Study on Plant Growth and Nutrient Uptake under Different Aeration Intensity in Hydroponics with the Application of Particle Image Velocimetry

Aeration is considered beneficial for hydroponics. However, little information is available on the effects of aeration, and even less on solutions that use bubble flow and their agronomic effects. In this study, the effects of aeration intensity on plants were studied through cultivation experiments and flow field visualization. It was found that the growth of plants did not increase linearly with an increase in aeration intensity. From the results of this study, when the aeration intensity was within the low range (0.07–0.15 L·L−1 NS·min−1), increasing the aeration intensity increased the plant growth. However, after the aeration intensity reached a certain extent (0.15–1.18 L·L−1 NS·min−1), some indicators did not change significantly. When the aeration intensity continued to increase (1.18–2.35 L·L−1 NS·min−1), growth began to decrease. These results show that for increasing dissolved oxygen and promoting plant growth, the rule is not “the higher the aeration intensity, the better”. There is a reasonable range of aeration intensity within which crops grow normally and rapidly. In addition, increasing the aeration intensity means increasing energy utilization and operating costs. In actual hydroponics production, it is very important to find a reasonable aeration intensity range.

Effect of Aeration on Yeast Community Structure and Volatile Composition in Uninoculated Chardonnay Wines

Uninoculated wines are regarded as having improved mouthfeel and texture and more complex flavor profiles when compared to wines inoculated with commercial S. cerevisiae strains. Uninoculated fermentation involves a complex microbial succession of yeasts and bacteria during fermentation. Microbial population dynamics are affected by several factors that can ultimately determine if a particular species or strain contributes to wine aroma and flavor. In this work, we have studied the effect of aeration, a common winemaking practice, on the yeast microbiota during uninoculated Chardonnay wine fermentation. The timing of aeration and then aeration intensity were evaluated across two successive vintages. While the timing of aeration significantly impacted fermentation efficiency across oxygen treatments, different levels of aeration intensity only differed when compared to the non-aerated control ferments. Air addition increased the viable cell population size of yeast from the genera Hanseniaspora, Lachancea, Metschnikowia and Torulaspora in both vintages. While in 2019, a high relative abundance was found for Hanseniaspora species in aerated ferments, in 2020, T. delbrueckii was visibly more abundant than other species in response to aeration. Accompanying the observed differences in yeast community structure, the chemical profile of the finished wines was also different across the various aeration treatments. However, excessive aeration resulted in elevated concentrations of ethyl acetate and acetic acid, which would likely have a detrimental effect on wine quality. This work demonstrates the role of aeration in shaping yeast population dynamics and modulating a volatile profile in uninoculated wines, and highlights the need for careful air addition to avoid a negative sensory impact on wine flavor and aroma.

Corrosion Inhibition of Brass by Biochemical Process in Circulating Cooling Water System

Controlling the corrosion rate of metal materials is one of the key issues in circulating cooling water treatment. In recent years, the treatment of circulating cooling water by microorganisms has become a research hotspot. Compared with the traditional chemical treatment, microbial treatment is an environmentally friendly technology. In this paper, the effects of ammonia nitrogen concentration, microbial dosage and aeration intensity on copper corrosion rate were studied. In order to analyze the experimental data more comprehensively, a full factor experimental design was used to investigate the effects of ammonia nitrogen concentration, microbial dosage and aeration intensity on copper corrosion. The corrosion rate of copper was less than the national standard (< 0.005 mm / a), in which ammonia nitrogen concentration and aeration intensity were significant factors (P < 0.05), and the interaction between ammonia nitrogen concentration and aeration intensity was also significant (P < 0.05), After optimization, the regression rate of the model increased from 85.02% to 92.41%.

Decentralized proportional-integral control with carbon addition for wastewater treatment plant

Two main challenges in activated sludge wastewater treatment plant (WWTP) are cost and effluent quality, which has forced the wastewater treatment operator to find an alternative to improve the existing control strategy. The Benchmark Simulation Model No. 1 (BSM1) is applied as operational settings for this study. In BSM1, the standard control variables are the internal recirculation flow rate and the oxygen transfer rate. To improve the existing control strategy of BSM1, three alternative control handles are proposed, which are the individual aeration intensity control, carbon source addition and combination of both. The effect of each control handles in terms of the effluent violation, effluent quality, aeration cost, and total operational cost index are examined. The simulation result has shown that the individual control of aeration intensity improved the effluent quality index, and reduced the aeration, pumping, and total operational cost index when compared to the standard BSM1 control handle. Nonetheless, the addition of a fixed external carbon source has shown a significantly improved effluent quality with a lower number of total nitrogen violations as compared to the standard BSM1 control handles. Thus, the proposed control handles may be beneficial if applied in a real WWTP.

Determination of the parameters of the submerged cultivation of micromycete Trichoderma asperellum VKPM F-1323 for obtaining spore forms of culture

The basic physical parameters of the cultivation of micromycete Trichoderma asperellum VKPM F-1323 are determined on complex nutrient media. The choice of the object of study was due to its antagonistic activity with attitude to many phytopathogenic fungi such as Ascochyta pisi, Cercospora beticola, Claviceps purpurea, Sclerotinia sclerotiorum, Alternaria alternata, Botrytis cinerea, Fusarium graminearum, Passalora fulva, Verticillum dahliae, as well as growth-stimulating activity with attitude to plants, suggesting a motivation for the use of Trichoderma asperellum VKPM F-1323 as the basis for biological products used in agriculture. During the experiment, the nutrient medium composition (g/l) was used: molasses – 20, yeast extract – 7, NaNO3 – 2, K2HPO4 – 1, KCl – 0.5, MgSO4 – 0.5, FeSO4 – 0.01. Before sterilization, the pH was adjusted to 7.5. Cultivation was carried out at a temperature of 27 °C with constant stirring and aeration in autoclaved laboratory fermenters with a working volume of 2 l. The cultivation of micromycete in a liquid nutrient medium was chosen in connection with the rapid progress of the process. In addition, unlike solid-phase cultivation, the deep one allows accumulating in the finished product form numerous secondary metabolites with antagonistic activity against phytopathogens, as well as growth-stimulating activity with attitude to plants. In the work, the values of mixing speed, aeration intensity, and initial pH of the medium are determined, which determine the maximum productivity of the process according to the conidia concentration (titer) of the studied culture. During the cultivation process, the pH level was monitored without maintaining it during the process, since it is known that a change in pH values characterizes the course of the cultivation process with the formation of spore forms, and the initial pH value is an important factor in the conidia formation of Trichoderma fungi. It is shown that during cultivation for 72 hours the maximum concentration of conidia is achieved for a stirring speed of 700 rpm, without reflective baffles (chippers) in the design of the fermenter, aeration intensity of 0.25 l/l of medium×min and the initial pH of the nutrient medium 7.0. Subject to the above conditions, the concentration of conidia is 1.35 ± 0.09 conidia /ml.