polyphosphate granules when they are exposed under high temperature environments. Microwave irradiation was found to encourage large amount of phosphorus release from WAS, depending on pH and temperature conditions. Most of phosphorus was released below $59^{\circ}C$ within 30 min. A marked increase in phosphorus release was observed under alkaline or acidic conditions. However, based on control tests for phosphorus release under different pH conditions without microwave heating, the largest amount of phosphorus released by microwave irradiation was found at pH 7, followed by 5, 9, 11. On the other hand, crystallization was conducted to obtain magnesium ammonium phosphate (MAP) from phosphate released by microwave heating at pH 7. X-ray diffraction analysis confirmed that the recovered crystalline materials were MAP. MAP is an environmentally friendly fertilizer, which slowly releases ammonia and phosphorus in response to the demand of plant root. Thus, the recovered MAP as a phosphate fertilizer is fully expected to play a important role in the reduction of agricultural non-point pollution.

• 대한환경공학회지
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• 제28권2호
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• pp.165-172
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• 2006

생물학적 인 제거공정에서 인 제거 효율에 따른 인제거관련 미생물을 포함하는 슬러지 미생물상의 변화를 분석하기 위하여 2개의 반응조(SBR)에 각기 다른 탄소원(초산나트륨, 포도당)을 주입하여 작동시켰다. 초산나트륨을 주입한 SBR1에서는 반응 100일 후, 유출수에서 $PO_4-P$가 3.92 mg/L 검출되었고(제거효율 60.8%) 이때의 미생물상은 ${\beta}$-subclass proteobacteria(39.67%)와 인제거미생물인 PAO(45.10%)가 우점하는 양상을 보인 반면, 포도당을 주입한 SBR 2에서는 $PO_4-P$가 8.3 mg/L 검출되었으며(제거효율 17%), ${\gamma}$-subclass proteobacteria(23.89%)가 우점하였고 PAO는 21.42%를 차지할 뿐이었다. DGGE결과에서도 ${\beta}$-subclass proteobacteria가 SBR1에서 우점하였다. 그러나 수온이 증가할수록 ${\beta}$-subclass proteobacteria and PAOs의 비율이 감소하였고 GAOs는 증가하였다. 그러므로 생물학적인 인제거공정에서 수온과 영양원의 상태 등 환경인자들이 인제거 미생물과 인제거를 저해하는 미생물의 우점도에 영향을 미친다고 할 수 있다.