[Effect of -Immobilized Nitrogen Cycling Bacteria on the Mechanism of Nitrogen Removal in Polluted River Water].

Surface water, and undisturbed sediment cores from the Qinshui River in Gonghu Bay were collected to carry out a simulation experiment in a laboratory to study the effect of -immobilized nitrogen-cycling bacteria on nitrogen removal mechanisms from the river water. In this study, the transformation and fate of ammonium among four different treatment groups were investigated by using a stable N isotope pairing technique combined with high-throughput sequencing technology[Treatment A:bare sediment, Treatment B:sediment+immobilized nitrogen cycling bacteria (INCB), Treatment C:sediment+, Treatment D:sediment+INCB+]. The results of the N mass-balance model showed that there were three pathways to the ultimate fate of nitrogen:precipitated with the sediments, absorbed by and consumed by microbial processes[denitrification and anaerobic ammonium oxidation (ANAMMOX)]. The percentages of assimilated in the NH were 25.44% and 19.79% for treatments C and D. The sediment storage ratio of NH accounted for 7.94%, 5.52%, 6.47% and 4.86% in treatments A, B, C, and D, respectively. The proportion of NH lost as N-labelled gas were 16.06%, 28.86%, 16.93% and 33.09% in the four different treatment groups, respectively. Denitrification and anammox were the bacterial primary processes in N and NO production. The abundance and diversity of microorganisms was relatively higher in the treatment with -immobilized nitrogen cycling bacteria (E-INCB) assemblage technology applied. Furthermore, the removal rates of NH were 24%, 34.38%, 48.84% and 57.74% in treatments A, B, C and D, respectively. These results show that the E-INCB assemblage technology may improve the capacity for nitrogen removal from the river water.