• Journal of Korea Soil Environment Society
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• v.4 no.1
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• pp.85-96
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• 1999

Biofiltration is an attractive technique for elimination of VOCs and odorous compounds from low-concentration, high-volume waste gas streams because of its simplicity and cost-effectiveness. The objective of this study was to estimate the removal characteristics of Odorous Compounds including $H_2$S, $NH_3$End BTEX in MSW landfill gases. This Study was conducted at Nanjido landfill site. A compost from the Nanjido composting facility was used as a filling material for biofiltration. Extracted landfill gases were injected into biofilter reactors after mixing with air. Experiments were performed in an incubator being set to $20^{\circ}C$ $H_2$S concentrations were monitored at the depths of 25, 50, 75 and 100cm from the bottom Of the biofilter reactors. 98% of $H_2$S was removed at the filling depth of only 25cm. NH$_3$removal rate was about 85%. Toluene removal rate was the highest among BTEX. Significant pH drop of a filling material was not observed during the biofilter operation of 1 month. Without mixing the landfill gas stream with all, the removal rate of $H_2$S decreased down to 30%.

• Economic and Environmental Geology
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• v.32 no.2
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• pp.177-187
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• 1999

Gravity, magnetic and VLF surveys were conducted to investigat the structural stability and hazards associated with the Ubong landfill in Pohang City, which has been built to dump industrial wastes. In 1994, the collapse of a bank happened in the 6th landfill site due to sudden heavy rain, and a large quantity of waste materials flowed out to the nearby landfill sites, factories and roads. We used $10{\times}10m$ resolution DEM data for gravity reductions. The maximum variation of the terrain effect in the survey area is about 0.5 mgal and the terrain effect is large in the vicinity of bank boundary. The Bouguer gravity anomaly map shows the effect due to the variatino of thickness and type of waste materials. The small negative gravity anomaly increases from the 9th site to the 6th site. The small negative gravity anomaly of the 9th site reflects the relatively shallow dumping depth of average 14.5 m in this site and increased density of waste materials by the repeated stabilization process of soil overlaying. The 6th site is located at the center of the former valley and rainfall and groundwater are expected to flow from south-east to north-west. Therefore, considering the previous accident of mixing waste and bank materials at the north-west boundary of the landfill, there may be some environmental problems of leakage of contaminated water and bank stability. The complex inversion technique using Simulated annealing and Marquardt-Levenberg methods was applied to calculate three-dimensional density distribution from gravity data. In the case of 6th site, it is apparent that the landfill had been dumped in four sectors. However, most part of the 9th site and showed that high magnetic industrial wastes were concentrated in the 6th site. The result of magnetic survey showing low magnetic anomalies along the boundaries of two sites is similar to that of gravity data. The VLF data also reveals four divided sectors in the 6th site, and overall anomaly trend indicates the directio of former valley.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.8
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• pp.586-591
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• 2013

This experiment was performed to enhance $CH_4$ purity of landfill gas by applying gas separator membrane for purified nitrogen gas production. 1:6 area ratios of $1^{st}$ to $2^{nd}$ membrane module was suitable for $CH_4$ recovery. After separation membrane system was installed, 249 tries were performed. Average permeability for $CH_4$ was 28.4% and for $CO_2$ was 94.3%. This can explain nitrogen gas separator membrane can be applied to collect $CH_4$ from LFG. However, nitrogen permeability only reached up to 16.5%. Therefore, the final purified landfill gas concentration was rounded up to 69.7% for $CH_4$, 4.3% for $CO_2$ and 26.0% for $N_2$. For the high degree of $CH_4$ purity, $N_2$ should be kept at least under 2.0% by controlling air inflow to landfill.

• Economic and Environmental Geology
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• v.31 no.1
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• pp.59-68
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• 1998

Gravity, magnetic and VLF surveys were carried out to investigate the dimension, nature and stability of the waste materials filled in the Seokdae landfill, Pusan. The Seokdae landfill, which is located in a former valley, was used as a dump for mainly domestic-type waste materials for 6 years from 1987. The landfill site is classfied into A, B, C and D areas according to the sequence of dumping period. The Bouguer gravity anomaly map shows maximum variation of 3.1 mgals on the landfill and its general appearance has close relation with the thickness of waste filled. The local variation of anomaly, however, reflect the degree of compactness of waste materials which may be affected by the nature of waste and dumping time. In the case of area A, where dumping process was terminated at the very last stage, most part show negative anomaly compared to other areas. We think that the composition of the waste materials in the area A is high in leftover food and paper trash and they are still in uncompacted condition. In area B, the general trend of variation of gravity anomaly is appeared to be high anomaly in northern part and decrease to the southern part. This is well matched with the prelandfill topography of the landfill site. The southern part of area B is located in the center of valley and its present surface is comparatively rugged, which may be due to the differential settlement of deep burried waste. The thickness of waste in area C is relatively thin, but the gravity anomaly appears to be low. Considering the present condition of surface, it can be inferred that low density wastes such as leftover food were mainly filled in this area. Area D, as in the case of area B, shows gravity anomaly that has close relation with the prelandfill topography. Magnetic data show the variation of total field intensity varies in the range of 46600~51000 nT, and reach maximum anomaly of 4400 nT. The overall pattern of magnetic anomaly well reflects the distribution of magnetic materials in the landfill. The result of VLF survey reveals several low resistivity zones, which may serve as underground passages for contaminant flow, in the area C located near the small Village.

• Journal of Soil and Groundwater Environment
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• v.12 no.3
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• pp.75-80
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• 2007

This study evaluated groundwater quality around an uncontrolled landfill in W sity, Korea, which was monitored for about two years (2005-2006). Parameters of concern include redox-sensitive indicators such as pH, DO, EC, ORP, DOC (dissolved organic carbon), NH3, NO3 and SO4. About 10 years have elapsed after closing dumping of municipal wastes in the landfill. Leachates showed widely varying concentrations in COD(136${\sim}$263 mg/L), T-N(121${\sim}$186 mg/L), and NH3-N(14${\sim}$369 mg/L). Groundwater at the immediate downgradient of the landfill showed weakly acidic pH condition but very high levels of EC (3,000-4,000 ${\mu}S/cm$), which indicated that the groundwater was largely affected by the landfill leachate. Cl, a conservative ion, showed over 200 mg/L at the landfill border, but a gradually decreasing level with distance from the landfill, representing dispersion and dilution (natural attenuation) due to mixing with surrounding groundwater and replenished rainwater. Redox potential showed negative value at the landfill border but it increased up to 350 mV at downgradient wells, which indicated conversion of redox condition from reducing oxic ones. Ammonia, was largely enriched at most of the monitoring wells and its level greatly exceeded drinking water standard. In summary, all the parameters evidenced occurrence of natural attenuation with distance and with time but further monitoring is still required.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.9
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• pp.793-802
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• 2009

Adsorption properties were estimated for the organic silicon compounds (siloxanes) in an actual landfill gas (LFG) using adsorbents such as coconut activated carbon, coal activated carbon, silica gel, sulfur adsorbent, carbonized sludge, and molecular sieve 13X. Coconut activated carbon showed the highest removal efficiency of more than 95%. The desorption of hexamethyldisiloxane (L2) from the adsorbent, however, resulted in the remarkable concentration variation of the compound in the treated gas. Silica gel, which had high adsorption capacity for L2 in single substance adsorption experiment in the other study, could not remove the component in the actual landfill gas while it adsorbed well octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) in the LFG. Therefore the elimination of hexamethyldisiloxane is an important factor to determine the level of total organosilicon compound in pretreated landfill gas. Moreover, the L2 from the actual landfill gas was effectively adsorbed by the serial adsorption test using two columns packed with coconut activated carbon which has the great capacity of siloxanes removal among others. In order to utilize efficiently LFG as a renewable energy, the emission and adsorptive characteristics of the substance to be treated should be considered for the organization, operation, and management of pretreatment process.

• Journal of the Korean Geophysical Society
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• v.1 no.1
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• pp.41-50
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• 1998

Schlumberger soundings, dipole-dipole survey and electrical conductivity mappings were carried out inside and in front of the entrance of the Okmyung waste landfill in August, 1997 and January, 1998. Inside and in front of the landfill, 11 and 4 electrical soundings and 1 dipole-dipole survey were carried out, respectively. Electrical conductivities were measured at 164 points along the 4 lines in front of the entrance of the landfill. Interpretations of survey data show that low resistivity zones of 0.3∼3 Ωm extend down to 65 m depth from the surface in the 6th landfill, which indicates subsurface contamination by leachate and leachate level at 3∼6 m depth from the surface. In the 9th landfill, low resistivity zones below 2 Ωm appear at 11∼15 m depth from the surface, which indicates a very slim chance of subsurface contamination. On the other hand, electrical surveys and electrical conductivity mappings reveal low resistivities at shallow depths in front of the entrance of the landfill, indicating a high possibility of contamination of weathered zone in this area. It appears that southern part of this area close to the 6th landfill is more contaminated by leachate.

• Journal of Environmental Health Sciences
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• v.23 no.3
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• pp.27-39
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• 1997

This study, collaborated Gifu University, Japan, was performed to analyze chemical pollutants and microorganism and to clarify the distribution of sulfate-reducing bacteria and their insolubilization of heavy metal ions in leachates sampled seasonally between 1994 and 1996 from Nanjido waste landfill site, sampled 4 times between 1995 and 1996 from Pusan and Daejeon waste landfill site, and sampled 1 time between 1992 and 1994 from Hokkaido, Nagoya, Osaka and Hukuoka waste landfill site in Japan. The results were as follows: 1. The temperatures of internal leachate and leachate effluent were 40$\circ$C and 30$\circ$C, respectively, and the pH values of both leachates were about 8.0 at Nanjido waste landfill site. The concentration of SO$_4^{-2}$ gradually increased with the degree of stabilization and that of NO$_3$-N was detected in a part of sampling sites at one and half years, and in all sampling sites at 3 years after completion of landfill. 2. The organic substances in leachate of Nanjido waste landfill site decreased with the degree of stabilization and they were very fluctuated with measuring point and time. The concentration of organic substance and heavy metals in internal leachate were higher than in leachate effluent and those of Cd, Hg, and Pb were lower than detection limit except a part of samples in 1996. 3. APCs in internal leachate and leachate effluent were not much different and the minimum of APCs in internal leachate and leachate effluent were $1.0\times 10^4$/ml and $4.0\times 10^1$/ml, respectively. 4. The maximums of SRBs in Nanjido, Pusan, and Daejeon waste landfill site were 9180 MPN/ml, 24000 MPN/ml, and 348 MPN/ml, respectively and the maximum of SRBs in Japan waste landfill site was 9300 MPN/ml. 5. During 2-week-SRB culture, the values of MPN were high at 50$\circ$C for initial culture period and at 30$\circ$C for last culture period. MPN started to appear at first day and rapidly increased between 7th day and 9th day. 6. Cadmium and copper were insolubilized by SRB within 6 hr and iron and zinc were done within 48 hr. The rates of insolubilization of Cd, Cu, Fe, Zn, T-Cr were 100%, 99.5%, 95.0%, 99.8%, 16.1% after 48 hr treatment with SRB, respectively.

• Journal of Korean Society on Water Environment
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• v.21 no.6
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• pp.643-650
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• 2005

In order to treat leachate from aged landfill site effectively, removal of biologically recalcitrant organic matter and denitrification efficiency were evaluated through the combination of $H_2O_2/O_3$ AOP pretreatment process and UASB process. The results can be summarized as follows. In case of leachate having low COD/N ratio from aged landfill site, it is possible to increase available COD for denitrification in nitrate utilizing denitrification and nitrite utilizing denitrification both by enhancing biodegradability of recalcitrant organic matter as applying $H_2O_2/O_3$ AOP to pretreatment process. In this experiment, it is found that available COD for denitrification can be increased to 1.0 and 0.4 g/day, respectively. Comparison has been made between requiring COD and available COD for denitrification in each experimental stages. It is expected that high rate of denitrification can be achieved with leachate from young landfill site because higher amount of available COD for denotrification is present in the leachate than the amount of requiring COD for denitrification. Especially, In leachate from aged landfill site with low COD/N ratio, it can be concluded that denitrification using nitrite nitrogen can enhance overall denitrification performance efficiently because denitrification using nitrite nitrogen requires less amount of carbon source than denitrification using nitrate nitrogen. Comparing the biogas production rate and nitrogen content of biogas under the condition of same amount of nitrate and nitrite addition, biogas production and nitrogen content of biogas are increased during denitrification after $H_2O_2/O_3$ AOP pretreatment process. Therefore, it can be confirmed that COD/N ratio in the leachate is increased. Applying $H_2O_2/O_3$ AOP as pretreatment system of landfill leachate seems to have little economic benefit because it requires additional carbon source to denitrify ammonia nitrogen in leachate coming from aged landfill site. However, it is possible to apply this pretreatment process to leachate from old landfill site in view of AOP process can achieve removal of biologically recalcitrant organic matter and increase of available COD for denitrification simultaneously.

• Journal of the Korea Organic Resources Recycling Association
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• v.23 no.2
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• pp.21-27
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• 2015

An introduction of landfill tax has been recently in issue in order to raise the financial resource for establishing waste resource-circulation society. The objectives of this study are to evaluate the plan of increasing energy recovery from waste at Incheon Metropolitan City, and to propose several points to be considered in terms of introducing the landfill tax. There are a lot of problems that impede energy recovery from waste at Incheon Metropolitan City, such as high-calorific waste from decrease of food waste to the municipal incineration plant, metals and batteries in the standard plastic garbage bag, etc. Alternative policies to solve these major problems have been drawn.