• 대한환경공학회지
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• 제33권9호
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• pp.636-643
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• 2011

초음파를 사용한 슬러지 가용화는 슬러지 부피 감소 및 혐기성 바이오가스 생산시의 소화효율 강화를 위해 그 이용이 증가하고 있다. 본 연구에서는 세 종류의 슬러지(G 하수처리장의 반송슬러지, 잉여슬러지와 혼합슬러지)를 대상으로 가장 효율적인 가용화를 위해 전기장단독처리와 초음파단독처리 및 전기장-초음파 복합처리를 연구하였다. 폐쇄된 회로로서, 평균 $0.7m^3/h$의 유량으로 200 L의 슬러지(이는 1시간당 3.5회 처리에 해당)를 24시간 동안 84회까지 연속적으로 가용화 공정을 통과시켰다. 전기장만 단독으로 적용하였을 때의 경우 슬러지 종류와 관계없이, 처리 전과 후에 어떤 sCOD/tCOD 변화도 발생하지 않았다. 그러나 초음파 단독 또는 복합된 공정을 이용한 경우 통과횟수에 따라 두 방법 모두 슬러지 가용화율이 증가하였고 복합된 경우 더 크게 증가하였다. 또한, 입자의 직경(0.9)과 직경(0.5)이 원 슬러지보다 감소하는 동시에 VSS/TSS는 2~6% 범위까지 감소하였다. 잉여슬러지와 혼합슬러지에는 전기장 및 초음파 복합처리가 더 적합했던 것에 비해 반송슬러지는 초음파 처리가 더 가용화를 효과적으로 촉진하였다. 가장 효율적인 슬러지 파괴를 위해서는 슬러지 종류에 따라 가용화 공정이 선택적으로 적용되어져야 할 것으로 판단할 수 있었다.

• 한국토양비료학회지
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• 제45권3호
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• pp.428-434
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• 2012

A fungal strain, capable of solubilizing insoluble phosphate under diverse temperature, pH and salt conditions was isolated from Waste Mushroom bed of Agaricus bisporus in South Korea. Based on 18S rRNA analysis, the strain was identified as Aspergillus awamori bxq33110. The strain showed maximum phosphate solubilization in AYG medium (525 ${\mu}g\;mL^{-1}$) followed by NBRIP medium (515 ${\mu}g\;mL^{-1}$). The strain solubilized $Ca_3(PO_4)_2$ to a greater extent and rock phosphate and $FePO_4$ to a certain extent. However $AlPO_4$ solubilizing ability of the strain was found to be very low. Glucose at the rate of 2% ($561{\mu}g\;mL^{-1}$) was found be the best carbon source for Aspergillus awamori bxq33110 to solubilize maximum amount of phosphate. However, no significant difference ($P{\leq}0.05$) in phosphorus solubilization was found between 1% and 2% glucose concentrations. $(NH_4)_2SO_4$ was the best nitrogen source for Aspergillus awamori bxq33110 followed by $NH_4Cl$ and $NH_4NO_3$. At pH 7, temperature $30^{\circ}C$ and 5% salt concentration (674 ${\mu}g\;mL^{-1}$) were found to be the optimal conditions for insoluble phosphate solubilization. However, strain Aspergillus awamori bxq33110 was shown to have the ability to solublize phosphate under different stress conditions at $30-40^{\circ}C$ temperature, pH 7-10 and 0-10% salt concentrations indicating it's potential to be used as bio-inoculants in different environmental conditions.

• 한국토양비료학회지
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• 제46권6호
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• pp.494-501
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• 2013

Two phosphate solubilizing Pantoea strains (P. agglomerans and P. rodasii) were employed in elucidating their phosphate solubilizing potential under different carbon and nitrogen sources, pH, temperature and salt conditions. Plant growth promoting characteristics such as ACC deaminase activity, indole acetic acid (IAA), HCN, ammonia, and siderophore production of the two strains were assessed in vitro. Potential applicability of the strains as bio-inoculants was also evaluated in pot experiments conducted under green house conditions. Phosphate solubilization measured as the amount of phosphorous released into the medium was recorded as 810 and $788{\mu}g\;ml^{-1}$ respectively by P. agglomerans and P. rodasii. Glucose at the rate of 2% was found be the best carbon source, while $(NH_4)_2SO_4$ was the best nitrogen source for both strains. Despite a slight decrease in phosphate solubilization observed at higher temperature, pH and salt concentrations, both strains could withstand against a range of temperature ($30-35^{\circ}C$), pH (7-9) and the presence of NaCl (up to 5%) without much compromising the phosphate solubilization. Different plant growth promoting traits (ACC deaminase activity, IAA, HCN, ammonia, and siderophore production) of the strains and their ability to promote the growth of green gram seedlings indicate that both strains possess high potential to be used as bio-inoculants.

• 상하수도학회지
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• 제28권1호
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• pp.25-32
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• 2014

In order to investigate the effective pretreatment methods in WAS(=waste activated sludge) solubilization, the values of SCOD yield per unit SS (SCOD/gSS.hr) were compared. After the hydrodynamic cavitation with pH of 12.5, SCOD increased to 7800 mg/L, SS decreased to 45 % and the solubilization rate was 29 %. Combination of alkality (pH 12.5) and the cavitation seems to be the optimal condition for sludge solubilization. After the cavitational pretreatment, efficiencies of anaerobic digestion of the unfiltered sludge(the control), raw sludge and pretreated sludge were evaluated with BMP(=biochemical methane potential) tests. For evaluation of the biodegradability characteristics of pretreated sewage sludge, the methane production has been measured for 6 months. The methane production of pretreated sludge increased 1.4 times than that of untreated sludge. The result indicates that the cavitationally pretreated sludge was a better biodegradability substrate in anaerobic condition compared to raw sludge. It is obvious that cavitational pretreatment could enhance not only solubilization but also biodegradability of WAS. In conclusion, cavitational pretreatment of WAS to convert the particulate into soluble portion was shown to be effective in enhancing the digestibility of the WAS.

• Journal of Pharmaceutical Investigation
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• 제29권3호
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• pp.205-210
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• 1999

To formulate the parenteral delivery of a new cephalosporin derivative, 7-${\beta}$-[(2)-2-(2-arninothiazol-4-yl)-2methoxyiminoacetamido]- 3- [(2,3-cyclopenteno-4-carbamoyl-l-pyridinium)methyl]- 3-cephem-4-carboxylate sulfate( CKD604), the stability and solubility of CKD-604 in various aqueous media were investigated. The degradation kinetics of CKD-604 in aqueous solutions (ionic strength 0.1, pH 1-8) were studied at $37^{\circ}C$. The observed degradation rates followed pseudo first order kinetics. The pH-rate profile exhibited a minimum degradation rate at pH 5. The Arrhenius activation energy was 14.2 kcal/mol in pH 5 buffer solution. Excellent agreement between the cephalosporins' theoretical pH-rate profile and the experimental data indicated that the degradation pathway of CKD-604 could be predicted according to the general pathway of cephalosporins. The solubility of CKD-604 was 8.16 mg/ml at $25^{\circ}C$. To enhance the solubility and adjust the suitable pH, CKD-604 was solubilized by using sodium ascorbate, ascorbic acid and urea. The compositions were obtained to satisfy optimum pH and concentration, and the total amount of additives was several times of the active ingredient, CKD-604.

• Asian-Australasian Journal of Animal Sciences
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• 제9권1호
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• pp.75-81
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• 1996

The dry matter (DM) disappearance and ruminal solubility of calcium (Ca), phosphorus (P), magnesium (Mg) and potassium (K) in eight Philippine forages were studied. The forages were: paragrass (Brachiaria mutica (Forsk.) Stapf), stargrass (Cynodon plectostachyum Pilger), napiergrass (Pennisetum purpureum Schumach), clopo (Calopogonium mucconoides Desv.), centrocema (Centrocema pubescens Benth.), gliricidia (Gliricidia sepium (Jacq.) Walp.), leucaena (Leucaena leucocephala (Lam.) de Wit.) and sesbania (Sesbania grandiflora (L.) Poir. Nylon bags with samples were incubated for 0, 3, 6, 12, 24, 48 and 72 h in rumen cannulated sheep. The 0-h bags were washed with deionized water. For the 0-h samples, 20.4, 17.2, 50.7, 52.2 and 80.1% of the DM, Ca, P, Mg and K was solubilized, respectively. At 3-h incubation period, DM disappearance was 10 percentage units higher than that of 0-h incubation whereas mineral disappearance increased by 43, 21, 30 and 13% for Ca, P, Mg and K, respectively. At 72-h incubation period, greater proportion of DM, Ca, especially in P, Mg and K was solubilized with a value of 73.8, 71.5, 85.6, 91.4 and 98.2%, respectively. The average particulate passage rate obtained in the present study was 1.9%/h where as the range of disappearance rates of various mineral elements were : 0.4 to 1.2%/h for Ca, 0.1 to 1.6%/h for P, 0.7 to 2%/h for Mg and 0.1 to 2%/h for K. The effective ruminal solubilization (ERS) of the macrominerals was calculated where particulate passage rate and disappearance rate of the various elements were included in the equation. The ERS of Ca, P, Mg and K was 50.0, 72.6, 83.9 and 94.5%, respectively. Species differences (p<0.05) on the various mineral solubilities were also observed. This study shows that ruminal solubility of macrominerals in selected Philippine forages is K > Mg > P > Ca.

• 유기물자원화
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• 제30권4호
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• pp.5-13
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• 2022

현대의 환경문제는 다량의 폐기물의 발생과 무분별한 에너지의 소비로 인한 환경오염이 가속화 되고 있다는 것이다. 대표적인 에너지 생산 연료인 화석연료는 에너지를 생산하는 과정에서 연소가 이루어져 다량의 온실가스가 발생하고 최종적으로 기후변화를 야기한다. 또한 전 세계적으로 발생하는 폐기물의 양도 지속적으로 증가하고 있으며 처리하는 과정에서 환경오염이 발생하고 있다. 이와 같은 문제들을 동시에 해결하기 위한 방법 중 하나는 유기성 폐기물의 에너지화 및 감량화이다. 하수처리장에서 발생하는 하수슬러지는 해양매립이 전면 금지된 이후로 다양하게 처리되고 있으나, 그 발생량은 지속적으로 증가하는 추세이다. 하수슬러지는 유기물을 다량 함유하고 있어 혐기소화를 통하여 하수슬러지를 에너지화 하고 최종 배출되는 폐기물을 감량화 하는 것이 바람직하다. 하지만, 잉여슬러지의 경우 대부분이 하수처리에 이용되었던 미생물 덩어리로써 잉여슬러지가 혐기성소화 되기 위해서는 먼저 미생물의 세포벽이 파괴되어야 하는데 세포벽 파괴에는 많은 시간이 요구되기 때문에 혐기성 소화 과정만으로는 높은 바이오가스 생산율이나 폐기물 감량율을 달성할 수 없다. 따라서 잉여슬러지를 가용화하는 전처리 공정이 필요하며, 여러 가지 가용화 공법 중에서 열적 가용화 공정이 가장 효율적인 것으로 검증되었고, 혐기성소화 공정의 전처리 과정으로써 열적가용화 공정을 이용하여 잉여슬러지에 포함된 세포벽을 파괴한 후 전처리 된 잉여슬러지를 혐기성소화 함으로써 높은 바이오가스 생산율과 폐기물 감량율을 달성할 수 있다. 본 연구에서는 열적 가용화장치를 통하여 TS 10%의 농축 잉여슬러지를 전처리하는데 있어서 체류시간 및 운전온도 변수에 따른 가용화 특성에 대한 연구를 수행하였다. 열적 가용화장치의 체류시간에 대한 실험변수는 운전온도를 160 ℃로 고정한 상태에서 각각 30분, 60분, 90분, 120분이었다. 실험 결과로 도출된 TCOD와 SCOD를 통해 계산된 가용화율은 각각 12.11%, 20.52%, 28.62%, 31.40% 순으로 증가하였다. 또한, 운전온도에 따른 변수는 반응시간을 60분으로 고정한 상태에서 각각 120℃, 140℃, 160℃, 180℃, 200℃였으며 가용화율은 각각 7.14%, 14.52%, 20.52%, 40.72%, 57.85% 순으로 증가하였다. 이 외에 TS, VS, T-N, T-P, NH₄⁺-N, VFAs를 분석하여 농축 잉여슬러지를 대상으로 하는 열적 가용화 특성에 대한 평가를 수행 했으며, 그 결과 TS 10%의 농축 잉여슬러지에 대한 열적 가용화를 통하여 30% 이상의 가용화율을 얻기 위해서는 운전온도를 160℃로 고정할 경우 120분의 체류시간이 필요하며, 운전시간을 60분으로 고정할 경우 170℃ 이상의 운전온도가 요구되어 진다.

• 한국토양비료학회지
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• 제47권2호
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• pp.127-132
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• 2014

The effect of thermal pretreatment conditions on hydrolysis characteristics of dairy manure and sawdust mixtures has been evaluated. Thermal pretreatment temperature varied between 35 and $120^{\circ}C$ and the period of the treatment changed between 30 and 1440min (24h). As thermal pretreatment temperature and duration increased, organic material solublization rates were improved. Maximum solubilizations of chemical oxygen demand (SCOD), carbohydrates, and volatile fatty acids(VFAs) were observed when dairy manure treated for one day at $120^{\circ}C$. Although one day treatment duration at $120^{\circ}C$ showed the highest SCOD, soluble carbohydrates, and VFAs concentration, its hydrolysis rate was only about 12%. The results reveal that the thermal pretreatment conditions tried in this study are not enough to solubilize the organic matter contained in dairy manure and sawdust mixtures. In order to maximize hydrolysis performance, the further research needs to determine the factors influences on organic material solubilization in addition to thermal pretreatment temperature and duration.

• 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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• 제22권4호
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• pp.449-454
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• 2008

Some pretreatment methods have been proposed to enhance the biodegradability and to shorten the hydrolysis reaction time. By means of efficient pretreatment the suspended solids (SS) can be made of better accessible for the anaerobic bacteria. There are several ways how this can be accomplished, which include biological, mechanical, thermal, and chemical methods. For the sludge solubilization using the cavitation phenomenon, we have tried to develop a pretreatment process consisted of a reactor and pumps. The objectives of this study were to develop a advanced wastewater treatment consisted of IABR and the cavitation with PGA. The most effective removal for organic matter and nutrients were occured when both cavitation pretreatment and ${\gamma}$-PGA were applied at the IABR process. Only small portion of ${\gamma}$-PGA at a rate of 1.38mg/L, was enough to improve sedimentation ability, SS removal efficiencies, and sludge volume reduction. After the sludge solubilization by the cavitation, SCOD increased to 193% and SS decreased to 36%. The removal ratio of BOD was 94.5%, T-N removal ratio was 85.5% and T-P removal ratio was 84.9%. The combination process of the IABR with the cavitation and PGA addition seems to be very effective alternative wastewater treatment process.