The Experimental Study On The Removal Of Algae By Low Frequency Low Power Ultrasonic Enhanced Coagulation

Water resource is the important resources in the social development and humanlife, lakes and reservoirs is important fresh water resources in our country. With therapid progress and development of society, human activities causes of surface waterpollution is more and more, makes the phenomenon of eutrophication is more andmore serious. If not to control eutrophication phenomenon will cause seriousconsequences,not only destroy the ecological balance of water environment, but alsopose a threat to human health. At present, ultrasonic technology has its uniquesuperiority, so in the study of surface water to remove the algae has irreplaceableapplication prospects.This topic in laboratory pure culture of algae as the research object, through thelaboratory test, studied the environmental factors and algae factors effect on lowfrequency low power ultrasonic remove algae removal, And according to the algalgrowth curve is discussed in this test under the condition of the most suitableultrasonic function factor’s influence on the effect of alga, also studied the influencefactors of ultrasonic strengthening coagulation.The experimental results showed that: Concentration of algal cells as theextension of ultrasonic time presents the downward trend, there was a sudden changein5min. The change of turbidity removal rate fluctuation is not big, all above60%.Comprehensive comparison under this experimental condition, the most economicand efficient processing time is5min. In the case of power and duration must be, thisexperiment in40kHz ultrasonic effect better than20kHz and80kHz, the removaleffect of chlorophyll a is the same. So40kHz for appropriate ultrasonic frequency inlow frequency range. To remove the algae from the ultrasonic effect is enhanced withthe ultrasonic power is getting better and better, But after the power over a certainrange, no longer significant effect of removing, but leveled off. The test results showthat the comprehensive consideration of economy and removing effect,80w can achieve a better removal effect. Four different ultrasonic power on the turbidityremoval rate can reach more than68%.Low frequency low intensity ultrasound can inhibit the growth of algae, and thesame energy of ultrasound repeatedly applied to algae than one-time continuousprocessing way of algal inhibiting effect more apparent. So in total energyconsumption of the same situation, the processing of low dose and high frequencymode is helpful to improve the effect of algal inhibiting.Ultrasound on the patina of algae removal rate with the increase of temperaturerise, When the temperature is15℃, the concentration of algae removal rate was24%,When the temperature of35℃, the concentration of algal removal rate of24.5%.Overall temperature on ultrasonic remove algae has certain influence.Ultrasonic treatment of different algae will get different results. Effect onblue-green algae removal is better than that of diatoms and green algae. Using40KHZ,80w ultrasonic treatment for5min removal effect for verdigris microcystinalgae> small ring algal> scenedesmus, removal rate is47.27%,35.45%and13.8%.Visible, have air bags of algae are more likely to be removed.Ultrasonic enhanced coagulation of blue-green algae removal effect is better thanthe green algae and diatoms. Experiments on verdigris microcystin algae processingeffect is best, in the ultrasonic function5s, patina of algal cells in the removal rate of95.51%. Ultrasound can make coagulation algae removal efficiency was improved,and the removal rate of the same cases, reduced the amount of coagulant. When thePolyaluminium chloride (PAC) as the dosage of16mg/L, after ultrasonic treatment ofturbidity removal rate is increased by80.42%than single coagulation.