Abstract

Ozonation is a widely applied water treatment process, used for oxidation of contaminants, as well as for the disinfection of water. However, the conventional ozonation process demands a high energy requirement and deep tanks to ensure effective mass transfer and oxidation. Microbubble technologies have emerged which have the potential to improve gas-liquid contacting. Microbubbles have diameters of 1–100 µm, while conventional bubbles used in ozonation are between 2 and 6 mm. Microbubbles have many favorable characteristics that make them suitable for ozonation. In this review, the attributes of microbubbles for ozonation have been compared with those of conventional bubbles. The higher interfacial area and lower rise velocity of microbubbles compared with conventional bubbles means that ozone in the gas phase can be more efficiently transferred into the liquid phase. This is due to a higher contact time and increased contact area of the bubble with the bulk liquid. The analysis reveals that the volumetric mass transfer coefficient can be significantly enhanced through the use of microbubbles. In addition, the steady state dissolved ozone concentration was positively impacted by the use of microbubbles. Microbubbles were shown to be able to oxidize a broader range of organic compounds more quickly than for conventional bubbles. However, the review highlighted that comparison of microbubbles with conventional bubbles is not always carried out in a fair and consistent way with respect to reactor configuration. Requirements for future research, more consistent experimental comparisons and the steps needed to enable implementation of microbubbles have been discussed.

• Highlights

• Extensive comparison of microbubbles with conventional bubbles for ozonation.

• Ozone mass transfer enhanced through the use of microbubbles.

• Improved micropollutant removal when using microbubble ozonation.

• Opportunities for more efficient ozone reactor design using microbubbles.

摘要

臭氧化是一种广泛应用的水处理工艺，用于氧化污染物以及对水进行消毒。然而，常规的臭氧化工艺要求高的能量需求和深的罐以确保有效的质量转移和氧化。已经出现了微泡技术，其具有改善气液接触的潜力。微气泡的直径为1–100 µm，而用于臭氧氧化的常规气泡的直径在2至6 mm之间。微泡具有许多有利的特性，使其适合于臭氧化。在这篇综述中，将用于臭氧化的微泡的属性与常规泡的属性进行了比较。与常规气泡相比，微气泡的界面面积更大，上升速度更低，这意味着气相中的臭氧可以更有效地转移到液相中。这是由于更长的接触时间以及气泡与散装液体的接触面积增加所致。分析表明，通过使用微泡可以显着提高体积传质系数。此外，使用微泡对稳态溶解臭氧浓度有积极影响。与常规气泡相比，微气泡能够更快地氧化更广泛的有机化合物。但是，该评论强调指出，就反应堆配置而言，微气泡与常规气泡的比较并不总是以公平，一致的方式进行。

• 强调

• 微型气泡与传统气泡进行臭氧化的广泛比较。

• 通过使用微泡增强了臭氧质量传递。

• 使用微泡臭氧化技术时，改善了微污染物的去除。

• 使用微气泡进行更有效的臭氧反应器设计的机会。