Frontiers of Environmental Science & Engineering
>> 2019,
Volume 13,
Issue 6
doi:
10.1007/s11783-019-1166-8
RESEARCH ARTICLE
The impact of ultrasonic treatment on activity of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria in activated sludge
1. State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
2. Advanced Water Management Centre, The University of Queensland, St. Lucia QLD 4072, Australia
3. China Academy of Urban Planning & Design, Beijing 100084, China |
Available online: 2019-10-30
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Abstract
• Conditions for ultrasonic treatment to achieve partial nitritation are optimized. • Ultrasound reduces metabolic activity and releases intracellular metabolites. • Mechanical shearing is essential to inhibit nitrite oxidation. The ultrasonic treatment of sludge has been considered as an effective method to facilitate the partial nitritation of municipal sewage. This study aims to reveal the effects of ultrasound on ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). The impact factors including ultrasonic irradiation time and intensity, sludge concentration, thermal effect and released free radicals were studied. The maximized difference between the changes in AOB and NOB activities were obtained with 10 g mixed liquor suspended solids (MLSS)/L, using 0.9 kJ/mL ultrasonic energy density and 12 h interval time. The increased ultrasonic intensity destroyed the floc structure of activated sludge, increased the microbial death, and decreased the cellular ATP level. Further, the mechanism exploration indicated that the mechanical shearing could be a critical factor in achieving the nitritation with inhibitory effect on nitrite oxidation.
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