In this study polyaluminurn chloride (PAC) has a high Al-b content, 80.1 %. It was the most efficient species of PAC. PAC was synthesized with a membrane reactor which made of a hollow-fiber (HF) ultrafiltration membrane (UFM). The UFM was made from PPESK, a novel membrane material with properties of excellent thermal, chemical and mechanical stability. In this reactor, a sodium hydroxide solution permeated slowly through the microspores of HF UFM into AlCl3 wastewater. Because the alkali drop size was reduced to nano-scale, it is beneficial to bring a dramatic reduction of localized super-saturation and enhancement of the Al-b quantity. The purpose of the study is to prepare liquid PAC utilizing the aluminum chloride wastewater as a raw material through a membrane reactor system and to evaluate the performance by using an orthogonal array of the design of experiments (OADE) on the sedimentation to four different dyestuffs: Titan Yellow, Methyl Orange, Food Yellow and Procion Red. The results show that PAC prepared by the membrane reactor has higher Al-b and better flocculation properties to different dyestuffs than the commercial PAC, whose average sedimentation can exceed 96%.