Study on effect of polyacrylamine on characteristics of activated sludge

Key words: 
• polyacrylamine /
• activated sludge /
• fluorescence in situ hybridization (FISH) /
• SBR

Abstract: The addition of polymer coagulant PAM is an effective way to enhance particle pelletization. However, it is still unclear whether PAM has influence on the characteristics of activated sludge and its biological degradation process. A laboratory experiment was thus conducted to investigate the effect of continuous PAM addition on the activated sludge using a sets of SBR and application of fluorescence in situ hybridization (FISH) and other microbiological techniques. As a result, no significant difference was noticed in the growth of activated sludge between the two SBR, with PAM dosage of 3 mg/L.Moreover, certain increase in both the MLSS density and the amout of microorganism in the weight of sludge per unit was found by PAM addition. The experiment with FISH also indicates that the numbers of total bacteria, ammonia-oxidizing bacteria and nitrifiers were detected as 1.0×106, 2.0×105 and 1.2×105 CFU/mL, respectively, in the SBR with PAM addition, comparing with 9.1×105, 1.8×105 and 1.1×105CFU/mL, respectively in the SBR with no PAM addition,which shows that PAM addition did not impose negative impacts on microbial growth. Slight improvement was also noticed for the removal of COD and NH+4-N in the process of 80 d operation with PAM addition.