Effect of weight ratios of PHBV/PLA polymer blends on nitrate removal efficiency and microbial community during solid-phase denitrification

This study investigates the effect of weight ratios of poly (3-hydroxybutyrate-co-3-hydroxyvalerate)/poly (lactic acid) (PHBV/PLA) polymers blends on the denitrification performance and microbial community in fixed-bed reactors. Nitrate removal efficiency was enhanced with the increasing weight ratio of PHBV/PLA polymers, while the total organic carbon in the effluent increased. Meanwhile, there was an obvious negative correlation between PHBV/PLA weight ratio and the effluent pH. Moreover, fluorescence excitation emission matrix spectra (EEM) indicated that the effluents from all reactors mainly contained soluble microbial by-product-like substances and Fourier transform infrared spectra (FTIR) analysis indicated that there were compounds containing hydroxyl groups generated through hydrolysis. The weight-averaged molecular weight (Mw) of the degradation products in the effluent were distributed into high, intermediates and low Mw and the proportion of low-molecular-weight substances consisting principally of acetic acid correlated positively with to the nitrate removal efficiencies. Illuminasequencing indicated that weight ratios did partly affect the microbial diversity, while the dominant genus of denitrifying bacteria in both biofilms of PHBV/PLA blends mainly included Dechloromonas, Desulfovibrio, and Flavobacterium. (C) 2016 Published by Elsevier Ltd.