Abstract: The bio-reactor is a key process and important limiting factor during the treatment of livestock and poultry wastewater through microalgal bacterial biofilm. In this paper, a biofilm reactor was designed for microalgal bacterial consortia to treat piggery wastewater, and the influent ammonia nitrogen mass concentration was adjusted to explore its impact on nutrients removal and microalgae biomass production. Moreover, scanning electron microscopy was used to observe the formation of microalgal bacterial biofilm on the carrier. High-throughput sequencing was also used for microbial community analysis. The aim of this study was to reveal the change regularities of nutrients removal and the response mechanism of microbial community of microalgal bacterial biofilm wastewater treatment with the fluctuation of influent ammonia. The results showed that the maximum daily removal rate of ammonia nitrogen could reach 35.60 mg/（L·d） when the influent ammonia nitrogen mass concentration was 200 mg/L, and the dominant bacterial genus wasPrevotella_ 9,Clostridium_ Sensu_ Stricto_ 1,AcinetobacterandBifidobacterium. Moreover, a large number of microalgal bacterial clusters were observed on carrier illustrating the formation of microalgal bacterial film. When the influent ammonia nitrogen mass concentration increased to 300 mg/L, the daily removal rate of ammonia nitrogen significantly increased reaching a maximum of 45.70 mg/（L·d）. However, the sustained high ammonia nitrogen load made a certain impact on the microalgal bacterial biofilm, while the dominant bacterial genera turned toComamonasandChristensenellaceae_ R-7_ Group.

Key words: microalgal bacterial consortia, biofilm reactor, the mass concentration of influent ammonia nitrogen, nutrients removal, microbial community