Seong Joo Park

Oxidation of polycyclic aromatic hydrocarbons by laccase of Coriolus hirsutus

The oxidation of five polycyclic aromatic hydrocarbons; anthracene, benzo(α)pyrene, fluoranthene, phenanthrene and pyrene was catalyzed by laccase from Coriolus hirsutus in the presence of the redox mediators, 2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) and 1-hydroxybenzotriazole (HBT). In the ABTS-mediated system, benzo(α)pyrene was the most rapidly oxidized substrate, with anthracene being the most rapidly oxidized in the HBT-mediated system. There was no clear relationship between the ionization potential and the oxidation of the substrates. ABTS increased the oxidation of benzo(α)pyrene more than HBT but the oxidation of the other PAHs tested were the opposite. The mediators used in conjunction increased the oxidation of benzo(α)pyrene compared to using the mediators alone.

Structure and Characteristics of Bacterial Community on Biofilm of Food Wastewater Treatment System in Winter

Biofilm and aeration tank of pilot and full RABC (rotating activated Bacillus contactor) plant were analyzed to characterize and determine bacterial community structure in food wastewater treatment system at winter. Concentration of heterotrophic bacteria and Bacillus group was and CFU/ml, respectively, at biofilm of pilot-plant while others represented and CFU/ml, respectively. Five and eight phyla were detected at biofilm of pilot- and full-plant, respectively, by 16S rDNA sequencing. Biofilm of pilot-plant was dominated by -Proteobacteria (38.8%), -Proteobacteria (22.4%), and Bacteroidetes (12.2%), and the most dominant genus was Zoogloeae genus (22.4%). Candidate division TM7 (12.5%) was only detected at biofilm of full-plant and it was dominated by Bacteroidetes (33.3%), -Proteobacteria (29.2%), and -Proteobacteria (20.8%). Clostridium genus specific primer set enabled to detect the sequences of Clostridium genus. These suggested that anaerobic and aerobic bacteria were coexisted even from the initial period of biofilm formation and -Proteobacteria, -Proteobacteria and Bacteroidetes were major phyla in biofilm of food wastewater treatment system at winter.

Enumeration and Comparison of Fecal Indicator Bacteria in a Sewage Treatment Plant Using Activated Sludge Process

Indicator bacteria of fecal pollution were enumerated and compared by various detection methods for influent and final effluent of a sewage treatment plant. Total coliforms were enumerated by four methods including most probable numbers, chromogenic enzyme substrate test, membrane filtration, and plate counts and were about 10 for influent and 10 ~10 CFU/ml for final effluent. Fecal coliforms ranged between 10 and 10 for influent and 10 CFU/ml for effluent by chromogenic enzyme substrate test and membrane filtration. Fecal streptococci counts were 1-log less than fecal coliforms counts, 10 ~10 for influent and 10 CFU/ml for effluent. Total coliforms numbers by plate count both in influent and in effluent showed 1-log higher than by the other three methods. Statistical analysis revealed that numbers of total coliforms by plate count in final effluent had the highest average of correlation (r=0.778, p<0.01) compared with those by the other three methods. In addition, total coliforms numbers by plate count showed most significant correlation (r=0.835, p<0.01) with those by chromogenic test which is well-known as its highest recovery efficiency. These results suggest that the plate count would be the optimum detection method for total coliforms in wastewater treatment plants which are the only microbiological standard of final effluent from wastewater treatment plants in the Republic of Korea, considering economic aspects and difficulties in laboratories.

APPARATUS AND METHOD FOR ACHIEVING REPRODUCIBLE MEASUREMENTS OF DIAUXIC LAG LENGTH AND ANOXIC NET MAXIMUM SPECIFIC GROWTH RATE

Abstract An apparatus for continuous growth of pure bacterial cultures under oxic conditions followed by a switch to anoxic batch conditions was designed. The application of this apparatus gave variability of measured parameters (diauxic lag length, anoxic net maximum specific growth rate) which were significantly lower than the variability of previously reported data. The improvement is attributed to more consistent nitrate reductase levels as a result of achieving steady state under oxic condition prior to switching to anoxic batch conditions.