Inactivation Of Synedra Sp By Intermediate Frequency Ultrasound: Mechanism And Safety On Water Quality

Running of the Three Gorges reservoir makes that the dam upstream maintain alow water level in flood season, while in the dry season maintain a high water level. Itmakes that the hydrology, water environment and water ecological of reservoirundergone tremendous changes compared to store water before. The diatom “blooms”phenomenon of Three Gorges Reservoir tributaries type have occurred, seriouslyaffecting the water supply. Ultrasonic technology has unparalleled advantages thanother algae technology, and the current researchs on the ultrasonic algae were single andnot full. In this paper, inactivation mechanism of Synedra sp. by ultrasonic wereinvestigated, meanwhile the rule of release and degradation and the safety of drinkingwater in the process has been discussed. The key results are as follows:1) The performance of different modes (frequency, power, and time), mechanism(mechanical effects and free radicals) and inactivation kinetics by intermediatefrequency ultrasound had been researched. It found that inactivation mechanism ofSynedra sp. by intermediate frequency ultrasound were cavitation bubble resonance todamage the chloroplast structure and hydroxyl radical to degradate chlorophyll a.2) After stopped ultrasound treatment, the photosynthetic parameters of Synedra sp.such as Y, α, rETRmax would immediately restored. As ultrasound inhibited celldivision, so the recovery of chlorophyll a has lagged.3) The study on the release and degradation of organic matter by the change ofTOC concentration and the analysis of cell integrity showed that in10min the removalrate of cells was86%, and the cell disruption was serious. Meanwhile the percent ofcells with only shell were90%in these with complete morphology, and TOCconcentration increasing, and massive organic matters releasing. After10~15min, TOCconcentration decreased and organic matters were degraded. Combining the correlationanalysis, the release of organic matter and cell removal increased with the degradationof the photosynthetic parameters proportionally. The results showed that the integrity ofmost cells were destroyed and intracellular organic matters were also massively released.Therefore, it needs to further research the formation potential of disinfection byproducts,to deeply discuss the influence of organic matter releasing in drinking water safety.