▎ 摘　　要

NOVELTY - Preparing alum water purifying agent involves weighing 100 pts. wt. alum, 15-25 pts. wt. nano additives, 2-10 pts. wt. chitosan, 1-4 pts. wt. antibacterial agent, 30-50 pts. wt. complexing agent, adding alum, nano-additives, chitosan, antibacterial agent and complexing agent into a high-speed mixer for stirring and mixing, and after uniform mixing to obtain product. USE - Method for preparing alum water purifying agent used in aquiculture industry and to water quality modifying agent, water purification agent for waste water recycling, and antibacterial agent. ADVANTAGE - The method has good sterilizing effect, large specific surface area and pore structure, characteristics adsorption, good effect and strong anti-bacterial, improves the sterilizing effect of alum water purifying agent, and accelerates the effect of aggregation and sedimentation impurities.