[Denitrification performance of PBS as a solid carbon source of denitrification]

Poly-butylenes succinate (PBS) was used as solid denitrification carbon source and biofilm carrier, to investigate the denitrification performance and the influence of adding inert carrier. The experimental results showed that PBS could serve as solid carbon source for denitrification of low C/N ratio wastewater, but the startup time was longer, about 33 d. There was no accumulation of nitrite nitrogen in the process of denitrification, but it produced less than 0.8 mg x L(-1) ammonia nitrogen. Increasing the amount of biofilm in PBS supported denitrification system by adding the inert carrier could improve the denitrification rate. The denitrification rates of PBS, PBS + 30 g gravel, PBS + 60 g gravel and PBS +90 g gravel systems were 5.33, 7.04, 10.05 and 6.93 mg x (L x h)(-1), respectively, and all reactions were zero order. During the denitrification process (0-9 h), DOC increased before it was reduced. At the end of the denitrification reaction (24 h), DOC of the denitrification system with inert carrier 60 g gravel and 90 g gravel was 16.34 mg x L(-1) and 19.22 mg x L(-1), respectively, higher than that without gravel of 13.48 mg x L(-1). The pH of all denitrification systems were lower than the initial value, which was the result of comprehensive function of acidic substances and alkalinity produced in the process of degradation of solid carbon source and denitrification, respectively.