[Analysis of the Effect of Temperature on the Microbial Flora Structure During the Nitrite Oxidation Process Using 16S rRNA High-throughput Sequencing].

In order to further understand the influence of high temperature shock on the microbial community structure of activated sludge during the process of nitrite oxidation, the enriched nitrifying activated sludge under different NO2--N concentration was taken as the research object in this study. 16S rRNA high-throughput sequencing technology was used to analyze the changes in the microbial community abundance and structural characteristics of activated sludge by changing the environmental temperature. The results of high-throughput sequencing showed that microorganisms were more likely to grow at 25℃, and the diversity of the microbial community in the activated sludge was the most abundant. With increased temperature, the richness, evenness, and diversity of the flora in the system decreased. In addition, it was found that the main nitrifying bacterium in the system was Nitrospira of Nitrospirae, whereby 35℃ was more suitable for its growth. Meanwhile, a higher temperature also caused differences in the structure of non-nitrifying functional microorganisms (e.g., Bacteroidetes, Chlorofulexi, Halomonas, and Pseudomonas) in the activated sludge. The results of this study provide some theoretical reference for the investigation of the distribution characteristics of microbial flora during the process of nitrite oxidation under high temperature shock, and can also be used as reference for relevant high temperature shock tests.

Impact Behavior of Hydrophilic Micron Particles on a Planar Gas-Liquid Interface.

The behavior of hydrophilic micron particles impacting on the gas-liquid interface has been further experimentally studied using a high-speed camera at different surface tensions and dynamic viscosities of liquids. The results show that the impact behavior exhibits suspension and submergence modes, whose boundary cannot be clearly identified because the overlap between the impact velocity ranges occurs because of the unstable pinning of the three-phase contact line on the surface of hydrophilic particles. The liquid properties have little effect on the wettability of hydrophilic particles but greatly influence the hydrodynamic and capillary force exerted on the particles, leading to the expansion of the suspension mode range. In addition, the penetration probability changes little with the decrease in surface tension, while it significantly reduces with the increase in dynamic viscosity. A penetration probability model is predicted as an exponential function of the inertial and supporting forces, and the experimental values agree well with the predicted values. The outcomes of this research will be helpful for understanding the mechanism of particle-interface interaction and providing guidance for enhancing the separation of hydrophilic fine ash via a bubble scrubbing system.