Effect of Fe3+ on Physicochemical Properties of Aerobic Activated Sludge during Domestication by Pulping Middle-stage Effluent

The changes of physicochemical properties of aerobic activated sludge for pulping middle-stage effluent treatment including mixed liquid suspended solid（ MLSS）,extracellular polymer substances（ ECPs） content,ratio of protein（ PN） and polysaccharide（ PS）,sludge volume index（ SVI） during domestication were studied. The results showed that MLSS and PN / PS ratio of the system with Fe3+were higher than that of the blank control,while SVI was lower. ECPs content of the system with Fe3+ was higher in the earlier stage,but lower in the later period compared to the blank control. The settleability and flocculating performance of the sludge with Fe3+ were better than that of the blank control.