• 상하수도학회지
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• 제22권5호
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• pp.571-580
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• 2008

The influence of bacterial stress on anaerobic hydrogen-producing microorganisms was investigated in batch tests using serum bottles. Several physical and chemical stresses (i.e., heating, adding methane producing inhibitor and chemical acidification) were adapted as a pretreament of the seed sludge. In this experiment, the cultivation temperature were set at mesophilic ($35^{\circ}C$) and thermophilic conditions ($55^{\circ}C$) with adjusting pH at 5, 6, and 7 when using the mixture of food waste and activated sludge as a substrate. In conjunction with the pretreatment, hydrogen production was significantly enhanced as compared with that from untreated sludge. However, less biogas (hydrogen and methane) was produced without the pH control, resulted from the decrease of pH to below 4, mainly due to the formation of VFAs. Hydrogen and carbon dioxide gas were analyzed as main components of the biogas while methane not detected. With an application of chemical acidification, the highest hydrogen production value of 248 ml/l/day achieved at pH 7 and $35^{\circ}C$. In addition, more hydrogen gas produced when the ratio of butyric/acetic acid ratio increased. The optimum pH and temperature for hydrogen production were found to be 7 and $35^{\circ}C$, respectively.

• 생태와환경
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• 제49권1호
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• pp.1-10
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• 2016

산업 및 기술의 발달과 인간 활동의 증가로 인해 자연적인 질소 순환의 균형이 무너지고 다량의 질소가 대기, 토양 및 물 환경 생태계에 과잉으로 존재하게 되었다. 이로 인한 과잉의 반응성 질소화합물이 토양과 물 환경생태계에 영향을 미치고 있는 것을 국내외 문헌과 사례 조사를 통해 확인하고 유역생태계에서 질소화합물로 인한 토양 및 물 환경 생태계의 산성화 영향 감소방안을 제시하였다. 반응성 질소는 대기, 토양 및 물의 여러 매체를 이동하면서 다른 유형으로 전환될 수 있으며 유형 간 상호작용이 일어나기도 한다. 효과적인 질소관리 방안으로 반응성질소 배출원의 다양성 및 유형에 따른 배출량을 규제하는 정책과, 반응성 질소화합물로 인한 토양 및 물 환경생태계의 환경적 피해 (산성화)를 조사 및 평가 (모니터링 및 안전성 지표 적용)하고 복원하는 전략 (예, 화학적 복원 연구 및 개발)이 필요하다.

• 펄프종이기술
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• 제38권4호
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• pp.53-60
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• 2006

Paper materials for long term conservation suffer slowly mechanical and chemical deterioration, the extent of which may depend upon their conservation environment. Those deterioration includes discoloring, low moisture content, acidification, and brittleness. To slow deterioration, washing treatment, deacidification, and polymer reinforcement on paper materials are usually used. One easy and simple method of fixing low moisture content and acidification was an washing method, and we used both distilled and alkali water in washing method in this study. Alkali water is electrolyzed cathode water of high pH, and has no alkali metal ions in it. Experiment showed that washing treatment with both distilled and alkali water gave improvement in raising moisture content, pH, and mechanical strength of paper materials even after severe accelerated aging test. Advantageous effect of alkali water over distilled water on preventing deterioation was also shown clearly.

• 한국작물학회지
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• 제41권spc1호
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• pp.94-109
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• 1996

Antioxidants of sesame have been reported to cure and prevent various diseases by means of diverse physiological activities, prevention of acidification in organisms, prevention of acidification and decay of lipids, cholesterol depression, preventive effects on chemical breast cancer, skin beauty and senescence inhibition, and so on. Recognizing their significance to health and disease prevention, researchers in Japan and America have given so much importance to study antioxidants in the last decade. In addition, they are actively pursuing studies on production, processing for food use and development of new varieties that have high antioxidant content. Recently, researchers in Korea have shown the same interest and have conducted similar studies, however, the importance of the following basic issues must be recognized to guide in future activites : First, improvement of sesame quality must be done to raise the contents of not only the fat and fatty acid but also sesamin, sesamolin and sesaminol glucoside. For the use of these components it is necessary to study the gentic pattern and individual selections developed from minimum sample size and fast lipid analysis techniques. Second, sesaminol of sesame has a remarkable function in preventing acidification and so sesame can be utilized as a food that prevents or delays aging caused by automatic acidification of fat. Therefore, for maximum medicinal benefit from sesame oil there is a need to develop food materials having new medicinal functions. Third, the sesamin and sesamolin content of sesame germplasms collected in Korea showed lower ranges of $0.04\~0.68$ percent and $0.08\~0.68$ percent respectively, while Japanese germ-plasm showed 1.9 percent maximum content of seasmin. Thus, germplasm collection and analysis of worldwide genetic resources are urgently needed.

• 한국환경농학회지
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• 제20권5호
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• pp.317-324
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• 2001

Short-term effect of phosphogypsum on soil properties including acidification, salinity and metal availability were investigated under laboratory and field conditions. Phosphogypsum and mixtures of phosphogypsum and compost were added to soil and incubated in a laboratory condition with 15% moisture content. Phosphogypsum treatments were 2.5 and 5.0 g/kg soil and in the treatments of phosphogypsum and compost mixture 10 g of compost was added additionally. After the 30 days of incubation, an additional phosphogypsum and/or compost were added to the remaining soils at the same rates of the first treatments. pH, electrical conductivity, and available hazardous elements were measured periodically during the incubation. Field experiment was conducted in a plastic film house of mellon with four treatments of phosphogypsum and compost mixtures - 25+125, 50+125, 50+250 and 100+250 kg/165 $m^2$. pH, electrical conductivity, and hazardous elements in soil and total hazardous elements in leaf were measured. In the laboratory experiment, after 30 days of the first phosphogypsum application, soil pHs were lowered by 0.7-0.8 units. After the second treatment of phosphogypsum 0.2 units of additional acidification occurred. However, acidification was not observed in the soils treated with mixtures of phosphogypsum and compost. In the laboratory experiment, phosphogypsum treatments increased electrical conductivity very significantly. In field experiment, pH and electrical conductivity of soils treated with phosphogypsum were nearly the same as those of soil not treated with phosphogypsum. Since soil condition in the field study was an open system, the free acids and salts derived from phosphogypsum could be diffused down with water leaching through the soil profile and then any significant acidification or salt accumulation in the topsoil could not be observed. In both laboratory and field experiments, levels of available hazardous elements in soils treated with phosphogypsum were quite low and not different from the levels found in the control soil. Results obtained from this study suggest that application of phosphogypsum at appropriate rates on agricultural land appears of no concern in terms of acidity, salinity and hazardous element content of soil.

• Environmental Engineering Research
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• 제23권1호
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• pp.54-61
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• 2018

Biodiesel production parameters and the impact analysis of the potential emissions from both soybean biodiesel and washing water stored in three different environmental conditions were investigated. The effects of the reaction temperature, methanol/oil mole ratio and catalyst concentration on biodiesel yield were considered. And the results showed optimum biodiesel yield of 99% obtained at $54^{\circ}C$, 7 methanol/oil mole ratio and 0.4 wt/wt % catalyst concentration. The potential emissions from both the biodiesel produced and washing water stored (for six weeks) in refrigerator (${\leq}10^{\circ}C$), vacuum (50 kPa) and direct exposure to atmosphere were identified and quantified. Impact analysis of the emissions involved their categorization into: terrestrial acidification, freshwater eutrophication, human toxicity, terrestrial ecotoxicity, climate change and freshwater ecotoxicity. Freshwater ecotoxicity category had the most pronounced negative impact of the potential emissions with $5.237710^{-2}kg\;1,4-DB\;eq$. emissions in Atmosphere, $4.702610^{-2}kg\;1,4-DB\;eq$. emissions in Refrigerator and $3.966110^{-2}kg\;1,4-DB\;eq$. emissions in Vacuum. Climate change had the least effect of the emissions with $6.214106^{-6}kg\;CO_2\;eq$. in Atmosphere, $3.9310^{-6}kg\;CO_2\;eq$. in Refrigerator and $1.6710^{-6}kg\;CO_2\;eq$. in Vacuum. The study showed that the order of preference of the storage environments of biodiesel is vacuum environment, refrigerated condition and exposure to atmosphere.

• 콘크리트학회논문집
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• 제11권4호
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• pp.13-20
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• 1999

Recently, the study for practical construction application no recycled aggregate concrete is actively being proceeded, on the purpose of technical development for recycling on the construction waste concrete occurred at the time of destruction of building construction by the rapid increase of building wastes and exhaustion of natural aggregates. But, the durability of investigation with all sorts of fluidity and engineering property for application recycled aggregate concrete to practical construction must be done at the same time. Especially, because of the real condition for chemical attack of concrete construction by the acid rain, acidification of soil, deepening of air pollution and dirty water etc. being come to the fore a serious problem, the study on the chemical soundness of concrete durability must be accompanied. This study is composed as: I series: Analysis for chemical soundness of aggregates. II series: Analysis for chemical soundness of natural and recycled aggregate concrete against $Na_2$$SO_4$ solution in drying and wet curing condition ($at20~80^{\circ}C$).

• The Korean Journal of Ecology
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• 제17권3호
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• pp.287-297
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• 1994

수도권에서 보고된 리기다소나무 생장감소의 원인을 밝히기 위하여 33장소의 리기다소나무 숲에서 교목의 밀도, 수령 및 토양의 물리화학적 특성을 조사하였다. 토성을 제외하고 토양의 물리적 특성들은 도심지와 전원지에서 차가 없었다. 그러나 토양의 pH값, 염기포화도 및 염기성 양이온 함량은 전원지에 비해 도심지에서 낮았지만, 수용성 Al 함량과 S함량은 그 반대였다. 도심지의 토양산성화는 산성강하물에 의한 영향으로 해석된다. 다중회귀분석 결과, 수도권에서 리기다소나무 생장은 토양의 가비중<토양의 Al 함량<교목의 밀도<토양의 Mg 함량<수령의 순으로 영향이 컸다. 결론적으로 수도권에서 리기다소나무 생장의 감소는 1차적으로 토양산성화가 주요한 요인이었을 것으로 판단된다.

• 한국물환경학회지
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• 제36권2호
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• pp.137-147
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• 2020

A direct contact membrane distillation (DCMD) was applied to treat strong nitrogenous wastewater of anaerobic digestion supernatant (ADS) and human urine (HU). The ammonia transfer was evaluated in terms of specific ammonia transfer (SAT) value, which is the ratio of total ammoniacal nitrogen divided by the amount of water transferred. The acidification resulted in low SAT values and high quality of produced water. The ammonia transfer control in the acidic condition was stronger for HU than ADS due to higher alkalinity (pH 8.8) and ammonia concentration (5700 mg-N/L) of HU. Acidified HU at pH 4 exhibited a SAT value of 1.64 × 10^-5, which was significantly smaller than the SAT value of 3.00 × 10^-3 for the original HU. The low pH enhanced the water flux for ADS, but HU showed a steep decrease in water flux due to enhanced fouling. It was considered that the fouling intensity in acidic conditions depends on the characteristics of the wastewater source. The major foulants on the MD membrane were NaCl, CaCO₃ and CuSO₄ as recognized by the SEM-EDS. Acidified ADS and HU at pH 4 showed relatively high N content of 8.18 % and 28.03 %, respectively, as organic fouling.

• 기술사
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• 제34권2호
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• pp.46-51
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• 2001

It Is not uncommon to see some reports that livestock wastes are discharged into land, streams or seas without any treatment in the protective area of water resource. This study reports the development of the technique of protecting water resources through making use of treated livestock in organic farming after the procedures of collecting livestock wastes in 100% water tight PDF tanks, mixing Pedac, etc and fermenting. This techinque makes organic farming products possible without experiencing soil acidification caused by chemical fertilizer.