A biofilm reactor based on slow-release carbon source effectively improved the continuous denitrification capacity of slightly polluted surface water at low carbon to nitrogen ratio

A biofilm reactor was exploited using Burkholderia sp. CF6. Polymers were attached to alkali-modified corn stover (CS) to prepare a novel slow-release carbon source. The slow-release carbon source not only released carbon into the nutrient-poor water in a stable manner to ensure denitrification, but also the microporous structure of the slow-release carbon source promoted the degradation of cellulose. Box-Behnken design was used to study the effects of hydraulic retention time (HRT), pH, and carbon to nitrogen ratio (C/N) on the nitrate removal efficiency. Under the HRT of 4 h, pH of 7.0, and C/N of 1.0, the nitrate removal efficiency reached 98.03%. Three-dimensional excitation emission matrix (3D-EEM) results showed that soluble microbial products (SMP) play a dominant role in denitrification. The PCR amplification technique showed that Burkholderia sp. CF6 assumed the main denitrification role in the reactor. This study provides a theoretical basis for the effective management of micro-polluted water bodies.