• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.71-77
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• 2005

Combustion of RDF and wastewater sludge was performed in a 0.1MWth bench scale circulating fluidized bed combustor(CFBC), Combustion characteristics of the RDF and sludge mixture demonstrated stable combustion conditions. Component analysis, Combustion characteristics was measured before and after the test, and applications for commercial 1MWe CFBC boiler were prepared. The release of hazardous components such as $SO_2$ and HCl was relatively low values of 50 and 150ppm, respectively.

• Environmental Engineering Research
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• v.13 no.3
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• pp.112-118
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• 2008

Residual solid in excess sludge treated by hydrothermal reaction was investigated as raw material for its recycling. Treated excess sludge and residual solid were also focused on their content change during hydrothermal reaction. Two kinds of excess sludge, obtained from a local food factory and a municipal wastewater treatment process, were tested under various conditions. Following hydrothermal reaction, depending on the reaction conditions, biodegradable substrates in treated excess sludge appeared to increase. The separated residual solid was a composite composed of organic and inorganic materials. The proportion of carbon varied from 34.0 to 41.6% depending on reaction conditions. Although 1.89% of hazardous materials were detected, SiO2 (Quartz) was a predominant constituent of the residual solid. X-ray diffraction (XRD) experiments revealed that the residual solid was of a partially amorphous state, suggesting that the residual solids could be easily converted to stable and non harmful substances through a stabilization process. Thus, this technology could be successfully used to control excess sludge and its reuse.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.448-452
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• 2001

An Experimental study was carried out to develop a simple method of processing copper waste sludge which is produced by PBC manufacturing. The procedure is based on leaching of wet sludge in 2N H$_2$SO$_4$, and the solid / liquid ratio is controlled approximately at 1/10. The recovery of copper is 85.4%, and pH of the leachate is 3.20. Adding ammonia solution into leachate forms ammine, and hydroxide compounds derived from other impurities in leachate at pH 10. The hydroxide compound can be treated by ferrite process, and the product is a stable oxide compound. Then the ammine solution is heated to evaporate ammonia, and the copper hydroxide is formed. Heating at 8$0^{\circ}C$by aeration, copper hydroxide is transformed into copper oxide with a purity of 98.4%. This process can recover most copper from sludge and the residue can be stabilized by the formation of a stable oxide compound which is not hazardous to environment.

• Journal of Environmental Health Sciences
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• v.31 no.1
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• pp.86-93
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• 2005

Because generally large amount of sludges are generated from the process of sewage and wastewater treatment, the management and controlment of those sludge has become a important issue in many researches. In this dissertation, we conducted the research to see the physico-chemical characteristics of sludges generated from various sources. Moisture of sludges were 81.5% in textile industries, 81.4% in frame metal industries, 80.7% in 1st metal industries. Volatile solid were 22.1% in hide · rubber industries, 21.9% in coke · petroleum industries. Fixed solid were 18.5% and 17.7% in the 1st metal industries and frame metal industries. High heating value by wet base were 1,850 kcal/kg in coke · petroleum industries, 1,220 kcal/kg in hide · rubber industries, but sludges from the 1st metal industries and frame metal industries were impossible to incinerate because most of those sludges were inorganic. The leaching test showed that hazardous materials was detected in nearly every kinds of sludges. Some of sludges from hide · rubber industries and frame metal industries exceeded the leaching criteria and so they were classified as specific wastes. And other sludges generated in sewage treatment plants or other industries was below the leaching criteria.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1138-1142
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• 2002

Slag cement and supersulfated slag cement were fabricated by mixing blast furnace slag and ordinary portland cement and adapted to solidify/stabilize heavy metal contained hazardous waste sludge. In case of slag cement, it showed continuous increase of their compressive strengths, which is attributed to the formation of the C-S-H, ettringite and monosulfate with STS sludge. However, BF and COREX sludge has a different shape and composition. therefore, adequate compressive strength could not be achieved with this slag cement. In case of the mixture of the each sludge like the STS-BF or the STS-COREX, the compressive strength over the standard level for disposing the wastes could be obtained with slag cement. The supersulfated slag cement that contain accelerators was very effective in solidifying the COREX sludge, which was difficult to solidify using different cement and obtained high compressive strength only for 3 days.

• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.21-30
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• 2002

This study was Performed to evaluate the effective solidification of Cd sludge using cement and power plant fly ash as cement admixture, to identify the leaching characteristics of the heavy metal Cd sludge solidified, and to develope proper KLT(Korean Leaching Test) of hazardous waste. KLT was compared with EPT(Extraction Procedure Toxicity) and TCLP(Toxicity Characteristics Leaching Procedure). Fly ash contents ranged from 0% to 30% of cement weight. The experimental results showed that the optimum amount of fly ash replaced was 10% to 15% and KLT was less appropriate than EPA and TCLP. Also the purpose of the study was to suggest the modification factors on the leaching test currently used, based on the above mentioned aspects. The effects of pH, leaching time, leaching for agitating intensity, and leaching solvent were investigated. As the result of test, the leaching potential was relatively high when the pH and agitation intensity of leaching solution were 5 and 150rpm, respectively. Leaching time of six hours was found to be sufficient and the use of acetic acid as a leaching solvent is more useful in landfill site particularly.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.89-98
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• 1988

This research evaluated factors on cement-based solidification process designed for hazardous sludge produced from electroplating industry. Four factors of sand/cement ratio, water/cement ratio, amount of wet sludge and amount of a precipitator, were investigated in terms of leachability and compressive strength of the solidified materials. Results of triplicate tests and statistical analysis indicated that sand/cement ratio(S/C) had the greatest effect on leaching of Cr(VI) from the solidified materials while water/cement ratio(W/C) on Zn and compressive strength. Cr(VI) was fixed better than Zn by portland cement. An experimental modeing was developed to estimate leached metal concentration and compressive strength at a given condition. Proper mixing criteria were also suggested for the use of the solidified mixture as construction materials. In solidification of 30g dry sludge, optimal condition was studied for S/C ratio, W/C ratio and the weight of precipitator which were 1, 1.5 and 1.075g respectively.

• Environmental Engineering Research
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• v.23 no.1
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• pp.28-35
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• 2018

$17{\alpha}-ethinylestradiol$ (EE2), a synthetic estrogen which interfere the endocrine and reproductive function in living organisms, has been found extensively to be deposited into municipal wastewater treatment plants and the environment via human excretion. EE2 has long been known to be efficiently cometabolized by ammonia-oxidizing bacteria (AOB) during ammonia ($NH_3$) oxidation. Current study aims to investigate the effect of culture history on the biotransformation of EE2 by nitrifying sludge which was enriched under different ammonia loading rates in continuous flow reactors. Result showed that past growth condition largely affected not only the metabolic rate of $NH_3$ oxidation but also EE2 cometabolism. Sludge previously acclimated with higher $NH_3$ loads as well as sludge dominated with AOB belong to high growth cluster (Nitrosomonas europaea-Nitrosococcus mobilis) showed higher rate of EE2 biotransformation than those one being acclimated with lower $NH_3$ loads because of its ability to provide more reducing power from $NH_3$ oxidation. Moreover, the correlation between the degradation rates of $NH_3$ and EE2 was higher in sludge being acclimated with higher load of $NH_3$ in comparison with other sludge. Implication of the findings emphasized the role of volumetric $NH_3$ loading rate in determining EE2 removal in wastewater treatment system.

• Journal of Environmental Health Sciences
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• v.10 no.1
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• pp.13-20
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• 1984

The hospital wastewaters have to be so disposed as to prevent disease and to protect water resources from hazardous substances disinfectants, medicines, and chemicals. Polyvinylpyrrolidone-iodine complex (povidone-iodine) is widely used in the hospital as one of disinfectants. This study was carried out to manifest the effect of disinfectants in growth of activated sludge in treatment of the hospital wastewater by the activated sludge process. The results are as follow. 1. An average water quality of the hospital wastewater showed 7.2 in pH, 3.2 ppm in DO, 293.3 ppm in SS, 96.0 ppm in BOD, 151.1 ppm in COD, 0.4 ppm in povidone-iodine, 0.5 ppm in phenols, 5.4 ppm in surfactants, 1.6 ppm in o-phosphate, 4.6 ppm in $NH_3-N, 249\times 10^4$ counts/100 ml in coliform group organisms, and $1,369\times 10^2$ counts/ml in general counts of bacteria. And wastewater amounts discharged per bed was calculated 70 l/d/bed. 2. In batch culture activated sludge process, each of cresol and povidone-iodine was not effected in less than 0.1 ppm concentration, but the more concentration, the more inhibit the growth rate of activated sludge. In the mixture of two disinfectants, the growth was more inhibited the effect of single disinfectants. So that this reaction is considered as addition effect of two disinfectants. 3. The removal rates of the disinfectants-by continuous culture activated sludge process were 77.6% in 0.4 ppm povidone-iodine, and in BOD was 85.6%. 4. It is desirable that the hospital wastewater is planed in order to be discharged to two system separately, sewer from life system and wastewater from medical system. From those results, it has been concluded that the hospital wastewater has to be treated safely by the activated sludge process.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.362-367
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• 2006

Waste activated sludge(WAS) collected from domestic wastewater treatment plant is biomass that contains large quantities of organic matter. However, relevant literature show that the bio-hydrogen yield using WAS was too low. In this study, the effect of pretreatment of WAS on hydrogen yield was investigated. Pretreatment includes acid and alkali treatments, grinding, heating, ozone and ultrasound methods. After pretreatment organic matters of WAS were solubilized and soluble chemical oxygen demand(SCOD) was increased by 14.6 times. Batch experiments were conducted to investigate the effects of pre-treatment methods and buffer solution, hydrogen partial pressure, and sodium ion on hydrogen production from WAS by using heated anaerobic mixed cultures. Experimental results showed that addition of buffer solution, efficient pre-treatment method with alkali solution, and gas sparging condition markedly increased the hydrogen yield to 0.52 mmol $H_2/g$-DS.