Effect Of Aeration Research Articles

Effect of aeration operation on crystallization induction time of melt with the difficulty of nucleation

Quality control of the crystalline materials obtained from melts with the difficulty of nucleation is challenging. When nucleation is enhanced in such melts, the quality distribution is improved. Herein, the aeration method, which enhances nucleation in solution systems, was employed in a melt to investigate the aeration effect on nucleation in a melt and the effect of the crystallization conditions with aeration on the induction time τind. Experimental results show that aeration enabled nucleation in a melt under supercooling conditions, where nucleation could not occur without aeration. Furthermore, τind depended on the operating conditions with aeration (initial supercooling, aeration period, and atmospheric temperature). The crystal size in the obtained solid phase decreased as the atmospheric temperature decreased. These results suggest that the desired nucleation timing and crystal size can be obtained by manipulating the crystallizer and aeration conditions. Thus, aeration is promising for improving the quality distributions in crystalline materials.

Kinetics of cyclone dust flotation separation in polluting industries

This article describes the study of the kinetics of flotation separation of silicate and carbon dust phases of silicon cyclones. For research, we selected 50 samples of dust gas purification production of silicon to the Silicon situated in the city of Shelekhov of the Irkutsk region. The dust caught by bag filters can be applied as an additive in concrete, rubber products or subjected to processing for expansion of a scope of application. Silicate and carbonate phase of the cyclone dust silicon production separately represent the products in demand. The cost depends on the degree of purity, structure and particle size distribution. Describes the basic dependence of the flotation nanoscale this part of carbon and microsilica. Micro particles inherent in the formation of stable heterogeneous conglomerates. Dissimilar particles can both be introduced into the foam product and remain in the chamber reducing the quality of concentrates. To solve this problem, pulp conditioning is used with the help of sonochemical installations, which contributes to the separation of a large number of conglomerates. The effect of aeration on the flotation process of nanoscale particles is described. Conducting experiments on laboratory experimental flotation machine in different modes and with different flotation reagents. A method of conditioning the pulp, which increases the efficiency of flotation and, as a consequence, the quality of the output products. The dependences of the foam layer height on the concentration of the foaming agent, the dependence of the quality and quantity of the output products on the time and flotation regime are constructed. Important conditions for providing a high degree of separation of micro-sized media are determined. This solution was developed for the enrichment of the cyclone dust gas purification silicon. The study identified the main features of the flotation separation of silicate and carbon phases of cyclone dust. The technical solutions allowing to make effective separation despite the revealed features are offered. Application of this technology leads to reduction of sludge accumulation near silicon plants and production of innovative modifiers for various industries.

Moisture content and aeration control mineral nutrient solubility in poultry litter

Poultry litter waste is typically land-applied as a soil amendment but repeated application in the vicinity of poultry houses has led to phosphorus accumulation in soil. Such application can also lead to runoff that causes eutrophication. Most farmers store litter under dry conditions or compost the litter prior to land application, but it is not clear if these approaches are best from a nutrient management-perspective. The objective of this study was to investigate the effects of moisture content and active aeration on soluble mineral forms of nitrogen and phosphorus in poultry litter incubated for roughly one month. Mineral forms of nutrients are immediately plant-available upon field application and also most conducive to low-cost stripping and recovery methods. Litters were incubated at 50% and 70% moisture content with and without active aeration. Litter aeration led to significant ammonia losses and a consequent decline in litter pH but it had no effect on phosphate solubility. Moisture content during litter incubation governed the levels of plant-available phosphate and nitrification. High (70%) moisture led to 41%–78% higher plant-available phosphate (4.2–4.8 mg/g litter) compared to litters with 50% moisture content (2.7–3.0 mg/g litter). In contrast, the 50% moisture litters experienced 5–6 fold higher levels of nitrification (0.11–0.12 mg NO3-N/g litter) than litters with 70% moisture content (0.02 mg NO3-N/g litter), regardless of aeration. The implication is that lower-moisture litter storage is likely best for field application because phosphate is less soluble under neutral-alkaline conditions and therefore less likely to end up in runoff. In contrast, higher-moisture litter storage may be amenable to low-cost processes to leach and recover phosphate from litter.

Effects of fine bubble aeration at the sediment‒water interface on distributions of organic phosphorus fractions and related microbial activity in a heavily urban river

Effects of fine bubble aeration at the sediment‒water interface on distributions of organic phosphorus fractions and related microbial activity in a heavily urban river

Experimental study on the stability and flame characteristics of LPG flames in O2/N2 and O2/CO2 environment

The current energy crisis and the escalating concern over pollution level necessitate the development of various low emission and clean technologies for efficient utilization of fossil fuels. These technologies offer the benefits of using fossil fuels continuously without harming the environment. Oxy fuel combustion technology is one of the promising low emission combustion technologies having an additional advantage of being a better retrofit option compared to other clean technologies. In the present study, the stability and flame characteristics of LPG flame in a tubular burner has been investigated with oxygen as the oxidizing gas and nitrogen or carbon dioxide as the balance gas. The experiments were conducted to study the effect of primary aeration and the effect of balance gas on the stability and flame characteristics of air and oxy flames. The experimental results from the preliminary experiments show that the flame height decreases with increase in primary aeration for both air and oxy cases and the premixed blue zone increases with primary aeration. The flames observed for oxy cases are dull and weak at all equivalence ratio (or primary aeration). The measured axial flame temperature indicated that the temperature of oxy flames is lower than that of the air flames for the same primary aeration. The data obtained from the stability tests show that the oxy flames can withstand relatively lower port velocity than its air counterpart. Therefore, the stable operating range of the given burner design is lower when CO2 is used as the balance gas. These differences in the stability and flame characteristics is attributed to the difference in the thermo physical properties like molar heat capacity, mass diffusivity and thermal conductivity of the balance gas CO2 and N2.

Reduction in VOC emissions by intermittent aeration in bioreactor landfills with gas-water joint regulation

Landfill mining and reclamation is a new strategy for addressing the lack of space available for new landfills and realizing the sustainable development of landfills. A gas-water joint bioreactor landfill is regulated by injecting water and/or recirculating leachate, and a blasting aeration system to optimize waste stabilization. In this study, four landfill reactors were constructed to investigate the effects of ventilation methods, including continuous (20 h d−1) and intermittent aeration (4 h d−1 in continuous or 2-h aeration per 12 h, twice a day), on the degradation of organic matter and volatile organic compound (VOC) emissions in comparison with traditional landfills. A total of 62 VOCs were detected in the landfill reactors. Among them, halogenated compounds had the highest abundance (39.8–65.4 %), followed by oxygenated compounds, alkanes and alkenes, and aromatic compounds. Both intermittent and continuous aeration could accelerate the degradation of landfilled waste and increase the volatilization rate of VOCs. Compared with intermittent aeration, the degradation of landfilled waste was more quickly in the landfill reactor with continuous aeration. However, intermittent aeration could create anaerobic-anoxic-aerobic conditions, which were conducive to the growth and metabolism of anaerobic and aerobic microorganisms in landfills and thereby reduced more than 63.4 % of total VOC emissions from the landfill reactor with continuous aeration. Moreover, intermittent aeration could reduce the ventilation rate and decrease the cost of aeration by 80 % relative to continuous aeration. Firmicutes, Bacteroidetes, Proteobacteria and Tenericutes predominated in the landfill reactors. The environmental variables including organic matter and VOCs concentrations had significant influences on microbial community structure in the landfilled waste. These findings indicated that intermittent aeration was an effective way to accelerate the stabilization of landfilled waste and reduce the cost and environmental risks in bioreactor landfills with gas-water joint regulation.

Root Aeration Promotes Cadmium Accumulation in Rice by Regulating Iron Uptake-Associated System

Different cadmium (Cd)-accumulated rice genotypes (Erjiunan 1 and Fupin 36) were used to explore the effect of rice rhizosphere aeration on Cd uptake and accumulation. Aeration in the nutrient solution influenced the agronomic characteristics induced by Cd-stress, such as the increases of rice root length and root vigor, but the reductions of plant height and shoot dry weight. Aeration also alleviated the decreasing effects of Cd stress on antioxidant enzyme activities and soluble protein, malonaldehyde and nicotianamine contents in rice. Moreover, with aeration treatment, the accumulation and bioavailability of metal elements changed significantly, with a Cd increase and an Fe reduction in both rice genotypes. In addition, at the molecular level, aeration upregulated the expression of Fe-inducible genes (such as OsIRT1, OsNRAMP1, OsYSL15 and OsNAS3). Furthermore, as a Cd2+/Fe2+ transporter, the high transcription level of OsNRAMP1 can elevate the Cd uptake and translocation in rice due to the Fe reduction caused by aeration and Cd-exposure, which indicated that OsNRAMP1 might play a crucial role in the effect of aeration on Cd uptake and accumulation.

Fermentation of whey and its permeate using a genetically modified strain of Escherichia coli K12 MG1655 to produce 2,3‐butanediol

AbstractWhey is generated during cheese manufacturing, and permeate whey is obtained after whey deproteinization. Both effluents contain lactose, which can cause environmental issues if they are released into the environment. The aim of the present study was the valorization of lactose contained in whey and permeate whey via fermentation into 2,3‐butanediol (2,3‐BD) with genetically modified strain of Escherichia coli K12 MG1655. Both effluents were first fermented at various dilution ratios with the culture medium M9 (50:50, 75:25, and 100:0, v/v). The fermentation of undiluted effluents produced the highest 2,3‐BD yield (0.43 g/g lactose) at 72 h. Afterwards, the effects of initial pH, inoculum size and agitation rate on 2,3‐BD yield in flask fermentation of undiluted effluents were studied. The agitation rates of 50 and 200 rpm resulted in lower 2,3‐BD yields compared with 100 rpm (67% lower). The effect of aeration (2.5 vvm) on 2,3‐BD yield was tested in a 2 L bioreactor, where a 2,3‐BD yield of 0.40 g/g lactose was obtained after 24 h. In the present study, it was demonstrated that both whey and permeate whey can be used to produce 2,3‐BD, reaching near 80% of the theoretical yield after 24 h of fermentation.

Study on the Shape of the Aerator of High-Head Discharge Tunnel with Mild Bottom Slope

Due to the high flow velocity and easy cavitation of high-head drainage tunnels, it is usually necessary to set up aeration facilities. In particular, when the bottom slope of the tunnel is mild, the aeration facilities often have problems such as difficulty with air intake, short cavity, and serious water accumulation, which aggravate the risk of cavitation damage. In this paper, based on the Rumei hydropower station and the Gushui hydropower station, a method combining theoretical analysis and model testing is used to solve the connection problem between the aeration facility and the 3% mild bottom slope of a tunnel body, and the aeration facility shape of “lifting ridge + flat (mild) slope + steep slope” is put forward. The research shows that the steep slope section can smoothly connect the water flow over the cantilever, reduce the jet impact angle, prevent the water from backtracking, and produce a long and stable cavity in the flat (mild) slope section. The aeration concentration along the bottom of the tunnel is higher than 3% at 140 m over the top of the dam. The aeration effect of this type is better, and it can provide effective long-distance protection for a drainage tunnel with high head and a mild bottom slope.

Simultaneous removal of ibuprofen, organic material, and nutrients from domestic wastewater through a pilot-scale vertical sub-surface flow constructed wetland with aeration system

Pharmaceutical compounds in wastewater are currently becoming emerging concern as the utilization of drugs in anthropogenic activities. This research analyzed the effectiveness of pilot-scale vertical subsurface flow constructed wetland (VSSFCW) planted with Scirpus grossus using an aeration system for simultaneous removal of ibuprofen, chemical oxygen demand (COD) and nutrients (NH3-N, NO3-N, and PO4-P) from domestic wastewater. The constructed wetland (CW) platforms (500 L capacity) filled with gravel and sand and planted with native species of S. grossus were used to treat pharmaceutical content in domestic wastewater continuously for 21 days. Three experiments were performed with hydraulic retention time (HRT) of 3, 4 and 5 days. Aeration rates of 0, 1, and 2 L/min were employed for each HRT. The combined effect of HRT, exposure period, and aeration to simultaneously remove ibuprofen, organic materials, and nutrients were examined statistically using Two-way ANOVA and Tukey HSD test. Filtration and adsorption mechanisms of ibuprofen compound by sand medium matrix were proven to occur using solid phase extraction method. The removal efficiency of ibuprofen and COD were dependent on the applied aeration and HRT (p < 0.05). A longer HRT increased the removal efficiency of ibuprofen, while it did not significantly affect the nutrient removal (p ≥ 0.05). The VSSFCW under 2 L/min aeration and HRT of 5 days has removed 99.3% of ibuprofen, 88.2% of COD, 99.1% of ammonia, 72.9% of nitrate-nitrogen, and 83.2% of orthophosphate with effluent successfully met the effluent Standard B set by Malaysian Government. Therefore, the VSSFCW planted with S. grossus becomes a technically feasible method for treating sewage containing pharmaceutical compounds.

“Cattle dung biochar-packed vertical flow constructed wetland for nutrient removal”: Effect of intermittent aeration and wastewater COD/N loads on the removal process

The effect of varying COD/N ratio (1:1, 3:1, 5:1, 8:1, 10:1) of wastewater and intermittent aeration on treatment efficiency of biochar (BC)-packed (with 10% V/V biochar) vertical flow constructed wetland (VFCW), planted with Colocasia esculenta was assessed in this study. Three setups of VFCW were prepared in two sets: aerated (with an airflow rate of 1.0 ± 0.6 L min−1 for 6 h d−1) and non-aeration, and changes in COD, NH4+-N, NO3-N, TN, and TP (total phosphorous) in the effluent was investigated. In VFCWS with intermittent aeration, COD, NH4+-N, NO3-N, TP removal was 99.0, 97.0, 81.0, and 89.0%, significantly higher (p < 0.05) than non-aerated VFCW setups as 91.3, 70.9, 86.97 and 64.4%, respectively. In non-aerated VFCWs, BC addition in combination with plantation was advantageous in the nutrient removal process than setups without BC. COD/N ratio of wastewater did not show a significant impact on the working of VFCWs if amended with BC and intermittent aerations, suggesting slow adsorption rate and fast aerobic degradation of organic matter. The study suggests that oxygen supply management and BC addition in VFCWs could be an effective strategy to treat wastewater with a high organic load. Apart from that study results will be useful for refinement of the operational strategy with varying organic load.

Distribution and Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes in Petrochemical Wastewater Treatment Plants

A petrochemical wastewater treatment plant (PWWTP) was selected to investigate the distribution and removal of antibiotic-resistant bacteria (ARB) and three forms of antibiotic resistance genes (ARGs), namely intracellular ARGs (iARGs), adsorbed-extracellular ARGs (aeARGs), and free extracellular ARGs (feARGs). Tetracycline, sulfanilamide, and ampicillin ARB were detected with the total absolute concentration of 8.45×102-2.38×105 CFU·mL-1; the absolute concentrations of three types of ARB decreased by 0.04 lg-0.21 lg through anaerobic treatment. The effect of aeration and precipitation treatment on ARB varies with its type, and the absolute concentration of ARB in effluent was 0.12 lg-0.63 lg higher than that in influent. The absolute abundance of aeARGs and iARGs in activated sludge was 1.96×107-3.02×1010 copies·g-1 and 5.22×107-4.15×1010 copies·g-1, respectively; the absolute abundance of feARGs in wastewater was 5.90×108-1.01×1012 copies·L-1. Anaerobic treatment can remove 0.13 lg-0.65 lg aeARGs and 0.04 lg-0.28 lg iARGs, while the removal efficiency of aeARGs and iARGs by aeration and precipitation process was affected by ARGs types and forms. The absolute abundance of feARGs in effluent is 0.06 lg-0.81 lg higher than that in influent. Redundancy analysis showed that the concentration of ARB was significantly positively correlated with chemical oxygen demand (COD), Cl-, and total nitrogen concentration (P<0.05). The abundance of aeARGs was positively correlated with COD and total nitrogen concentration (P<0.05), and both the abundance of iARGs and feARGs are positively correlated with heavy metals concentration (P<0.05). This study confirmed the enrichment risk of ARB and different forms of ARGs in PWWTPs, which provided references for the research and prevention of antibiotic resistance pollution in industrial wastewater.

Micro-nano aeration is a promising alternative for achieving high-rate partial nitrification

Biological nitrogen removal is the most prevalent wastewater nitrogen removal process but nitrification limits the rate of the whole process mainly due to the low efficiency of oxygen transfer. In this study, clean-water oxygenation tests, batch tests, long-term operational tests and metagenomic analyses were applied to assess the effects of micro-nano aeration on nitrification. The oxygen transfer coefficient (KLa), oxygen transfer rate (OTR) and oxygen transfer efficiency (OTE) were determined to be 0.56 min−1, 0.36 kg·m−3·h−1 and 71.43%, respectively during micro-nano-bubble aeration. Impressively, these values were 15 times greater than those of conventional aeration. The results of batch tests and long-term operation experiments found that the ammonia removal rate of micro-nano aeration was 3.2-fold that of conventional aeration. The energy cost for micro-nano aeration was calculated to be 3694.5 mg NH4+-N/kW·h, a 50% energy saving in comparison to conventional aeration. In addition, the nitrite accumulation ratio in the Micro-nano (MN) reactor was 1.5 that of the Conventional (CV) reactor. Metagenomic analysis showed that after long-term operation in micro-nano aeration, the abundances of genes encoding ammonia monooxygenase (amoA) and hydroxylamine oxidoreductase (hao) was more than 8-fold and 4-fold of those in conventional aeration, respectively. The abundance of the gene encoding nitrite oxidoreductase (nxrA) was similar in both reactors. Read taxonomy revealed that abundance of AOB-Nitrosomonas increased significantly when using micro-nano aeration, while abundance of NOB-Nitrospira abundance was similar in both reactors. The results of this study indicated that the micro-nano aeration process will increase the ammonia oxidation performance by enhancing oxygen transfer but was also shown to be beneficial for enhancing partial nitrification by specific enrichment of ammonia oxidizing bacteria. This latter result demonstrates the potential benefits of the micro-nano aeration process as an alternative approach to establishing high-rate partial nitrification.

Effects of Soil Aeration and Fertilization Practices on Alleviating Iron Deficiency Chlorosis in “Huangguan” Pears Grafted onto Quince A in Calcareous Soils

In North China, the high-quality pear cultivar “Huangguan” (Pyrus bretschneideri Rehd. cv), which is grafted onto dwarf quince A (Cydonia oblonga Mill. cv) rootstock and grown in calcareous soil, experiences severe iron (Fe) deficiency; this deficiency greatly constrains tree growth as well as fruit yield and quality. Therefore, we evaluated the effects of six practices for alleviating chlorosis caused by Fe deficiency in “Huangguan” grafted onto quince A (HG-QA). The practices included ridging with landscape fabric mulching as a control, flattening with landscape fabric mulching (FM), ridging without landscape fabric mulching (R), flattening without landscape fabric mulching (F), Fe fertilizer application in soil (SFe), foliar Fe application (FFe), and manure application (M). The results showed that the leaf Fe concentration increased by 356% under FFe, compared to that under the control, but the practice failed to alleviate Fe deficiency chlorosis. In contrast, an increase in leaf Fe concentration and chlorosis alleviation were observed under F. F alleviated chlorosis mainly by increasing the root ferric-chelate reductase activity. These results indicate that Fe uptake and utilization in leaves are independent biochemical processes and soil aeration improvement have positive effect on increasing Fe uptake. M improved both the soil active Fe concentration and leaf Fe utilization. Thus, manure application should be the first choice for alleviating Fe deficiency chlorosis in HG-QA grown in calcareous soils. Combining manure application with other practices that increase Fe uptake would likely be an effective way to address the problem of Fe deficiency chlorosis.

Comparative analysis of aeration and oscillation in a suspended catalyst photocatalytic membrane reactor

Comparative analysis of membrane oscillation and aeration in a photocatalytic membrane reactor is conducted. The investigation involved degradation of methylene blue dye as model pollutant using suspended ZnO photocatalyst and UV illumination. The effect of reactor hydrodynamics and design parameters on the system performance and its relation to the membrane-catalyst retention characteristics is evaluated using flat surface membranes roughed with transverse turbulence promoters (TP). The investigation showed that membrane oscillation is more energy efficient than aeration and can provide higher shear rates and better mixing which decreases both the catalyst agglomeration and deposition on the membrane surface. These, in turn, increase both the suspended catalyst concentration in solution and enhance the membrane flux. Compared to oscillation, achieving high shear rates through aeration is limited due to the adverse effects of high gas flow on photocatalytic reactions. Considering the above together with the small effect of aeration on ZnO photocatalytic kinetics, the need for aeration may be relaxed when using membrane oscillation in a ZnO photocatalytic reactor.

Photo-biodegradation of imidacloprid under blue light-emitting diodes with bacteria and co-metabolic regulation

Imidacloprid (IMI) is existence in the soil environment with a half-life habitually more than hundred days. This study targets to determine, identify and characterize photo-biodegradation bacteria from neonicotinoids (NEOs) contaminated agricultural field soils. The sub-surface soil had a higher level contamination of NEOs, in specifically greater concentration of IMI (3445.2±0.09μg/g) and thiacloprid (4084.4±0.09μg/g) has been found. Three bacteria Ralstonia pickettii (PBMS-2), Bacillus cereus (PBMS-3) and Shinella zoogloeoides (PBMS-4) was identified from soil-free stable enrichment cultures. The biodegradability of IMI (50mgL-1) by three bacteria under different colors of light-emitting diodes (LEDs) with a constant 12V power supply was tested and found that the blue-LEDs had greatest efficiency in supporting biodegradation of IMI which is called photo-biodegradation. In specific, the rate of photo-biodegradation of IMI by Ralstonia pickettii (87%), Bacillus cereus (80%) and Shinella zoogloeoides (80%) was measured. Besides this study also tested the effect of aeration (rpm), pH, and temperature on photo-biodegradation of IMI. There were seven intermediate metabolites were measured as biodegradation products of IMI under photo-biodegradation conditions and they are; IMI-urea, IMI-desnitro, 6-chloronicotinic acid, 6-hydroxy nicotinic acid, IMI- aminoguanidine, IMI-nitrosoguanidine and 4,5-hydroxy IMI, these metabolites are may non-toxic to the environment.

A mathematical model for predicting the flow behavior through a CFB reactor U type loop - seal

A mathematical model for predicting the flow behavior through a conventional U type loop-seal was developed by considering the loop-seal as a lumped system. The change rate of the gross forward particle flow rate (GG) with respect to the fluidization number at its bottom (Fn), GG', is assumed to be a function of the products of the gross forward particle flow rate coefficient (k) and the differential head across it. In addition, the flow resistance is considered as the virtual backward particle flow rate (Gr). Its change rate (Gr') is assumed to be a function of the products of the virtual backward flow coefficient (f) and the solid circulation rate provided by the loop-seal (Gs). The effects of the side aeration at the recycle side walls and heat exchanger in the chamber on the performance of the loop-seal was investigated. It was found that the relation between Gs and Fn is an asymptotic or a saturated function. From the regression analysis of the experimental data from a cold model circulating fluidized bed system according to the function, the function constants are obtained with the coefficient of determination of not less than 0.97. GG' is constant, while Gr' increases with Fn. The loop-seal with heat exchanger (LSHE) has a lower Gs. The LSHE with side aeration has a change rate of the forward particle flow rate with respect to Fn, and the virtual backward flow coefficient higher than the conventional loop-seal for the side aeration flow rate less than a certain value. After that, the opposite trend was found. The loop-seal having a higher fwill have a lower Fnor side aeration flow rate corresponding to saturated Gs. The developed model may be applied to any types and sizes of loop-seal and suggests that in order to have a high Gs, loop-seals should have their configuration provide a high gross forward particle flow rate coefficient (k) and a low virtual backward flow coefficient (f).

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.

Unplanted wetland-type filter for co-treatment of landfill leachate and septic tank wastewater: Analysing gravel replacement by plastic and passive (filling-emptied) aeration effects at pilot scale

Nowadays, traditional residential and industrial wastewater treatment methods have been mainly developed as complex systems that consider costly infrastructure, which requires advanced control systems and highly qualified labour for their operation. The use of wetland-type infrastructure has been recognized both, by scientists and authorities, as an efficient and effective method to obtain good results in these processes.The most relevant elements in the design of horizontal subsurface filters are filtering media, as biofilm supporting material and flow control methods. Usually, these treatment systems use gravel as filling material. Despite the functionality of the stone material, its weight presents serious difficulties for its handling at source and on site. The use of a plastic support would lower transportation costs, improve manageability and reduce the probability to damage the underlying impermeable layer. In addition, it might extent the useful life of the reactor by cleaning it when clogged, and the potential use of recycled plastic would improve the sustainability of the process.To verify the possibility of using a lightweight plastic material to replace heavy gravel, an unplanted pilot scale treatment system, composed of four independent treatment units in parallel was implemented. The treatment units differed in the filtering media and the input flow regime. Two of the treatment units used gravel (Specific surface 305 m2/m3, 1475 kg/m3 apparent density) and two units used plastic material (Specific surface 750 m2/m3, 172 kg/m3 apparent density).To check the incidence level of passive aeration procedures, on the effectiveness of each material, two of the treatment lines used a continuous flow system and two of them used an automatic filling and emptying flow method that allows passive aeration of the support media.A mixture of landfill leachate and septic tank wastewater was treated, and the evolution of turbidity, chemical oxygen demand, nitrogen and phosphorus was monitored. Results showed that, in general, there are no significant differences regarding the performance of the materials tested, whereas passive aeration notably improves the abatement and solids retention performance of the pilot units.It is concluded that the plastic material tested can be used as a replacement for the stone material, without having appreciable losses in the efficiency of the system. Further research is needed to quantify the benefits associated with the use of this support in constructed wetlands-type technologies.

Effect of aeration on the growth and sporulation of Aspergillus niger in cassava stalks bioconversion

Aspergillus niger is a mould which can be used in bioconversion of cassava stalks through solid-state fermentation. Mould is aerobic microorganism and require oxygen for their growth. Sufficient supply of oxygen by aeration will give better growth of mold, but excess of oxygen will act as a bad condition and encourage production of spores. Moulds at sporulation stage will not produced enzymes required for bioconversion of lignocellulosic material, for example cassava stalks. The aim of this study was to know effect of aeration on the growth and sporulation of Aspergillus niger in bioconversion of cassava stalks. Aspergillus niger FNCC 6114 were grown on media of cassava stalks powder moistened with water in 1:1 ratio, incubated inside of two kinds of incubators. The first, incubator of plastic box at 20 L capacities without aeration. The second, incubator equipped with aquarium aerator for force-aeration and IV needles for controlling the speed of aeration at 40 mL/min. Based on the result, it was shown that fermented media from aerated incubator were: higher glucosamine content, lower reducing sugar content, and higher spores quantity. These indicated that aeration at the speed of 40 mL/min will encourage growth and increase sporulation of Aspergillus niger FNCC 6114.