1 research outputs found
Ultrasonic Treatment Enhanced Ammonia-Oxidizing Bacterial (AOB) Activity for Nitritation Process
Oxidation of ammonia
to nitrite rather than nitrate is critical
for nitritation process for wastewater treatment. We proposed a promising
approach by using controlled ultrasonic treatment to enhance the activity
of ammonia-oxidizing bacteria (AOB) and suppress that of nitrite-oxidizing
bacteria (NOB). Batch activity assays indicated that when ultrasound
was applied, AOB activity reached a peak level and then declined but
NOB activity deteriorated continuously as the power intensity of ultrasound
increased. Kinetic analysis of relative microbial activity versus
ultrasonic energy density was performed to investigate the effect
of operational factors (power, sludge concentration, and aeration)
on AOB and NOB activities and the test parameters were selected for
reactor tests. Laboratory sequential batch reactor (SBR) was further
used to test the ultrasonic stimulus with 8 h per day operational
cycle and synthetic waste urine as influent. With specific ultrasonic
energy density of 0.09 kJ/mg VSS and continuously fed influent containing
above 200 mg NH<sub>3</sub>–N/L, high AOB reproductive activity
was achieved and nearly complete conversion of ammonia-N to nitrite
was maintained. Microbial structure analysis confirmed that the treatment
changed community of AOB, NOB, and heterotrophs. Known AOB <i>Nitrosomonas</i> genus remained at similar level in the biomass
while typical NOB <i>Nitrospira</i> genus disappeared in
the SBR under ultrasonic treatment and after the treatment was off
for 30 days