• Journal of environmental and Sanitary engineering
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• v.16 no.1
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• pp.108-116
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• 2001

It is difficult to task to achieve high biological nutrient removal from municipal wastewater because of low organic content. Volatile fatty acids(VFAs) produced from acid fermentation of food wastes can be utilized as external carbon sources for the biological nutrient process. Significant reduction and stabilization of the food wastes can also be obtained from the acid fermentation. The objective of this study is to evaluate characteristics of acid fermentation of the food wastes. Results obtained from the batch experiment of various organic wastes showed that the food wastes had high potential to be used as an external carbon source because of the largest production of the VFAs with low nitrogen and phosphorus content. The fish waste was found to be the next possible organic waste, while the others such as radish cabbage and molasses waste showed high VFAs consumption potential as a results of high nitrogen and phosphorus content. alkaline hydrolysis of the food waste was carried out using NaOH prior to the acid fermentation. As the alkali addition increased, solubilization of the organics as well as TSS reduction increased. However, fraction of soluble COD to total COD became stable after a sharp increase. Alkali addition greater than 0.5g NaOH per g TS resulted in significant increase in pH.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.4
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• pp.11-20
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• 2015

In the present work, a basic study on the in-situ biogenic methane generation from low grade coal bed was conducted. Lignite from Indonesia was used as a sample feedstock. A series of BMP (Biochemical Methane Potential) tests were carried out under the different experimental conditions. Although nutrients and anaerobic digester sludge were added to the coal, the produced amount of methane was limited. Both temperature control and particle size reduction showed little effect on the increase of methane potential. When rice straw was added to lignite as an external carbon source, methane yield of 94.4~110.4 mL/g VS was obtained after 60 days of BMP test. The calorific value of lignite after BMP test decreased (4.5~12.1 %) as increasing the content of rice straw (12.5~50 wt % of lignite), implying that anaerobic digestion of rice straw led to partial degradation of lignite. Therefore, rice straw could be used as an external carbon source for the start-up of in-situ biogas generation from low grade coal bed.

• Journal of Korean Society on Water Environment
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• v.31 no.2
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• pp.151-158
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• 2015

The aim of this research is to derive an optimum operating condition for the thermal solubilization equipment that is employed to increase concentration of soluble organic materials and to assess whether it would be possible to use the waste sludge generated by thermal solubilization reaction as an external carbon source in biological denitrification process. For the purpose, we have constituted a laboratory-size thermal solubilization equipment and have assessed thermal hydrolysis efficiency based on various reaction temperature and reaction time. We have also derived SDNR using the waste sludge generated by thermal solubilization reaction through a batch experiment. As a result of research, the highest thermal hydrolysis efficiency of about 42.8% was achieved at $190^{\circ}C$ of reaction temperature and at 90 minutes of reaction time. And when SDNR was derived using the waste sludge, the value obtained was $0.080{\sim}0.094\;g\;NO_3{^-}-N/g\;MLVSS{\cdot}day$, showing SDNR that is higher than that obtained by the results of existing researches that used common wastewater as an external carbon source. Accordingly, in view of the fact that food wastes vary quite a bit in characteristics based on the area they are generated from and seasonal change, it seems that a flexible operation of thermal solubilization equipment is required through on-going monitoring of food wastes that are imported to food wastes recycling facilities.

• Journal of Korean Society on Water Environment
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• v.39 no.5
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• pp.390-395
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• 2023

The feasibility of applying the shortcut nitrogen removal process to treat livestock wastewater on individual farms was examined, and appropriate operating parameters were established. As a result,, it was determined that the nitrification reaction was carried out under 550 mg/L of ammonium nitrogen concentration, but it was less effective under conditions of high ammonia concentration. Consequently, it was confirmed that a partial injection of inflow water was necessary to minimize the effects of ammonia toxicity. Following the sequential batch reactor (SBR) operation results, it was difficult to achieve the effluent quality standard without an external carbon source. Also, selection of the appropriate hydraulic retention time was critical for the optimal SBR operation. Following the livestock farm application, with external carbon source injecting, the total nitrogen concentration in the effluent was 85.1 mg/L. This result revealed that the standard could be accomplished through a single treatment on individual livestock farms. The ratio of nitrite nitrogen to ammonia nitrogen in the effluent was verified to be suitable for implementing the anammox process with a 10 days of hydraulic retention time. This study demonstrated the potential applicability of process in the future. However, in order to apply to livestock farms, managing variations in wastewater load across individual farms and addressing reduced nitrogen oxidation efficiency during the winter season are crucial.

• Environmental Engineering Research
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• v.21 no.3
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• pp.256-264
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• 2016

2-Methylisoborneol (2-MIB) is one of typical odorants in potable water sources, which is hardly removed by conventional water treatment process. In this study, three strains capable of removing 2-MIB singly from drinking water were isolated from activated carbon of sand filter. They were identified to be Shinella zoogloeoides, Bacillus idriensis and Chitinophagaceae bacterium based on 16S rRNA gene sequence analysis. In mineral salts medium without external carbon source, removal efficiencies of $20{\mu}g/L$ 2-MIB in three days were 23.3%, 32.9% and 17.0% for Shinella zoogloeoides, Bacillus idriensis and Chitinophagaceae bacterium, respectively. The biodegradation of 2-MIB was significantly improved with the presence of cometabolism carbon(glycerol, glucose, etc.). In the period of 20 days, Bacillus idriensis can remove 2 mg/L MIB to $368.2{\mu}g/L$ and $315.4{\mu}g/L$ in mineral salts medium without and with glycerol respectively. The removal of 2-MIB by Bacillus idriensis was from 2 mg/L to $958.4{\mu}g/L$ in Xiba river samples on 15 days.

• Fire Science and Engineering
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• v.26 no.4
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• pp.18-23
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• 2012

After produce the extracted wood to silicic acid gel, sodium carbonate and silicon dioxide with application of the making method for carbon dioxide, ignition time, ignition temperature, mass loss rate and critical heat flux are measured according to external radiation source (20, 25, 35 and 50 $kW/m^2$). From the results, pressure impregnation wood to use with water glass and carbon dioxide has fire retardant performance at heat flux (less than 20 $kW/m^2$) of Pre-Flashover fires. If we find out the excellent maxing ratio through continuously study, it might be decided to be able to be utilized as fire-retardant wood.

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.207-213
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• 2003

Carbon-14 is one of the major radionuclides released by CANDU Nuclear Power Plants(NPPs). It is almost always emitted as gas through the stack. From CANDU NPPs about 95% of all carbon-14 is released as carbon dioxide. Carbon-14 is a low energy beta emitter which, therefore, gives only a small skin dose from external radiation. As carbon dioxide Is physiologically rather inert gases for man's metabolism, the inhalation dose is probably less than 1 % of the ingestion dose. But this source of carbon-14, formed in a closed, nor-oxidative environment, was subsequently released into the workplace as an insoluble particulate when these systems were opened lip for re-tubing at CANDU NPPs. As a part of the improvement of dosimetry program at Wolsong Nuclear Power Plants, the carbon-14 metabolism based on references was investigated and studied to setup the internal dosimetry program due to inhalation of carbon-14.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.9
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• pp.926-934
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• 2006

In this study, nitrate uptake rate(NUR) and oxygen uptake rate(OUR) tests were conducted for the assessment of application of Terephtalic acid(TPA) by-product as an alternative external carbon source for sewage treatment plant(STP). With the ASM1 installed in GPS-X the substrate removal characteristic was investigated with simulation by obtained data from NUR and OUR test. As a result, the fraction of RBDCOD(readily biodegradable COD) was mort than 90% and specific denitrification rate was observed about 8.00 mg $NO_3^-$-N/g VSS/hr that was similar to conventional external carbon source. In the next step, sensitivity analysis for heterotrophic biomass in ASM1 was conducted. Optimized parameters of ${\mu}_{max,H}$, $K_s$, ${\eta}_g$, and $b_H$ were 6.60/day, 23.3 mg/L, 0.88, and 0.54/day, respectively. Then, relative mean squared error(RMSE) was reduced to about 40%. Optimized parameters value were well corresponded with the substrate removal characteristics of high maximum and final endogenous specific OUR and high specific NUR.

• Journal of Korean Society of Water and Wastewater
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• v.27 no.3
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• pp.339-349
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• 2013

Biological treatment of RO concentrate from wastewater reuse process is known to be very difficult due to its high concentration of non-degradable organics and salt ions such as chloride, nitrate and phosphate. In this research, the treatment performance of MBR was examined using RO concentrate mixed with raw wastewater as the influent of MBR. Addition of PAC (powdered activated carbon) to MBR was also evaluated in order to enhance the treatment performance and stability. The performance of MBR for treating only RO concentrate decreased gradually although external carbon source was added. The average removal performance of MBR with and without PAC decreased from 99.1 %(98.8 %) to 94.9 %(91.4 %) for COD, 81.3 %(80.3 %) to 42.0 %(41.9 %) for T-N and 57.3(55.0 %) to 30.0 %(21.0 %) for T-P with the increase of RO concentrate mixing rate of 0 % to 20 % in the feed water. Addition of PAC showed positive effect on the performance of MBR for the removal of COD and phosphorus in case that the ratio of RO concentrate to feed water increased.

• Journal of Aquaculture
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• v.10 no.3
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• pp.335-346
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• 1997

Denitrification is one of the important processes of removing nitrate from in recirculating aquaculture systems. And this process is affected by many factors such as external organic carbon sources, hydraulic retention time (HRT), COD/NO3--N (C:N) ratio, etc. However, not many studies were done for the optimum conditions of denitrification in the recirculation system for aquaculture. Therefore, this study was conducted to find out the optimum removal condition of NO3--N using submerged denitrification biofilter. The combinations of two external organic carbon sources (glucose and methanol), two HRT (4 and 8-hour) and four differnent C : N ratios (3, 4, 5, 6) were tested. The removal efficiencies of NO3--N and total inorganic nitrogen (TIM) at 8-hour HRT were better than those at 4-hour's (P<0.05). The maximum removal efficiency of NO3--N by methanol (97.8%) was achieved at HRT and C : N ratio were 8-hour and 4.0 respectively. The efficiencies of methanol for the removal of NO3--N and TIN were always better than those of glucose (P<0.05). The maximum removal efficiencies of total inorgainc nitrogen (TIN) were gained at C : N ration of 5.0. The maximum removel efficiencies of TIN using methanol and glucose were 96.9% and 71.5% respectively. Anaerobic condition which is necessary for denitrification process was not made until the 8-hour HRT and higher C : N ratio (5.0). Removal of NO3--N at 4-hour HRT and C : N ration lower than 5.0 were inhibited by oxygen and/or low quantity of external organic carbon. Removal efficiencies of NO3--N were also inhibited by high C : N (6.0) ratio when HRT was 8-hour.