• 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.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2002.11a
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• pp.25-30
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• 2002

유기성 폐기물은 음식물쓰레기, 농ㆍ수ㆍ축산폐기물, 식품가공산업 폐기물 등에서 주로 발생되고 있다. 이러한 유기성 폐기물은 함수율이 70∼85% W.B.정도로 높고 부패성이 크기 때문에 악취 및 침출수 등의 여러 가지 환경유발 가능성이 높은 것으로 평가되고 있다. 최근에는 이러한 젖은 폐기물의 매립장 반입이 규제되고 있으며, 함수율이 높아 직접 소각도 어려운 실정이므로 유기성 폐기물의 안정화, 감량화 및 재자원화를 위한 처리기술개발이 시급한 실정이다.(중략)

• Resources Recycling
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• v.4 no.3
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• pp.2-9
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• 1995

The rccoverg and separation pracess of nikcl, vanadium and molybdenum from spent dcsulfilrizing catalyst ofpetrochemical rndustries was studied. Tnis process was canied out wet process which is consist of roasting, ammonialeaching and solve111 exDaction techniqcs. The metal ions of NI, V and Mo as vduable compollents were treated byroasting them a1 low lernperatuc, 400$^{\circ}$C in first dep, and then dlssah'ed nu1 at 80$^{\circ}$C wlth ammonium cabonate mlulion.Aftcr cooling them a1 room tempertaure, vanadium wa rccavered from mathcr iiquur in thc f n m of precipitate, sodiumvanadales The Secand slep, roasting the catalyst which is added sodium carbonate ul IOOO"C, was employed. Leachingwith distilled ~ a l e rga ve a iwo phase resultant, solutio~c~a ntaning Ni, V and Mo and solid residue containing sibca,alurmniu~n and iron. A solvcnt exlclction technique uslng vvriuus extractanls, MSP-8, TOIUC, LIX64Pi was eflecnve farthc extraclion and scparation ol thrcc mcfals from thc ammonical 11qou1 thc ammonical 11qou1.

• Resources Recycling
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• v.14 no.5 s.67
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• pp.24-31
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• 2005

In order to recover valuable metals from fine-grained electronic waste, bioleaching of Cu, Zn, Al, Co, Ni, Fe, Sn and Pb were carried out using Aspergillus niger as a leaching microorganism in a shaking flask. Aspergillus niger was able to grow in the presence of electronic scrap. The formation of organic acids(citric and oxalic acid) from Aspergillus niger caused the mobilization of metals from waste electronic scrap. In a preliminary study, in order to obtain the data on the leaching of Cu, Zn, Al, Fe, Co and Ni from electronic scrap, chemical leaching using organic acid(Citric acid and Oxalic acid) was accomplished. At the electronic scrap concentration of 50 g/L, Aspergillus niger were able to leach more than 95% of the available Cu, Co. But Al, Zn, Pb and Sn were leached about 15-35%. Ni and Fe were detected in the leachate less than 10%.

• Resources Recycling
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• v.24 no.3
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• pp.3-10
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• 2015

A study has been made on the recovery & separation of cobalt and copper from organic acid leaching solution by solvent extraction. The experimental parameters such as the equilibrium pH, concentration of extractant and phase ratio were observed. Copper was extracted using LIX 84 and Cobalt was extracted using cyanex 272 and versatic acid 10. Experimental results showed that extraction percent of copper was 99% at above eq. pH 2.0 and then more than 90% of cobalt were extracted by cyanex 272 in eq. pH 6.0 and versatic acid 10 in eq. pH 7.5. Stripping of copper and cobalt from the loaded organic phases can be accomplished by sulfuric acid as a stripping reagent and 120 ~ 150 g/L of $H_2SO_4$ was effective for the stripping of copper and cobalt respectively. Finially, the basic optimal process for recovery of copper and cobalt from the bio-leaching solution was proposed.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.2
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• pp.45-54
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• 2010

Field study was conducted for 5 months to investigate the effect of leachate recirculation on aerobic landfill stabilization at active landfilling site. The area of field experiment was $24{\times}24m$ and 9 vertical air injection wells with screen ranging 3~9 m were installed. Aerobic landfill operation for 5 months increased average internal landfill temperature to $70^{\circ}C$ and 8 % of landfill height was settled down. $94m^3$ of leachate was recirculated for 1 month to increase moisture content of landfill to favor microbial degradation of organic matter, which resulted in temporary increase of groundwater level and anaerobic environment. But leachate recirculation triggered increase of internal landfill temperature of neighboring monitoring well. Because excessive leachate recirculation decreased internal landfill temperature by cooling effect, internal landfill temperature should be checked to avoid abrupt decrease of temperature during leachate recirculation. Also, to prevent anaerobic environment, intermittent leachate recirculation was recommended.

• Resources Recycling
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• v.14 no.6 s.68
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• pp.28-36
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• 2005

A hydrometallurgical process to leach cobalt from the waste cathodic active material, $LiCoO_{2}$, and subsequently to separate it by solvent extraction was developed. The optimum leaching conditions for high recovery of colbalt and lithium were obtained: 2.0 M sulfuric acid, 5 $vol.\%$ hydrogen peroxide, $75^{\circ}C$ leaching temperature, 30 minutes leaching time and an initial pulp density of 100 g/L. The respective leaching efficiencies for Co and Li were $93\%$ and $94.5\%$. About $85\%$ Co was extracted from the sulfuric acid leach liquor containing 44.72 g/L Co and 5.43 g/L Li, using 1.5 M Cyanex272 as an extractant at the initial pH 5.0 and in organic to aqueous phase ratio of 1.6:1 under the single stage extraction conditions. The Co in the raraffinate was completely extracted by 0.5 M Na-Cyanex272 at the inital pH 5.0, and an organic to aqueous phase ratio of 1;1. The cobalt sulfate solution of higher than $99.99\%$ purity could be recovered from waste $LiCoO_{2}$, using a series of hydrometallurgical processes: sulfuric acid leaching of waste $LiCoO_{2}$- solvent extraction of Co by Na-Cyanex 271 - scrubbing of Li by sodium carbonate solution - stripping of Co by sulfuric acid solution.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.1
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• pp.171-177
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• 2007

In order to investigate the effect of the methanogenic bacteria in bacteria in leachate on the degradability of landfill waste, this study has created 4 cylinder-shape PVC lysimeters (Diameter: 30cm, Height: 200cm, Volume: 140L) and for the biological treatment and recirculation of the leachate, two anaerobic batch reactors (Diameter: 20cm, Height: 30cm) were created. To simulate a conventional landfill, no recycling was done in L1. In L2, 1,068ml of leachate (twice of rainfall amount) was recycled. In L3 and L4, the leachate was anaerobically digested in a dark room (with $35{\pm}1^{\circ}C$) for a week and them recycled by 1,064ml and 2,128ml, respectively, with recycled water only. In terms of cumulative $CH_4$ production, however, L3 and L4 were much higher (three times) than L1 and L2. Between L3 and L4, the latter was 1.23 times higher than the former in terms of cumulative CH4 production. In other words, the more the methanogenic bacteria-activated leachate is recycled, the more active the degradation due to active methane fermentation by the recyled methanogenic bacteria. And methane recovery is different according to the amount of recycled the methanogenic bacteria in leachate.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.109-117
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• 2007

In order to investigate the quantitative and qualitative properties of leachate with different composition of MSW in solid waste landfill, three lysimeters filled with bottom ash only (Lysimeter A), bottom ash 70%+municipal solid waste 30% (Lysimeter B), and municipal solid waste only (Lysimeter C) respectively were operated under actual meteorological conditions. From the results, Lysimeter A and Lysimeter B were much higher than Lysimeter C in terms of cumulative generation rates of leachate. The pH in leachate from Lysimeter A are in the range of pH 9 to 11, however, the pH of the leachate was gradually changed to the neutral with time. In the case of $Cl^-$, leachates from Lysimeter A and B with bottom ash have high $Cl^-$ concentration whereas leachate produced from Lysimeter C has low $Cl^-$ concentration. In the Lysimeter C with municipal solid waste only, concentration of organic materials in the leachate was much higher than that of leachate produced from the other Lysimeters.

• Journal of Korean Society of Environmental Engineers
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• v.29 no.3
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• pp.317-324
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• 2007

Fluorescence measurements of dissolved organic matter(DOM) have the superior advantages over other analysis tools for applying to water quality management. A preliminary study was conducted to test the feasibility of applying synchronous fluorescence measurements for tracing and monitoring pollution sources in a small stream located in an upstream area of the Sooyoung watershed in Busan. The water quality of the small stream is affected by leachate from sawdust pile and discharge of untreated sewage. The sampling sites included an upstream site, two pipes discharging untreated sewage, leachate from sawdust, and a downstream site. Of the five field samples, the leachate was distinguished from the other samples by a high peak at a lower wavelength range and a blunt peak at 350nm, suggesting that synchronous fluorescence can be used as a discrimination tool for monitoring the pollution. The efficacy of various indices derived from the spectral features to discriminate the pollution source was tested for well-defined mixture of the sawdust leachate and the upstream stream by comparing (1)the difference between measured values and those predicted based on mass balance and the characteristics of the two samples and (2)the linear correlations between index values and mass ratios of the sample mixtures. Of various discrimination indices selected, fluorescence intensities at 276 nm$({\Delta}\lambda=30nm)$and 347 nm$({\Delta}\lambda=60nm)$ were suggested as promising potential discrimination indices for the sawdust pollution source. Despite the limited number of samples and the study area, this study illustrates the evaluation process that should be followed to develop rapid, low-cost discrimination indices to monitor pollution sources based on end member mixing analyses.