Study On Effect Of Algal Control By Low-Frequency And Low-Power Ultrasonic Irradiation

Ultrasonic radiation can inhibit the growth of algae and remove algae. Considereconomic, ecological security, the effects of algal control and other aspects，adoptlow-frequency and low-intensity ultrasound may be more applicable to technology ofalgal control. This article studied the low-frequency and low-intensity ultrasound on theeffect of algal instantaneous removal and algal growth inhibition, and studied thediversification of water quality which treatment by low-frequency and low-intensityultrasound. Moreover, studied the low-frequency and low-intensity ultrasound on thedestruction of gas vesicle and recovery of gas vesicle after destructed by ultrasonicradiation and the impact of algal photosynthesis by ultrasonic radiation. The resultsshow that: the low-frequency and low-intensity ultrasound can damage and inhibit algae,and the effect of blue-green algae better than green algae and diatoms, and the effect ofAnabaena better than Microcystis. Low-frequency and low-intensity ultrasound caninhibit the growth of algae, and the effect of intermittent frequently ultrasoundtreatments on the inhibition of algae is more obviously. low-frequency and low-intensity ultrasound (40kHz,0.25W/cm2) can broken gas vesicle completely in algalcells but not broken cells in3second; and the gas vesicle in algal cells can restore byitself after a certain period of time, Anabaena were almost entirely restored in five days,and microcystis were almost completely restored only two days. the longer ultrasound(40KHz,0.25W/cm2) can broken algal cells and released their contents to the waterbody and affect water quality. Moreover, a shorter time ultrasonic radiation (Anabaenaspiroide <1min, Microcystis wesenbergii, Scenedesmus quadricauda and Nitzschiapalea <5min) also can released their contents to the water body and affect water qualitybut not break algal cells. In addition when waters take play of cyanobacteria bloomwhich have gas vesicle in algal cells, the low frequency and low intensity ultrasonic mayleads to the algae loses buoyancy and sink to the bottom by broken gas vesicle, thusalgae were decomposed by microorganism or be fed on by zoobenthos. This way may bea practical feasible plan from the point of energy saving and security of aquatic ecology.