• 한국지하수토양환경학회지:지하수토양환경
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• 제21권3호
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• pp.88-94
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• 2016

The simultaneous biodegradation between MTBE (Gasoline additives) and BTEX (Benzene, Toluene, Ethyl-benzene, o-Xylene, m-Xylene, p-Xylene) was achieved within a competitive inter-relationship, with not only electron accepters such as nitrate, sulfate, and iron(III) without oxygen, but also with electron donors such as MTBE and BTEX. Preexisting indigenous microorganisms from a domestic sample of gasoline contaminated soil was used for a lab-scale batch test. The result of the test showed that the biodegradation rate of MTBE decreased when there was co-existing MTBE and BTEX, compared to having just MTBE present. The growth of indigenous microorganisms was not affected in the case of the MTBE treatment, whereas the growth of the microorganisms was decreased in combined MTBE and BTEX sample. This may indicate that an inhibitor related to biodegradation when BTEX and MTBE are mixed will be found. This inhibitor may be found to retard the anaerobic conditions needed for efficient breakdown of these complex carbon chain molecules in-situ. Moreover, it is also possible that an unknown competitive reaction is being imposed on the interactions between MTBE and BTEX dependent on conditions, ratios of mixture, etc.

• Geomechanics and Engineering
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• 제30권5호
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• pp.461-469
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• 2022

One of the most important factors that should be considered for using any ground improvement technique is the stability of stabilized soil and the durability of the provided solution for getting the required engineering properties. Generally, most of the earth structures that are constructed on clayey soils are exposing movements due to the long periods of drying or wetting cycles. Over time, environmental changes may result in swells or settlements for these structures. In order to mitigate this problem, this research has been performed on mixtures of high plasticity clay with traditional additives such as lime, cement and non-traditional additives such as polypropylene fiber. The purpose of the research is to assess the most appropriate ground improvement technique by using commercially available additives for resisting the developed desiccation cracks during the drying process and resisting the volume changes that may result during wet/dry cycles as an attempt to simulate the changes of environmental conditions. The results show that the fiber-reinforced samples have the lowest volumetric deformation in comparision with cement and lime stabilized samples, and the optimum fiber content is identified as 0.38%. In addition, the desiccation cracks were not visible on the samples' surface for both unreinforced and chemically stabilized samples. Regarding cracks resistance resulting from the desiccation process, it is observed, that the resistance is connected with the fiber content and increases with the increase of the fiber inclusion, and the optimum content is between 1% and 1.5%.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.354-357
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• 2004

The addition of oxygenates to diesel fuel can significantly reduce particulate emissions. Dibutyl maleate (DBM) and tripropylene glycol methyl ether (TGME) have been identified as possible additives based on their physicochemical characteristics and performance in engine test. However, their potential environmental impacts are unknown. therefore, practical considerations in the selection of an oxygenate additives should include cost, availability, compatibility with engines and fuel, and, particularly, its overall environmental impact. This study was investigated to determine optimal condition for the analysis of potential diesel oxygenates using SPME technique with GC-FID. Four fibers were compared and CAR/PDMS fiber was found to be the most sensitive when used direct-sampling. An absorption time of 30min and a desorption time of 5min provided to be the most sensitivity. The effects of experimental parameters such as the addition of salts, agitation, absorption time, compositon on the analysis were investigated. Analytical parameter such as linearity was also evaluated.

• Geomechanics and Engineering
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• 제8권1호
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• pp.67-79
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• 2015

This article presents the result of laboratory study conducted on expansive soil specimens treated with lignin, rice husk powder (RHP) and rice husk ash (RHA). The amount of lignin produced from paper industry and RHP were varied from 0 to 20% and RHA from 0 to 10% by weight. The treated specimens were subjected to unconfined compressive strength (UCS),swelling test and Atterberg limit tests. The effect of additives on UCS and atterberg limit test results were reported. It was observed that the additives and curing duration had a significant effect on the strength value of treated specimens. Generally (except the sample treated with 20% RHP for 3-day) with increasing additive and curing duration the UCS value increases. A RHP content of 15% was found to be the optimum with regard to 3-day cure UCS.

• 한국환경농학회지
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• 제42권4호
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• pp.358-370
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• 2023

Composting has been proposed for the management of organic waste, and the resulting products can be used as soil amendments and fertilizer. However, the emissions of greenhouse gases (GHGs) such as CO₂, CH₄, and N₂O produced in composting are of considerable concern. Hence, various additives have been developed and adopted to control the emissions of GHGs. This review presents the different additives used during composting and summarizes the effects of additives on GHGs during composting. Thirty-four studies were reviewed, and their results showed that the additives can reduce cumulative CO₂, CH₄, and N₂O emission by 10.5%, 39.0%, and 28.6%, respectively, during composting. Especially, physical additives (e.g., biochar and zeolite) have a greater effect on mitigating N₂O emissions during composting than do chemical additives (e.g., phosphogypsum and dicyandiamide). In addition, superphosphate had a high CO₂ reduction effect, whereas biochar and dicyandiamide had a high N₂O reduction effect. This implies that the addition of superphosphate, biochar, and dicyandiamide during composting can contribute to mitigating GHG emissions. Further research is needed to find novel additives that can effectively reduce GHG emissions during composting.

• 한국토양환경학회지
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• 제3권1호
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• pp.65-74
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• 1998

계면활성제에 의해 형성되는 미셀의 바깥층에 전기적인 영향을 주는 전해질과 미셀의 구조 자체를 변화시키는 유기물질 단량체를 첨가제로 각종 혼합 계면활성제 용액에 적용함으로써 토양세척 효율에 미치는 영향을 검토하였다. 혼합 계면활성제[$POE_5$/SDS] 및 NaCl을 첨가농도를 변화시키면 용액의 표면장력과 CMC 값을 측정하여 세척효율과의 상관 관계를 규명하고, 세척효율이 상승되는 혼합 계면활성제와 NaCl의 최적 혼합조건을 도출하고자 하였다. 실험 결과, 0.01M의 NaCl이 첨가될 때가 NaCl을 넣지 않았을 때보다 $POE_5$의 혼합 농도비가 80%까지 증가됨에 따라 세척효율이 비례적으로 증가하였으며, $POE_5$/SDS(80%/20%) 3%용액 적용시 90%의 높은 세척효율을 나타내었다. 반면 비이온계 계면활성제인 $POE_5$ 단일 성분 수용액에 대한 NaCl의 영향은 극히 미미하였다. SDS 단일 성분 수용액에 대한 CMC값은 0.049% 로 $POE_5$ 단일 성분 수용액에 대한 CMC값인 0.016%보다 높지만, 혼합 게면활성제의 CMC값은 $POE_5$의 혼합 농도비가 증가됨에 따라 감소되는 경향을 나타내었다. 유기물질 단량체인 알코올류는 탄화수소 사슬의 길이가 길수록, 직쇄형보다는 가지형이 토양세척용 첨가제로 적합하였다.

• 한국지반공학회지:지반
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• 제8권3호
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• pp.51-60
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• 1992

요지 국내 폐기물 매립장에서 캡 및 바닥차수재로서 이용이 기대되는 혼합차수재를 선정하여 이들의 재료 특성을 살펴보기 위하여 물리, 역학적시험을 실시하였다. 혼합차수재의 주재료로는 플라이애쉬와 화강토 그리고 첨가제로는 벤토나이트와 시멘트를 선정하였다. 본 차수재에 대한 시험결과 최대건조밀도는 서천 및 삼천포 플라이애쉬 혼합재의 경우 벤토나이트 함량이 5%와 25%인 지점을 전후로 하여 증가 감소하고 화강토 혼합재의 경우 벤토나이트의 함량이 증가함에 따라 증가하였다. 강도는 벤토나이트 첨가의 경우 증감현상이 뚜렷하지 않았지만 시멘트 첨가의 경우는 크게 증가하였다. 혼합차수재의 투수계수가 1$\times$10-7cm/sec가 되기 위한 벤토나이트의 첨가량은 서천 및 삼천포 플라이애쉬 그리고 화강토의 경우 각각 18, 30, 10%로나타났으며 주재료의 입도분포, 점토성분함유정도에 따라 첨가제의 필요 함량이 큰 차이가 있음을 알 수 있었다.

• 한국환경보건학회지
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• 제34권5호
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• pp.387-394
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• 2008

The toxicity of methyl tert-butyl ether (MTBE), tert-butyl alcohol (TBA) and formaldehyde (FA) on the indigenous microbial community in forest soil was studied. MTBE, TBA and FA with different concentrations were added into microcosms containing forest soil samples. After 10 and 30 days, total viable cell number and dehydrogenase activity in the microcosms were evaluated. Bacterial communities in the microcosms were also analyzed using a denaturing gradient gel electrophoresis (DGGE). Dehydrogenase activity and total viable cell number were decreased according to the increase of MTBE, TBA and FA concentrations (P<0.05). FA toxicity was the highest, but TBA toxicity was the lowest. The results of principal component analysis using DGGE fingerprints showed that the microbial communities contaminated MTBE, TBA and FA were grouped by exposure time not exposure concentration. Dominant species in the microcosms were as follows: Photobacterium damselae sub sp. and Bacillus sp. KAR28 for MTBE; Mycobacterium sp. and Uncultured Clostridium sp. for TBA; and Uncultured Paenibacillaceae bacterium and Anxynobacillus, Flavithermus for FA.

• 한국농공학회지
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• 제40권2호
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• pp.102-111
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• 1998

Large amount of sludge have been generating in the process of water and wastewater treatment in urban area, and it has been making many environmental problems. Currently almost of sludge is landfilled, and since sludge is difficult to handle and dehydrate, the permeated water from the filled-in ground contaminate the surrounding soil and groundwater which may cause serious environmental and sociological problems. The organic component in sludge can be almost removed through the heat treatment process, and the final product is called artificial soil or artificial media according to the temperature control. To produce artificial media using sludge, chabazite and lime were used as an additive, and the mixture of sludge & additives was thermally treated in the firing kiln at about 800~1, 100。C for about fifteen minutes. The physical and chemical characteristics of the produced artificial media were analyzed, and it showed that it can be used as an artificial media for plant production or soil conditioner for farmland. The concentrations of the toxic heavy metals in the artificial media were lower than the soil quality standard for farmland. The characteristics of produced artificial media, using the mixture of sludge and additives through the heat treatment, is similar to the natural chabazite and soil. The analyzed result of the mineral composition of artificial media showed that it has a characteristics similar to natural stable soil, so the produced artificial media may be applied to farmland or water culture without causing adverse effect. Therefore this study showed that the above process can be a feasible alternative for sludge treatment.

• 공업화학
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• 제25권1호
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• pp.27-33
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• 2014

석유누출 사고로 인해 토양과 지하수 오염이 점차 증가되면서, 토양환경에 대한 중요성이 늘고 있다. 토양오염은 다른 환경오염에 비해 많은 정화비용과 긴 정화기간이 요구된다. 이런 이유로 토양오염이 발생되면, 어떤 오염물질에 의해 토양이 오염되었으며, 토양정화의 책임이 있는 오염자가 누구인지 법적 분쟁이 많이 발생되고 있다. 본 연구에서는 토양오염을 발생시킬 수 있는 항공유에 대한 물성 분석과 함께 항공유 내의 특정 첨가제를 분석함으로써 등유와 항공유의 구분법을 찾아내었다. 특히 발색제에 의해 등유 내 화학적 식별제만 발색되었으며, GC-MS 분석결과 항공유에서만 산화방지제와 금속불활성제가 분석되었다. 이는 추후 항공유에 의한 토양오염 야기 시, 어떤 석유제품에 의한 오염인지 쉽게 판단이 가능할 것이다.