抄録
The present study was conducted to obtain a bioflocculant from activated sludge by a simple procedure. An extracellular polymer mainly composed of protein was extracted by sonication from an activated sludge suspension. The polymer exhibited flocculating activity for kaolin clay, activated charcoal, and muddy water (when cations were present), and stimulated reflocculation of deflocculated sludge. Flocculating activity for kaolin clay was related to a concentration of the polymer below 10 ppm. The activity was significantly affected by pH since in basic buffer the activity was inhibited completely while in acidic buffer it was increased. When the polymer was digested with pronase, flocculating activity significantly decreased, although the activity was not affected by heat treatment at 100°C for 5 min. These results suggest that flocculating activity is mainly due to the portion of heat stable protein in the polymer. The results obtained in the present study suggest that the isolation of new biodegradable and economical flocculants from activated sludge is feasible.
