[Comparative study on the coagulation of PACl with different contents of aluminum polymeric species]

Based on the Ferron assay of aluminum species, jar test and filterability index, four types of PACl products of Al(a),, Al(b), Al(c), and Al(abc) are investigated on raw water samples from settling tank of water plant, which denote the different dominant aluminum species of AlCl3 for monomer or oligomer, PACl with high Al13 contents for mediate polymer of Al(b), PACl with high Al(c) contents for aluminum high polymer or Al (OH)3 sol, and industrial PACl for the mixed aluminum polymeric species with variety of alkalinity of Al(a), Al(b) and Al(c), respectively. Multiple parameters including the residual turbidity, UV254, particles removal, filterability index as well as the floc formation kinetics are monitored to make a comprehensive evaluation of their coagulation and settling-filtration performance. It indicates that PACl with high Al(b) contents demonstrate their predominant ability in the turbidity removal, whereas PACl with high Al(c) contents prefer to cutting down the particles and UV254.