• Biotechnology and Bioprocess Engineering:BBE
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• v.5 no.6
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• pp.469-474
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• 2000

In order to enhance the degradation efficiency of waste activated sludge (WAS) by thermophilic aerobic digestion, an ultrasonic pretreatment was examined. It was observed that ultrasonic pretreatment increased the solubilization of organic matter in the WAS and that the solubilization ratio of the organics increased during the first 30 min but did not extensively increase thereafter. Therefore, a pretreatment time of 30 min was determined to be the economical pretreatment time from the experimental results. From the digestion experiments, which was conducted using the WAS collected from an oil refinery plant in Inchon, Korea, investigating the effects of an ultrasonic pretreatment on thermophilic aerobic digestion, it was confirmed that the proposed ultrasonic pretreatment was effective at enhancing the release of the cellular components in WAS and the degradation of released components in the thermophilic aerobic digestion.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.4
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• pp.457-468
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• 2013

Based on the activated sludge model(ASM), a mathematical model which represents the aerobic sludge digestion by sequencing batch reactor(SBR) combined with ultrasonic treatment was composed and performed in this study. Aerobic digestion using sequencing batch reactor(SBR) equipped with ultrasound treatment was also experimented for the purpose of parameter calibration. Most of the presented kinetic parameters in ASM or ASM2 could be used for the aerobic digestion of sludge but the parameters related in hydrolysis and decay rate needed modification. Hydrolysis rate constant of organic matter in aerobic condition was estimated at $0.3day^{-1}$ and the maximum growth rate for autotrophs in aerobic condition was $0.618day^{-1}$. Solubilization reactions of particulate organics and nitrogen by ultrasonication was added in this kinetic model. The solubilization rate is considered to be proportional to the specific energy which is defined by specific ultrasound power and sonication time. The solubilization rate constant by ultrasonication was estimated at $0.202(W/L)^{-1}day^{-1}$ in this study. Autotrophs as well as heterotrophs also decomposed by ultrasonic treatment and the nitrification reaction was limited by the lack of autotrophs accumulation in the digester.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.4
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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.

• Journal of Energy Engineering
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• v.21 no.2
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• pp.194-201
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• 2012

In this research, a sewage sludge solubilization study using electrolysis was performed as a pre-treatment for anaerobic digestion efficiency improvement. SCOD potency increased as the treatment time and electric current density increased with sludge electrolysis treatment while SCOD, TN, and TP especially showed the highest increase of 7.4 times, 1.9 times, and 1.3 times respectively at the 60 minute point of treatment. Solubilization was high at the strong acidic and alkaline status for the sewage sludge electrolysis treatment results along early stage pH, and especially, a high solubilization percentage of 32.9% was seen at pH 12. The above result shows that there was an increase of organic matter able to be used by microorganisms from sludge floc and the destruction of EPS structure due to direct and indirect oxidation following electrolysis.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.35-45
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• 2017

In order to improve the anaerobic digestion efficiency of the sewage sludge, the methane potential of the hydrolysate generated from the hydro-thermal reaction at 170, 180, 190, 200, 210, $220^{\circ}C$ was analyzed and the constitutional characteristics of the organic materials were estimated by dividing organic materials of hydro-thermal hydrolysate into easily biodegradable, decomposition resistant, and non-biodegradable organic materials applying the parallel first order kinetics model. The ultimate methane potential of sewage sludge hydro-thermal hydrolysate increased to 0.39, 0.39, 0.40, 0.44, 0.45, and $0.46Nm^3/kg-VS_{added}$ as hydro-thermal reaction temperature increased from 170, 180, 190, 200, 210, $220^{\circ}C$. It has been shown that the organic matter of sewage sludge is solubilized to increase the content of biodegradable organic material($VS_B$). The easily degradable organic matter($VS_e$) content was highest at hydro-thermal reaction temperature of 200 and $210^{\circ}C$, and optimum hydro-thermal reaction temperature for organic matter solubilization of sewage sludge was in the range of $200{\sim}210^{\circ}C$. In addition, the amount of biodegradable organic material($VS_B$) and easily biodegradable organic matter ($VS_e$) in the hydrolysate of sewage sludge was the highest at hydro-thermal reaction temperature of $200^{\circ}C$.

• Journal of Dairy Science and Biotechnology
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• v.35 no.4
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• pp.244-248
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• 2017

The effects of ultrasonic (1.2~1.7 kJ/g TS) pretreatment on the solubilization of dairy and livestock sludge were separately evaluated to investigate the possibility of recycling dairy sludge as a potential source of organic carbon. Compared to other industrial wastewater and sewage sludge, dairy sludge has higher organic matter content and no toxic materials. The solubilization rates of dairy and livestock sludge, at a specific energy input of 1.7 kJ/g TS, were 14.5% and 10.6%, respectively. After the 90-minute ultrasonic treatment, the soluble COD (chemical oxygen demand) increased about 7.1 times that of the initial SCOD, at an increase rate of $0.022m^{-1}$. In comparison, the increase in soluble nitrogen, which was ~3.4 times that of the initial soluble nitrogen concentration, was much smaller than the increase in SCOD; thus, the C/N ratio increased from 4.0 to 8.7.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.348-353
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• 2008

With the aim to explore the possible role of phosphate-solubilizing bacteria in soil, we conducted a survey of phosphate-solubilizing microorganisms colonizing in upland and plastic film house soils. Soil EC, pH, organic matter, available phosphate, exchangeable cation such as potassium, calcium and magnesium, and total P of plastic film house soils were higher than those of upland soils. Phosphate-solubilizing bacteria population was higher in plastic film house soils than upland soils, but species of phosphate-solubilizing bacteria was more diverse in the upland soils than the plastic film house soils. There was significant positive correlation between phosphate solubilization and phosphate-solubilizing bacteria in soils. Bacillus, Cedecea, Brevibacillus, Paenibacillus, Pseudomonas, Serratia spp. were isolated from upland soils and Bacillus and Cellulomonas spp. were from plastic film house soils.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.113-119
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• 2011

The study purpose was to examine an effect of zero emission of excess sludge on biological reactor and treated water quality within the biological reactor in the process of biological treatment combined with excess sludge reduction system with ozone. Under an ozone injection rate 0.03 g $O_3/g$ SS, Sludge Disintegration Number (SDN) 3 and less than pH 4 as pre-treatment process, it was possible to maintain a stable biological treatment process without sludge disintegration. In the test of $OUR_{max}$, of sludge, its value was hardly under the condition of ozone injection rate 0.03 g $O_3/g$ SS. There were almost no changes of MLVSS/MLSS within biological reactor followed by a solubilization of excess sludge. Accumulation of microorganism within biological reactor was also not observed. After solubilization of excess sludge, an increase for organic matter and SS concentrations of an effluent was not observed and T-N concentration was reduced by increasing nitrification and denitrification rate within biological reactor. Most of T-P was not removed by zero emission of excess sludge and was leaked by being included in effluents.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.31-36
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• 2011

BACKGROUND: Disposal of slurry animal manure produced by an anaerobic slurry-type barn method is not easy since the animal slurry contain high moisture content which makes solid-liquid separation a difficult process. However, recently, the interest about anaerobic digestion process as an environment-friendly waste disposal method has gained a wide interest because it can treat highly organic matter contained by the piggery slurry, decrease the odor after treatment, and enable the effective recovery of the methane gas which is a valuable energy resource. The objectives of this study were to identify the solubilization characteristics and to improve the anaerobic digestion efficiency of piggery slurry through full-scale anaerobic digestion experiments. METHODS AND RESULTS: In a full-scale continuous anaerobic digestion operation, the adaptability of single anaerobic digestion and its digestion efficiency were also evaluated in the farm field. The actual pH range and alkalinity concentration of piggery slurry used during the operation were comparatively higher than the concentrations of pH and alkalinity in the digestion tank which were stable at 7.5~8.0, 4,008 mg/L (as$CaCO_3$), respectively. The removal efficiency of organic matter (TCOD) by anaerobic digestion was 75~90% and methane gas production amount was at 0.33 L/L/day, a little higher than that of ordinary animal manure. CONCLUSION(s): Our findings showed higher recovery of highly purified methane and greater efficiency of anaerobic tank digestion since its methane gas content was at 65~70%.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.7
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• pp.1049-1053
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• 1999

Chopped wheat straw (0.5-1.5 cm) was subjected to different treatment combinations in a $5{\times}4$ factorial arrangement involving the five levels of urea (0, 2, 3, 4 and 5%, w/w) and four levels of lime (0, 2, 4 and 6%, w/w) at 50% moisture and kept for 3 wk reaction period at about $35{^{\circ}C}$ in laboratory. Treated wheat straw samples were analyzed to study the associative effect of urea and lime on chemical composition, in sacco and in vitro digestibilities. Results showed that cell wall constituents (CWC) solubilized significantly (p<0.01) due to urea and lime treatment on one hand and substantially increase the crude protein (CP) on the other in wheat straw. The main effect on synergism of both chemicals was noticed on organic matter (OM), neutral detergent fibre (NDF), hemicellulose (HC), acid detergent lignin (ADL) and silica by solubilising their contents as a result of considerable increase in cell contents in treated wheat straw. The respective decreases were 5.45, 13.0, 37.23, 44.95 and 26.16% in different treatment combinations. The most interesting feature of the treatment was evident by increase in ash content on each level of lime application. CP content increase up to 12.78% due to urea treatment in comparison with untreated wheat straw (2.56%). The effect of solubilization of structural carbohydrates and increased crude protein due to synergistic effect of urea and lime were clearly seen on improved digestibility of OM and DM. The increase in ISOMD, ISDMD, and IVDMD were 21.67, 21.67, 16.24, and 17.5 units. The increase in digestibility were relative to additions of both chemicals and digestibility values increased with increasing levels of urea plus lime concentration in different treatment combination. The maximum improvement was noticed at 4% urea and 4% lime levels at 50% moisture for 3 wk reaction period in treated wheat straw.