Biological denitrification using PHBV polymer as solid carbon source and biofilm carrier

In this study, a poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) supported denitrification system was developed for nitrate removal. Results showed that nitrate removal efficiency exceeded 95% and the maximal volumetric denitrification rate reached 0.77 kg M-3 day(-1) with a hydraulic retention time (HRT) of 0.5 h. The effluent total organic carbon (TOC) decreased while the effluent pH increased with a shortage of HRT. Meanwhile, the weight-averaged molecular weight distribution analysis indicated that PHBV polymer's intermediate degradation products was divided into three ranges, and the low-molecular-weight substances were mainly identified as acetate by a gas chromatography. The fourier transformation infrared spectra (FTIR) analysis indicated that these degradation products contained lots of C=0 and O-H. Moreover, the microbial community structure of the PHBV biofilm was different with that of the inoculation sludge, and the abundant denitrifying bacteria mainly included Dechloromonas, Flcrvobacteriumand Stenotrophomonas. Functional protein, biological process and KEGG pathways were explored by Meta-proteomic approach, which further revealed the degradation and utilization mechanism of PHBV polymer.