Control of activated sudge bulking by adding calcium chloride
氯化钙控制污泥膨胀

The sludge bulking is one of the thorniest problems in the activated sludge process. The experiment used synthesis wastewater as the substrate, and operation process used sequencing batch reactor (SBR). The effect of adding inorganic coagulant calcium chloride to control activated sludge bulking and the change of filamentous bacteria and the floc-forming bacteria was studied in a laboratory activated sludge system. The results showed that, after adding the calcium chloride, the number of filamentous bacteria obviously decreased; and the shape of zoogloea became larger and more roughly spherical, the sludge bulking was under control. The sludge volume index (SVI) decreased from 309.5 mL/g to 67.1 mL/g, the sludge settling property was improved. The system continued to run 18 cycles without adding the calcium chloride, the activated sludge did not bulking again. Adding calcium chloride had no significant effect on COD removal rate. The results indicated that adding calcium chloride was one kind of effective emergency methods to control sludge bulking.