• Resources Recycling
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• v.8 no.1
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• pp.18-22
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• 1999

In order to utilize incineration fly ash of industrial wastes as resources, we present the recovery and separation of metals included in the fly ash by leaching with aqueous solution A great quantity of Cu, Pb, and Zn as well as a small amount oftoxic heavy metals are contained in the leach liquor of the fly ash, and the concentration of the ingredients of the fly ash depends on the industrial wastes which are fed into incinerators. In this paper, sequential Ieachiog operations are conducted using $H_2O$, $H_2SO_4$, $(NH_4)_2CO_3$ and NaOH as Icachants. Water soluble copper salt was leached by $H_2O$, Zn and Pb were separated by the NaOH leach liquor, and water insoluble copper was selectively leached as chelate ion with the $(NH_4)_2CO_3$ leach liquor of the third Ieaehant. Results show that the reduction percent of the fly ash in the leaching steps using $H_2O$, $H_2SO_4$, and $(NH_4)_2CO_3$ is 77%, and the other leaching procedures lose the weight of fly ash by above 60%.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 1998.06a
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• pp.33-37
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• 1998

본 연구에서는 다공성 지하에서 침출수에 지하 환경의 오염 및 대처 방안의 효과를 수치적으로 예측하였다. 연구대상으고 매립지 지하에서의 침출수의 흐름은 Darcy 법칙을 사용하여 해석하였고, 오염물질의 이동은 이산-분산 모델에 수착의 효과를 고려하여 해석하였다. 침출수의 흐름 및 오염물질의 이동 방정식을 2차원 계를 대상으로 하여 Galerkin유한 요소법을 사용하였다. 수치해석 결과 침출수의 흐름은 매립지 제방 근처에서 강하게 일어나는 것으로 나타났다. 연직 차수막은 오염물질의 이동을 막는데 별 도움을 주지 못하나, 수착은 오염물질의 이동을 지연시키는데 상당한 효과가 있는 것으로 보인다.

• Journal of Soil and Groundwater Environment
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• v.7 no.1
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• pp.33-40
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• 2002

The study was performed to evaluate the effect of landfill leachate on the hydraulic conductivity of Geosynthetic Clay Liner (GCL) with two types of leachate. GCL used in waste landfills have a significant ability as a barrier material, however, they also have a potential danger when exposed to some organic and inorganic leachate as well as humic materials. In this study, swelling tests and hydraulic conductivity tests were performed to evaluate the effect of humic materials and landfill leachate on the hydraulic characteristics of the GCL. The result of swelling tests showed that the amount of humic materials and high electronic conductivity caused a decrease of the swelling of bentonite. This is expected to increase the hydraulic conductivity of GCL. The increasing of hydraulic conductivity observed for GCL permeated with 0-leachate was significantly higher than that of Y-leachate. This result shows that humic materials are obviously affecting with the increasing of hydraulic conductivity of GCL.

• The Journal of Engineering Geology
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• v.5 no.3
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• pp.259-276
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• 1995

Electrical soundings and profilings were conducted for mapping the leachate in the region of Nanji - Do Landfill site. The results of electrical surveys conducted in the landfill area show that the basal leachate is formed at the height about 30 m above the mean sea level and that there is abundant floating leachate over the basal leachate. The surveys conducted around the landfill reveal that the groundwater which may be contaminated by the leachate from the landfill flows to the Han River. The top of the basement rock in this area has been severely affected by polluted groundwater. The layer which is thoroughly saturated with leachate in this region has the very low resistivity value below 10 ohm - m and this low resistivity value indicates that the groundwater and geology are severely contaminated by the leachate and wastes of the landfill.

• Resources Recycling
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• v.29 no.5
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• pp.48-54
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• 2020

Sulphuric acid (H₂SO₄) leaching and hydrolysis were experimented for the recovery of titanum dioxide (TiO₂) from the water-leached residue followed by soda-roasting spent SCR catalysts. Sulphuric acid leaching of Ti was carried out with leachate concentration (4~8 M) and the others were fixed (temp.: 70 ℃, leaching time: 3 hrs, slurry density: 100 g/L, stirring speed: 500 rpm). For recovering of Ti from the leaching solution, hydrolysis precipitation was conducted at 100 ℃ for 2 hours in various mixing ratio (leached solution:distilled water) of 1:9 to 5:5. The maximum leachability was reached to 95.2 % in 6 M H₂SO₄ leachate. on the other hand, the leachability of Si decreased dramatically 91.7 to 3.0 % with an increase of H₂SO₄ concentration. Hydrolysis precipitation of Ti was proceeded with leaching solution of 8 M H₂SO₄ with the lowest content of Si. The yield of precipitation increased proportionally with a dilution ratio of leaching solution. Moreover, it increased generally by adding 0.2 g TiO₂ as a precipitation seed to the diluted leaching solution. Ultimately, 99.8 % of TiO₂ can be recovered with the purity of 99.46 % from the 1:9 diluted solution.

• Economic and Environmental Geology
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• v.45 no.3
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• pp.265-276
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• 2012

Current study includes the analysis of mine tailings and leachate water and prediction of species originated from the tailings. The variation of contaminants were measured upon the distance from the tailings to the nearby stream. The ions concentration was highest at the tailings and pit mouth and it becomes lower as it goes far away from the origin. This is the reason that the leachate was diluted with the uncontaminated stream water. The tailings were mainly classified into reddish one and yellow one. The main mineral of reddish tailings were quarts, illite, plumbojarosite and a small amount of sphalerite. The main mineral of yellow tailings were muscovite, quarts, plumbojarosite, and a small amount of chalcopyrite and sphalerite. Pb and Zn were found in the leachate in high concentration and become the major contaminants. These come from the dissolution of plumbojarosite and sphalerite contained in the mine tailings.

• Journal of the Korean Society of Groundwater Environment
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• v.1 no.1
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• pp.1-5
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• 1994

The contaminant migration through the subsurface of Nanjido landfill is studied using a 2-D finite element model of contaminant transport. The leachate mounding caused by the installation of partial slurry wall around the pheriperal area of the Landfill is analysed using the finite difference model of groundwater flow. Model parameters were validated using in-situ concentration data and the behavior of the transport next 30 years is predicted. The sensitivities of chloride concentration by the change of model parameters, e.g. leachate mounding in the Landfill and the dispersivity are analysed. The results of the analyses show that the maximum chloride concentration level near Han River caused by the leachate of Nanjido Landfill would be 1488mg/1 and comes 17 years after the landfill closure. Increase of the leachate concentration is caused by the increase of both the leachate mounding and the dispersivity. However, the rate of concentration increase becomes higher with the rise of leachate mounding level, while it tends to converge a certain concentration with the increase of the dispersivity.

• Economic and Environmental Geology
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• v.41 no.6
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• pp.657-672
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• 2008

The purposes of this study are to investigate the hydrogeochemical characteristics of groundwaters around Keumsan municipal landfill, and to evaluate the contaminant dispersion from the landfill and its environmental impact. To achieve these goals, groundwater quality logging, hydrochemical analysis, multivariate statistical analysis, and contaminant transport modeling were performed. The water quality logging indicated a leaking from the landfill at the depth of 4-12m around a leachate sump. Electrical conductivity data indicated that groundwaters within 70-100m from landfill were affected by the landfill leakage. Principal components 1 and 2 obtained from principal components analysis (PCA) reflect the influence of leachate and the characteristics of aquifer media, respectively. The results of principal component analysis also indicated the natural attenuation processes such as cation exchange, sorption, and microbial biodegradation. The modeling results showed that groundwater flow westward along a valley from the landfill and contaminants transport accordingly.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.1
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• pp.31-40
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• 2016

In this study, mesophilic anaerobic digestion of source separated food waste was carried out by leachate recirculation system and methane gas was produced. Two systems - system A and B were fabricated and placed within water bath to maintain $36^{\circ}C$. Each system was comprised of an anaerobic bioreactor and a leachate tank. Leachate in bioreactor was separated through the screen located at 30 mm above the bottom and a pump was installed to transfer collected leachate to the leachate tank. Everyday, 2.5 L of the leachate was pumped from the bioreactor to the leachate tank for 30 min and transferred leachate was pumped back to the top of the bioreactor for 30min, sequentially. Source separated food waste used for this experiment was washed by water before transferring to the laboratory. Transferred food waste was warmed to $36^{\circ}C$ before being fed to bioreactors. System A was fed to 49.1 g VS (Volatile Solids) and System B was fed to 54.0 g VS at every two weeks, respectively. $NH_4{^+}-N$ and salinity were monitored to see the inhibition toward anaerobic bioreaction and it was found that concentrations of these materials were not high enough to affect the bioreaction. Although the food waste was fed biweekly for 112 days and 140 days at system A and B, respectively, there was no sludge withdrawal from each system. Average methane productions rates were 0.439 L $CH_4/g$ VS and 0.368 L $CH_4/g$ VS for system A and B, respectively.

• Journal of Animal Environmental Science
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• v.8 no.3
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• pp.145-152
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• 2002

This experiment was conducted to investigate the efficiency and compatibility of the coagulation and settling processes of leachates from the compost of two swine farms. And results obtained are as follows : 1 In the farm A where $COD_{Cr}$, $COD_{Mn}$ and $BOD_5$ of original leachate were 4,400, 2,950 and 87mg/l, respectively, the rate of coagulation and settling process was more efficient in the leachate treated with the conjugate of Alum and cation polymer than that of Alum and anion polymer. The concentrations of BOD$_{5}$, T-N and T-P of the effluent after treatment with the conjugate of Alum and cation polymer under the optimum condition were 19, 257.5 and 0.4mg/l, respectively which are under the governmental regulation level. 2. In the farm B where $COD_{Cr}$, $COD_{Mn}$ and $BOD_5$ of original leachate were 4,720, 3,040 and 95mg/l, respectively, the conjugate of $FeCl_3$, 1,500mg/l and cation polymer 10mg/l ($FeCl_3$+FO4240) was most effective coagulation and settling agent compared with the others. The concentrations of BOD$_{5}$, T-N and T-P of the effluent after treatment with $FeCl_3$+FO4240 were 15.3, 829.4 and 2.8mg/l, respectively. And the concentration of T-N was higher than the governmental regulation level, presumably because of too high concentration of NH$_4$$^{+}$-N in the leachate.