Particle Moisture Content Research Articles

Effect of Particle Size, Moisture Content and Density on the Hyperbolic Model Parameters for Non-cohesive Soil

Effect of Particle Size, Moisture Content and Density on the Hyperbolic Model Parameters for Non-cohesive Soil

Breakage behaviour of single rice particles under compression and impact

Grain breakage is mainly caused by impact and compression load in harvest and processing. At present, the mechanism of grain breakage under loading, especially the statistics of breakage characteristics, is not clear. The analysis of breakage process of single particle provides a foundation for the understanding of breakage mechanisms. This paper aims to examine breakage behaviour of a single rice particle under compression and impact experiments. Firstly, the equivalent diameter (Dp) and moisture content (MC) of rice particles were regarded as important factors that may affect breakage. Then, by performing quasi-static compression and dynamic impact experiments under different values of Dp and MC, the detailed compression failure force, rice strength, breakage modes, breakage probability, and the breakage probability models were analyzed comprehensively. Furthermore, breakage processes of rice particles under these two breakage experiments were compared and discussed. Finally, the Weibull distribution of the compression breakage characteristics, the “non-size effect” of compression and impact breakage, the tensile failure forms, velocity threshold of impact breakage and the close relationship between the breakage characteristics under impact and compression were mainly found. The findings are useful for providing guidance for the revelation of breakage mechanism and optimizing related agricultural equipment design.

Global Sensitivity Analysis of a Water Cloud Model toward Soil Moisture Retrieval over Vegetated Agricultural Fields

The release of high-spatiotemporal-resolution Sentinel-1 Synthetic Aperture Radar (SAR) data to the public has provided an unprecedented opportunity to map soil moisture at watershed and agricultural field scales. However, the existing retrieval algorithms fail to derive soil moisture with expected accuracy. Insufficient understanding of the effects of soil and vegetation parameters on the backscatters is an important reason for this failure. To this end, we present a Sensitivity Analysis (SA) to quantify the effects of parameters on the dual-polarized backscatters of Sentinel-1 based on a Water Cloud Model (WCM) and multiple global SA methods. The identification of the incidence angle and polarization of Sentinel-1 and the description scheme of vegetation parameters (A, B and α) in WCM are especially emphasized in this analysis towards an optimal estimation of parameters. Multiple SA methods derive identical parameter importance ranks, indicating that a highly reasonable and reliable SA is performed. Comparison between two existing vegetation description schemes shows that the scheme using Vegetation Water Content (VWC) outperforms the scheme combing particle moisture content and VWC. Surface roughness, soil moisture, VWC, and B, are most sensitive on the backscatters. Variation of parameter sensitivity indices with incidence angle at different polarizations indicates that VV- and VH- polarized backscatters at small incidence angles are the optimal options for soil moisture and surface roughness estimation, respectively, while VV-polarized backscatter at larger incidence angles is well-suited for VWC and B estimation and HH-polarized backscatter is well suited for roughness estimation. This analysis improves the understanding of the effects of vegetated surface parameters on multi-angle and multi-polarized backscatters of Sentinel-1 SAR, informing improvement in SAR-based soil moisture retrieval.

Simulation of Microencapsulation Avocado Seeds Oil by Spray Drying

Drying air inlet temperature is one of the critical variables in the microencapsulation process by spray drying. However, when spray drying is carried out at inappropriate drying air inlet temperature, it can impact the particle produced. This study presents a simulation of spray drying from a mathematical model was developed to determine the effect of drying air inlet temperature on moisture content, particle diameter, particle density, and drying air outlet temperature in the microencapsulation process of avocado seeds oil as core materials and gum arabic as wall materials. For this aim, the mathematical model was developed then simulated using a matrix laboratory (Matlab) computer program with Euler numerical method for drying air inlet temperatures of 160, 180, and 200 °C. The selected model was validated with Cotabarren’s experimental results indicating the model was acceptable. The particles’ moisture contents predicted from simulation results are 1.170, 1.049, and 0.933 kg water/kg solid for 160, 180, and 200 °C, respectively. On the other hand, the predicted particle diameters are 29.73, 29.49, and 29.23 urn for 160, 180, and 200 °C, respectively. The predicted particle densities are 1215.72, 1225.21, and 1233.25 kg/m3 for 160, 180, and 200 °C, respectively. The prediction of drying air outlet temperatures was 39.76, 41.94, and 43.89 °C for inlet air temperatures of 160, 180, and 200 °C, respectively. The proposed models’ simulation results show that the higher temperatures caused lower particle moisture content, smaller particle diameter, and higher particle density. Also, the outlet drying air temperatures were always the same as the outlet particle temperatures.

Devising optimal technological parameters for spray drying to produce whole camel milk powder

Camel milk is a valuable source of protein and nutrients, it has therapeutic and prophylactic properties. The production of dry dairy products based on camel milk implies prolonging its shelf life, a decrease in the cost of its transportation and storage. To manufacture dry camel milk, it is necessary to optimize the technological parameters of drying, which affect its physical-chemical properties. Whole milk from camels (Camelus dromedarius) was dried on a spray drying plant under the following modes: the inlet temperature from 140 °C to 160 °C; the feed rate from 30 ml/min to 40 ml/min. The dependence of such physical properties of milk powder as the water solubility index, water absorption index, moisture content, hygroscopicity, density, water activity, the stickiness and size of particles on the technological parameters of drying has been established. The study results show that the highest index of solubility of samples was equal to 81.25±0.11 %, which corresponded to the air temperature at the inlet of 150 °C and the feed rate of 30 ml/min. At the same time, the lowest solubility was 62.89±0.27 % under the modes of 140 and 40 ml/min, respectively. With an increase in the air temperature at the inlet and a decrease in the rate of supply of dairy raw materials, there was a decrease in the moisture content and water activity. However, an increase in the air temperature at the inlet above 150 °C led to a decrease in the solubility index in water. The optimal particle sizes of whole camel milk powder, preceding a relatively high solubility index, were 36.22±0.33 μm, 108.89±0.56 μm, and 229.19±0.74 μm. The data reported in this paper could be useful in devising the technology for manufacturing a dry milk product from camel milk.

Effect of Tempering Conditions on White Sorghum Milling, Flour, and Bread Properties.

The effects of room temperature water, hot water, and steam tempering methods were investigated on sorghum kernel physical properties, milling, flour, and bread-making properties. Overall tempering condition and tempering moisture content were found to have a significant effect on the physical properties. Milling properties were evaluated using a laboratory-scale roller milling flowsheet consisting of four break rolls and eight reduction rolls. Room temperature tempering (18% moisture for 24 h) led to better separation of bran and endosperm without negatively impacting flour quality characteristics i.e., particle size distribution, flour yield, protein, ash, damaged starch, and moisture content. Bread produced from the flour obtained from milling sorghum kernels tempered with room temperature water (18% m.c for 24 h) and hot water (16% m.c at 60 °C for 18 h) displayed better bread-making properties i.e., high firmness, resilience, volume index, higher number of cells, and thinner cell walls when compared to other tempering conditions. Room temperature water tempering treatment (18% m.c for 24 h) could be a better pretreatment process for milling white sorghum kernels without negatively impacting the flour and bread-making quality characteristics.

Influence of pelletizing process parameters on the performance of V–Ti magnetite green pellets for composite agglomeration

ABSTRACT To use vanadium–titanium magnetite (VTM) resources for sintering, a composite agglomeration process (CAP) is applied. This paper studies the effects of pelletizing parameters, including particle size, moisture content and bentonite content on VTM green pellets, composite agglomeration process and mineralogy. The experimental results show that the optimal pellets particle size, water and bentonite content are 5–8 mm, 8.75% and 2.0%, respectively, for the strength of VTM pellets. In the sintering process, the economic and technical indexes obtained by using VTM pellets based on CAP are significantly better than those obtained by traditional sintering process. When using CAP, VTM pellets with the particle size of 5–8 mm have more advantages in the air permeability of the feed layer compared with those with the particle size of 10–12 mm, and accordingly have higher sintering speed, yield, productivity and lower fuel consumption. The addition of 15% ordinary magnetite concentrates into VTM pellets did not improve the productivity, but it was helpful to reduce the solid fuel consumption. By analysing the mineral phase structure of sintering products under different schemes, it is found that the pellets are closely bound to the matrix in the CAP. The main phase in the pellet part is hematite phase, and a large amount of SFCA phase can be observed in the matrix part. When ordinary magnetite concentrate is added, the crystal connections within the particles become more complete.

Influence of nozzle outlet diameter on the atomization process of zirconia dry granulation

In order to predict the atomization characteristics of the atomization process of zirconia dry granulation accurately, the influence of nozzle outlet diameter on the atomization characteristics of the atomization process of zirconia dry granulation is analyzed. The VOF method and RNG k-ε turbulence model are applied to numerically analyze the flow field of pressure-swirl nozzles with different outlet diameters of the atomization process of zirconia dry granulation, and the effects of outlet diameters on the spray cone angle, liquid film thickness, pressure distribution and velocity distribution are analyzed. The result shows that when the outlet diameter is increased from 3 to 4 mm, the diameter of air core and the outlet velocity of atomized liquid are increased, the spray cone angle is increased from 30.5° to 59.7° while the liquid film thickness is decreased, but when the outlet diameter is increased to 5 mm, the diameter of air core and the outlet velocity of atomized liquid are decreased, the spray cone angle is decreased to 27.6°, while the thickness of liquid film is decreased. The spray cone angle, moisture content of zirconia particles corresponding to nozzles with different outlet diameters are measured by the design of atomization experiment platform and the microstructure of zirconia particles are observed, which verifies the correctness of numerical analysis. Taking the atomization performance of nozzle into consideration, the pressure-swirl nozzle with the outlet diameter of 4 mm is better suitable for the atomization process of zirconia dry granulation.

EVALUATION OF NUTRIENT STOCKS AND SOME SOIL INDICES OF AGRO-ECOSYSTEM AS AFFECTED BY LONG-TERM MONOCROPPING SYSTEM

Objectives: This study investigates nutrients stock and some soil indices of agro-ecosystem soil as affected by monoculture cropping system (cacao plantation). This was with a view to provide comprehensive understanding of soil nutrient dynamics in the ecosystems due to their different management practices.
 Methods: The study was carried out in 0.063 ha sample plots, three each in natural forests and cacao plantations adjacent to each other. In each plot, five core soil samples were randomly collected at two depths (0–15 and 15–30 cm), bulked according to depth, air-dried, sieved through 2 mm sieve, and analyzed for soil physicochemical properties using standard methods. One-way analysis of variance was used to test significant mean differences of the soil properties among cacao plantation and natural forest at probability level (p≤0.05) at different soil depth.
 Results: The results showed that soil physical properties such as particle size distribution, moisture contents, and bulk density; chemical properties such as pH, exchangeable cation, organic carbon, organic matter, phosphorus, and sulfur from natural forest were higher than the soil properties in cacao plantation for both top and subsoil. Soil indices such as soil structural stability index, base saturation percentage, and sodium adsorption ratio were higher in natural forest ecosystem than the soil indices of cacao plantation.
 Conclusion: From this study, it can be concluded that long-term monoculture cropping system had significant effect on nutrients stock and soil indices. This subsequently might result in permanent soil degradation and productivity.

Sustainable usage of carrot discards in food processing

ABSTRACT The Processed carrot discards (PCDs) separated during the primary processing of carrots are partially utilized towards animal feed and the remaining end in the landfills. The study was undertaken to evaluate the prospects of using the PCDs towards preparation of carrot puree. PCDs were procured from the processing unit in Ontario, Canada. These were processed into carrot puree (with and without thermal pretreatment). The prepared purees were evaluated for the physical and nutraceutical properties, and the most desirable among these was compared with the commercially available carrot purees. Carrot puree processed from steam blanched PCDs reported β-carotene (94.56µgg-1), α-carotene (86.62µgg-1), Total Soluble Solids (5.50 °Brix) and color values with L (36.40), a (22.90) and b (30.00). The regression model correlated the presence of β-carotene to color values (a, b) and particle size D (0.9) with R2(0.9939) and p-value (0.0091 < 0.05). Comparing the properties of carrot puree prepared from PCDs with commercially available carrot purees, significant differences (p ≤ 0.05) were recorded in color, β-carotene and α-carotene content. No significant difference (p≤0.05) was recorded for the particle size, density, sedimentation index and moisture content. The study concluded that the thermally pretreated PCDs can be used for carrot puree preparation. It is suggested to include some percentage of graded carrots with PCDs to enhance the nutraceutical properties of the carrot puree.

A Study on Characteristics of Unsaturated Sandy Soils Based on the CT Scanning Method

In the hydrologic cycle, sandy soils play the role of a connecting reservoir of surface water and groundwater, particularly in arid areas. Therefore, to provide water conservation and ecological environment protection, it is important to study the soil water behavior in the unsaturated zone. At present, the CT-scan method is commonly used to study the soil hydraulic properties. In the field of materials science, the industrial CT high-resolution instruments are applied for quantitative research on the porous microstructure and fluid filtration law in sandy soils. In this study, we have studied five samples of sand scans of the quartz sand and CUGB coarse sand types. The industrial-type CT instrument XTH225ST was used for the sample microstructure scanning. In order to identify water: air, and solid particle distribution of the sample cross section, and to analyze the particle size distribution and moisture content, the scanned images were processed using the VG-Studio and ImageJ software. Comparing the CT-scan results of the four quartz sand samples, it can be concluded that the optimal particle size, ranges from 1 to 2 mm. According to the porosity quantitative analysis, with decrease in the particle size, the total porosity grate soil sample increases. After applying the image recognition and VG- Studio software, we can see that for different particle sizes of the sand sample, the average pore size increases with increase in the particle size. To study the moisture absorption and desorption phenomenon, two samples of the CUGB coarse sand are experimentally studied. The particle size of the samples range: from 1 to 2 mm. The CT scanning analysis is used to obtain the unsaturated characteristic curve of the soil when the moisture content reaches stability. Due to the lag phenomenon, the characteristic curve of the soil moisture has an obvious “loop,” or hysteresis, shape. As shown by a 3D modeling, the distribution of capillary water in the sand column is complex, and the water flow forms multiple winding paths, like “worms” creeping in the soil. The CT-scan method is used to overcome the limitations of the traditional experimental methods and to evaluate the relationship between the moisture content and the matrix suction. The obtained characteristic curve of soil moisture can be used to improve the efficiency of technological operations. The CT-scan method provides a new way of evaluating the water distribution characteristics of unsaturated soil.

Effects of water pretreatment on properties of pellets made from beech particles

Particles of beech wood were treated with hot water at the temperature of 150 oC, during 60 min, prior to the pelleting process. The applied hot water pretreatment affected the chemical composition and heating value of particles. Two groups of pellets, designated as PT 10 and PT 20, were produced from treated beech particles, with the moisture content of particles being 10.5 and 20.5 %, respectively. Pellets from nontreated beech particles (PNT) served as controls to assess the hot water pretreatment effects on the pellet properties. Both, the applied pretreatment, and the particle moisture content, affected properties of the obtained pellets. The heating value of PT 10 ad PT 20 pellets has increased for ~6 and 1 %, respectively. The mineral (ash) content in treated pellets decreased for about 24 % in comparison to that in PNT pellets. In addition, the bulk (apparent) density of pellets has increased for 21 % (PT 10) and 10 % (PT 20), as a consequence of the hot water pretreatment of particles. The specific density of PT 10 pellets was for 16 % higher, while the equilibrium moisture content (after conditioning at RH 68 % and 20.1?C) was for about 32 % lower in comparison to the respective properties of PNT pellets.

Research on Basic Mechanical Properties and Fracture Damage of Coal Gangue Concrete Subjected to Freeze‐Thaw Cycles

In order to study the freeze‐thaw damage law of the basic mechanical properties and fracture performance of coal gangue concrete, four kinds of coal gangue concrete specimens with different replacement rates of coal gangue coarse aggregate were designed, and then, the basic mechanical test and three‐point bending loading were carried out under different times of the freeze‐thaw cycle. The test results show that the compressive strength and flexural strength of concrete decrease with the increase of coal gangue aggregate content, and the higher the content of coal gangue aggregate is, the greater the freeze‐thaw damage of coal gangue concrete is. The coal gangue reduces the fracture resistance of concrete, and the higher the replacement rate of coal gangue coarse aggregate is, the lower the fracture toughness and fracture energy of concrete is. The freeze‐thaw cycle causes the obvious decrease of fracture toughness and fracture energy of concrete because the moisture content of coal gangue particles is higher; the freeze‐thaw damage of coal gangue concrete is more serious than that of ordinary concrete, and the higher the substitution rate of replacement of coal gangue coarse aggregate is, the higher the freeze‐thaw damage of fracture toughness and fracture energy is. The correlation between the freeze‐thaw times and the two parameters of fracture toughness and fracture energy damage of coal gangue concrete after freeze‐thaw cycles is good. The relationship between the two parameters and the freeze‐thaw times can be fitted by power function y = axb, and the fitted power index value of fracture toughness is higher than that of fracture energy.

Monitoring of high-moisture content particle drying in a fluidized bed by microwave and capacitance tomographic sensors

Particle drying in fluidized beds is a common and important process in food and pharmaceutical industry. However, the fluidization characteristic is complex due to the moisture content change in the process and it is a challenge to monitor the flow characteristics by conventional measurement approach, likes pressure and thermal probes. In this research, process tomography including capacitance and microwave tomographic systems are used to investigate the flow characteristics in a fluidized bed dryer with high-moisture content particles. Static tests were firstly carried out to investigate the image characteristics based on microwave tomography (MWT) and electrical capacitance tomography (ECT). The imaging ability was compared between MWT and ECT. In the dynamic tests, the drying process for particles with high-moisture content was monitored on-line by MWT and ECT separately. The static test results show that the high calibration for ECT is critical and particles with low moisture content should be used for high calibration of an ECT system to achieve high quality images for the dynamic tests. For the high calibration of ECT, there is an upper limit for the moisture content. With a fixed calibration background, the moisture content of particles should not exceed this upper limit value. MWT basically has no limitation on the moisture content both for high calibration and measurement. Dynamic test results illustrate that MWT is a good option to monitor high-moisture content particles drying in a fluidized bed and it is possible to combine ECT together to identify the gas–solids flow regime transit and to determine the moisture content by MWT in a fluidized bed drying process.

Analysis of terahertz wave attenuated by sand and dust storms with different modes

The research on space transmission characteristics of terahertz wave is of great significance for the application of terahertz wave in space. In order to study the transmission characteristics of terahertz wave in sand and dust storm weather, according to the lognormal distribution of dust particle sizes, Mie scattering theory and Monte Carlo method are used to analyze the attenuation characteristics of six dry sand modes of sand and dust storm in different regions of China in a frequency band of 1–10 THz, and the relationship of the extinction parameters and attenuation rate to the frequency is given. The results show that with the increase of frequency, the attenuation rate of 1–10 THz terahertz wave first increases and then decreases. Different mode of sand and dust storm leads to different frequency range of strong attenuation of terahertz wave. In order to analyze the influence of sand dust particle moisture content on terahertz wave propagation attenuation, the relationship of three efficiency factors to water content of sand dust particles with different sizes is calculated. The results show that the influence of water content on extinction is different from that of the particle size. Monte Carlo method is used to calculate the attenuation of terahertz wave by sand and dust storm in two kinds of wet sand modes, and the relationship of the attenuation rate and water content to the frequency is given, the results are compared with those from the dry sand mode, showing that the albedo of wet sand mode is obviously lower than that of dry sand mode with the same size distribution. The absorption of wet sand particles increases with water content increasing. The extinction of wet sand and dust storm results from scattering and absorption. With the increase of water content in sand particles, the frequency band with strong attenuation of terahertz wave by wet sand and dust storm moves toward low frequency. When the water content is less than 5%, the attenuation rate of terahertz wave increases significantly with the increase of water content. Sand and dust storms with higher humidity have a greater influence on the transmission attenuation of terahertz wave.

Drying process of black pepper in a swirling fluidized bed dryer using experimental method

Black pepper (piper nigrum) is one of the well-known spices extensively used worldwide. Drying is the most popular methods of preserving the black pepper. Unfortunately, this operation may negatively influence product quality. Moreover, due to the high heat capacity of water, drying is usually a long-lasting and energy-intensive process, thus new drying techniques are continuously being sought. Fluidized bed dryers have been applied to dry raw materials due to the advantages of good mixing efficiency and high heat and mass transfer rate. In order to control and optimize the drying process of fluidized bed dryers, it is necessary to develop reliable methods to measure the moisture content of solid particles in the bed. For this project we dried the black pepper using two methods which is drying under sun drying and swirling fluidized bed dryer using heater. The temperature for both drying will be the same. Then, the characteristic and the drying moisture ratio of the black pepper were compared between these two drying methods. The performance of the swirling fluidized bed dryer was evaluated based on the percentage of moisture content of loss reduction. The time taken for this drying is 10 hours, which considered as 1 day of drying process. The percentage of moisture content loss reduction is 57.9%. The moisture ratio after 10 hours of drying is 0.3420. In conclusion, drying using swirling fluidized bed dryer is the new technology that can be used in drying industry.

RETRACTED: Synthesis and characterization of polyurethane-based softwood composite as effective thermal insulation with low density and high mechanical properties

Abstract In this paper, a new low-density (0.40 g/cm3), high-flexibility, high-mechanical property cork composite (RC16) was prepared by using one-component moisture-curing polyurethane U030 as a softwood adhesive. The effects of adhesive content, moisture content of softwood particles and curing conditions on the thermal insulation properties, flexibility and mechanical properties of RC16 composite were investigated. The results show that the synthetic adhesive U030 has excellent compatibility and adhesion with the cork particles, and can completely wrap the cork particles and disperse uniformly. The mechanical properties of the material increase first with the increase of the moisture content of the cork particles but soon decline, and the maximum value is reached at 7.0%. With the increase of U030 content, the performance of RC16 first increased and then stabilized, while its thermal conductivity increased accordingly. When the content of U030 is 30%, the overall performance of the material is the highest; the optimum curing conditions for determining RC16 are: curing temperature 110 °C, curing time 1.5 h. RC16 composite has a good heat resistance and can withstand high-temperature ablation at 800 °C within the 20 s. The effects of adhesive content, moisture content of softwood particles and curing conditions on the thermal insulation properties, flexibility, mechanical properties and ablation resistance of the materials were systematically studied, aiming to further improve theoretical basis for the preparation and application of lightweight and efficient softwood thermal protection composite materials.

Potential food additive of Boswellia carterii essential oil encapsulated within gum arabic: a particle size distribution and zeta potential analysis

Boswellia carterii (BC) {Burseraceae family} essential oil (EO) were extracted by hydrodistillation process. Gum Arabic (GA) {Acacia senegal} polymer particles containing a BCEO were prepared by spray drying technique. The mean particle size and its distribution, as well as the zeta-potential of the microcapsules, were analyzed and found Z-Average 382±203nm, PDI 0.77±0.3, ZP-25±2.73mV, respectively. Product encapsulation efficiency (EE %) was found at 75±0.8%. The surface morphology of the particles was obtained by scanning electron microscope (SEM). Furthermore, particles moisture content was analyzed by the oven drying method. The efficiency of encapsulation (EE %) was estimated by specifying the content of essential oil in the product. Gas chromatography (GC) coupled with time-of-flight mass spectrometry (TOFMS) analysis of EO has been performed to determine the chemical compounds and their prevalence concentrations respectively. The composition of initial essential oil (added in the emulsion) and the encapsulated essential oil (extracted from spray dried powder) were analyzed and compared. The outcome of the research encourages the high potentiality and usefulness of the product in the food industries sector as a food additive agent, moreover, it suggests for further research to unravel potential implementation of BCEO microcapsules in the food production chain

Visual Experimental Analysis of the Residence Time of Flexible Biomass Particles in a Baffled Rotating Cylindrical Tube

Drying of biomass or biofuels is a major issue during pretreatment because of a high initial moisture content, which results in low energy efficiency and combustion temperature and high emission of hydrocarbons. As the motion behaviors of biomass fuels play an important role in the drying process, it is of great significance to investigate the motion of biomass. In this study, visualization experiments on the motion of flexible nonspherical biomass particles in a baffled rotating cylindrical tube were performed. The residence time of biomass particles was obtained and analyzed by taking into account gas velocity, mass flow rate of flexible biomass, initial moisture content of biomass particles, slope and rotational speed of the cylindrical tube, and other parameters under several operational conditions. The results indicated that the mean residence time of flexible biomass increased with the increase in the mass flow rate and initial moisture content and decreased with the increase of the cylindrical tube’s rotational speed and slope and the velocity of the gas phase. Despite the quite small sliding friction coefficient between the tube’s inner wall and biomass particles, a larger slope could lead to stronger sliding friction force in the axial direction when these biomass particles moved to the bottom of the tube. Mean residence time is observed to decrease significantly and gradually decrease with the increase in rotational speed from 6 to 9 rpm and from 9 to 18 rpm, respectively. In addition, the mean residence time increased from 78.5 to 99.4 s when the inlet mass flow rate increased from 60 to 240 kg/h without the gas phase, but it increased from 57.4 to 78.5 s within the same range of the inlet mass flow rate at a gas velocity of 0.3 m/s.

Enhanced bioremediation of lindane-contaminated soils through microbial bioaugmentation assisted by biostimulation with sugarcane filter cake

Lindane is a toxic and persistent organochlorine pesticide, whose extensive use generated its accumulation in different environmental matrices. Bioremediation is a promising technology that can be used combining bioaugmentation and biostimulation processes to soil restoration. The aim of the present work was to determine the conditions of maximum lindane removal by bioaugmentation with an actinobacteria consortium and biostimulation with sugarcane filter cake (SCFC). The assays were carried out on lindane-contaminated silty loam (SLS), clayey (CS), and sandy (SS) soils. Through complete factorial designs, the effects of three abiotic factors (moisture content, proportion and size of SCFC particles) were evaluated on lindane removal. In addition, a response optimizer determined the optimal conditions for pesticide removal in bioaugmented and biostimulated soils, in the range of levels studied for each factor. In these conditions, bioaugmentation of biostimulated soils increased the pesticide removal (SLS: 61.4%, CS: 70.8%, SS: 86.3%), heterotrophic microbial counts, and soil enzymatic activities, and decreased lindane T1/2, regarding the non-bioaugmented biostimulated controls, after 14 days of assay. The values of these parameters confirmed the efficiency of the bioremediation process. Finally, the viability of the four strains was demonstrated at the end of the assay. The results indicate that the simultaneous application of bioaugmentation with the actinobacteria consortium and biostimulation with SCFC constitutes a promising tool for restoring soils contaminated with lindane, by using the optimal conditions obtained through the factorial designs.