To solve the problems of high energy consumption, complex process, and low nitrogen removal efficiency of the currently available low carbon source wastewater treatment processes, a novel coagulation sedimentation/post solid-phase denitrification biofilter process was proposed. Domestic wastewater with low carbon to nitrogen ratio was treated. The changes in the microbial community structure along the biofilters were studied and the functional bacteria were identified using the polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that the microbial diversity and richness of the microorganisms increased from the bottom to the top along the nitrification filter, while in the denitrification filter, there parameters increased firstly and then decreased from the bottom to the top along the cylinder. A bigger population of nitrifying and denitrifying bacteria was observed at the top and the middle of the nitrification and denitrification biofilter, respectively. Moreover, Nitrosomonas sp. Nm47 and Candidatus Nitrospira defluvii were the predominant nitrifying bacteria in the nitrification biofilter, and Myxobacteria and Rubrivivas gelatinosus were the predominant denitrifying bacteria in the solid-phase denitrification biofilter.
Keywords: PCR-DGGE; biological filter; microbial community; post solid-phase denitrification; solid carbon source.