Physico-chemical properties of the activated sludges(Suyoung and Changlim treatment plant), such as SVI(sludge volume index), absorbance, specific surface area, and specific resistance using Buchener funnel test were investigated with changing anaerobic storage time. This experimental condition was found that it was possible to estimate a linear relationship between their parameters such as specific surface area, specific resistance, and sludge volume index(SVI).
The specific surface area and the specific resistance to filtration of the activated sludges of Suyoung and Changlim treatment plant were found as 123.6~136.6㎡/gDS and 41.5~44.9㎡/gDS(dry solid), and 1.09×1014 ~ 5.48×1014m/kg and 1.05×1014 ~ 2.48×1014m/kg, respectively. The results gave a good linear relationship between the specific surface area and the specific resistance, r=2.25×1012s-8.10×1013(R2=0.8885) at Suyoung treatment plant and r=1.26×1013s-4.75×1014(R2=0.8756) at Changlim treatment plant.
Optical microscope, SEM (Scanning Electron Microscopy) and fluorescent microscope were used for qualitative and morphological studies of the attached biomass on PE (polyethylene) substratum under anaerobic condition. It was shown by the observation of optical microscope that the initial attachment of biomass began in crevices of the surface of PE. The shape and structure of the attached biofilm could be observed by SEM photographs, but species of bacteria were and methanogens were not classified. A large number of methanogenic bacteria were identified on the surface of PE substratum by fluorescence under 480nm of radiation. It was estimated that methanogenic bacteria was also related to initial attachment of biomass under anaerobic condition.
The lab-scale anaerobic continuous reactor which was filled with the sludge of anaerobic digestion from Suyoung wastewater treatment plant was operated by feeding of various concentrations and flow rates. This experiment indicated that more than 6,870 mgCOD/L of substrate concentration was required to promote good metabolism and growth of anaerobic biomass. And increasing loading rate slowly was also required in order to treat substrate of higher concentration and higher loading rate. The substrate concentration of about 10,000 mgCOD/L was adequate to generate biogas efficiently. The pH was sharply decreased at the onset of higher loading rate, but the pH was restabilized soon at 8. During the experiment, the amount of the attached biomass was kept constant.