Screening and immobilizing the denitrifying microbes in sediment for bioremediation

Abstract

In this study, immobilized microbial beads were proposed as a solution for excessive nitrogen concentration of the river sediment. The predominant denitrifying microbes were screened from the river sediment. The optimized production of immobilized microbial beads and long-term nitrogen removal efficiency were investigated. 16S rRNA gene sequencing analysis showed that denitrifying bacteria such as Pseudomonas, Alcaligenes, Proteiniclasticum, Achromobacter and Methylobacillus were dominant microflora in the enriched microbial agent, which accounted for 94.43% of the total microbes. Pseudomonas belongs to Gammaproteo bacteria, accounting for 49.22% and functioned as the most predominant denitrifying bacteria. The material concentration of 8% polyvinyl alcohol, 0.5% sodium alginate and 12.5% microbial biomass were found to be the optimal immobilizing conditions. The NH4+-N and total nitrogen (TN) removal rates in sediment with dosing immobilized microbial beads were estimated as 68.1% and 67.8%, respectively, when compared to the dosing liquid microbial agent were 50.5% and 49.3%. Meanwhile, the NH4+-N and TN removal rates in overlying water went up from 53.14% to 59.69% and from 68.03% to 78.13%, respectively, by using immobilized microbial beads.