• 한국토양비료학회지
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• 제45권2호
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• pp.260-265
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• 2012

담수 토양에서의 토양호흡량은 호기 상태에 비해 매우 낮은 수준이나, 혐기 상태에서의 유기물의 분해는 담수 생태계의 탄소순환에 매우 중요한 역할을 한다. 한편, 비산회(fly ash), 석탄바닥재 (bottom ash)와 같은 석탄 연료 부산물들은 이산화탄소 발생을 저감하고 토양 탄소를 격리하는 효과가 있음이 보고된 바 있다. 이에 본 연구는 혐기조건 토양에서 석탄바닥재 단일 처리 및 석탄바닥재와 유기물 혼합 처리가 토양 미생물 호흡량 및 미생물 생체량 변화에 미치는 영향을 조사하였다. 이산화탄소 발생속도는 석탄바닥재 처리에 의해 유의하게 감소하였고, 처리수준에 따라서도 감소하는 것을 보였다. 유기물과 석탄바닥재를 혼합 처리하였을 때에도 발생속도가 감소되는 것을 확인하였다. 석탄바닥재 처리에 따라 토양미생물 생체량은 유의하게 증가하였고, 토양 중 암모니아태 질소, 질산태 질소, 유효인의 함량은 감소하는 경향이 있었다.

• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.845-855
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• 2022

In response to climate change, the world is continuing efforts to reduce fossil fuels, expand renewable energy, and improve energy efficiency with the goal of achieving carbon neutrality. In particular, R&D is being made on the value chain covering the entire cycle of hydrogen production, storage, transportation, and utilization in order to shift the energy supply system to focus on hydrogen energy. Hydrogen-based energy sources can produce heat and electricity at the same time, so it is possible to utilize heat energy, which can increase overall efficiency. In this study, calculation of the optimal scale for hydrogen-based cogeneration and the composition of heat sources were reviewed. It refers to a method of the optimal heat source size according to the external heat supply and heat storage to be considered. The results of this study can be used as basic data for establishing a hydrogen-based energy supply model in the future.

• 한국환경보건학회지
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• 제35권3호
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• pp.214-219
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• 2009

This study examined the removal efficiency of the nitrogen and phosphorus in order to compensate for the combined process of ATAD(Autothermal Thermophilic Aaerobic Digestion) and EGSB(Expended Granular Sludge Bed), which are treatment methods for livestock wastewater, by introducing SBR(Sequencing Batch Reactor) as post-treatment process. The analysis on the treatment efficiency of each operation mode showed that, in the case of T-N, the treatment efficiency were 67.1% and 74.2% for Run-1 and Run-2, respectively, and in the case of T-P, the values were 71.2 and 74.1, respectively, which are indicating that the treatment efficacy is higher in the condition of Run-1, in which the time period of Anoxic and Aerobic segments were increased. In addition, the result of analyzing removal characteristics of nitrogen and phosphorus by Influx load showed that removal efficiency of nitrogen was better in the case of high influx load than in the case of low influx load. Regardless of Influx load, phosphorus showed constant influx concentration, so that removal efficiency of phosphorus was influenced littler by Influx load than that of nitrogen. This study also fed methanol as an external carbon source and performed experiment to induce denitrification under anoxic condition by using nitrate among nitrogen compounds of SBR reactor, and the results showed that intermittent feeding was more effective in Nitrogen Removal than composite feeding.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.226-230
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• 2005

본 논문에서는 MWCNT 분산도가 증가된 새로운 전도성 형상 기억 폴리우레탄을 연구하였고 전기적 특성을 검출하기 위한 실험과 작동 성능을 측정하기 위한 실험들을 수행하였다. 전이온도 이하 범위에서의 온도변화에 따른 저항변화는 거의 없었으며, 시편이 100% 신장됨에 따라 저항값도 100% 증가하였다 (비저항 300% 증가). 작동변위는 페이로드가 증가함에 따라 선형적으로 줄어들었다. 그리고, CSMPU 작동기의 보다 세부적인 특성 및 성능을 알기 위해서는 더 많은 연구와 실험이 필요하다.

• Advances in environmental research
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• 제1권2호
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• pp.153-166
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• 2012

Decolourization potential of white rot fungal organism, coriolus versicolor, was investigated in a batch reactor, for textile dye industry wastewater. The influence of process parameters like pH, temperature, agitation speed and dye wastewater concentration on the decolourization of textile dye wastewater was examined by using Response surface methodology (RSM). The maximum decolourization was attained at: pH- 6.8, temperature - $27.9^{\circ}C$, agitation speed - 160 rpm and dye wastewater concentration - 1:2. From the analysis of variance (ANOVA) results it was found that, the linear effect of agitation speed and dye wastewater concentration were significant for the decolourization of textile dye wastewater. At these optimized condition, the maximum decolourization and chemical oxygen demand (COD) reduction was found to be 64.4% and 79.8% respectively. Various external carbon sources were tried to enhance the decolourization of textile dye wastewater. It was observed that the addition of carbon source enhances the decolourization of textile dye wastewater. Kinetics of textile dye degradation process was studied by first order and diffusional model. From the results it was found that the degradation follows first order model with $R^2$ value of 0.9430.

• 한국환경과학회지
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• 제13권9호
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• pp.779-878
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• 2004

This study was conducted to analyze the operating conditions of predenitrification process to improve the treatment efficiency in low organic loading sewage plant in use today, and to investigate the treatment efficiency of pilot plant added night soil as well as the nitrogen removal characteristics of pilot plant added carbon sources. In the operation under the condition of $BOD_{5}$ sludge load 0.03-0.28kg $BOD_{5}$/kg VSS/d and oxic ammoniac nitrogen sludge load 0.02-0.24 $kgNH_{4}^{+}$-N/kg MLVSS/d, nitrification efficiency is higher than 95%. In order to achieve 70% nitrogen removal at the T-N sludge loading 0.06kg T-N/kg VSSㆍd and the SRT 6～11 days, optimum operating factors were revealed to $CODc_{r}$/T-N ratio 9, recycle ratio 2.6, and denitrification volume ratio 0.33. At this time, denitrification capacity was approximately 0.09 kg $NO_{3}^{-}$-N/kg $CODc_{r}$; specific nitrification rate was 3.4mg $NH_{4}^{+}$-N/g MLVSS/hr; and specific denitrification rate was 4.8mg $NO_{3}^{-}$-N/g MLVSS/hr.

• Journal of Microbiology and Biotechnology
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• 제22권8호
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• pp.1155-1160
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• 2012

Sulfur-utilizing autotrophic denitrification relies on an inorganic carbon source to reduce the nitrate by producing sulfuric acid as an end product and can be used for the treatment of wastewaters containing high levels of nitrates. In this study, sulfur-denitrifying bacteria were used in anoxic batch tests with sulfur as the electron donor and nitrate as the electron acceptor. Various medium components were tested under different conditions. Sulfur denitrification can drop the medium pH by producing acid, thus stopping the process half way. To control this mechanism, a 2:1 ratio of sulfur to oyster shell powder was used. Oyster shell powder addition to a sulfur-denitrifying reactor completely removed the nitrate. Using 50, 100, and 200 g of sulfur particles, reaction rate constants of 5.33, 6.29, and $7.96mg^{1/2}/l^{1/2}{\cdot}h$ were obtained, respectively; and using 200 g of sulfur particles showed the highest nitrate removal rates. For different sulfur particle sizes ranging from small (0.85-2.0 mm), medium (2.0-4.0 mm), and large (4.0-4.75 mm), reaction rate constants of 31.56, 10.88, and $6.23mg^{1/2}/l^{1/2}{\cdot}h$ were calculated. The fastest nitrate removal rate was observed for the smallest particle size. Addition of chemical oxygen demand (COD), methanol as the external carbon source, with the autotrophic denitrification in sufficiently alkaline conditions, created a balance between heterotrophic denitrification (which raises the pH) and sulfur-utilizing autotrophic denitrification, which lowers the pH.

• Environmental Engineering Research
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• 제20권3호
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• pp.246-253
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• 2015

The effects of carbon-to-nitrogen (C/N) ratio in simulated rice straw hydrolysates using glucose and ammonium chloride on polyhydroxyalkanoates (PHA) accumulation by Cupriavidus necator was investigated. In general, PHA accumulation rate was higher under higher degrees of N-deficient conditions (e.g., C/N ratio of 360:1) than lower degrees of N-deficient conditions (e.g., C/N ratio of 3.6:1 and 36:1). Also, the most PHA accumulation was observed during the first 12 h after the PHA accumulation initiation. This study showed that the similar PHA accumulation could be achieved by using different accumulation periods depending on C/N ratios. N source presence was important for new cell production, supported by approximately ten times greater PHA accumulation under the N-deficient condition ($NH_4Cl$ 0.01 g/L) than the N-free (without $NH_4Cl$) condition after 96 h. C/N ratio of the rice straw hydrolysate was approximately 160:1, based on the glucose content, and this accumulated $0.36{\pm}0.0033g/L$ PHA with PHA content of $21{\pm}3.1%$ after 12 h. Since external C or N source addition for C/N ratio adjustment increases production cost, an appropriate accumulation period may be used for PHA accumulation from organic wastes, based on the PHA accumulation patterns observed at various C/N ratios and C and N concentrations.

• 한국물환경학회지
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• 제23권5호
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• pp.781-788
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• 2007

The Carbon source to enhance the denitrification is essential matter in the advanced sewage treatment. For the high level of nutrient removal, external carbons such as ethanol, methanol, volatile fatty acids and so on should be needed. In this study, the methods to increase the sludge solubilization and acidification rate were compared with waste activated sludges and food waste leachate. Ultrasonication and acids were used for the pretreatment of organic particles in sludges. As a results, the optimal temperature and HRT were $60^{\circ}C$ and 5 days, respectively. HAc, HPr, HBr, and other VFAs for acid fermentations reduced up to 22, 16, 14, and 48% with HRT reduction. For the increase of solubilization, 28% of solids destruction rate was shown at 0.3 watts/mL.

• 한국환경과학회지
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• 제15권10호
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• pp.975-982
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• 2006

This study has been conducted to optimum operating conditions for effective acid fermentation according to OLR(organic loading rate) in the mesophilic and thermophilic acid fermentation process. The results are summarized as follows. In order to obtain reasonable acid fermentation efficiency in performing acid fermentation of food wastes in thermophilic condition, organic loading rate was required below 20 gVS/L.d. As $SCOD_{Cr}/TKN,\;SCOD_{Cr}/T-P$ of thermophilic acid fermented food wastes In organic loading rate 20 gVS/L.d were 18.9, 73.4 respectively, it was possible to utilize as external carbon source for denitrification in sewage treatment plant after solid-liquid separation as well as co-digestion of fermented food wastes and sewage sludge.