Wastewater

Engineering

Sewage treatment

Ecology

Bacteria

Biology

Sewage sludge

Thermophile

Denitrification

Mesophile

Biochemistry

Nitrogen

Genetics

Environmental engineering

Organic chemistry

Environmental chemistry

Enzyme

Environmental science

Denitrifying bacteria

Chemistry

Pulp and paper industry

Aerobic denitrification

Nitrate

Bioresource Technology

Thermophilic biological nitrogen removal will provide low-cost strategies for the treatment of high-temperature nitrogenous wastewater (greater than 45 ℃). In this study, a thermophilic denitrifying granular sludge system was established at 50 ℃ and compared with mesophilic systems (30 ℃ and 40 ℃). 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 ℃. Moreover, the functional gene prediction also denoted an enrichment of nitrate reduction genes and carbon metabolism pathways at 50 ℃, 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.

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