title: Ultrasonic frequency effects on the removal of Microcystis aeruginosa.
abstract: Algae bloom in source water causes high chemical consumption and deteriorates water quality in waterworks. This paper studied the ultrasonic removal of Microcystis aeruginosa. The results showed that algae cells could be effectively removed by sonication and gas vesicle collapse was the main mechanism. The ultrasonic algae removal followed the first order reaction with a rate constant of 0.023 min(-1) (80 W, 80 kHz). Higher ultrasound frequency benefited algae removal; the algae removal rate constant was 0.114 min(-1) at 1320 kHz and 0.0224 min(-1) at 20 kHz (80 W). Higher ultrasound power also accelerated algae removal; the algae removal rate constant was 0.023 min(-1) at 80 W and 0.007 min(-1) at 32 W (80 kHz). However, high ultrasound power and long irradiation caused microcystins to increase. 80 W, 80 kHz sonication for 5 min increased the extracellular microcystins concentration from 0.87 microg/L to 3.11 microg/L. Sound frequency had little impact on the microcystins release. The chlorophyll a concentration initially decreased and then stabilized after 5 min of sonication.
authors.affiliation: Shenzhen Graduate School, Tsinghua University, Shenzhen 518055, China. zhanggm@sz.tsinghua.edu.cn
authors.forename: Guangming
authors.initials: G
authors.lastname: Zhang
authors.forename: Panyue
authors.initials: P
authors.lastname: Zhang
authors.forename: Bo
authors.initials: B
authors.lastname: Wang
authors.forename: Hong
authors.initials: H
authors.lastname: Liu
mesh_terms: D002621:Chemistry / Q000379:methods; D002734:Chlorophyll / Q000737:chemistry; D000077194:Chlorophyll A; D056890:Eukaryota / Q000378:metabolism*; D005609:Free Radicals; D007700:Kinetics; D046931:Microcystis / Q000378:metabolism*; D013010:Sonication; D014465:Ultrasonics; D014871:Water Microbiology; D014873:Water Pollutants / Q000378:metabolism*; D018508:Water Purification / Q000379:methods*
chemical_list: D005609:Free Radicals; D014873:Water Pollutants; D002734:Chlorophyll; D000077194:Chlorophyll A