Showing papers by "Hang-Sik Shin published in 1999"

Removal of polychlorinated phenols in sequential anaerobic-aerobic biofilm reactors packed with tire chips

Abstract: Scrap vehicle tire chips were used as packing material for sequential anaerobic-aerobic biofilm reactors to remove persistent chlorinated hydrocarbons. Adsorption capacity of scrap tires was greater under acidic conditions than under basic conditions. However, it was only approximately 0.04 to 0.3% of that of activated carbon. The amount of biomass that attached to the surface of scrap tires was 3.16 and 3.72 mg volatile suspended solids/cm{sup 2} after 14 and 37 days, respectively. Two laboratory-scale, down-flow anaerobic-aerobic biofilm reactors packed with tire chips were operated to remove 2,4-dichlorophenol (DCP) and 4-chlorophenol (CP). More than 98% of DCP was dehalogenated to CP in the anaerobic reactor, 70 to 98% of which was subsequently degraded in the aerobic reactor. Scrap tires did not cause any operational problems when used as biofilter media.

The Effects of Seed Inoculation on the Rate of Garbage Composting

Abstract: Enhancement of composting efficiency by seeding specialized inoculum was studied quantitatively by means of general composting parameters, kinetic constant, and maximum degradation rate of compostable substrates General parameters such as temperature, CO2 and O2 concentrations, pH, and dry matter decrease were improved by inoculating specialized microorganisms Seed inoculation increased final percent conversion of garbage to 875%, while 727% of garbage degraded without inoculation It was obvious that the seed inoculation could enhance composting rate from the comparison of kinetic constants and maximum degradation rates The decomposition rates of organic matter in initial stage of inoculated case were 4 to 5 or 17 to 21 times higher than the values in the case of no inoculation, in terms of kinetic constant and maximum degradation rate, respectively It was suggested that seed inoculation is applicable to the on-site treatment because it could initiate composting reaction efficiently without initi

Ammonium exchange and bioregeneration of bio-flocculated zeolite in a sequencing batch reactor

Abstract: Natural zeolite was added to the sequencing batch reactors to assess its role in ammonium exchange. Even though the biofilm was fully developed on the zeolite surface, ammonium removal and the biological regeneration of the zeolite occurred constantly during the anoxic-fill phase and the reaction phase, respectively. However, the specific nitrification rate of the bio-flocculated zeolite was lower than that observed in the control on account of the limited ammonium release to the liquid phase.

Degradation Mechanism of PVA and Hec by Ozonation

Abstract: In the past, PVA (polyvinyl alcohol) and HEC (hydroxyethyl cellulose) were used in the chemical industry, especially in the expandable polystyrene manufacturing process. They remained in the environment for a long time and could not be destroyed effectively by conventional wastewater treatment processes. In this study, PVA and HEC were treated with ozone. PVA was completely removed in 20 min. by ozonation, and about 75% of HEC was removed at pH 12. Increased pH enhanced the ozonation efficiency of PVA and HEC. From molecular weight distribution tests, the fraction of m.w. from 10000 to 30000 amu decreased, but the portion of m.w. from 1000 to 10000 amu increased to 50%. It was concluded that the removal of PVA and HEC was not due to complete mineralization but to the breakdown of macromolecules to micromolecules.

Biological uptake of influent organic matter as an electron donor for denitrification by activated sludge

Abstract: To preserve organic materials in the sludge required for denitrification, a study was made with a contact process. The contactor, when operated with a short retention time (30 min), gave incomplete metabolism of organic matter. With 64% of the influent soluble COD (SCOD) was adsorbed to activated sludge within 30 min. The specific mass of organic matter uptaken was 55 mg SCOD/g Mixed Liquor Suspended Solids that enhanced the denitrification efficiency up to 63% in the following denitrification step.