Aeration Experiments Research Articles

Turning waste into Wealth: Collaborative enhancement of sucralose degradation and ilmenite aeration purification

Integrating sucralose degradation with the aeration purification of reduced ilmenite presents an untapped opportunity for enhancing aeration efficiency and promoting wastewater utilization. Herein, aeration experiments conducted at 80 °C with a 2 % sucralose concentration yielded an 18 % enhancement in aeration efficiency, a 21.5 % decrease in energy expenditure, and the sucralose content was reduced to 2.5 %. Density functional theory calculations and computational fluid dynamics confirm the formation of Fe-O interactions between sucralose and γ-FeOOH colloids, which produce flocculation, decrease slurry viscosity, and enhance oxygen transfer, thereby improving aeration efficiency. Furthermore, FeCl3, generated during aeration, catalyzes sucralose degradation. This study provides a theoretical foundation and practical experience for the synergistic application of wastewater and mineral processing.

Modelling and prediction of aeration efficiency of the venturi aeration system using ANN-PSO and ANN-GA

The significance of this study involves the optimisation of the aeration efficiency (AE) of the venturi aerator using an artificial neural network (ANN) technique integrated with an optimisation algorithm, i.e., particle swarm optimisation (PSO) and genetic algorithm (GA). To optimise the effects of operational factors on aeration efficiency by utilising a venturi aeration system, aeration experiments were conducted in an experimental tank with dimensions of 90cm×55cm×45cm. The operating parameters of the venturi aerator include throat length (TL), effective outlet pipe (EOP), and flow rate (Q) to estimate the efficacy of the venturi aerator in terms of AE. A 3–6-1 ANN model was developed and integrated with the PSO and GA techniques to find out the best possible optimal operating variables of the venturi aerator. The coefficient of determination (R2), root mean square error (RMSE), and mean absolute error (MAE) determined from the experimental and estimated data were used to assess and compare the performance of the ANN-PSO and ANN-GA modelling. It is shown that ANN-PSO provides a better result as compared to ANN-GA. The operational parameters, TL, EOP, and Q, were determined to have the most optimum values at 50 mm, 6 m, and 0.6 L/s, respectively. The optimised aeration efficiency of the venturi was found to be 0.105 kg O2/kWh at optimum operational circumstances. In fact, the neural network having an ideal design of (3-6-1) and a correlation coefficient value that is extremely close to unity has validated the results indicated above.

Enhancing insights: exploring the information content of calorespirometric ratio in dynamic soil microbial growth processes through calorimetry.

Catalytic activity of microbial communities maintains the services and functions of soils. Microbial communities require energy and carbon for microbial growth, which they obtain by transforming organic matter (OM), oxidizing a fraction of it and transferring the electrons to various terminal acceptors. Quantifying the relations between matter and energy fluxes is possible when key parameters such as reaction enthalpy (∆rH), energy use efficiency (related to enthalpy) (EUE), carbon use efficiency (CUE), calorespirometric ratio (CR), carbon dioxide evolution rate (CER), and the apparent specific growth rate () are known. However, the determination of these parameters suffers from unsatisfying accuracy at the technical (sample size, instrument sensitivity), experimental (sample aeration) and data processing levels thus affecting the precise quantification of relationships between carbon and energy fluxes. To address these questions under controlled conditions, we analyzed microbial turnover processes in a model soil amended using a readily metabolizable substrate (glucose) and three commercial isothermal microcalorimeters (MC-Cal/100P, TAM Air and TAM III) with different sample sizes meaning varying volume-related thermal detection limits (LODv) (0.05mW L-1). We conducted aeration experiments (aerated and un-aerated calorimetric ampoules) to investigate the influence of oxygen limitation and thermal perturbation on the measurement signal. We monitored the CER by measuring the additional heat caused by CO2 absorption using a NaOH solution acting as a CO2 trap. The range of errors associated with the calorimetrically derived , EUE, and CR was determined and compared with the requirements for quantifying CUE and the degree of anaerobicity (. Calorimetrically derived and EUE were independent of the instrument used. However, instruments with a low LODv yielded the most accurate results. Opening and closing the ampoules for oxygen and CO2 exchange did not significantly affect metabolic heats. However, regular opening during calorimetrically derived CER measurements caused significant measuring errors due to strong thermal perturbation of the measurement signal. Comparisons between experimentally determined CR, CUE,, and modeling indicate that the evaluation of CR should be performed with caution.

A singlet oxygen dominated process through photocatalysis of CuS-modified MIL-101(Fe) assisted by peroxymonosulfate for efficient water disinfection

Singlet oxygen (1O2) is an effective reactive oxygen species in disinfection due to its long lifetime and sensitivity to bacteria. This study tried to develop a 1O2 dominated process for bacterial inactivation by visible light (vis) photocatalysis assisted by PMS. A novel CuS-modified MIL-101(Fe) (CSMF) photocatalyst was synthesized for the first time. Compared with MIL-101(Fe), CuS-modified MIL-101(Fe) enhanced the photocatalytic performance by increasing absorption of visible light, narrowing down the bandgap and promoting photo carrier separation efficiency. 7.5-log Gram-negative Escherichia coli (E. coli) could be inactivated by Vis/CSMF/PMS system within 40 min, showing much better performance of 3.5-log E. coli inactivated by Vis/PMS system. The Vis/CSMF/PMS system is applicable in a broad pH range from 3.0 to 9.0, remaining quite steady disinfection efficiency after regenerations of the catalyst. Quenching experiments and electron paramagnetic resonance (EPR) analysis demonstrated 1O2 was the dominated ROS rather than OH• and SO4•−. Three pathways, including photo-generated electrons (e−) and O2 dependent pathway, photo-generated holes (h+) dependent pathway and CSMF enhanced PMS dissociation pathway, were evidenced to responsible for 1O2 formation by aeration experiments and specific 1O2 fluorescence probe. 1O2 in water attacked the bacterial cell membranes first, got inside the cell and up-regulated the level of intracellular ROS, which further led to cell membrane damage and DNA degradation so as to irreversible cell death. In addition, the developed Vis/CSMF/PMS system could also efficiently inactivate gram-positive bacteria Staphylococcus aureus and fecal coliform bacteria in practical wastewater, suggesting its wide applicability as a promising alternative to conventional disinfection process.

Vortex Impeller-Based Aeration of Groundwater

Iron oxidation and removal from groundwater is a necessary and costly process in drinking water production. In most cases, iron removal is done via aeration, succeeded by precipitation. Most systems for aeration are based on increasing the interfacial area via injecting air in the system or spraying. Both methods have disadvantages, like clogging and formation of aerosols. In this study, a new vortex-based flow-through reactor consisting of a cylindrical tank with an impeller located at the bottom was studied regarding its aeration and iron oxidation capabilities in groundwater. During the aeration experiments, the flow rate, impeller rotation and aerated volume were varied. A nondimensional constant α was proposed to relate the system’s physical characteristics and its aeration capabilities, expressed in dissolved oxygen and system volumetric mass transfer coefficient (KLa). Three distinct operational regimes were defined: formation, complete and bubble regime. These regimes showed very specific characteristics regarding the air–water interface structure and the area to volume ratio, resulting in different aeration capabilities and iron oxidation efficiency values. The system presented KLa values similar to commercially available aeration systems, especially inside the bubble regime. By using dimensionless coefficients, the presented analysis provided the basis for the design of continuous impeller aeration and oxidation systems of arbitrary size.

Effect of Varying Discharge Rate on the Performance of Venturi Aeration System

Venturi aeration is an economical method to increase dissolved oxygen (DO) in aquatic water bodies. For this paper, aeration experiments were conducted with 200 litres volume of the water tank, having dimensions of 90 cm length, 55 cm breadth, and 45 cm depth. The venturi was fabricated keeping the dimension of converging and diverging length same, i.e., 76 mm and throat length of 100 mm. The venturi aeration system was operated with six different discharge rates (0.00025, 0.00033, 0.00042, 0.00050, 0.00058 and 0.00067 m3/s). This work is intended to estimate the effect of varying discharges on the efficiency of venturi aerator in terms of standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE). The experiment shows promising results in terms of SOTR and SAE at moderate to high discharge rates, on the other hand a declining trend is seen when the liquid discharge rate is too high. The oxygen transfer rate was found to have a good relationship with the discharge rate.

Growth performance of Tilapia (Oreochromis niloticus) cultivated in water from ex-sand pit lakes by phytoremediation treatments

Utilization of ex-sand pit lakes for aquaculture is difficult due to low water quality and high concentrations of iron (Fe). Phytoremediation using aquatic plants has been proven to be effective in reducing Fe in waters. This study aims to determine the growth, feed conversion efficiency and survival rate of tilapia (Oreochromis niloticus) cultured with ex-sand mining water media with phytoremediation treatment. Phytoremediation treatment was carried out by Eichhornnia crassipes, Azolla pinnata, and Salvinia molesta. Fish culture experiments were carried out in plastic tarpaulin tanks for 40 days, with ad satiation feeding, three times a day using the commercial feed. The results showed that phytoremediation with aquatic plants had succeeded in reducing Fe to a level suitable for fish culture. Fish culture experiments showed an absolute length growth rate of 0.09-0.18 cm/day and an absolute weight growth rate of 0.11-0.16 g/day. The feed conversion ratio was 1.18-1.40 and the survival rate was 98.04-99.08%. The survival rate of tilapia is high, the feed conversion ratio is medium and growth is low. The high environmental temperature and the decrease in water quality due to the absence of water changes and aeration are suspected of causing the low growth of fish. Therefore, further research with water change and aeration experiments and the use of other species of fish is needed to follow up the results of this study.

Design characteristics of showering aeration system

AbstractThe showering aeration system (SAS) was designed and its performance was evaluated by conducting the aeration experiments in a tank of dimension 2 × 4 × 1.5 m. Initially, the aeration experiments were conducted to optimize the radius of curvature of the SAS with different values, such as = 0, 5, 10, 15, and 20 mm, and maintain other geometric parameters, i.e. number of holes in the shower (); height of water fall (H); diameter of the shower hole (d); volume of water under aeration (V) and water flow rate (Q) as constants. The optimum radius of curvature () was found to be 10 mm. The aeration experiments were further conducted with four different non-dimensional geometric parameters such as the number of holes , the ratio of the height of water fall to the length of shower arm the ratio of the diameter of the hole to the length of shower arm and the ratio of the volume of water to the cube of the length of shower arm The Response Surface Methodology and Box–Behnken Design were used to optimize the non-dimensional geometric parameters of the SAS to maximize the Non-Dimensional Standard Aeration Efficiency. The result indicates that the maximum NDSAE of 16.98 × 106 was obtained from the SAS performance at = 80; = 2; = 4 and = 48.

Modelling and controlling dissolved oxygen in recirculating aquaculture systems based on mechanism analysis and an adaptive PID controller

In aquaculture, dissolved oxygen (DO) content is critical to the growth and development of aquatic products, and it must be precisely controlled. Based on the theory of microporous aeration mass transfer and mass conservation equations, this paper analyzed the influence of the four main factors of recirculating water flow, mechanical aeration, surface reaeration and respiration of shrimp on the dynamic changes of DO, and established a DO system dynamics model in the recirculating aquaculture system. Based on the established model, this paper proposed a fuzzy rule-optimized single neuron adaptive PID controller (FL-SN-PID) for precise control of DO. In order to verify the reliability of the established model, several aeration experiments with different aeration flows were conducted in Simulink and actual breeding system. All fitting R2 between simulated data and measured data of the DO response are above 0.94, indicating that the established dynamics model can accurately approximate the actual breeding system and can provide a basis for the design of the controller. In the simulation experiment, the proposed controller was applied to the DO tracking control in three scenarios, and its tracking performance was also compared with the traditional PID controller and the SN-PID controller. In performance analysis, the integral of absolute error (IAE) and the integral of squared error (ISE) of the FL-SN-PID controller are obviously smaller than the other two controllers, indicating this controller has better control accuracy and robustness, and can be competent for precise control of DO in aquaculture.

Contribution of Nanobubbles for PFAS Adsorption on Graphene and OH- and NH2-Functionalized Graphene: Comparing Simulations with Experimental Results.

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in aquatic environments around the world. In recent years, the enrichment of PFAS on the surface of nanobubbles on adsorbents has been proposed, but no direct evidence has been provided to support this new adsorption mechanism. In this study, we used density functional theory (DFT) and molecular dynamics (MD) to simulatively investigate the contribution of nanobubbles for PFAS adsorption on the pristine and functionalized graphene (GR). The adsorption energy of PFAS on GR-NH2 was higher than that of GR-OH, while GR showed the lowest adsorption energy. When the effect of water molecules was considered, the oleophobic property of the C-F chain made it difficult for hydrophobic interaction to be involved in the adsorption of PFAS on nonpolar GR. With the existence of nanobubbles, both GR and GR-NH2 can effectively remove PFAS, but their adsorption mechanisms were quite different. For hydrophobic GR, the nanobubbles initially attached to the surface of materials played a major role, while for hydrophilic GR-NH2, the nanobubbles dispersed in the solution were more important. Moreover, the nanobubbles had a more significant contribution to long-chain PFAS. Our degassing and aeration experiments could support the simulation results. The removal of PFOS decreased by 27.7% at maximum after degassing and increased by 21.0%-29.2% after aeration. The study could provide a theoretical basis for the environmental process and contamination control of PFAS at the solid-liquid interfaces.

Control and Real-Time Data Acquisition of an Experimental Platform for Stored Grain Aeration Study.

Aeration is one of the most important methods to keep stored grain safe and maintain its quality. Experimental platforms are used for stored grain aeration study in a laboratory-scale. The purpose of this paper was to provide the real-time data acquisition and control system design of a new experimental platform with multifunction for stored grain study. Requirements of the aeration experiments were analyzed, and multi running modes were designed. The aeration inlet air conditions were designed to be adjustable and multi variables need to be controlled simultaneously, which was a key problem to be solved for the platform. An ON/OFF-PID based multivariable cooperative control method was proposed, and two control loops were formed where inlet air temperature and humidity were considered separately while could be controlled simultaneously with a logic judgement strategy. Real-time data needed to be monitored was acquired with different sensors and displayed intuitively. Experiments were carried out to test the static and dynamic characteristics of the control method and three inlet air flow rates of 0.03, 0.08 and 0.13 m·s−1were used. Performance of the data acquisition system was also tested. The results showed that, the inlet air conditions control error was within ±1 °C and 10% for temperature and relative humidity, respectively. The real-time data acquisition of multi parameters during aeration process was realized. The experimental platform can be used for studies of different aeration objectives.

Application of Mechanical Relations in Mathematical Modeling to Oxygenate Synthetic Wastewater through a Circular Rotary Aerator

This paper expounds the issue about the evolution of the dissolved oxygen concentration in synthetic wastewater with a circular rotary by setting a mathematical model. The mathematical model is based on the Lewis and Whitman relations to transfer oxygen to water, and includes the mechanistic models proposed by Lee, to determine the global oxygen transfer coefficient and the oxygen saturation concentration in water, as a function of the fifth power temperature. For this purpose, historical data from aeration experiments with two types of discs and two levels of COD concentration were compared. The equation allows to include the effect of the variation of the temperature and atmospheric pressure. Finally, through the data obtained, it’s concluded that the estimation error is not affected by the type of disc, the COD concentration of the synthetic wastewater or by the interaction of both, and is less than + - 0.086 mg / L dissolved oxygen.

Design characteristics of perforated pooled circular stepped cascade (PPCSC) aeration system

Abstract In the present study, an improvised design over circular stepped cascade (CSC) and pooled circular stepped cascade (PCSC) aerator, named the perforated pooled circular stepped cascade (PPCSC) aerator, has been conceptualized and tested for its suitability as an aerator for small intensive aquaculture ponds. Based on dimensional analysis, dimensionless geometric parameters – ratio of width of consecutive steps (Wi/Wi+1) and ratio of perforation diameter to bottom-most radius (d/Rb) and dimensionless dynamic parameters – Froude (Fr) and Reynolds (Re) number were proposed. Initially, aeration experiments were conducted to optimize the geometric parameters, keeping the dynamic parameters constant. Keeping the optimized values of Wi/Wi+1 = 1.05 and d/Rb = 0.0027 as constants, aeration experiments were further conducted at different discharges (Q) and different bottommost radius (Rb) to study the characteristics of oxygen transfer and power consumption of PPCSC aerator at different dynamic conditions. Based on the optimized results, four prototype PPCSC aerators with Rb = 0.75 m, 0.90 m, 1.05 m and 1.20 m were fabricated for their aeration performances. The results showed that the standard aeration efficiency (SAE) values of the prototype PPCSC aerators based on brake power ranged between 3.36 and 4.98 kg O2/kWh, with the average being 4.45 ± 0.741 kg O2/kWh. This shows that the SAE of the PPCSC aerator is many more folds higher than that of the other available cascade aerators, viz., PCSC (SAE: 2.873 ± 0.342 kg O2/kWh) and CSC (2.470 ± 0.256 kg O2/kWh) aerators. The study clearly indicates that this PPCSC aerator may very well be used as pre-aeration or post-aeration units in water or wastewater treatment plants and small-scale intensive aquacultural ponds, replacing the other existing aerators.

Influence of drying temperature on NO2 sorption ability of cedar timber

NO2 sorption ability of cedar (Cryptomeria japonica) timbers was evaluated using a new measuring system that was developed in our previous study. Four drying conditions were applied, namely natural drying and three kinds of kiln-drying at 45, 60, and 105 °C. Aeration experiments were conducted using discoid specimens which had a thickness in the longitudinal direction of 1.5 mm, and a diameter of 10 mm. The moisture content was conditioned to 0 or 9 ± 1.0% in each drying condition. As a result, the NO2 sorption ability declined as the drying temperature increased. Based on the analysis of extractives, it was shown that the extractives content had a high correlation with the contribution ratio of extractives in the NO2 sorption volume of the specimens that were dried below 60 °C. Therefore, it was elucidated that the specimen dried naturally has the greatest NO2 sorption ability. Furthermore, the result of the gas chromatography–mass spectrometry (GC/MS) indicated that abietadiene influenced the NO2 sorption ability. Also, the NO2 sorption volume was high especially at the initial stage, which is higher under the condition with moisture.

An experimental study to evaluate the efficacy of air entrainment holes on the throat of a venturi aeration system

Dissolved oxygen (DO) is a vital nutrient for the health of water bodies such as streams, rivers, and ponds, as it is used in respiration and other biological activity of aquatic animals. Natural replenishment of oxygen through photosynthesis in aquatic bodies is insufficient to meet the high requirements for an intensive aquaculture system, which compels farmers to use aeration systems to supplement the natural process of DO accumulation. When the demand for oxygen (KgO2/h) is lower, venturi aerators may be more effective than other aerators. The venturi device is an aeration system which is highly efficient in providing an adequate supply of DO, and is flexible in nature and easy to operate. To evaluate the efficacy of air entrainment holes on the throat of a venturi, aeration experiments were conducted for different throat lengths (Lt) of 20, 40, 60, 80 and 100 mm, varying the number of air holes according to throat length while maintaining a constant air hole diameter of 2 mm. Aeration efficiency was found to increase with an increasing number of air holes. The highest oxygen transfer coefficients for throat lengths of 20, 40, 60, 80 and 100 mm were 0.497 h−1, 0.756 h−1, 1.045 h−1, 0.627 h−1 and 1.072 h−1, respectively, with the maximum number of air holes (NH). The maximum standard aeration efficiency was found to be 1.25 × 10−2 kgO2/kWh for a throat length of 100 mm with the maximum number of air holes (NH17). Hence, the physical properties of throat length, number of air holes, and distribution of air holes on the throat section were proven to be key factors controlling the performance of the venturi aeration system.

Estimation of volumetric mass transfer coefficient (kLa)—Review of classical approaches and contribution of a novel methodology

The volumetric mass transfer coefficient, usually denoted by kLa, is an important parameter for both the design, scale-up and monitoring of aerated bioreactors. Significant research efforts have been expended over the last decades in order to develop reliable and easy to apply methodologies for determining kLa using aeration experiment and fast oxygen (polarographic) probes. These methodologies have been reviewed in this study followed by the presentation of a new and promising methodology for kLa determination, which can be used when data from step experiments are not available. Step and aeration experiments have been carried out in laboratory scale bioreactors and the experimental data were used for the validation of the proposed methodology and also to critically assess all alternative methodologies for estimating kLa.

Degradation and volatilization process of fragrance materials and triclosan in wastewater treatment plant – Comparison between field survey and laboratory experiment –

Abstract The concentrations of three fragrance materials (OTNE, HHCB, and AHTN) and triclosan at the inlet and outlet of a wastewater treatment plant were measured, and the decrease of these targeted compounds during aeration process of activated sludge was investigated experimentally and compared with that in the plant. The ratios of the decreases in the aeration experiments were 24%–46% for 8 h and were compared with the estimated decrease ratio in the plant. From a mass balance comparison including the transference to the air phase with bubbling, OTNE in the mixed liquor appeared to be majorly volatilized with bubble while HHCB to be volatilized and/or removed with excess sludge withdrawal. The volatilization for AHTN and triclosan was on the other hand, low (AHTN) or scarce (triclosan). The decrease of them is probably owing the biological decomposition.

Development of a Stored Grain Aeration Experimental Platform

Aeration was an important method to keep stored grain in good conditions. It was both time- and labor-consuming to conduct experiments of aeration in real grain storage bins. This paper aimed at developing an experimental platform for stored grain aeration study. Requirements of the aeration study were analyzed and the structure of the platform was introduced. Then the key parameters were calculated for the platform. Different parts of the platform were selected and designed. In order to conduct the aeration experiments, temperature of different positions should be collected. So the temperature data acquisition system was introduced in detail. Finally, this system was tested. Results showed that this platform could be used for different stored grain aeration process study.

Evaluation of NO2 sorption of cedar wood (Cryptomeria Japonica) with difference of the specimen size and contact condition between NO2 gas and specimen using new test system

We developed a new system for measuring the NO2 sorption ability of Japanese cedar (Cryptomeria japonica) wood by referring to Japanese Industrial Standard for JIS R 1701-1 (Test method for air purification performance of photocatalytic materials, Japanese Standard Association, Tokyo, 2004). Aeration experiments were conducted using plated specimen, particle specimen, discoid specimen and wood powder with consideration of aeration condition and surface area which can contact with NO2 gas. In the plated specimen, the NO2 sorption ability was greatly affected by the thickness of longitudinal direction, and high NO2 sorption ability of the transverse section was observed within a thickness range from the surface to ca. 3 mm. The average NO2 sorption volume for discoid specimen for 5 h was approx. five times larger than that those for the plated and particle specimens, which the thickness of longitudinal direction was 1.5 mm. This means that the NO2 sorption effect was especially high under the condition where the NO2 gas passed through tracheid. Also, it was suggested that the interface area between NO2 gas and specimen influenced to the NO2 sorption ability. Furthermore, it was confirmed that the NO2 sorption volume in discoid specimen and the grain size below 0.25–0.50 mm of wood powder reached the greatest.

Three-dimensional full-loop simulation of a high-density CFB with standpipe aeration experiments

Three-dimensional full-loop simulation of a high-density circulating fluidized bed (HDCFB) is conducted using the multiphase particle-in-cell (MP-PIC) method. The computational results are in good agreement with the experimental data of pressure distribution and solids circulation rate under different aeration conditions of the standpipe. The main feature of gas-solid flow in the riser is qualitatively predicted, with coexistence of the developed flow in the upper region and the acceleration flow in the lower region. The flow regime in the standpipe is mainly concurrent downward gas-solid flow in the close packing region. Due to the influence of the aeration gas, the pressure gradient presents a wave variation along the height of standpipe. The predicted solids residence time distribution in the standpipe exhibits a feature of early peak with an extended tail, indicating that the solids flow is not uniform in the standpipe.