Abstract: Immobilization of microalgae Prochlorococcus with sodium alginate embedding was carried to explore the removal effect of NH₄⁺-N from artificial sewage water. Different algae ball densities (0, 100×10⁴, 300×10⁴, 500×10⁴, 700×10⁴, 900×10⁴ cells·ball^-1), different dosages of algae balls (the ratio of algae balls and sewage 4∶1, 3∶1, 2∶1, 1∶1) and algae ball reinforcement with CaCl₂ were applied in the experiment. The results showed that the growth rate of the immobilized algae and its removal ratio of NH₄⁺-N were lower than those of suspended ones. The NH₄⁺-N removal effects of the immobilized algae were dosedependent; however, considering the average removal ratio of algal cell, 700×10⁴ cells·ball^-1 was the best cell density. The algae cells with N-starvation treatment showed much better removal effect than the untreated cells. The more the immobilized algae balls were used, the quicker removal of NH₄⁺-N was. After three days’ cultivation, the removal effect reached up to 100% with the volume ratio of the immobilized algae balls and artificial sewage of 1∶1. With CaCl₂ reinforcement, the algae balls worked longer and assimilated much more NH₄⁺-N.

Key words: Gongga Mountain, methanotrophic bacterial community, vegetation, diversity