Purification of Slightly Salt-alkaline Water Bodies by Microorganism Enhanced Combined Floating Bed

Abstract

In order to study the purifying effect of combined floating bed constucted by salinity plant Suaeda salsa and microorganisms on the slightly salt-alkaline water, blank floating bed A, S.salsa floating bed B, microbes floating bed C and S.salsa + microorganisms combined floating bed D were established, and slightly salt-alkaline eutrophic water body (pH 8.5-9.0, salinity 5‰-7‰) was purified under continuous flow conditions in the laboratory. Results showed that the removal rates of total nitrogen, total phosphorus, permanganate index by S.salsa floating bed were 32.5%, 14.3% and 28.2%, respectively. And the removal rates of total nitrogen, total phosphorus and permanganate index by S.salsa + microorganisms combined floating bed D which installed artificial medium with microorganisms reached 70.5%, 34.7% and 70.8%, respectively, of which the removal rates of total nitrogen, total phosphorus and permanganate index by microbial units were 37.7%, 21.6% and 44.5%, respectively. Synergies removal rates of nitrate nitrogen and total nitrogen by S.salsa + microorganisms combined floating bed were 12.2% and 0.3%, but there was no synergy in the process of removing ammonia nitrogen, total phosphorus and permanganate index, which indicated that the synergies of S.salsa and microorganisms in the combined floating bed were suppressed in slightly salt-alkaline environment. The high-throughput sequencing technique was adopted to analyze the microbial community in the floating bed C and D, which indicated that the abundance and diversity of microbial community in the combined floating bed were higher, and this was consistent with the result of the higher removal rate of the flotation bed D. Principal component analysis showed that the microbial degradation was a major factor in reducing the concentration of pollutants. This study provided a guide for the using of floating bed in purifying slightly salt-alkaline eutrophic water bodies in coastal area.