超声波控藻对氮磷释放及水质变化的影响

为探究超声波控藻的底泥氮磷释放过程与水质恶化风险，本研究从太湖梅梁湾采集泥样、水样和藻样，采用低频超声波（35kHz，0.035 W/mL）处理不同对象（泥体系：底泥和水；藻体系：微囊藻和水；泥藻体系：底泥、微囊藻和水），分析底泥与藻细胞的氮磷释放贡献率及水质变化过程.结果显示，20min内超声处理不会造成底泥氮磷的显著释放，40min后会造成底泥氮磷大量释放和藻细胞破裂.比较3个体系的水质参数变化过程后得知底泥比藻细胞的氮磷释放贡献率更大.超声处理对COD_Mn和TN有一定的削减效果，泥体系和泥藻体系在超声波作用后溶解性氮以氨氮和硝氮为主.为降低水质恶化风险，建议超声波控藻采用适当的超声强度进行短时间处理，避免底泥氮磷大量释放和藻细胞破裂.

Effects of ultrasound on the released amount of nitrogen and phosphorus and changes of water quality during blooms control

Ultrasonic technology for controlling cyanobacterial blooms has attracted much attention from the general public. In order to investigate the effects of ultrasonic treatment on water quality deterioration and the amount of nitrogen and phosphorus released from sediments or algal cells. In this study, samples were collected from Meiliang Bay of Taihu Lake, and then, three experimental groups were designed:mixture of sediment and water (sediment system), suspension solution of Microcystis (algae system), and combination of sediment and algae suspension (sediment + algae system), so as to evaluate effects of low-frequency ultrasound (35kHz, 0.035W/mL). Results showed that marked release of nitrogen and phosphorus from sediments seldom occurred within 20min, while prolonged treatment (over 40min) would lead to largely nutrients release and algal cells rupture. Based on the data comparison among three experimental groups, the contribution of nitrogen and phosphorus released from sediments was much greater than that from algal cells. To a certain extent, COD_Mn and TN could be reduced by ultrasonic treatment. In sediment system and sediment + algae system, dissolved nitrogen mainly existed as ammonia and nitrate forms after treatment. For the sake of water quality safety, the intensity and duration of ultrasonic treatment should be optimized, which means low-intensity and short-time treatment is suggested, so as to avoid nutrients largely released from sediments and algal cells rupture.