B.H. Moon

Degradation of Azo Dyes by the Reduction and Oxidation with Nano Sized Zero Valented Iron

The objective of this study is to investigate the efficient method to maximize both color and TOC removal of the azo dye solution by reduction and oxidation with a laboratory synthesized nano-sized zero valent iron (nZVI). The decolorization efficiency increased with the decrease of pH and increase of zero valent iron dosage. The optimum dosage of nano-sized zero-valent iron was 20mg/L at pH 3. The surface normalized constant of nZVI was higher than those reported for the discoloring of azo dye with other ZVIs. The sequential dose of nZVI/H2O2 remove color and TOC more effectively than the simultaneous dose. Pre-reduction by nZVI could convert azo dye to products whose oxidation is more degradable and therefore enhances the removal efficiency.

Comparison of saline wastewater treatment performance of SBR with repeated starvation under aerobic and non-aerobic conditions.

This study investigated the effects of repeated starvation and feeding on the performance of a sequencing batch reactor (SBR) used for treating saline wastewater. The effects of aerobic and non-aerobic conditions on the sludge during starvation were evaluated to recover the performance of the SBR in terms of floc size and pollutant removal after resuming wastewater feeding. The floc size, fractal dimension, sludge volume index (SVI), specific oxygen uptake rate (SOUR), and pollutant removal efficiency were monitored. Experiment results revealed that the floc size and fractal dimensions decreased during starvation under both aerobic and non-aerobic conditions and increased after re-feeding wastewater. However, the difference in floc physical characteristics and performance depended on the starvation condition and was pronounced as starvation and re-feeding were repeated. The floc size and fractal dimensions decreased from 152.7 to 72.2 and 1.98 to 1.79 at the end of the fourth starvation period, resulting in deterioration of the sludge settleability and effluent quality. On the other hand, the floc size and fractal dimensions decreased from 158.7 to 135.7 and 1.95 to 1.81 at the end of the fourth starvation period but remained relatively constant after sludge adaptation. Some correlations were observed between the parameters monitored in this study. The results showed that maintaining the sludge under non-aerobic conditions was an effective strategy for reducing the effects of repeated starvation.

Effects of Fill Time on the Fractal Dimension and Size of Floc for SBR Treating Low C/N Ratio Wastewater

Abstract The aim of this study was to investigate the effects of fill time of influent on the physical characteristics of biological floc for sequencing batch reactor (SBR) treating low C/N ratio wastewater. The fractal dimension and size of floc were measured for characterizing floc. The fractal dimension of floc was analyzed by using Small Angle Laser Light Scattering (SALLS) method. SBR with short fill time showed higher removal efficiencies of COD, BOD, T-N, and T-P than with long fill time. Larger floc size and fractal dimension were generated at SBR with short fill time. Short fill time generated the sludge with better settling and thickening properties. Alternating anaerobic and aerobic condition in the cycle also affected the floc size and fractal dimension. The floc size decreased under anaerobic phase, and floc size increased under aerobic phase. During fill time, the fractal dimension of floc decreased. As the fill stop, the fractal dimension of floc increased. Therefore, the fill time condition more affected the fractal dimension of floc. More efficient nitrification and phosphorus release were observed during a cycle with short fill time operation.