Nitrate removal from recirculating aquaculture system using polyhydroxybutyrate-co-hydroxyvalerate as carbon source

Abstract:

Abstract:［Objective］ Polyhydroxybutyrate-co-hydroxyvalerate (PHBV) was used as solid carbon source and biofilm carrier to remove nitrate from recirculating aquaculture system (RAS)．Dynamics of microbial community structure in biofilm coating on carbon source packed into denitrification reactor were investigated．［Methods］ Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial community in biofilm from denitrifiation reactor．Bacteria degrading PHBV were isolated from the reactor using pure culture method．［Results］Nitrate decreased remarkably in the RAS connected with dentrification reactor．In contrast，Nitrate increased continuously in the conventional RAS without dentrification reactor．According to the phylogenetic analysis，the microbes in the biofilm samples from denitrification reactor were divided into Proteobacteria (β-proteobacteria，γ-proteobacteria and δ-proteobacteria)，Firmicutes and Bacteroidetes．The major advantageous populations were Acidovorax and Bacillus in the 40-day reactor．The advantageous populations in the 150-day reactor were in order of Clostridium，Desulfitobacterium，Dechloromonas，Pseudoxanthomonas and Flavobacterium．Pure cultures of bacteria degrading PHBV isolated from denitrification reactor were classified into Acidovorax，Methylibium，Pseudoxanthomonas and Dechloromonas． ［Conclusion］Nitrate could be removed effectively from RAS using PHBV as carbon source．Advantageous bacteria and their dynamic changes were ascertained in biofilm from denitrification reactor packed with PHBV．