• Journal of Korean Society of Environmental Engineers
• /
• v.38 no.3
• /
• pp.110-116
• /
• 2016

Biogas yields point of view, the possibility of reusing excess sludge treated by thermal pretreatment for the purpose of improving the efficiency of the anaerobic digestion process has been investigated in recent year. Thermal pretreatment technology was considered as a pretreatment technique to improve excess sludge properties because of the solubilization of particulate organics. As a view point of sludge reduction and recycle, however, many researchers focused on the ability of particulate hydrolysis and COD solubilization under a high temperature, and few reports have addressed on the physical/chemical characteristics changing. This research was performed to evaluate the effects of a various temperature and chemical additives on carbon formation and fractionation in treated slurry from thermal pretreatment. Based on the results, it was revealed that oxidants injection and temperature changing have significantly caused the change of carbon fractions in slurry from thermal pretreament. Especially, it was considered that the efficiencies of particle hydrolysis increased with the increase of the reaction temperature. Low molecular weight(Mw < 350 g/mol) organic carbon formation increased with the increase of oxidants injection. It was expected that results of this research will provide an overview of the characteristics of thermal pretreatement for excess sludge reduction and recycle.

• Korean Journal of Soil Science and Fertilizer
• /
• v.42 no.5
• /
• pp.385-392
• /
• 2009

This study was conducted to reclassify Namweon series, black volcanic ash soils, in Jeju Island based on the second edition of Soil Taxonomy : A Basic System of Soil Classification for Making and Interpreting Soil Surveys. Morphological properties of typifying pedon of Namweon series were investigated and physicochemical properties were analyzed according to Soil Survey Laboratory Methods Manual. The typifying pedon of Namweon series has black (10YR 2/1) silt loam Ap horizon (0~11 cm) and black (10YR 2/1) silt loam BA horizon (11~72 cm). Bw horizon (72~100 cm) is very dark brown (10YR 2/2) silt loam. That occurs on lava plain derived from volcanic ash materials. The typifying pedon contains 5.2~6.4% oxalate extractable (Al + 1/2 Fe), over 85% phosphate retention, and lower bulk density than $0.90Mg\;m^{-3}$. Ap, BA, and Bw horizons of the pedon have andic soil properties. That can be classified as Andisol. The typifying pedon has an udic soil moisture regime and has a 1,500 kPa water retention of 15% or more on air-dried samples throughout all horizons, and can be classified as Udand. Ap and BA horizons (0~72 cm) have a color value, moist, and chroma of 2 or less, melanic index of 1.70 or less, and 6% or more organic carbon. That meets the requirements of melanic epipedon. That keys out as Melanudand. That has more than 6.0% organic carbon and the colors of mollic epipedon throughout a layer 50 cm or more thick within 60 cm of the mineral soil surface.. Thus, that keys out as Pachic Melanudand. The pedon has a fine-earth fraction that has a water content at 1,500 kPa tension of 12% or more on air-dried samples and has less than 35% (by volume) rock fragments. Thus, the substitute for particle-size class is medial. That has a sum of 8 times the Si (percnt by weight extracted by acid oxalate) plus 2 times the Fe (percnt by weight extracted by acid oxalate) of 5 or more, and 2 times the Fe is more than 8 times the Si. Thus, the mineralogy class is ferrihydritic. Namweon series can be classified as medial, ferrihydritic, thermic family of Pachic Melanudands, not as ashy, thermic family of Typic Melanudands.