| With the economic and social development, China’s water environmental issuesbecome increasingly serious. Eutrophication has become a global environmentalproblem. Increasingly serious water blooms caused by eutrophication caused greatinconvenience to the people’s work and life, but also restricted the further developmentof economic and social. Methods of algal blooms treatment can be divided into physical,chemical and biological. However, all of the above methods are very slow and willcause secondary pollution. As a new environmentally-friendly algaecide technology,ultrasonic technology caused a great deal of attention by its quick, non-polluting andcontrollability characteristics. This article aims to provide theoretical and technicalsupport for the further application of ultrasonic technology in the water treatmentthrough research the impact of different factors on ultrasonic algae removal effect.Firstly, this paper studied the low power ultrasonic inhibitory effect on algae. Thenultrasonic power, ultrasonic frequency and ultrasonic irradiation time on the inhibitionof the growth of algae and immediate removal rate were studied. Studies have shownthat the low-power ultrasonic could have a good treatment effect on algae with afrequency of600kHz. While the frequency and irradiation time is constant, the effectincreases with the power increase, but gradually becomes saturated. In this paper40Wwould achieve the economic and effective result. And if irradiation time and power isconstant, the ultrasonic frequency of600kHz is the best. With a certain frequency andpower, irradiation for5min would achieve satisfactory results. Using600kHz,40Wultrasonic to irradiate Microcystis aeruginosa liquid for5min, the instant algae removalrate could reach26%, and algae control rate of could reach93.56%5days later.Secondly,①the impact of environmental factors and algae algaecide effectshowed that light intensity played an influential role on ultrasound algae removal. Thelight intensity is the higher within limits, the better.②The higher the temperature is,the better treatment effect is on the alginate solution. Ultrasonic treatment effect onMicrocystis aeruginosa would be better with an increasing temperature.③A normal pHvalue in the water blooms without adjustment is able to achieve better results byultrasonic.④The regularity of treatment effect by ultrasonic irradiation with aeration isnot obvious,but overall, the micro-aeration is conducive to algae removal.⑤Thealgae’s Shape and structure are very effective to algae removal by ultrasonic. Comparatively speaking, algae with stripe shape are more susceptible to ultrasound thanspherical algae. And algae with pseudo vacuoles are more susceptible than algae thatnot have.⑥The inhibitory effect of lag phase by ultrasound is higher than thelogarithmic phase and stable. And the inhibitory effect of optical algae solution is higherthan the dark period.⑦Ultrasound treatment effect is higher while the initialconcentration is lower, so ultrasonic can achieve better results in lower concentrations.⑧Processed under the same conditions of ultrasound, the more algae solution is, theless effective the treatment effect is.Finally, it is indicated by the research of algae removal mechanism of ultrasonicthat ultrasonic irradiation could affect algal cells’ structure, and the effects of ultrasoundon Microcystis aeruginosa, Scenedesmus obliquus and Synedra is also different. Thissuggests that ultrasound exert different influence on algae with different shape andstructure. In addition, ultrasonic also inhibit cell growth, reduce the growth rate of thealgal cells. Meanwhile, ultrasonic could damage the chlorophyll a and phycobiliproteinand inhibit its synthesis. Moreover, the ultrasonic radiation can ruin cells’pseudo-vacuoles and increase the settlement. The use of ultrasonic treatment in thenatural water shows that the average removal rate of algae could reach59.08%afterultrasonic irradiation which means that ultrasonic techenolgy is available. |
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