Enhanced thermophilic denitrification performance and potential microbial mechanism in denitrifying granular sludge system

Thermophilic biological nitrogen removal will provide low-cost strategies for the treatment of high-temperature nitrogenous wastewater (greater than 45 degrees C). In this study, a thermophilic denitrifying granular sludge system was established at 50 degrees C and compared with mesophilic systems (30 degrees C and 40 degrees C). The results showed a significant increase in COD and nitrate removal rate with the elevating temperature. Besides, the microbial community analysis indicated an obvious succession of key functional bacteria at different temperatures. Enriched thermophiles including Truepera, Azoarcus, and Elioraea were the dominant denitrifiers in the thermophilic denitrifying granular sludge system, which ensured the high nitrate removal at 50 degrees C. Moreover, the functional gene prediction also denoted an enrichment of nitrate reduction genes and carbon metabolism pathways at 50 degrees C, which could explain the enhancement of thermophilic denitrification. These findings could provide new insight into the application of denitrifying granular sludge in thermophilic wastewater treatment.

Automated summary

The study suggests that increasing temperature has a positive impact on thermophilic biological nitrogen removal, leading to an increase in COD and nitrate removal rates, as well as succession of key functional bacterial communities at different temperatures. Enriched thermophilic bacteria in the thermophilic denitrifying granular sludge system can effectively remove nitrate.