• Environmental Engineering Research
• /
• v.12 no.1
• /
• pp.8-15
• /
• 2007

Two phase UASB reactors for treating wastewater with sulfate were operated to assess the performance and competition of organics between sulfate reducing bacteria(SRB) and methane producing bacteria(MPB), and the change of characteristics of microorganisms. The reactors were fed in parallel with a synthetic wastewater of 4,000-5,000 mgCOD/L and sulfate concentration of $800-1,000\;mgSO_4/L$. In the MPR(methane producing reactor) and CR(control reactor), COD removal efficiencies were 90% and 60%, respectively, at the OLR(organic loading rate) of 6 gCOD/L, while the amount of biogas and methane content were 6.5 L/day and 80%, and 3 L/day and 50%, respectively. However, the portion of electron flow used by SRB at the OLR of 6 gCOD/L day in MPR and CR was 3% and 26%, respectively. This indicated that the increase of OLR of wastewater containing high sulfate like CR resulted in activity decrease and cell decay of MPB, while SRB was adapted immediately to new environment. The MPB activities in MPR and CR were 2 and $0.38\;kgCH_4-COD$/gVSS day at the OLR of 6 gCOD/L. This indicated hat SRB dominated gradually over MPB during long-term operation with wastewater containing sulfate as a consequence of outcompeting of SRB over MPB. In addition, the solution within AFR was maintained around pH 5.0, the MPB such as Methanothrix spp. which was very important to formation of granules was detached from the surface of granules due to the decrease of activity by limitation of substrate transportation into MPB. Therefore, a significant amount of sludge was washed out from the reactor.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.4 no.1
• /
• pp.13-21
• /
• 1996

For treating tannery wastewater containing high sulfate and heavy metals, test was performed to assess their performance, competition between SRB (sulfate reducing bacteria) and MPB (methane producing bacteria), and the activity of MPB according to change of chromium concentrations. COD removal efficiency was above 70% at VLR (volumetric loading rate) of 2.0 gCOD/I.day and HRT (hydraulic retention time) of 18hrs at $35^{\circ}C$. In the competition between SRB and MPB, about 15% of the removed COD was utilized by SRB in the begining, but it became 43% at the end. It indicated that MPB was strongly suppressed by the occurrence of significant sulfate reduction since a large electron flow was uptaken by SRB. For the entire experiment, removal efficiencies of chromium concentration were more than 90%. Despite high removal efficiencies of chromium concentration, performance of reactor did not change significantly during the experimental periods. Expecially, chromium (III) is tannery wastewater is less toxic than chromium (VI).

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.10
• /
• pp.865-872
• /
• 2009

Continuous operation of aerobic sludge digestion reactor was attempted for 279 days. Anaerobic digester sludge, the target material of the experiment, was pretreated by sodium hydroxide at $40^{\circ}C$ for 120 minutes, and the pretreated sludge was fed to 5 L CSTR (continuous stirred tank reactor). Reactor performance was affected by properties of input sludge and HRT (hydraulic retention time). 6 days of HRT showed best and stable performance, and under this condition, removal rates of $NH_3$-N, SCOD, TKN, TCOD, SS, and VSS were 97.4%, 81.7%, 68.7%, 61.4%, 50.6%, and 47.0%, respectively. 73.9% of SS in anaerobic digester sludge was reduced by pretreatment and aerobic digestion. Effluent sludge had low soluble COD of 350 mg/L. This implied the sludge was stabilized and suitable for use as liquid fertilizer. Nitrification took place when HRT was higher than 4 days. $NO_3$-N concentration was as high as 658 mg/L while $NH_3$-N was as low as 20 mg/L.

• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.4
• /
• pp.417-430
• /
• 2009

A BNR comprehensive performance evaluation (BNR CPE) system was established employing system-oriented evaluation methodology for biological nutrient removal (BNR) processes based on the CPE techniques developed by U.S. EPA for evaluation of conventional biological processes. The BNR CPE system applied to five domestic BNR plants adopting $A^2/O$ process confirmed that all target plants except the smallest one had not any serious defective performance and process stability was enhanced with increasing plant size. The system also clearly verified relatively poor performances in anoxic reactors without exception mainly due to influent carbon limit rather than functional defect. Consistent good performances were confirmed even during both winter season and wet weather generally known to be difficult to achieve satisfactory removals. Presentation of evaluation results by modified radar chart system simplified and clarified the evaluation and analysis procedures. The BNR CPE system could not only discover readily the causes of present and prospective poor performances but also facilitate the suggestion of their optimization options. Mutual effect and cause-and-effect among operation parameters and unit processes were also found easily using the evaluation system. The system justified that the adverse effect of defective operating parameters could be compensated by other favorable parameters, especially in anaerobic and anoxic reactors as well as during the winter season.

• Journal of Sport and Applied Science
• /
• v.7 no.4
• /
• pp.13-18
• /
• 2023

Purpose: This study aims to determine what changes occur in body composition and performance by subjecting youth soccer players to weight training and combined training, which are known to be effective in improving anaerobic capacity, for 6 weeks. Research design, data, and methodology: This study was conducted on 30 high school soccer players from S City who had no current injuries or medical problems and had been registered as players with the Korea Football Association for more than 3 years. Subjects were divided into a weight training group (WTG, n=15) and a combined training group (CTG, n=15). Training lasted 6 weeks, and measurements were taken before and after training. Mean (M) and standard deviation (SD) were calculated to present the descriptive statistics of all dependent variables. Paired t-tests were used to test for within-group differences. Further, Independent t-tests were employed to test for between-group differences. Results: In terms of body composition, height significantly increased in WTG and CTG, and body fat percentage significantly decreased in CTG. As for performance, WTG's 20m sprint record decreased significantly. Conclusion: As a result, this study confirmed that weight training improved the 20m sprint ability of youth soccer players. Future research could provide more useful information by extending the study period and incorporating the physical characteristics of adolescents.

• KSBB Journal
• /
• v.23 no.1
• /
• pp.90-95
• /
• 2008

In this study, a combined process of sequential anaerobic-aerobic digestion (SAAD), fluidized-bed bioreactor (FBBR), and ultrafiltration (UF) for the treatment of small scale food waste leachate was developed and evaluated. The SAAD process was tested for performance and stability by subjecting leachate from food waste to a two-phase anaerobic digestion. The main process used FBBR composed of aerators for oxygen supply and fluidization, three 5 ton reaction chambers containing an aerobic mesophilic microorganism immobilized in PE (polyethylene), and a sedimentation chamber. The HRTs (hydraulic retention time) of the combined SAAD-FBBR-UF process were 30, 7, and 1 day, and the operation temperature was set to the optimal one for microbial growth. The pilot process maintained its performance even when the CODcr of input leachate fluctuated largely. During the operation, average CODcr, TKN, TP, and salt of the effluent were 1,207mg/L, 100mg/L, 50 mg/L, and 0.01 %, which corresponded to the removal efficiencies of 99.4%, 98.6%, 89.6%, and 98.5%, respectively. These results show that the developed process is able to manage high concentration leachate from food waste and remove CODcr, TKN, TP, and salt effectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2017.05a
• /
• pp.617-621
• /
• 2017

The performance characteristics of aluminized high explosive are considered by varying the aluminum(Al) concentration in a two-phase model. Since the time scales of the characteristic combustion process of high explosives and Al particles differ, the process of energy release behind the leading detonation wave front occurs over an extended period of time. Two cardinal observations are reported: a decrease in detonation velocity with an increase in Al concentration and a double front detonation (DFD) feature when anaerobic Al reaction occurs behind the front. In the current study, a series of confined rate sticks are considered for characterizing the performance of aluminized HMX with a maximum Al concentration of 50%. The simulated results are compared with the experimental data for 5%-25% concentrations.

• Journal of Korean Society of Water and Wastewater
• /
• v.28 no.2
• /
• pp.195-206
• /
• 2014

Immobilization of anaerobic ammonium oxidizing bacteria has been studied to enhance the biomass retention of the slowly growing bacteria and the process stability. The purpose of this study was to compare the nitrogen removal efficiency of granular and immobilized anammox bacteria with poly vinyl alcohol and alginate. The specific anammox activity of the granular, homoginized and immobilized anammox bacteria were $0.016{\pm}0.0002gN/gVSS/d$, $0.011{\pm}0.001gN/gVSS/d$ and $0.007{\pm}0.0005gN/gVSS/d$, respectively. Although the activity decreased to 43.7 % of the original one due to low pH and $O_2$ exposure during the homogination and the immobilization, it was rapidly recovered within 7 days in the following continuous culture. When synthetic T-N concentrations of 100, 200, 400, 800 mg/L were fed, the immobilized anammox bacteria showed higher nitrogen removal efficiencies at all operational conditions than those of granular anammox bacteria. When the sludge retention time was shorten below 30.7 days and the reject water was fed, the nitrite removal efficiency of the granular anammox bacteria dropped to 8 % of the initial value, while that of the immobilized anammox bacteria was maintained over 95 % of the initial one. The immobilization with poly vinyl alcohol and alginate would be a feasible method to improve the performance and stability of the anammox process.

• Environmental Engineering Research
• /
• v.22 no.4
• /
• pp.339-346
• /
• 2017

The objective of this study is the evaluation of the performance of a large-scale respirometer (LSR) of 17.7 L in the determination of the methane generation rate constant (k) values. To achieve this objective, a comparison between anaerobic (GB21) and LSR tests was conducted. The data were modeled using a linear function, and the resulting correlation coefficient ($R^2$) of the linear regression is 0.91. This result shows that despite the aerobic conditions, the biodegradability values that were obtained from the LSR test produced results that are similar to those from the GB21 test. In this respect, the LSR test can be an indicator of the anaerobic biodegradability for landfill waste. In addition, the results show the high repeatability of the tests with an average coefficient of variance (CV) that is lower than 10%; furthermore, the CV for the LSR is lower than that of the GB21, which indicates that the LSR-test method could provide a better representation of waste samples. Therefore, the LSR method allows for both the prediction of the long-term biodegradation potential in a shorter length of time and the reduction of the sampling errors that are caused by the heterogeneity of waste samples. The k values are $0.156y^{-1}$ and $0.127y^{-1}$ for the cumulative biogas production (GB21) and the cumulative oxygen uptake for the LSR, respectively.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.4
• /
• pp.269-275
• /
• 1993

The performance of Upflow Anaerobic Sludge Blanket(UASB) reactor for treatment of corn starch wastewater was investigated using continuous and batch experiment. Results showed that the corn starch wastewater had different characteristics in terms of biodegradability and methane potential, depending on the manufacturing precess. COD removal efficiencies were maintained over 70% up to the loading rate of 3.2 kg $COD/m^3{\cdot}day$ and the maximum gas production rate was about 55 l/day, equivalent to 3.5 l/day per liter of reactor volume, at the loading rate of 8.4 kg $COD/m^3{\cdot}day$. In the anaerobic serum bottle test(SBT) carried out along with continuous operation, the sludge activity was found to increase from 0.03 to 0.53 g $COD-CH_4/g\;VSS{\cdot}day$ as granular sludges were developed in 130 days operation. SBT gave valuable informations on the characteristics of wastewaters to be treated as well as on the sludge activity. The overall morphological characteristics of granular sludges cultivated on corn starch wastewaters were similar to those cultivated on various organic industrial wastewaters such as distillery and sugar.