Aeration System Research Articles

Effectiveness of ventilation regulation in a simple diagonal system of underground mines

Purpose. Each ventilation system has its own important elements, such as the various branches of the system, which can be connected in a normal and diagonal pattern, ventilation regulators and fans. Based on a professional approach to the analysis of this aeration system, a comparison of reliability results has been conducted, which indicates the real state of the microclimate in underground mines, affecting the increase in the prospects for the development of mining activity. Methods. This paper deals with the problem of ventilation in underground mines, especially in diagonal systems, and the importance of regulating ventilation to provide the required amount of air (Q, m3/min) through the entire system, taking into account the determination of the main fan depression. Findings. To ensure the required (designed) amount of air through the system branches, various methods of effective regulation are used in mining engineering. Therefore, based on research and measurements in different mine workings, our findings provide complete safety and comfort of microclimate during mining activity. Originality. The measurements performed and the database created according to the values and results obtained from the analytical calculations present the best possible estimate, which is substantiated in the paper. Practical implications. The problem of calculating and regulating aeration for a simple diagonal system has been solved, taking into account the determination of the main mine fan depression before and after the use of aeration regulators.

Enhancing nitrogen removal from domestic sewage with low C/N ratio using a biological aerated filter system with internal reflux-coupled intermittent aeration

Biological aerated filter (BAF) systems with internal reflux-coupled intermittent aeration enhance the removal of nitrogen pollutants from low-C/N ratio domestic sewage. Two experimental systems with the same specifications, a BAF system with internal reflux-coupled intermittent aeration (system A) and a traditional BAF system (system B) was constructed to explore the efficiency of nitrogen removal. Overall, the nitrification in system B was higher than that in system A due to the influence of aeration model. Conversely, the system A can use the alternating anoxic (DO<0.5 mg·L−1) and aerobic (DO around 1 mg·L−1) environment to obtain better Total Nitrogen (TN) removal rate of 21.56 mg·(kg·h)−1 in the bottom of 30–70 cm zone of the reactor by combining reflux nitrate with influent COD. This section had a low specific oxygen uptake rate but high triphenyl tetrazolium chloride-dehydrogenase activity, indicating that the system enhanced nitrogen removal by denitrification in this section. The 16 S rDNA high-throughput sequencing analysis showed that the diversity index of system A was higher than that of system B. The abundance of microorganisms involved in denitrification was higher in the 30–50 cm zone of system A, mainly in the phylum (10.63%) and the phylum Bacillus (32.05%), indicating that system A was used for denitrification through nitrate reflux and intermittent aeration.

Separation of dye from aqueous solution by a new gravity compression and aeration system

ABSTRACT Filtration is one of the important technologies for separating suspended particles. Under the condition of gravity compression, the filtration density can be increased and the separation effect of suspended particles can be improved. Considering the complex composition and the difficulty in degrading dye in industrial wastewater, a gravity compression aeration system with a modified polyester fibre ball (denoted as MPFB) was evaluated for the separation of dye from water. Congo red azo dye solution (0–40 mg/L) was selected as the model treatment compound. The MPFB was prepared by adjusting the concentrations of alkali (Quality score 0–25%), β-cyclodextrin (0∼80 g/L), reaction temperature (40–90°C), and silane coupler concentration (Concentration fractions 0–0.8%). We used Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to characterise the MPFB. The separation was affected significantly by adsorption conditions such as MPFB dose and pH. The lower the MPFB dose, the higher the expected adsorption capacity. For the treatment of a dye solution at 500 mg/L, 100% removal was achieved with 48 g/L MPFB, at pH 8 during adsorption under non-circulation aeration. For 24 h of reaction, the system could reach the maximum adsorption capacity of 11.2 mg/g, which followed the pseudo-first order kinetics model and the intraparticle diffusion model. We discovered that circulation aeration provided the best adsorption and electrostatic and hydrogen bonding were the dominant components of adsorption. Overall, the system is a promising technology and has the potential to treat large volumes of dye wastewater.

Multi-Attribute Utility Theory Decision Analysis for Biodegradable River Debris Composting Treatment in Surakarta City

River waste in Surakarta City primarily consists of biodegradable waste that can be processed by biological processes such as composting. However, there are various kinds of composting application techniques. This, of course, must be adapted to the conditions in Surakarta City. This study aims to conduct a decision analysis on debris processing techniques in Surakarta City using the Multi-Attribute Utility Theory (MAUT) method. The criteria used are aesthetics, land requirements, ease of operation, ease of construction, and investment and operational costs. Alternatives used in composting are bamboo aerator system, hollow brick, and takakura arranges. The final assessment by MAUT showed that waste processing with hollow brick (0.802) had the highest weight and was followed by the bamboo aerator system (0.643). The final score for the takakura method is only 0.250, and this is because the weight on costs and land requirements is considerable compared to the other two alternatives.

A new approach to estimating oxygen off-gas fraction and dynamic alpha factor in aeration systems using hybrid machine learning and mechanistic models

The aeration process is the largest energy consumer in wastewater treatment plants (WWTP), and the optimization of the process based on computational models can offer significant savings for the plant. Recent theoretical developments have revealed that many of the parameters commonly assumed as constants in aeration modelling have a dynamic nature; however, there still lacks a universal way to model these factors accurately. This work proposed a new framework and optimal time scale for building hybrid machine learning-mechanistic oxygen transfer rate models. The data used for the modelling were from existing sensors in a full-scale WWTP supplemented by a two-month field sampling campaign for collecting 15 min of dynamic data, including off-gas air fraction. Two machine learning (ML) models were built: the first set was a novel hybrid ML-mechanistic model developed to estimate the off-gas aeration fraction from wastewater parameters and calculate dynamic alpha per the off-gas method. The second ML model directly estimated dynamic alpha from wastewater process and operation parameters. The performance of the ML models was compared with recalibrated published regression-based models. Results showed that the hybrid ML-mechanistic alpha model (NSE = 0.96 and RMSE = 0.03) were more accurate than the direct ML alpha (NSE = 0.67 and RMSE = 0.07) and recalibrated regression (NSE < 0 and RMSE = 0.18 to 0.28) models, and therefore could be efficiently applied to predict dynamic alpha factor of an activated sludge plant. In addition to typical surfactant indicators such as MLSS and COD, other parameters like temperature and aeration ammonia concentration were substantial in dynamic off-gas and alpha estimation.

Komposisi Kimia Pupuk Kompos dari Limbah Padat Rumah Potong Hewan Tamangapa Kota Makassar

Abstract. Slaughterhouses (RPH) produce large amounts of solid waste every day and have not been utilized optimally. RPH solid waste has great potential to be used as plant fertilizer through the composting process. Composting is expected to change the organic material composition of the abattoir solid waste to be more ideal to support plant growth. This study aims to determine the chemical composition of compost made from waste at RPH Tamangapa Makassar City before and after the composting process. Composting from solid waste at Tamangapa RPH Makassar was carried out using the main ingredients, namely rumen contents (treatment I) and rumen contents mixed with livestock manure in a ratio of 1:1 (Treatment II). The composting process was carried out in a compost box with a size of 40x40x60 cm with a passive aeration system for 4 weeks with three replications. Quantitative data tested in this study included the content of N-total (%), C-Organic (%), P-total (%), K-total (%), C/N ratio, organic matter (%), water content (%) and compost reduction (%). The results showed that the content of elements C, N, P, K, C/N ratio, organic matter, and water content before composting in both treatment I and treatment II were generally still low and almost the same as the raw materials. After the composting process took place, the content of C, P, K, C/N ratios generally showed an increase, while the N content was relatively constant. The results of the analysis showed that there was no significant difference between the chemical composition of the compost in the treatment and both before and after the composting process.Keywords: RPH solid waste, composting process, chemical composition of compost, C/N ratio.

Direct Method to Design Solar Photovoltaics to Reduce Energy Consumption of Aeration Tanks in Wastewater Treatment Plants

Photovoltaic (PV) energy systems are considered good renewable energy technologies due to their high production of clean energy. This paper combines a PV system with wastewater treatment plants (WWTPs), which are usually designed separately. For this, a recent methodology was adopted, which provides direct steps to estimate the peak powers of PV plants (PVPs) by using the airflow of blowers. The goal was to reduce the energy consumption of aeration tanks in WWTPs. Analytical equations and parameters based on the air temperature, solar irradiation, biological kinetic, dissolved oxygen, and mechanical oxygenation are adopted. The key parameter in this methodology is the air temperature variation that represents an approximated temperature in the WWTP’s oxidation tanks. It is shown, through the analysis of small WWTPs, that since the temperature changes for each season, there is a peak in the function of the quantity of oxidation, which is high in the summer season. Further, the curve trends of temperature for WWRPs are similar to PVPs. Therefore, it could be possible to design the PV system with the WWTPs well. The results show that the air temperature curves increase in a directly proportional way with the consumption of energy from oxidation blowers; this could induce a more conservative PVP design. Furthermore, the results show that the mean trend of the energy consumption of the analyzed aeration systems reaches about 8.0% at a temperature of 20–25 °C, covering a good part of the oxidation tank consumption.

Effect of Lens Aperture for Analysis of Bubble Image Size Microbubble Generator Aeration System

Investigates Microbubble characterization is an essential component of any experimental investigation of new microbubble generator design. The use of microbubble generators as aeration systems often experiences blockages. That is caused by the broad cross-section of nozzles and air holes with small diameters. The microbubble generator was redesigned by increasing the cross-sectional area and diameter of the air hole. The method of investigating the bubble process uses image capture with three aperture speeds of the lens of 1/125f, 1/160f, and 1/200f with a combined airflow rate of 0.5 Lpm, 1.5 Lpm, and 2.5 Lpm. The result was characterized with multiple lens apertures with 1/160f bubble results ranging from 5.4 - 94.3 μm at all airflow rates.

Comparative analysis of nitrogen removals and microbial communities in air and pure oxygen aeration systems during treatment of municipal solid waste incineration (MSWI) leachate

MSWI leachate contain high concentrations of ammonium nitrogen (NH4+-N). The conventional submerged air-diffusing (CSA) system are the dominant oxygen supply in the aerobic process for NH4+-N removal from leachate. However, it carries high energy consumption. In this study, Pure oxygen (PO), which is more environmentally friendly, was used as an alternative to air for solving this problem. For comprehensive analysis the effects of PO supersede air on nitrogen removals and microbial diversities in the aerobic process during treatment of MSWI leachate, two parallel full-scale anoxic-oxic systems were set with the floating Praxair's in situ oxygenation (I-SO™) system and the CSA system, respectively. Compared to the CAS system, the removal efficiency of total nitrogen (TN) increased by 9.79% with the I-SO™ system but COD and NH4+-N removals reduced by 6.83% and 1.19%, respectively. Metagenomic studies revealed that the bacterial richness, diversity, and evenness decreased with PO aeration, while the abundances of ammonia-oxidizing bacteria (AOB) and denitrifying bacteria (DNB) increased, as well as the AOB/nitrite-oxidizing bacteria (NOB) ratios. In addition, the nitrite-denitrification functional genes (nirK and nirS) deposited from autotrophic and Heterotrophic bacteria were more predominant and accounted for the higher efficiency of TN removal in the PO aeration treatment, while complete nitrification and nitrate-denitrification were dominant in the air aeration anoxic-oxic system. Therefore, nitrogen removal from MSWI leachate by using PO aeration provided theoretical perspective for engineering applications.

Breathing life into trees: the physiological and biomechanical functions of lenticels

Summary Lenticels can be defined as pores that are the entrance of a continuous aeration system from the atmosphere via the living bark to the secondary xylem in the otherwise protective layers of the periderm. Most work on lenticels has had an anatomical focus but the structure-function relationships of lenticels still remain poorly understood. Gas exchange has been considered the main function of lenticels, analogous to the stomata in leaves. In this perspective review, we introduce novel ideas pertaining to lenticel functions beyond gas exchange. We review studies on lenticel structure, as this knowledge can give information about structure-function relationships. The number of species investigated to-date is low and we provide suggestions for staining techniques for easy categorization of lenticel types. In the follow-up sections we review and bring together new hypotheses on lenticel functioning in the daily “normal operation range”, including regulative mechanisms for gas exchange and crack prevention, the “stress operation range” comprising flooding, drought and recovery from drought and the “emergency operation range”, which includes infestation by insects and pathogens, wounding and bending. We conclude that the significance of dermal tissues and particularly of lenticels for tree survival has so far been overlooked. This review aims to establish a new research discipline called “Phytodermatology”, which will help to fill knowledge gaps regarding tree survival by linking quantitative and qualitative lenticel anatomy to tree hydraulics and biomechanics. A first step into this direction will be to screen more species from a great diversity of biomes for their lenticel structure.

Enhanced Biodesulfurization with a Microbubble Strategy in an Airlift Bioreactor with Haloalkaliphilic Bacterium Thioalkalivibrio versutus D306.

Biodesulfurization under haloalkaline conditions requires limiting oxygen and additional energy in the system to deliver high mixing quality control. This study considers biodesulfurization in an airlift bioreactor with uniform microbubbles generated by a fluidic oscillation aeration system to enhance the biological desulfurization process and its hydrodynamics. Fluidic oscillation aeration in an airlift bioreactor requires minimal energy input for microbubble generation. This aeration system produced 81.87% smaller average microbubble size than the direct aeration system in a bubble column bioreactor. The biodesulfurization phase achieved a yield of 94.94% biological sulfur, 84.91% biological sulfur selectivity, and 5.06% sulfur oxidation performance in the airlift bioreactor with the microbubble strategy. The biodesulfurization conditions of thiosulfate via Thioalkalivibrio versutus D306 are revealed in this study. The biodesulfurization conditions in the airlift bioreactor with the fluidic oscillation aeration system resulted in the complete conversion of thiosulfate with 27.64% less sulfate production and 10.34% more biological sulfur production than in the bubble column bioreactor. Therefore, pleasant hydrodynamics via an airlift bioreactor mechanism with microbubbles is favored for biodesulfurization under haloalkaline conditions.

Unjuk Kinerja Sistem Aerasi Dalam Kotak Penyimpanan Kentang (Solanum tuberrosum L) Tipe Kotak

The purpose of this study was to determine the performance of the box type potato storage aeration system in terms of changes in temperature and RH of the air during storage. Research on a box type aeration system for potato storage was carried out by measuring the temperature and RH of the incoming air, the temperature and the RH of the outgoing air during storage of potatoes for 21 days. In addition, calculating the heat of respiration, heat to increase the temperature of potatoes, heat to evaporate water and heat lost to the environment using a simple mathematical model approach. The results showed that the temperature and RH of the room and the incoming air flow tended to form a linear pattern, while the RH of the process room and the outgoing air flow tended to form a polynomial pattern. The temperature of the potato storage room was in the range of 24.07-25.70oC and the RH was in the range of 56.0-65.6%. The heat value of respiration varied between 261.42 - 311.88 k.Joule/kg potato tubers, because the storage temperature was 24.07-25.70oC. The heat generated by the respiration process used to evaporate water from the potato tubers to the environment is 6.01±0.3% on average, the average heat to raise the temperature of the potato tubers and the air temperature around the potato is 24.08±1, 3%, and the average heat loss to the environment with the flowing air is 59.89±3.4%.

Experimental characterization of an oxygen transfer model of a fine pore diffuser aerator

Dissolved oxygen (DO) is an important aspect of water quality in aquaculture. To prevent oxygen deficiency, aeration is used to improve DO and increase yields in aquaculture farms. However, the experimental quantification of standard oxygen transfer rate (SOTR) of aerators is highly case dependent and varies under different aerator operational conditions. Hence, using SOTR for modeling, simulation, and aerator design purposes tends to be unreliable. This work validates an existing theoretical oxygen transfer model of an economical fine-pore diffuser using a bench-scale aeration system. Modifications were made to the model to account for physical conditions and to relate the model to SOTR. Aeration tests were conducted using various airflow rates and diffuser depths for three water volumes (137 L, 160 L, 192 L). As a parameter to the model, bubble diameters were determined for each experiment using an automated image processing tool developed for this study. The percentage error between the theoretical and experimental oxygen transfer coefficients range from 12.87% to 19.99% and are well within the 95% confidence interval of both respective results. The oxygen transfer coefficient and rate increased with diffuser submergence and airflow rate. However, standard aeration efficiency decreased exponentially with increasing airflow rates. The use of this model provides an approximate estimate of oxygen transfer rates in different conditions, which can be used to optimally design aerators and strategically create cost-saving practices for both intensive and extensive aquaculture applications.

Experimental study on design and operational performance of solar-powered venturi aeration system developed for aquaculture – A semi-floating prototype

Venturi-type injectors have been used usually due to the practical use and modular design that allows for quick configuration, ready-to-use, and low-cost solutions in the last years. This study aims to design a solar-powered venturi aeration system (SVAS) and determine its flow characteristics, standard, and real-time operational performance parameters. SVAS has a design providing the maximum vacuum and air velocity at air inlets and allowing for all technical measurements. Moreover, a solar-powered experimental apparatus having a weather station, a pool station, and a data logger station was constructed. Experiments were carried out using a plastic pool with a capacity of 4000 L, a diameter of 3 m and a depth of 0.75 m, four venturi injectors, and a submersible pump of 0.3 kW operated at the constant water flow regime of 4.1 m3 h-1. According to flow tests, the oxygen mass flow rates ranged from 2.77 to 2.84 kg h−1. The specific energy consumption values are 263.2 kJ per cubic meter for water flow and 380 kJ per kg for oxygen transfer.Standard performance experiments were repeated four times. The maximum overall oxygen mass transfer coefficient obtained during the experiments was 5.58 h−1. The maximum values of standard oxygen transfer rate (SOTR), standard aeration efficiency (SAE), and standard oxygen transfer efficiency (SOTE) were 0.206 kgO2 h−1, 0.681 kgO2 kWh−1, and 7.32%, respectively. The pool conditions were simulated using de-oxygenation and mixing systems to determine the operational performance. For simulation experiments, six procedures and two processes were applied. Throughout operational experiments of four days, real-time dissolved oxygen levels fluctuated between 1.05 mg L−1 and 6.65 mg L−1. The maximum performance values were 0.143 kgO2 h−1 for the actual oxygen-transfer rate, 0.474 kgO2 kWh−1 for aeration efficiency, and 5.1% for oxygen transfer efficiency.

Demonstration study of bypass stabilization pond system in the treatment of eutrophic water body.

This study involved a comprehensive renovation of fish ponds to improve the water quality of a eutrophic river in Dongguan City. The abandoned fish ponds were transformed into three different types of stabilization ponds: facultative, aerated biological, and submerged plant stabilization ponds. The water of the eutrophic section of the river was pumped into the facultative stabilization pond and discharged into the Haizai River through an aerated biological pond and a submerged plant pond. In the aerated biological pond, secondary treatment was carried out using plant zoning and artificial floating island aeration system. The submerged plant pond used fountain-type aeration and an underwater forest for tertiary treatment. After four months of monitoring the water quality of the stabilization pond and the river, the ammonia nitrogen (NH3-N), total phosphorus (TP), and chemical oxygen demand (CODCr) levels in the raw sewage reduced from 6.53 mg/L to 1.13 mg/L, 1.76 mg/L to 0.29 mg/L, and 63 mg/L to 22 mg/L, respectively; the transparency of water increased to 45 cm, and dissolved oxygen (DO) level increased to 5.32 mg/L. This study provides a reference for the ex-situ treatment of urban eutrophic waterbodies.

Cleaner production and carbon reduction target: Analysis of sewage treatment plants in Nort-Central China

ABSTRACT In order to realize cleaner production of Sewage Treatment Plants and reduce the emission of carbon, the current situation of various sewage treatment plants of varying scales in Nort-Central China from 2019 to 2020 was investigated. For contrast, the energy consumption and material consumption of each sewage treatment plant and their cleaner production potential were analyzed. The results revealed that the implementation of a cleaner production scheme in the 14 investigated sewage treatment plants resulted in a cost reduction of 2.13 million annually. Further, the energy-saving effects of the cleaner production schemes of the sewage treatment plants were compared, and the results revealed that the use of a magnetic levitation fan reduced the power consumption of the wastewater treatment unit and carbon emission by 13.16–17.87 and 4.58–7.69%, respectively. In addition, the utilization of a modified precise aeration system reduced the wastewater power consumption and carbon emission by 2.8–6.33 and 10.37–17.24%, respectively. This study demonstrates that the Sewage Treatment Plants can become cleaner by using magnetic levitation fan and precise aeration system. The paper highlights the value of increased energy efficiency and reduction of greenhouse gas emissions.

Analysis of Plant Growth and Gallic Acid Content for Cavendish Banana (Musa acuminata) Shoot Culture with Bubble Column Bioreactor

Cavendish banana (Musa acuminata) is one of the most important fruits in the world. Cavendish shoots tissue culture using bubble column bioreactor can be a solution to produce high yielding plantlet and gallic acid due to the aeration with minimum shear stress. In this study, the average growth rate, presence of gallic acid, and antioxidant activity (IC50) in the bubble column bioreactor (200 mL capacity) with the aeration rates of 1 mL/s and 2 mL/s using Murashige &amp; Skoog half-strength liquid medium supplemented with 0.5 ppm gibberellic acid will be analyzed. The aeration system used was atmospheric air. The leaves and stems were extracted by maceration using 96% ethanol solvent (1:10 (w/v)). A qualitative phenolic test with FeCl3, thin layer chromatography, and antioxidant test with 2,2-diphenyl-1-picrylhydrazyl was carried out. The average growth rate in the bioreactor were 0.22 ± 0.001 g/day (1 mL/s) and 0.21 ± 0.001 g/day (2 mL/s). All the leaf and stem extracts showed positive results for the phenolic test, but the presence of gallic acid could not be detected clearly by thin-layer chromatography. The IC50 values in aeration rates of 1 mL/s and 2 mL/s of the leaves were 41.35 and 79.54 μg/mL, respectively, while the stems were 51.87 and 104.94 μg/mL, respectively. It could be concluded that the growth of the banana plantlet and the production of antioxidants in the bubble column bioreactor was higher in aeration rate of 1 mL/s than 2 mL/s.

Applications of gravity aeration system in aquaculture—a systematic review

Applications of gravity aeration system in aquaculture—a systematic review

Experimental study of scour morphology from plunging water jets

Abstract Scour due to plunging water jets is a key topic in hydraulic engineering. This study presents the topography of the scour hole formed by water jets from circular nozzles in the downstream pool. Experimental studies for topographic changes in the downstream pool are limited in the literature. Several experiments were carried out to determine scour morphology due to turbulent water jets obliquely impinged on the downstream pool. The topographic changes, maximum scour depths, volume of scour hole and upstream and downstream slopes of scour hole at the equilibrium time were studied in detail. The densimetric Froude number and impingement angle affect the scour morphology. The volume of scour hole increases with the increase of densimetric Froude number and the decrease of impingement length. The topographic maps clearly show that the water jet affected the scour with the decrease of its velocity due to contact with the air at large impingement distances. Moreover, the upstream scour hole angle is approximately equal to the downstream scour hole angle. The findings will be useful in hydraulic applications such as design of plunge pool of an impinging jet spillway, bottom outlet structures, pond water aeration systems, outlets of culverts and storm drainage pipes.

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.