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Ultrasound-enhanced coagulation for cyanobacterial removal: Effects of ultrasound frequency and energy density on coagulation performance, leakage of intracellular organic matters and toxicity
Water Research ( IF 12.8 ) Pub Date : 2021-06-10 , DOI: 10.1016/j.watres.2021.117348
Yangrui Huang 1 , Lei Li 2 , Xinmiao Luan 1 , Xinmin Wei 3 , Huaizheng Li 4 , Naiyun Gao 2 , Juanjuan Yao 5
Affiliation  

Ultrasound-enhanced coagulation is capable of effectively removing algal cells in algae-laden water. However, study differences in ultrasound settings, algal cell conditions and coagulant properties complicate the accurate evaluation of this technique for practical applications. No study has yet compared algae (and algal organic matters) removal among different frequencies of ultrasound in the ultrasound-coagulation process. In this study, the ultrasound at three typical frequencies, 29.4, 470 and 780 kHz, were applied for this purpose. The results showed that high-frequency ultrasound at 470 and 780 kHz had substantially greater improvement of coagulation than low-frequency ultrasound at 29.4 kHz (For example, the turbidity removal at 1 mg-Al/L of polymeric aluminum chloride increased by 204.2%, 571.9% and 563.2% under 29.4, 470 and 780 kHz ultrasound-coagulation, respectively, at 3.42 J/mL). Algal cells exhibited irreversible physical damage and the release of intracellular organic matters (such as odorous compounds) under low-frequency ultrasound with energy densities ≥ 3.42 J/mL, whereas high-frequency ultrasound was characterized by nonviolent impairment, including oxidative degradation and gas vacuole destruction (particularly reversible) resulting from ultrasound-induced radicals and cell resonance, respectively. Avoiding the severe destruction of algal cells is crucial for minimizing the toxicity and secondary pollution of the treated water. To achieve satisfactory removal, protected safety and better economy, the optimal energy density for each frequency was also determined. The findings from the analyses of the laboratory-cultured sample were confirmed via real eutrophic surface water. This study provides new insights and guidance for the ongoing study of harmful algal removal by ultrasound-enhanced coagulation.



中文翻译:

超声增强凝固去除蓝藻:超声频率和能量密度对凝固性能、细胞内有机物渗漏和毒性的影响

超声增强凝聚能够有效去除富含藻类的水中的藻类细胞。然而,研究超声设置、藻类细胞条件和凝血剂特性的差异使该技术在实际应用中的准确评估变得复杂。目前还没有研究比较超声波凝固过程中不同频率超声波对藻类(和藻类有机物)的去除效果。在这项研究中,为此目的应用了三个典型频率(29.4、470 和 780 kHz)的超声波。结果表明,470和780 kHz的高频超声比29.4 kHz的低频超声具有明显更大的凝血改善作用(例如聚合氯化铝1 mg-Al/L的浊度去除率提高了204.2%, 571.9% 和 563.2% 低于 29.4,470 和 780 kHz 超声凝固,分别为 3.42 J/mL)。藻类细胞在能量密度≥ 3.42 J/mL的低频超声下表现出不可逆的物理损伤和细胞内有机物(如气味化合物)的释放,而高频超声的特点是非暴力损伤,包括氧化降解和气泡分别由超声诱导的自由基和细胞共振引起的破坏(特别是可逆的)。避免对藻类细胞的严重破坏对于最大限度地减少处理水的毒性和二次污染至关重要。为了达到令人满意的去除效果、保护安全性和更好的经济性,还确定了每个频率的最佳能量密度。实验室培养样品的分析结果通过真正的富营养化地表水得到证实。这项研究为正在进行的通过超声增强凝结去除有害藻类的研究提供了新的见解和指导。

更新日期:2021-06-22
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