In-Cheol Lee

Field experiments on remediation of coastal sediments using granulated coal ash.

Field experiments were carried out to evaluate the effect of Granulated Coal Ash (GCA) on remediation of coastal sediments in terms of removing phosphates and hydrogen sulfide. Phosphate concentrations in the sediment were kept below 0.2 mg/l after the application of GCA, whereas those in the control sites increased up to 1.0 mg/l. The concentration of hydrogen sulfide in the sediment was maintained at almost zero in the experimental sites (GCA application sites) for over one year, whereas it ranged 0.1-2.4 mg S L(-1) in control sites. Meanwhile, individual number of benthos increased in the experimental sites by several orders of magnitude compared to the control sites. The major process involved in hydrogen sulfide removal by GCA was thought to be the increase in pH, which suppresses hydrogen sulfide formation. From our findings, we concluded that GCA is an effective material for remediating organically enriched coastal sediment.

Temperature-Compensated Damage Monitoring by Using Wireless Acceleration-Impedance Sensor Nodes in Steel Girder Connection

Temperature-compensated damage monitoring in steel girder connections by using wireless acceleration-impedance sensor nodes is experimentally examined. To achieve the objective, the following approaches are implemented. Firstly, wireless acceleration-impedance sensor nodes are described on the design of hardware components to operate. Secondly, temperature-compensated damage monitoring scheme for steel girder connections is designed by using the temperature compensation model and acceleration-impedance-based structural health monitoring methods. Finally, the feasibility of temperature-compensated damage monitoring scheme by using wireless acceleration-impedance sensor nodes is experimentally evaluated from damage monitoring in a lab-scaled steel girder with bolted connection joints.

Ecological Restoration Index for Evaluation of Artificial Salt Marsh

Abstract Coastal areas of ecological importance, like tidal flats and salt marshes, are gradually decreasing because of large-scale coastal development projects, land reclamation, and so on. The Nakdong estuary is the most developed estuary in South Korea. The development of artificial tidal flats and salt marshes has been promoted as mitigation countermeasures. Previous studies evaluated artificial tidal flats and salt marshes for their degree of restoration of natural sites. In this paper, an in situ pilot plant of a tidal flat and a salt marsh was conducted to monitor and quantify bio-chemical indicators (biodiversity, population, and biomass of macro benthos; survival ratio of reeds; number of heterotrophic bacteria) and physicochemical characteristics. The content of dredged soil was varied to assess the difference and similarity between the natural and dredged soil. The degree of restoration and creation of ecological environmental zones is evaluated quantitatively with the use of a restoration index. The utility of this restoration index and the beneficial use of dredged soil are demonstrated for this pilot plant.

Application of Granulated Coal Ash for Remediation of Coastal Sediment

본 논문에서는 석탄회 조립물을 이용한 저질개선 기술의 안전성 및 저질개선기구에 대해 논하고, 일본 카이타만 석탄회 조립물 피복구간에서의 저질개선효과에 대해 검토하였다. 석탄회 조립물의 중금속 농도 및 용출량은 일본의 환경기준을 만족하는 것으로 조사되었으며, 석탄회 조립물의 저질개선기능은 다음과 같이 요약할 수 있다. (1) 인산염 및 황화수소의 제거 (2) 산성 저질의 중화 (3) 투수성의 증가 및 이로 인한 환원상태 저질의 개선 (5) 지반강도의 증가 (6) 부착성 조류의 서식 기반. 일본 카이타만에서 실시한 현장실증실험 결과로부터 연안저질의 pH중화, 인산염 및 황화수소농도 감소 등 석탄회 조립물의 저질개선효과가 검증되었으며, 이에 따른 저서생물의 증가가 확인되었다. 석탄회 조립물을 이용한 연안저질의 개선기술이 실용화 된다면 오염저질의 정화에 소요되는 비용의 절감은 물론 산업부산물인 석탄회의 재활용에 기여할 것으로 기대된다.Abstract − This paper aims to explain the safety assessment and remediation mechanism of Granulated Coal Ash(GCA) as a material for the remediation of coastal sediments and to evaluate the improvement of the sediment inKaita Bay, where GCA was applied. The concentrations of heavy metal contained in GCA and the dissolvedamounts of heavy metal from GCA satisfied the criteria for soil and water pollution in Japan. The mechanisms onthe remediation of coastal sediments using GCA is summarized as follows; (1) removal of phosphate and hydro-gen sulfide (2) neutralization of acidic sediment (3) oxidation of reductive sediment (4) increase of water perme-ability (5) increase of soil strength (6) material for a base of seagrass. From the results obtained from the fieldexperiment carried out in Kaita Bay, it was clarified that GCA is a promizing material for remediation of coastalsediment. This remediation technology can contribute to promote waste reduction in society and to decrease cost ofcoastal sediment remediation by applying GCA in other polluted coastal areas. Keywords: Granulated Coal Ash(석탄회조립물), Remediation of Coastal Sediment(연안저질개선), HydrogenSulfide(황화수소 ), Phosphate(인산염)

Quantitative Measurement on Removal Mechanisms of Phosphate by Class–F Fly Ash

ABSTRACT The role of Class-F fly ash in the removal of phosphate from aqueous solutions and the removal mechanism were quantitatively investigated. The relative contributions of precipitation and adsorption with various pH conditions showed that precipitation was predominant under alkaline conditions, whereas adsorption was effective under acidic conditions. The precipitation accounted for 79% of the total phosphate removal without adjusting the pH of the solution. This result suggests that the phosphate was predominantly removed by precipitation with fly ash, and that adsorption on hydroxylated oxides may have contributed to the removal of phosphate. The precipitate was revealed to be calcium hydrogen phosphate (CaHPO4) from X-ray absorption fine structure analysis. The adsorption process was expressed well by the Freundlich isotherm and phosphate adsorption by fly ash is favorable (n = 1.308).

A Study on Phosphate Removal Efficiency by Pre-Treatment Conditioning of Oyster Shells

In this study, we investigated phosphate removal efficiency according to pretreatment (pyrolysis temperature, pyrolysis time, particle size) of oyster shells as a basic study for their recycling. And XAFS analysis and isothermal adsorption experiments were performed to investigate the phosphate removal characteristics of oyster shells. As a result, the removal efficiency was good at 600°C pyrolysis temperature with 6 hour pyrolysis time and 0.355 ~ 0.075 mm particle size. Isothermal adsorption experiments showed that the Langmuir model is suitable for adsorption of oyster shells. XAFS analysis showed that calcium phosphate formed on the oyster shell pyrolyzed at 600°C. In other words, it was confirmed that the formation of calcium phosphate by the calcium ion elution of the oyster shell contributes to the decrease of phosphate concentration.

A pilot study on remediation of muddy tidal flat using porous pile

In order to prove that porous piles are effective in remediating muddy tidal flat sediments and increasing the biomass, field experiments were carried out at the tidal flat of a brackish river located in Hiroshima City, Japan. Porous piles with a diameter of 16cm and height of 50cm were installed in the muddy sediment that covers the sand layer of the tidal flat. After installation, concentrations of dissolved oxygen in interstitial water in and around the porous piles increased to a maximum concentration of 6mg/l due to enhancement of the groundwater flow. The increase of dissolved oxygen in the interstitial water produced a decrease in the concentration of ammonia and an increase in the individual number of benthos at the porous pile site. From these results, we concluded that the porous pile is an effective technology for remediation of muddy tidal flats.

An Influence of Salinity on Resuspension of Cohesive Sediment

ABSTRACT Kim, K.H.; Yoon, H.S., Lee, I.C. and Hibino, T., 2016. An influence of Salinity on Resuspension of Cohesive Sediment. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 68–72. Coconut Creek (Florida), ISSN 0749-0208. Field observations were carried out at Tenma River which passes through Hiroshima City to investigate turbidity variations in various salinity conditions. And resuspension experiments with cohesive sediments were conducted using an unidirectional flow channel with varying salinity. Changes in the sediment strength due to the salinity variation were evaluated by using liquid limit test. It was found that turbidity varied in reverse proportion to the salinity in the Tenma River. Also, increases in salinity reduced the resuspension flux and enhanced the settling velocity of cohesive sediment by enhancing the cohesion between the particles. From the results obtained above, we concluded that salinity is an important factor in the transport of cohesive sediment in addition to shear stress and water content in estuaries and blackish rivers.

Remediation of Muddy Tidal Flat using Porous Pile

Field experiment were carried out to investigate the formation of ground water flow and remediation of muddy tidal flat by installation of porous pile at the tidal flat of brackish river located in Hiroshima City, Japan. After the installation of porous pile, the concentrations of Dissolved Oxygen (DO) in the interstitial water in the porous pile increased with maximum concentration of 4 mg/L due to a formation of groundwater flow. It was observed that a increase in Oxidation Reduction Potential (ORP) and a decrease in Ignition Loss (IL) in the porous pile site and these must be caused by the increase of dissolved oxygen in the interstitial water. From these results obtained above, it is concluded that the porous pile is an effective technology for remediation of muddy tidal flats.