• Journal of the Korean GEO-environmental Society
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• v.15 no.10
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• pp.15-21
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• 2014

In this study, biochemical methane potential test was conducted to estimate ultimate methane and carbon dioxide yield for anaerobic digestion and pretreatment with sewage sludge cake. Two of 0.2 % TS of sewage sludge cakes were treated with 5M NaOH or sonication of 0.51 W/mL during 30 min respectively. Another sample was treated simultaneously with NaOH and sonication in same condition. Then, initial soluble COD increased from 33.1 mg/L to 494 mg/L. After BMP test, methane production ranged from 3.12 and 84.2 mL $CH_4$ per g of Volatile Solid (VS) and 9.2 and 13.5 mL $CO_2$ per g of Volatile Solid (VS) for carbon dioxide. In other tests, injection of nutrient media or sludge supernatant produced 73.1 and 73.8 mL $CH_4$ per g of Volatile Solid (VS) and 11.2 and 13.6 mL $CO_2$ per g of Volatile Solid (VS) respectively. When BMP test finished, 62 % of initial volatile solids decreased to 33.8~45.4 %. Simultaneous pretreatment increased soluble COD, reduction rate of volatile solids and digestion efficiency than those for alkaline and ultrasonic pretreatment.

• Proceedings of KOSOMES biannual meeting
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• 2007.11a
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• pp.97-102
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• 2007

The piggery wastewater is the major source of the water pollution problem in the rural area. The treatment alternatives for piggery wastewater are limited by the characteristics of both high organic and nitrogen(N) content. In order to investigate an efficient N removal system, the thermophilic aerobic digestion process was examined. The experiment was investigated organic and nitrogen removal efficiency at various HRTs and air supply volume. The results of semi-continuous experiment indicated that a higher removal of the soluble portion of COD was achieved with the longer HRTs. However, the inert portion of COD in piggery wastewater was not much changed by thermophilic aerobic digestion. In addition, with the higher HRT of 3 days, up to 79% of NH4-N removal efficiency was achieved. Lower the HRTs, a decrease of NH4-N removal was founds. The gas samples from the lab reactor were analyzed along with the N content in influent and effluent. The N2O formation in our system indicates a novel aerobic deammonification process occurred during the thermophilic aerobic digestion. Both N02 and N03 were not presented in the effluent of thermophilic aerobic digester. With the HRT of 3 days, 36.4% of influent N(or 57.5% removal N) was aerobically converted to N2O gas. The ammonium conversion to N2O gas significantly decrease to 4.5% at low HRT of .05 day..

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1231-1238
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• 2008

This study was performed to evaluate the treatability of food waste leachate using lab-scale two-phase anaerobic digestion system. Effects of influent pH, hydraulic retention time (HRT), and recycle of methanogenic reactor effluent to the thermophilic acidogenic reactors were investigated. For methanogenic reactors, effects of internal solids recycle and temperature were studied. Performance of the acidogenic reactors was stable under the conditions of influent pH of 6.0 and HRT of 2 d with the recycle of methanogenic reactor effluent, and acidification and VS removal efficiency were about 30% and 40%, respectively. Up to the organic loading rate (OLR) of 7 g COD/L/d, effluent SCOD values of mesophilic and thermophilic methanogenic reactors either lower or kept the same with the internal solids recycle. Also, decreasing tendency in specific methane production (SMP) due to the organic loading increase became diminished with the internal solids recycle. Mesophilic methanogenic reactors showed higher TCOD removal efficiency and SMP than thermophilic condition under the same OLR as VSS was always higher under mesophilic condition. In sum, thermophilic acidogenesis-mesophilic methanogenesis system was found to be better than thermophilic-thermophilic system in terms of both organic removal and methane production.

• Journal of the Korea Organic Resources Recycling Association
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• v.9 no.1
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• pp.90-98
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• 2001

The slow degradation rate of sewage sludge in anaerobic digesters is due to the rate limiting step of sludge hydrolysis. Therefore, the pre-treatment process had been carried out using acidic(pH 1.5, 3, 4, 5) and alkaline(pH9, 10, 13), thermal(50, 100, 150, $200^{\circ}C$) and ultrasonic treatment(400W, 20kHz, 15, 20, 25, 30, 35, 40, 50, 60min). In the best conditions of each treatment, the SCOD ratio(%) of treated/untreared samples were increased 102% in acid(pH5), 986% in alkali(pH13), 959% in thermal($200^{\circ}C$) and 1123% in ultrasonic(35min) treatment. As the result, the ultrasonic treatment was most effective, followed by alkali, thermal, acidic treatment. In the effects of total gas productivity, the thermal($200^{\circ}C$) pretreatment was the highest, followed by thermal($150^{\circ}C$), ultrasonic(90min), alkaline(pH9) and ultrasonic(50min).

• Journal of Animal Environmental Science
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• v.19 no.2
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• pp.81-88
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• 2013

We planned to study how the chemical disposal designed by SOP can affect on physicochemical compositions of the livestock excrement. According to Livestock Manure Management Scheme, we experimented in two steps; the first step, NaOH treatment-Citric acid neutralization, and then the second procedure, Thermophilic Aerobic Oxidation (TAO) system. Physicochemical compositions of the 3-days-old samples after NaOH treatment were pH 10.31, EC 24.54 mS/cm, SCOD 3,022 mg/L, T-N 4,315 mg/L, $NH{_4}^+-N$ 1,960 mg/L, and not detected E. coli.. And those of one-day-old samples after citric acid neutralization were pH 7.36, EC 32.89 mS/cm, $SCOD_{Mn}$ 12,733 mg/L, T-N 4,787 mg/L, $NH{_4}^+-N$ 2,450 mg/L, and E. coli. not detected. In contrast, the physicochemical compositions of the treatment plots after the second treatment with TAO system (72hr) were pH 9.42 EC 24.21 mS/cm, $SCOD_{Mn}$ 3,660 mg/L, T-N 3,616 mg/L, $NH{_4}^+-N$ 1,190 mg/L, and no detection of E. coli.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.2
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• pp.90-95
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• 2009

Sludge pre-treatment utilizing cavitation is one of the commercialized methods at present. Cavitation can be generated by two different methods, sonotrode and hydrodynamic principle, and there has been no direct comparison between the two methods. In this study, solubilization efficiency, changes in sludge size distribution, and the methane production potential after pre-treatment by the two methods were compared. The maximum solubilization efficiency per unit energy input with the two methods was similar, and was 302 mg ${\Delta}SCOD/g$ TS at the energy input of 0.18 kWh/L. Break-up of sludge flocs were dominant during the early period of pre-treatment, while cell disintegration continued through the pre-treatment with the increase in the number of particles with less than 1 ${\mu}m$. BMP test results indicated that the methane potential increased up to 24.3% without differences between the two pre-treatments, and the increase in methane potential did not proportional to energy input. Although the energy efficiency of the two methods was quite similar, hydrodynamic methods might be a better choice for field application considering the operation and maintenance cost, and its potential improvement in energy efficiency.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.10
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• pp.558-562
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• 2015

This study was tested to evaluate the effect of the six different combinations of microbubble, catalyst, and air as oxidant on the sludge and organic matter reduction. When all of microbubbles and catalyst, and an oxidizing agent (under Conditions 1) such as air were used, the sludge was removed more than 99%, and TCOD and SCOD removal was 58% and 13%, respectively. This result was the highest value of six conditions. In the following order, the sludge reduction of the microbubbles with air (Condition 2) and catalyst with air (condition 4) was 95% and 93.1%, respectively. TCOD removal was found to be each 53% and 47%. When the microbubbles were used with oxidant like air, the removal of sludge and organic matter was high. All of these values were higher than that of using only microbubbles and catalyst without air. In the microbubbles and catalyst react under air supply condition, OH-radicals were generated in the reaction process. These OH-radicals in the reaction process decomposed the pollutants by the strong oxidizing power. In all conditions with air, the sludge reduction was high removal rate more than 93% and TCOD removal was over 47%.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.10
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• pp.578-582
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• 2015

It was investigated whether the removal of nitrogen ions included livestock wastewater were increased by increasing the reaction time of livestock wastewater and microbubbles with catalyst. For this study, the nitrogen reduction system using microbubbles with catalyst was used. The two reactors were consecutively arranged, and the second reactor (Step 2) was located to next the first reactor (Step 1). Each reactor was reacted for 2 hours and air or oxygen as oxidant was fed into the reactor during operation before microbubble device. When oxygen was used, ammonia nitrogen was removed each 18.3% and 52.8% during 2 (only step 1) and 4 (step 1 and step 2) hours reactions. This value was higher than that of when air was fed. When oxygen was used, the longer the reaction time, the ammonia nitrogen removal was higher. The longer the reaction time, the higher the nitrite and nitrate was also removed such as ammonia nitrogen. Also this system was examined whether organic matter removal is effective. The total chemical oxygen demand (TCOD) removal was higher than the soluble chemical oxygen demand (SCOD). Some materials among causing substances COD were difficult to decompose biologically. Therefore, it means that it will be easy to operate the biological processes following step and reduce the concentration of organic contaminants in effluent.

• Resources Recycling
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• v.24 no.2
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• pp.46-54
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• 2015

In this study, an applicability of thermal pretreatment for primary and secondary sludge, which are generated in a sewage treatment plant, was evaluated. The efficiency and charateristics was investigated with each sludge after pretreatment under the condition of $100{\sim}220^{\circ}C$ for 30 minutes. As the result, it was found that $SCOD_{Cr}$, $NH_4{^+}$, VFAs concentrations increased as the pre-treatment temperature increased. For COD solubilization, it was also highly dependent on an increase of temperature resulting in acceleration on hydrolysis and acid fermentation. In the BMP (Biochemical Methane Potential) experiment, for the primary sludge, it showed the higher biogas production rate at a temperature of $220^{\circ}C$, however, the effect was insignificant (5.6%). Whereas, for the secondary sludge, the increase on biogass production rate was 38.8% ($180^{\circ}C$) and this means that the secondary sludge is more suitable for an applicability of thermal pretreatment.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.121-132
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• 2000

This study is to investigate the performance of a new BNR process using predenitrification scheme focusing on nitrogen removal and the possibility of adapting a computer simulation scheme in BNR process development. By using a pre-denitrification basin, higher $COD/NO_3-N$ ratio could be sustained in this BNR process. The results of the investigation showed a SDNR value of 9.04mg/gMv/hr. In the anoxic tank, the average value of SPRR of 6.25mgP/gMv/hr was observed to be very sensitive to SCOD load of influents. By calibrating internal parameters (stoichiometric and kinetic parameters) of the simulation model, the results of simulation for various BNR processes gave good agreement with observed data. The major adjustment was given with three parameters, maximum specific growth rate of heterotrophic biomass, short chain fatty acid (SCFA) limit, and phosphorous release rate. With the series of simulations on varying operational conditions, the simulation by computer program can be a useful tool for process selection, and design and operation of municipal wastewater treatment plant.