Using the powder of autoclaved fly ash bricks from the construction waste, chitosan and allelochemicals (N-phenyl-l-naphthylamine and N-phenyl-2-naphthylamine) ,this paper prepares the composite algaecide to remove Microcystis aeruginosa in water. Then the paper investigates the dosage of substances on the algae removal efficien- cy. Under the optimal condition, the removal rate of Microcystis aeruginosa is over 99 %. The experiment indicates that the composite algae...