• Geomechanics and Engineering
• /
• v.10 no.5
• /
• pp.689-707
• /
• 2016

Soil stabilization is one of the useful method of ground improvement for soil with low bearing capacity and high settlement and unrequired swelling potential. Generally, the stabilization is carried out by adding some solid materials. The main objective of this research was to investigate the feasibility of stabilization of organic soils and sewage sludge to obtain low cost alternative embankment material by the addition of two different slags. Slags were used as a replacement for weak soil at ratios of 0%, 25%, 50%, 75% and 100%, where sewage sludge and organic soil were blended with slags separately. The maximum dry unit weights and the optimum water contents for all soil mixtures were determined. In order to investigate the influence of the slags on the strength of sewage sludge and organic soil, and to obtain the optimal mix design; compaction tests, the California bearing ratio (CBR) test, unconfined compressive strength (UCS) test, hydraulic conductivity test (HCT) and pH tests were carried out on slag-soil specimens. Unconfined compressive tests were performed on non-cured samples and those cured at 7 days. The test results obtained from untreated specimens were compared to tests results obtained from soil samples treated with slag. Laboratory tests results indicated that blending slags with organic soil or sewage sludge improved the engineering properties of organic or sewage sludge. Therefore, it is concluded that slag can be potentially used as a stabilizer to improve the properties of organic soils and sewage sludge.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.7
• /
• pp.665-675
• /
• 2010

The effects of chemical binders (ladle slag, ordinary portland cement (OPC), hydroxyapatite and calcium hydroxide) on the solidification/stabilization of heavy metals (Cd, Cu, Ni, Pb, Zn) in sewage sludge were evaluated by chemical leaching tests such as EDTA extraction, TCLP and sequential extraction. The results of EDTA extraction showed that heavy metal concentrations in sewage sludge were highly reduced after solidification/stabilization with slag, cement or calcium hydroxide. However, EDTA interrupted solidification/stabilization of heavy metals by hydroxyapatite. The TCLP-extracted heavy metal concentrations in sewage sludge after solidification/stabilization with chemical amendments were highly reduced. However, Cu concentration in the sewage sludge solidified/stabilized with slag, cement or calcium hydroxide increased because the pH of TCLP solution was higher than 7. Mixtures of sludge 1 : slag 0.2 : calcium hydroxide 0.1 (wt ratio) showed the least leachability in batch TCLP and EDTA extraction. The results of sequential extraction (SM&T, formaly BCR) indicated that the distribution of heavy metals changed from exchangable and carbonate fractions to strongly bound organic fraction. It was found that maximum leachate concentrations of Ba, Cd, Cr and Pb from sewage sludge amended with slag and calcium hydroxide were far below US EPA TCLP regulations.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 1998.10a
• /
• pp.541-546
• /
• 1998

To study the possibility of agricultural utilization of the sewage sludge and the converter slag, the chemical properties of soil, the growth response of corn plant and uptake of inorganic nutrients in plant tissues were investigated by application of the composts made of the sewage sludge and converter slag. Uptake of inorganic nutrients in stem and leaf of corn plant were decreased by applications of the composts. The content of heavy metals in soil and corn plant were investigated, but the results of show that the concentrations of heavy metals are much low.

• Journal of the Korean Ceramic Society
• /
• v.40 no.3
• /
• pp.273-278
• /
• 2003

The effects of content and particle size of sewage sludge slag on the sound absorption was investigated and the physical$.$mechanical properties of porous ceramics for sound absorbent material was studied. The physical$.$mechanical properties of specimens have depended on sintering temperature and slag content without particle size effect of slag. As water glass content increase and particle size of slag decrease at the same slag content, physical$.$mechanical properties of them have been improved. The bulk density and compressive strength of specimens with the batch composition of 77∼89 wt% of slag content and particles with 1∼3 mm, and sintered at 1,050$^{\circ}C$ for 2 h were 1.48∼1.71 and 86∼163 kgf/$\textrm{cm}^2$, respectively. The specimens with 1∼3 mm and <1 mm of particles size showed good sound absorption property at low frequency and high frequency region. With increasing thickness of specimens, sound absorption properties at low frequency region were increased.

• Journal of Korean Society of Water and Wastewater
• /
• v.9 no.3
• /
• pp.108-115
• /
• 1995

The feasibility study of using converter slag as a solidifying agent of digested sewage sludge cake has been performed. The availability of converter slag as solidifying agent has been investigated by several trial tests. Based on the trial test results, the optimum mixing ratios of sludge cake and solidification additive are estabilished. Finally the solidification characters of sludge cake are elucidated by SEM and EDS. It is ascertained that converter slag with a small amount of quicklime enhences the solidification. From the result of pH test, overall pH of specimens tends to decrease slowly with curing time. After solidifying specimens had been cured for 7 days, these are water-cured for 24 hours. The weight and strength of all the specimens are nearly the same regardless of the mixed ratios of solidifying agent. The result of leaching tests for four heavy metal ions, Cd, $Cr^{6+}$, Pb and Cu show that the leaching strength becomes below the decision criteria of the specific wastes, respectively. The SEM observation of the delicate structure shows that needlelike crystals appear after solidification which are not observed before. From the EDS analysis, it is found that the main ingredients of needlelike crystals are Ca, Si, Al and O.

• Journal of Korean Society on Water Environment
• /
• v.34 no.3
• /
• pp.316-327
• /
• 2018

Liquid fertilizers made from livestock manure contain high concentrations of nitrogen and phosphorus and thus are used as a fertilizer. However, excessive use of liquid fertilizer causes eutrophication of agricultural land and nonpoint source pollution. In this study, as a means of lowering the nutrient concentrations, struvite ($MgNH_4PO_4{\cdot}6H_2O$) production from the liquid fertilizer was investigated. When liquid fertilizers produced in Gyeonggido were analyzed, its characteristics differed by region and season, but the phosphorus concentration was commonly lower than that of nitrogen. When $K_2HPO_4$ and $MgCl_2$ were added to the liquid fertilizers, the optimal pH for struvite formation was pH 9.5. For environmentally friendly sources of magnesium and phosphate, ferronickel slag (FNS) and sewage sludge ash (SSA) were suspended in deionized water and extracted by sulfuric acid with various mass ratios. The optimum conditions for extracting FNS and SSA were 4.0 M sulfuric acid and 0.35 mass ratio of sulfuric acid to sewage sludge ash, respectively. For forming struvite, 0.233 L of SSA leachate (SSAL) was added into 0.3 L of liquid fertilizer containing 2,586 mg/L of ammonia and 110 mg/L of phosphate, pH was then adjusted to pH 9.5 using 10 M of NaOH. Afterwards 0.333 L of FNS leachate (FNSL) was added to this mixed solution. After a reaction for 1 hr at room temperature, the remaining concentrations of magnesium, ammonium, and phosphate were less than 50 mg/L, 500 mg/L and 150 mg/L, respectively, and 30 g of precipitates were obtained, most of which were struvite.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.2
• /
• pp.114-118
• /
• 2009

With the advance of industrialization and urbanization, a lot of waste has been discharged and treated by incineration. But fly and bottom ashes are generated in this process. In addition, the treatment method to recycle sewage sludge and melting slag is required to manage these wastes. The objective of this research was to prepare of multi-functional brick which were made from MSWI (Municipal solid wastes incinerator) fly ash, sewage sludge and slag. The bricks were made by mixing raw materials and then drying for 24 hours. Next, they were dried for 24 hours at $160^{\circ}C$ and fired for 2 hours. Calcination temperature was changed to discuss the effect of temperature from $1,080^{\circ}C$ to $1,130^{\circ}C$. Compressive strength of a brick was creased with the increase of temperature. To increase mixing ratio of fly ash and slag reduce the compressive strength the optimal condition was the mixing ratio of fly ash : melting slag : sewage sludge : clay as 10 : 20 : 5 : 65 and $1,150^{\circ}C$ of calcination temperature. Compressive strength was obtained as about 41 MPa at this condition.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.04a
• /
• pp.260-265
• /
• 2004

Acid mine drainage(AMD) is one of the most serious environmental concerns associated with the mining industry around the world. The objective of this study is to assess the potential of sewage sludge as a carbon source for sulfate reducing bacteria and waste lime and steel slag as a neutralize agent for acid mine drainage bioremediation for use in permeable reactive materials. The study was performed using synthetic AMD in six column experiments. The effluent solution was systematically analysed throughout the experiments. The results of the study indicated that sewage sludge, waste lime and steel slag were the most effective for the AMD treatment as a permeable reactive materials.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.1396-1399
• /
• 2005

Gas permeability of the solidified sewage sludge needs to be characterized in order to use as a large-scale landfill cover material. Four different types of the samples were prepared for gas permeability experiments: (1) granite soil, (2) dried sewage sludge, (3) solidified sewage mixed with slag and (4) solidified sewage mixed with granite soils. The experimental instrumentation and measurement devices were newly designed and created to effectively evaluate gas permeability of the samples.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.9
• /
• pp.857-861
• /
• 2010

Recently photochemical smog has become a serious urban air pollution. And VOC is the major pollutant for it. With the advance of industrialization and urbanization, MSWI fly ash and sewage sludge and melting slag were generated. It is necessary to de-toxificate ashes, because they contain many toxic constituents and probably lead to contaminate the environment. The objective of this research was to prepare multi-functional brick which is able to remove VOCs in ambient air. The bricks were made of MSWI fly ash, sewage sludge and slag. The benzene adsorption experiment by brick was acted to evaluate its adsorptivity. And also photocatalyst material was coated to enhance its adsorptivity and the endurance on the brick. According to the result, the benzene showed 74~96%. The removal efficiency was increased and the breakpoint time was lengthened by coating a brick.