• 대한환경공학회지
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• 제31권4호
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• pp.287-293
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• 2009

본 연구에서는 칼럼실험을 이용하여 석영모래와 철피복 모래에서 박테리아(Escherichia coli, Bacillus subtilis, 그리고 Staphylococcus aureus)의 부착 및 탈착에 미치는 이온강도의 영향을 조사하였다. 실험결과, 철피복 모래에서는 이온강도가 1 mM에서 100 mM로 증가함에 따라 질량회수율이 일정(E. coli = 13.7${\pm}$0.5%, B. subtilis = 9.8${\pm}$1.3%, S. aureus = 13.0${\pm}$2.1%)한 반면, 석영모래에서는 80.7%에서 45.3%로 감소하였다(S. aureus). 용출용액의 이온강도가 100 mM에서 0.1 mM로 감소함에 따라, 석영모래에서는 평균 39.1%의 박테리아 탈착이 일어났지만, 철피복 모래에서는 탈착이 관찰되지 않았다. 철피복 모래에서 관찰된 이러한 현상은 박테리아와 철피복 모래사이의 inner-sphere complexes(이온강도의 영향을 받지 않는)에 의한 결합 때문이다. 본 연구는 박테리아와 표면변형 다공성 여재의 상호작용에 대한 지식을 증진시킨다.

• 대한환경공학회지
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• 제29권7호
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• pp.833-838
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• 2007

본 연구에서는 양전하를 띤 여재 입자에서 박테리아의 부착 및 이동에 관한 연구를 위하여 회분 및 칼럼실험을 수행하였다. 본 실험에 사용된 박테리아는 E. coli ATCC 11105(길이: 2.2 ${\mu}m$ 직경: 0.6 ${\mu}m$)이었고, 여재는 석영모래(입경분포: 0.5-2.0 mm, 평균 입경: 1.0 mm)와 철코팅 모래이었다. 회분실험결과에 의하면 철코팅 함량이 증가함에 따라, 박테리아의 부착량이 증가하는 것으로 나타났다. 철코팅 모래의 함량 0%(석영모래 100%)에서는 약 46% 정도의 박테리아가 부착되었고, 철코팅 모래의 함량 100%(석영모래 0%)에서는 약 97% 정도의 박테리아가 부착되었다. 칼럼실험결과 또한 철코팅 함량이 증가함에 따라, 박테리아의 부착량이 증가하는 것을 보여주고 있다. 철코팅 모래의 함량이 0에서 100%로 증가함에 따라 박테리아의 부착량이 8에서 94%로 증가하였다. 본 연구의 실험결과를 통해 양전하를 띤 여재 입자가 박테리아의 이동에 영향을 미칠 수 있음을 알 수 있다.

• 한국환경과학회지
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• 제8권2호
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• pp.205-209
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• 1999

Iron hydroxides are good adsorbents for uncomplexed metals, some metal-ligand complexes and many metal oxyanions. However, their adsorption properties of these precipitations are not fully exploited in wastewater treatment operations because of difficulties associated with their separation from the aqueous phase. This study describes experiments in which iron hydroxides were coated onto the surface of ordinary adsorbents(Sea sand) that are very resistant to acids, The coated adsorbents were used in adsorption of oxyanionic metals. The process was successful in removing some anions such as $SeO_3(-II)$ over a wide range of metal concentrations and sorption of oxyanionic metals increased with decreasing pH. Formation of two surface complexes for oxyanionic metals adsorption on iron hydroxides comprise (1) complexation of the free anion by a positively charged surface site, and (2) protonation of the adsorbed anion (or alternatively adsorption of a protonated form from solution) The coated adsorbents are inexpensive to prepare and could serve as the basis of a useful oxyanionic metal removal.

• 상하수도학회지
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• 제31권6호
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• pp.521-527
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• 2017

Phosphorus is one of the limiting nutrients for the growth of phytoplankton and algae and is therefore one of leading causes of eutrophication. Most phosphorous in water is present in the form of phosphates. Different technologies have been applied for phosphate removal from wastewater, such as physical, chemical precipitation by using ferric, calcium or aluminum salts, biological, and adsorption. Adsorption is one of efficient method to remove phosphates in wastewater. To find the optimal media for phosphate removal, physical characteristics of media was analysed, and the phosphate removal efficiency of media (silica sand, slag, zeolite, activated carbon) was also investigated in this study. Silica sand showed highest relative density and wear rate, and phosphate removal efficiency. Silica sand removed about 36% of phosphate. To improve the phosphate removal efficiency of silica sand, Fe coating was conducted. Fe coated silica sand showed 3 times higher removal efficiency than non-coated one.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.489-496
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• 1999

The objective of this study is to present engineering properties required in use of co-mixtures of fly ash and WFS(Waste Foundry Sand)'s, which are Presently used as fill or (lovable backfill. The fly ash, generated at the Tae-An thermoelectric power plant was used in this research and was classified as Class F. Green Sand, Furane Sand, and Coated Sand, which had been used at a foundry located in Pusan, were used. Laboratory experiments were peformed to obtain the physical properties of the co-mixture of fly ash and WFS. The range of permeability for all the co-mixtures was from 3.0×10/sup -3/㎝/s to 6.0×10/sup -5/㎝/s. The unconfined strength of the 7-day cured specimens composed of Green Sand reached 94% of that of 28-day cured specimens but for the 7-day cured specimens composed of, respectively, Furnace Sand and Coated Sand, only 64% and 66% of the strength of the 28-day cured specimens were reached. Results of the consolidated-untrained triaxial test showed that the specimens composed of Furnace Sand showed a distinct increase of the internal friction angle, while the other specimens showed negligible increase. In the case of 28-day cured specimens, specimens composed of Furnace Sand showed an internal friction angle of 41.8°, while specimens of Green and Coated Sand showed those of 33.5° and 35.0°, respectively. From the shrinkage test, the shrinkage ratios of all specimens did not exceed 0.25%.

• 대한환경공학회지
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• 제31권7호
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• pp.515-520
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• 2009

본 연구에서는 칼럼실험을 이용하여 알루미늄 철 산화물 동시피복모래에서 박테리아(Bacillus subtilis)의 부착에 산화음 이온(질산염, 탄산염, 인산염)이 미치는 영향을 조사하였다. 실험결과, 질산염의 경우 피복모래에서의 박테리아 부착은 질산염 이온의 농도변화와 무관하였다. 질산염의 농도가 변화함에 따라(0.1, 1, 10 mM) 질량회수율은 10.9${\pm}$0.2 %로 일정하였다. 탄산염의 경우 농도가 0.1 mM에서 1 mM로 증가함에 따라 질량회수율이 25.6%에서 39.0%로 증가하였고, 인산염의 경우에도 동일한 농도조건에서 50.9%에서 78.9%로 증가하였다. 이러한 현상은 박테리아 부착에 대한 탄산염과 인산염 이온의 방해효과 때문이었다. 반면, 탄산염/인산염의 농도가 1 mM에서 10 mM로 증가함에 따라 질량회수율이 각각 39.0%에서 23.8%로 78.9%에서 52.6%로 감소하였다. 이러한 현상은 탄산염/인산염의 농도증가에 따라 피복모래표면에 흡착되지 않고 수용액상에 존재하는 탄산염이나 인산염 이온이 이온강도를 증가시킴으로써 일어나는 박테리아 부착에 대한 증진효과 때문이었다. 본 실험조건에서 피복모래에서의 박테리아 부착에 미치는 영향은 인산염, 탄산염, 그리고 질산염 중, 인산염이 가장 큰 것으로 나타났다.

• Environmental Engineering Research
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• 제15권3호
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• pp.149-156
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• 2010

The objective of this study was to investigate microbial removal using layered double hydroxides (LDHs) and iron (hydr)oxides (IHs) immobilized onto granular media. Column experiments were performed using calcium alginate beads (CA beads), LDHs entrapped in CA beads (LDH beads), quartz sand (QS), iron hydroxide-coated sand (IHCS) and hematite-coated sand (HCS). Microbial breakthrough curves were obtained by monitoring the effluent, with the percentage of microbial removal and collector efficiency then quantified from these curves. The results showed that the LDH beads were ineffective for the removal of the negatively-charged microbes (27.7% at 1 mM solution), even though the positively-charged LDHs were contained on the beads. The above could be related to the immobilization method, where LDH powders were immobilized inside CA beads with nano-sized pores (about 10 nm); therefore, micro-sized microbes (E. coli = 1.21 ${\mu}m$) could not diffuse through the pores to come into contact with the LDHs in the beads, but adhere only to the exterior surface of the beads via polymeric interaction. IHCS was the most effective in the microbial removal (86.0% at 1 mM solution), which could be attributed to the iron hydroxide coated onto the exterior surface of QS had a positive surface charge and, therefore, effectively attracted the negatively-charged microbes via electrostatic interactions. Meanwhile, HCS was far less effective (35.6% at 1 mM solution) than IHCS because the hematite coated onto the external surface of QS is a crystallized iron oxide with a negative surface charge. This study has helped to improve our knowledge on the potential application of functional granular media for microbial removal.

• Environmental Engineering Research
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• 제14권2호
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• pp.134-139
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• 2009

In this study, oxidation of As (III) as well as removal of total arsenic by adsorbents coated with single oxides or multi-oxides (Fe (III), Mn (IV), Al (III)) was investigated. In addition, multi-functional properties of adsorbents coated with multi-oxides were evaluated. Finally, application of activated carbon impregnated with Fe or Mn-oxides on the treatment of As (III) or As (V) was studied. As (V) adsorption results with adsorbents containing Fe and Al shows that adsorbents containing Fe show a greater removal of As (V) at pH 4 than at pH 7. In contrast adsorbents containing Al shows a favorable removal of As (V) at pH 7 than at pH 4. In case of iron sand, it has a negligible adsorption capacity for As (V) although it contains 217.9 g-Fe/kg-adsorbent, Oxidation result shows that manganese coated sand (MCS) has the greatest As (III) oxidation capacity among all metal oxides at pH 4. Oxidation efficiency of As (III) by IMCS (iron and manganese coated sand) was less than that by MCS. However the total removed amount of arsenic by IMCS was greater than that by MCS.

• 대한환경공학회지
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• 제28권8호
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• pp.878-883
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• 2006

망간코팅모래(MCS)와 철코팅모래(ICS) 21.5 kg씩 동량을 하부 및 상부층으로 2단 충진시킨 파일럿 규모의 여과시스템을 구성하여 3가 비소 함유 인공오염수 처리효율을 조사하였다. 파일럿 장치는 높이 200 cm와 내경 15 cm로 구성되어 있으며, 3가 비소함유 인공 오염수의 반응기 칼럼내 유입은 peristaltic pump를 사용하여 선속도 $5{\times}10^{-3}$ cm/s로 상향류로 시켰으며 148일 동안 여과실험을 실시하였다. MCS 통과지점(중간유출수)과 ICS 통과지점(최종 유출수)에서의 총 비소의 파과는 각각 18일 및 44일 경과 후에 이루어졌고 그 이후 파과가 급격히 진행되었으며 148일이 지났을 때 완전파과가 발생하였다. 비록 MCS 층을 통과한 유출수에서의 총 비소파과는 18일 경과 후에 나타났지만 유출수내의 3가 비소 농도는 61일 동안 50 ppb 이하로 나타났으며 이후에는 급격히 증가되어 나타났다. 이것은 칼럼에 충진된 MCS가 61일 동안 효과적으로 3가 비소에 대한 산화력을 나타내기 때문에 기인한 것이며 MCS 1 kg당 3가 비소 92 mg을 산화처리 함을 나타낸다. 그리고 완전파과가 발생할 때 까지 MCS에 의해서 흡착된 총 비소의 양은 MCS 단위 kg 당 79.0 mg에 해당하였다. 운전기간 동안 반응탑내의 각 지점에서의 시간에 따른 수두의 변화는 크게 나타나지 않아서 ICS 및 MCS를 갖춘 여과시스템은 큰 수두손실 없이 오염수를 장기간 처리할 수 있음을 알 수 있었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.157.2-157.2
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• 2016

Water repellent surfaces may enhance the condensation by efficiently removing the condensed droplets. However, such surfaces may lose their original performance as they are exposed to external mechanical stresses. In this work, we fabricated spray-coated mechanically robust superhydrophobic surfaces using treated titanium dioxide (Type 1) or silica particles (Type 2). Then we compared the mechanical robustness of such surfaces with the silane-coated superhydrophobic surface and PEEK coated surface using a controlled-sand blasting method. The results show that the spray-coated samples can maintain the same level of the contact angle hysteresis than silane-coated superhydorphobic surface after sand blasting at 2 bar. The spray-coating method was applied to the tube type condenser and the condensation behaviors were observed within the environmental chamber with controlled pressure, humidity and non-condensable gas. Previously-reported droplet jumping was observed in the early stage of the condensation event, but soon the droplet jumping stopped and only dropwise condensation was observed since the condensed droplets were pinned on the cracks at spray-coated surfaces. The static contact angle decreases from $158.0^{\circ}$ to $133.2^{\circ}$, and hysteresis increases from $3.0^{\circ}$ to $23.5^{\circ}$ when active condensation occurs on such surfaces. This work suggests the benefits and limitation of spray-coated superhydrophobic condensers and help develop advanced condensers for practical use.