Effects of Gas/Water Ratio on the Characteristics of Nitrogen Removal and the Microbial Community in Post Solid-Phase Denitrification Biofilter Process

Abstract

To solve the problems of high-energy consumption, complex processes, and low nitrogen removal efficiency in the currently available low carbon source wastewater treatment processes, a novel coagulation sedimentation/post solid-phase denitrification biofilter process (CS-BAF-SPDB) was proposed. The effect of gas/water ratio on nitrogen removal efficiency of the CS-BAF-SPDB was studied. The changes in the microbial community structure along the varying gas/water ratio were investigated, and the functional bacteria were identified using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that, to realize favorable nitrifying and denitrifying performance simultaneously in the BAF-SPDB unit, the gas/water ratio of the BAF should be set at 4∶1. In addition, the influence of the macro operational parameters on the performance of the BAF and SPDB had a direct relationship with the dynamic changes in the micro microbial community. The influence of gas/water ratio on nitrification performance in the BAF was mainly embodied in the changes of composition, amount, and activity of ammonia-oxidizing bacteria Candidatus and Nitrospira defluvii and nitrite-oxidizing bacteria Nitrosomonas sp. Nm47, whereas that on denitrification performance in the SPDB was mainly embodied in the changes of composition and amount of solid carbon substrate degrading denitrifying bacteria Pseudomonas sp. and Myxobacterium AT3-03 and heterotrophic denitrifying bacteria Dechloromonas agitate, Comamonas granuli, and Rubrivivax gelatinosus.