Abstract: tThe component of biogas slurry is usually complex, and it is easy to breed bacteria and other microorganisms which affect the removal efficiency of pollutants in microalgae cultivation. In this study, different pretreatment methods were performed before mciroalgae cultivation in the swine biogas slurry, including autoclaving, addition of NaClO, NaCl or ammonia. The sterilizing effects of different methods as well as their influence on the growth rate of Chlorella vulgaris were thoroughly compared, and the PCR-DGGE was used to monitor the microbial community structure changes during the different growth periods. Results showed that the addition of NaClO could significantly reduce the amount and species of microorganisms in the biogas slurry. In the microalgae cultivation with 60% volume ratio of biogas slurry, the algae density reached 4.78×107 cells/mL, and through 7 days cultivation, the removal efficiency of TN, TP, N-NH+4 and COD(chemical oxgged demand) reached 76.9%, 46.6%, 97.1% and 72.8%, respectively. Eventually, the water quality meets the discharge standard of water pollutants for livestock and poultry breeding after the purification by Chlorella vulgaris. 

Key words: Chlorella vulgaris, biogas slurry purification, sterilization methods, microbial community