Denitrification performance and microbial community using polyhydroxyalkanoate as carbon source and biofilm carriers in fluidized bed bioreactor

This project investigated the denitrification performance and microbial community dynamics in a fluidized bed bioreactor (FBBR) using [Poly (3-hydroxybutyrate)] (PHB) as both solid-phase carbon source (SCS) and biofilm carrier. The reactor achieved a removal of nitrogen loading rate (NLR_rem) of 1.02 kg N/(m³·d) when hydraulic retention time (HRT) was 0.88 h, with nitrate (NO₃⁻-N) removal exceeding 99.5 % and minimal nitrite (NO₂⁻-N) accumulation. Pseudomonadota (68.3∼88.7 %) and Bacteroidota (2.3∼13.5 %) were observed the dominant phylum via high-throughput sequencing analysis. Meanwhile, Dechloromonas, Zoogloea, and Thauera were identified as the key denitrifying and degradation genus. Biofilm thickness regulation via hydraulic shear force proved critical for maintaining mass transfer efficiency and preventing performance decline. This project demonstrates PHB's dual role as a biodegradable SCS and biofilm carrier, offering a sustainable strategy for wastewater treatment and biodegradable plastic waste valorization.