Materials Science Forum Vols. 544-545

Abstract: Bottom ash contains many ferrous materials (e.g. ferrous metals, Fe3O4, Fe2O3, FeS). In addition, ferrous metals include the heavy metals, as Ni and Cr have a chemical attraction to iron, with Cu used to coat with Ni and Cr metals for polishing or to prevent corrosion. For ferrous metals, the formation of a Fe3O4-Fe2O3 double layer (similar to pure Fe) was found during air-annealing in an incinerator (1000
C). A strong thermal shock, such as that which takes place during water-cooling of bottom ash, leads to the breakdown of this oxidation layer, facilitating the degradation of ferrous metals and the formation of corrosion products. Therefore, Fe-ion (heavy metal) oxides can be formed on ferrous metals, and magnetic separation can separate it from bottom ash. Thus, in this study the objection is to investigate the separation ratio of heavy metals by magnetic separation along with the mineralogical formation of Fe-ion (a heavy metal).

Abstract: Lab-scale batch experiments using several 150-L transparent acrylic reactors were conducted to develop optimum capping materials that can capture phosphorous released from polluted lake sediments. The sediment used in the experiment was very fine clay (7.7 Φ in mean grain size), and organic carbon (Corg) content was as high as 2%. Four kinds of batches with different capping materials; powdered-gypsum (CaSO4·2H2O), granular-gypsum, sand, composite material (gypsum+sand), and one control batch were operated for 45 days. Phosphorous fluxes released from bottom sediments in the control batch were estimated to be 4.3 mg·m-2·d-1, while 0.9 mg·m-2·d-1, 1.0 mg·m-2·d-1, 2.2 mg·m-2·d-1, and 0.5 mg·m-2·d-1 in the batch capped with powdered-gypsum, granular-gypsum, sand, and composite material, respectively. The results obtained from lab-scale batch experiments show that there were 80% reduction of phosphorous for some materials such as powdered-gypsum, granular-gypsum, and composite material, whereas sand only about 50%. Increase in apatite-P fraction (48% → 80%) in the gypsum batches, compared to the control batch, indicates that abundant Ca2+ and SO4 2- ions from the gypsum added into oxygen-depleted sediment surface might have supplied abundant oxygen by reducing the sulfate ions very actively, resulting in Ca-P precipitates.

Abstract: With the development of economic status and living standard, eutrophication of lakes has become serious problem. Due to continuous inflow of external nutrients into lakes, phosphorus, a critical nutrient for lake production, has been accumulated in large amount in the sediment. Thus phosphorus rich sediment acts as an internal nutrient source and reduction of phosphorus release from the sediment is very important for restoring eutrophied lakes. Among the various strategies to restore lakes, in-situ capping is known as an attractive and cost-effective method for remediation of contaminated sediments. In this paper, lab-scale batch column test was conducted to evaluate the characteristics of capping materials on reduction of phosphorus release from the sediment. Three different types of capping materials including sand, zeolite, and natural gypsum (CaSO4·2H2O) were used. Each column was filled 7 cm with sediment and covered by 1 cm of sand, zeolite, and natural gypsum, respectively. The change of water quality in supernatant solution was monitored for 10 days in each column. From the results, addition of gypsum showed higher treatment efficiency than sand and zeolite. In case of the capping with gypsum, it was found that the phosphorous release from the sediment could be reduced by around 90% as compared with untreated column. On the contrary, phosphorus reduction efficiencies of sand and zeolite were 60% and 14%, respectively. Moreover, in case of the capping with sand and zeolite, sudden increase of phosphorus concentration was observed with the generation of CH4 gas from sediment. Methanobacterial ebullition is one of the important factors for transporting phosphorus from sediment into water column. It was reported that the addition of gypsum could reduce the progress of methanogensis by supplying sulfate into sediment, which enhances the activity of sulfate-reducing bacteria (SRB) and mineralization rate of organic matter.

Abstract: To recycling the EAF dust as a ceramic raw material, the leaching concentrations of heavy metals (Zn, Pb, Cr, Cd) were analyzed with various pH and mixing ratios for EAF dust-clay bodies. The evaporation amounts of the some heavy metals were evaluated by measuring their total concentrations in the sintered bodies of EAF dust-clay mixtures with various mixing ratio and sintering temperature. TCLP test was conducted for evaluating the chemical stabilities of the heavy metal elements. The heavy metals in EAF dust are 'amphoteric metal' and leached a little at pH10. The leaching concentrations of heavy metal ion were effectively decreased by the formation of PSHP when adding the clay to the EAF dust and controlling the pH of the slurry at 12. Evaporation of heavy metal components were increased with increasing the sintering temperature and the contents of EAF dust. The leaching concentrations of heavy metal components were decreased with increasing the clay content and temperature.

Abstract: Pollutants such as heavy metals and PAHs (Polynuclear Aromatic Hydrocarbons) in stormwater runoff are a major problem in urban areas because these pollutants are discharged directly, in most cases without any treatment, into the receiving environments like river and lake. Since many of the pollutants are associated with suspended particulate materials in stormwater, SS (suspended solids) is of acknowledged importance in stormwater runoff treatment by BMPs (best management practices). Filtration, which is commonly used for removing particulate matter in stormwater structural BMPs, depends on various factors (e.g., filter media size, flow rate, bed depth, filter surface properties, etc). Especially, the characteristics of filter media are important factor affecting removal efficiency of pollutants and replacement period of filter media in filtration performance. In this study, EPM (expanded polypropylene media) as a filter media was manufactured at different expansion ratios (i.e., 5, 10, 15 times) and tested in the up-flow filtration for removing pollutants in urban stormwater runoff. The specific surface area of EPM10, EPM15, EPM30, EPM54 was 0.760 m2/g, 0.799 m2/g, 0.812 m2/g, 0.845 m2/g, respectively. The SS removal efficiency (64.1%) by EPM media was higher than that (44.2%) by sand media. In case of EPM10 media, it took 175min of removal rate of filtration system to be approached under 50% and EPM15 media was spent 110min. However, the SS removal efficiency of EPM15 was over 10% higher than that of EPM10. The CODCr removal efficiency of EPM media was also increased with increasing expansion rate. The experimental results in this work show that pollutant removal efficiency by EPM media was increased with increasing expansion ratio but replacement period of media was decreased. EPM media are expected to adsorb non-biological organics like PAHs owing to its hydrophobicity.

Abstract: A 16Mb 1T1C FeRAM device was successfully fabricated with the lead-free BLT capacitors. The average value of the switchable polarization obtained in the 32k-array (unit capacitor size: 0.68 μm2) BLT capacitors was about 16 μC/cm2 at the applied voltage of 3V and the uniformity within an 8-inch wafer was about 2.8%. But random bit failures were detected during the measuring the bit-line signal of each cell. It was revealed that the grain size and orientation of the BLT thin film were severely non-uniform. Therefore, the grain size and orientation was optimized by varying the process conditions of nucleation step. The random bit failure issue was solved by adopting the optimized BLT film. The cell signal margin of the optimized FeRAM device was about 340 mV.

Abstract: The artificial lightweight aggregate (ALA) was fabricated using a sewage sludge produced from a municipal wastewater, and impact sound reduction analysis for concrete slab made with the ALA was done. Specific gravity of ALA decreased with the sewage sludge content due to the gas bloating caused by melt films on the surface of ALA, which is formed easily because of low temperature melting P2O5 and modifiers, CaO, MgO and K2O contained in the sewage sludge. And water absorption of ALA increased with the sewage sludge content owing to open pores which were formed by connecting an inside pore to a surface. A specific gravity of 10mm diameter ALA was lower than that of 7mm ALA since a trapped gas could not escape from the core to the surface of ALA due to longer moving distance. The ALA containing 20 wt% sludge sintered in a electric furnace showed a specific gravity 15% lower and water absorption 50% higher than that of ALA sintered in a rotary kiln. It might be attributed to easy release of gases during the pre-heat zone (600-1000oC) in the rotary kiln, resulting in densification of ALA. Light and heavy weight floor impact sound of concrete slab made with ALA were 63-72dB and 44-76dB respectively, similar to a general concrete slab. The unit weight of concrete slab made with ALA, however, was 18% lower than that of general one owing to the lightweight of ALA, so it could be suitable to applying for high-rise building.

Abstract: Plasticity indexes (PI) of clay bodies including bottom ashes (BA) and various wastes by using Atterberg limits were measured for the effective recycling of coal bottom ashes from the power plant. Coal bottom ash (BA)-red clay (RC or simply clay), dredged soil (DS)-BA, coal fly ash (FA)-red clay, DS-FA were used as samples for the PI measurement. From the comparison of clay bodies with BA and DS, PI of DS-BA body was higher than that of BA-red clay body because liquid limit (LL) was high and plastic limit (PL) of DS-red clay was low, respectively. Comparing clay bodies with FA and BA, PI of BA-clay body was higher than that of FA-clay body because both LL and PL of BA-clay body were low. When stone ashes and sewage sludge (SS) were added to BA-clay bodies, PI decreased with increasing both stone ash and sewage sludge contents. It is concluded that the measurement of plasticity index can be used as an indicator of forming performance of green bodies with various compositions.

Abstract: The anti-corrosion properties of and catalytic effect of crosslinking on Bi2O3 were investigated in this study. The results of double rubs test with methyl ethyl ketone, cyclic corrosion test and FT-IR with ATR show that Bi2O3 performs anti-corrosion property and catalytic effect of crosslinking of resin.

Abstract: A direct analytical technique was developed and tested for correct estimation of recovery of Eco-elements such as Li, B, Br, in the seawater, and three processed seawaters from Hanjoo Co. Ltd. The reliability of recovery technique and the correct estimation of total recoveries become a major interest before the launch of pilot plant. High matrix solutions are frequently affected in analyte response during instrumental analysis as the concentration of major component changed drastically. To overcome such a complication during standard sample preparation and a better application in pilot plant, a modified matrix matching standard addition method was developed and the reliability was checked. The detection limit of elements in several seawaters analyzed by applying the modified matrix matching standard addition method were 0.144 – 0.258-g/dm3 for lithium, 0.0.013 – 0.18mg/dm3 for boron, and 4.23 – 17.8mg/dm3 for bromine. The instrumental analysis was carried by AAS for lithium and ICP-AES for boron and bromine.