Nanobubble technology in anaerobic digestion: A review

Does salting-out effect nucleate nanobubbles in water: Spontaneous nucleation?

“…Bulk nanobubbles possess distinct features such as extraordinary longevity, high surface to volume ratio , high mass transfer coefficient and Laplace pressure, ability to generate reactive oxygen species. Owing to such peculiar properties, nanobubbles have wide range of applications in the field of wastewater treatment [1] , [2] , medical application [3] , food processing [4] , environmental sectors [5] , bio-engineering sectors [6] , flotation [7] , therapeutic delivery [8] . Despite such overwhelming applications, the fundamental understanding of nanobubble generation [9] and a unique characterization technique to distinguish nanobubbles from the particle and nanodroplet [10] are still under infancy.…”

Untapped Potential: Applying Microbubble and Nanobubble Technology in Water and Wastewater Treatment and Ecological Restoration

“…115,116 The microaerobic environment further favors efficient electron transport and reduces the VFAs through enhanced facultative bacterial activity. 111 A recent study also demonstrated that air-NBs potentiated the enzymatic activity involved in both the hydrolysis/acidification and methanogenesis stages (including alkaline phosphatase, acid phosphatase, α-glucosidase, protease, coenzyme F420, and cellulase) as compared to the control group (without any NBs in deionized water) during AD of food waste. 121 Furthermore, besides enhancing the activity of functional enzymes, air-and CO 2 -NBs also shaped the microbial communities (both bacteria and archaea) in the digestor.…”

“…Studies reported that air-, H 2 -, CO 2 -, and N 2 -NB upregulated the activity of extracellular hydrolases and accelerated the hydrolysis rate. , CO 2 -NBs were capable of regulating pH levels, alleviating VFAs inhibition, and reinforcing the stability of anaerobic digesters with high-solid contents by possibly providing electron acceptors for hydrogenotrophic methanogenesis . Interestingly, both air- and O 2 -NBs decreased the cellulose crystallinity, thereby ameliorating the hydrolysis and the acidogenesis of cellulose in AD, which is likely due to the establishment of a microaerobic environment in the digestor. , The microaerobic environment further favors efficient electron transport and reduces the VFAs through enhanced facultative bacterial activity . A recent study also demonstrated that air-NBs potentiated the enzymatic activity involved in both the hydrolysis/acidification and methanogenesis stages (including alkaline phosphatase, acid phosphatase, α-glucosidase, protease, coenzyme F420, and cellulase) as compared to the control group (without any NBs in deionized water) during AD of food waste …”

“…Hydrogen (H 2 )-MBs/NBs can be applied for biogas upgrading via hydrogenotrophic methanogenesis. A more detailed discussion of the NB-integrated AD processes and possible underlying mechanisms for enhanced AD performance can be found in our recent review . Some of the important applications of MB/NB technology in the AD process are briefly discussed here.…”

Micro-bubble manipulation and its application in functional material patterning

“…泡 [1] 。毫米和亚毫米气泡主要是利用其在液相中的不 稳定性来增强传质传热 [2][3][4] ，或利用界面的电荷和浮 力对气泡的亲和程度不同进行颗粒浮选 [5][6][7] 。 微米气泡 可利用界面内部的气体空腔来合成多孔材料，或利 用爆破过程释放的高能自由基进行环境污染物的降 解 [8] 。纳米气泡则由于其特殊的尺寸效应具有了高内 压、 长寿命、 高活性等特性 [9,10] ，更多地应用在农业种 植、生物诊疗等领域 [11][12][13][14] 向运输、分子机器人等 [15,16] 。虽然单个自由气泡的运 动具有一定的可控性，但是自由气泡群的运动操控 十分困难，尤其是可控间距的气泡阵列的实现依然 是一个难点。限域空间的引入降低了体系的运动维度， 使气泡具有更高的可控性。首先，运动的受限减少了 气泡间的接触和融合，提高了气泡的稳定性。其次， 限域的固液界面的粘附作用可抵抗气泡的浮力作用， 从而稳定气泡。因受限而固定的气泡阵列还可作为模 板用于高精度图案化。 目前，针对自由气泡的理论 [17,18] 与应用研究 [19, 2 0] 已有很多系统的综述，但对受限空间内的气泡关注 较少。近年来，我们通过设计模板限制气泡的运动和…”