Low Bed Height Research Articles

A bio-augmented system with Methylosarcina sp. LC-4 immobilized on bio-carriers: Towards an integrated approach to mitigate and valorize methane emissions from landfills to biodiesel

Bio-augmented systems based on methanotrophs are indispensable in curbing anthropogenic methane emissions from engineered landfills or dumpsites to curtail rising levels of greenhouse gases. Using a defined methanotroph culture immobilized on an inert material-based bio-carrier makes it possible to harness these methane emissions for creating value-added products, thus contributing to the circular bio-economy. The methane oxidation capacity of the model methanotroph Methylosarcina sp. LC-4, a prospective organism for biodiesel production using methane present in landfill gas, immobilized on several inert bio-carriers, was evaluated to identify a bio-carrier that provided optimum conditions for the process.Among the several bio-carriers evaluated, perlite and vermiculite were selected due to their high specific surface area and superior water-holding capacity, which result in the retention of nutrients and biomass and higher methane elimination capacity. While perlite showed high biomass holding capacity and methane transport, vermiculite supported a high growth of methanotrophs. LC-4 immobilized on perlite and vermiculite as the bio-carrier showed maximum methane elimination capacity (MEC) of 291.3 g m−2 day−1 and 155.5 g m−2 day−1, respectively. The low bed height of only 0.13 m and a short start-up period of 2–4 days are promising for use as alternate daily cover in a landfill. The recovered biomass had 12% (w/w) fatty acid methyl ester (FAME), with a high fraction of (∼85%) of C14–C18 saturated and monounsaturated fatty acids, suitable for biodiesel production. The combination of perlite and vermiculite increased MEC and FAME content levels. The current study demonstrated a new bio-augmented system designed with a pure methanotroph for methane elimination with a short start-up time and the valorization of the assimilated methane.

Fabrication of 1-octane sulphonic acid modified nanoporous graphene with tuned hydrophilicity for decontamination of industrial wastewater from organic and inorganic contaminants.

This research work is based on the fabrication of a graphene oxide-based composite (GOBC) to remove the maximum number of contaminants from different industrial effluents. The GO was first intercalated with 1-octanesulphonic acid sodium salt and subjected to microwave irradiation to produce GOBC. Fixed-bed column tests and Jar-tests were performed for removal of the most harmful endocrine disrupting compounds (EDCs) such as bisphenol A, bisphenol S, endosulphan, beta-estradiol, dyes (methylene blue and violate) and toxic metal ions such as Pb2+, Li+, Ni2+, Co2+, Cr6+, Zn2+, Cd2+, Hg2+, Cu2+, and As5+via adsorption. The prepared material was thoroughly characterized for its unique functional and structural properties. The results obtained from Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, scanning electron microscopy, Raman spectroscopy, water contact angle and X-ray diffraction analysis confirmed the successful preparation of GOBC using the proposed intercalation/microwave method. The water contact angle results showed decreased hydrophilicity of GOBC as compared to GO as the contact angle of GOBC (77.75°) was higher than that of GO (53.98°). The effects of main column parameters such as bed height, initial analyte concentration and solution flow rate were investigated. The results revealed that shorter breakthrough time, and high adsorption capacity were obtained at high flow rates of 1 mL min-1, while longer breakthrough time and lower adsorption capacity were obtained at lower flow rates of 0.5 mL min-1. The effect of bed depth on the breakthrough curve of analyte adsorption was a steep breakthrough curve; or a shorter breakthrough time occurring at lower bed height. The adsorption data obeyed the Yoon-Nelson and Thomas models very well. The adsorption capacity for BPA, BPS, endosulphan, beta-estradiol, methylene blue and violate was found to be 307, 305, 260, 290, 230 and 195 mg g-1, respectively. The adsorption capacity of GOBC for toxic metal ions such as Pb2+, Li+, Ni2+, Co2+, Cr6+, Zn2+, Cd2+, Hg2+, Cu2+, and As5+ was found to be 156, 136, 126, 124, 118, 114, 82, 82, 72 and 72 mg g-1, respectively with excellent kinetics. The adsorption data obtained using Jar-tests revealed that GOBC obeys a Langmuir isotherm and a pseudo second order kinetics model. The analysis of industrial wastewater samples showed good removal efficiency of GOBC.

Intensification of coal slime separation in fluidized bed flotation column: change of turbulence

ABSTRACT Flotation cell and flotation column are widely used as the separation equipment for coal slime. In order to obtain better flotation results for different particle sizes, different turbulence intensity of flow field need to be created, but the turbulence intensity is not easy to adjust in conventional flotation equipment. In this paper, a new fluidized bed flotation column was designed to control turbulence intensity by the liquid velocity and static bed height. The effects of liquid velocities (0.198 m/s,0.226 m/s,0.254 m/s) and static bed heights (0.317 m,0.343 m,0.380 m) on coal slime flotation with different particle sizes were studied, which were evaluated by the combustible recovery, ash content, and the yield of clean coal. The research results showed that the flotation performance of coarse particles is better with low turbulence caused by low liquid velocity and great static bed height than that in high turbulence. Under the condition of high liquid velocity and low bed height, a high turbulence intensity environment is created, and the fine particle separation efficiency is better than that in low turbulence.

Optimum Drying Parameters of Fluidized Bed Dryer Operation for Rice and Corn

This study was carried out to develop a simulation model that can estimate the optimal drying parameters of a fluidized bed dryer such as drying time, moisture reduction rate and provide rough calculation of energy required and fuel consumption to dry a given volume of grains. Results shows that drying set up of 1400C drying temperature, bed height of 0.04m and an airflow rate of 2.3 m/s for paddy can provide lesser drying time and higher drying rate with a value of 164 minutes and 68.07 kg/hr, respectively. While for corn, a set-up of 1700C drying temperature, bed height of 0.1m and the fixed airflow rate of 2.7 m/s can deliver lesser drying time and higher drying rate with a value of 45 minutes and 369.9 kg/hr, respectively. The simulation results also showed that using a higher temperature, higher airflow and lower bed height gives a lesser drying time which also leads to higher drying rate. In terms of drying energy and fuel consumption, the results showed that the higher the drying temperature, the higher the energy and fuel consumption is required.

Fixed-Bed Adsorption of Lead from Aqueous Solution Using Chitosan-Coated Bentonite.

In this study, fixed-bed adsorption of Pb(II) from an aqueous solution using chitosan-coated bentonite (CCB) was investigated. Characterization of CCB was performed using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The effects of varying bed height (1.3 to 4.3 cm), flow rate (0.20 to 0.60 mL/min), and initial concentration (500 to 1500 mg/L) on the length of mass transfer zone (Zm) and adsorption capacity at breakthrough (qb) and exhaustion (qe) were examined. Low flow rate and high bed height were determined to cause a longer time to reach breakthrough and exhaustion. Meanwhile, the fixed-bed system was observed to quickly attain breakthrough and exhaustion under high initial concentrations. Kinetic column models such as the Thomas, Yoon–Nelson, and Clark models were used to predict the breakthrough curves. High R2 values (0.9758 ≤ R2 ≤ 0.8087) were attained for the Thomas model, which indicates that there is good agreement between experimental data and linear plots generated by the Thomas model. Moreover, the Thomas model is best in describing the breakthrough curves of Pb(II) removal under a fixed-bed system.

Healthcare worker choice and low back force between self-chosen and highest bed height when boosting a patient up in bed

Healthcare workers have a high rate of low back injury due to patient handling tasks. These workers receive training in patient handling methods such as adjusting bed height, but often ignore them. In this study, 35 healthcare workers completed patient boosts at a self-chosen bed height and again with the bed in a higher standardised position. Motion capture and force data were collected for analysis. Given the choice, less than half of participants adjusted the bed at all and none of them moved the bed to the highest position (99.1 cm). The self-chosen bed position yielded significantly higher low back force than the higher position at L4-L5 and L5-S1 (p = 0.02, p = 0.01 respectively). Low back forces can be reduced by raising the bed prior to engaging in patient handling tasks, which is a simple step that can reduce forces placed on healthcare workers’ low backs. Practitioner summary: Healthcare workers experience high rates of low back pain secondary to patient handling tasks. In this cross-sectional crossover study, healthcare workers consistently chose a low bed height when boosting a patient, which resulted in higher low back loads compared to the highest bed height.

Creating a Safer Patient Room Environment: The Contribution of Patient Bed Height

Elderly patient falls are expensive and may cause serious harm. Studies have identified the sit-to-stand-and-walk (STSW) task as the task where the greatest number of elderly patient falls occur. There is a great need to identify the particular movement and environmental conditions that lead to these elderly patient falls. This study begins to address this gap by evaluating the elderly patient during self-selected hospital bed egress. Using an observed fall risk episode (FRE) as a fall proxy, statistically significant parameters were identified which include bed height, pausing prior to initiating gait, level of fall risk, and Stand phase. Low bed height was identified as the least safe bed height. Patient-specific bed height (PSBH) using the patient’s lower leg length (LLL) is recommended. In addition, suggested guidelines are presented for clinical application in setting PSBH without measuring the patient’s LLL.

Investigation of Bubble Behavior in Gas‐Solid Fluidized Beds with Different Gas Distributors

AbstractThe behavior of gas bubbles in a gas‐solid fluidized bed was investigated by computational fluid dynamics simulation. A two‐phase flow model incorporating the kinetic theory of granular flow was used to study the effect of gas distributor design on the size distribution and the rise velocity of gas bubbles in the bed column. The experiments were conducted on four gas distributors with different orifice sizes and pitches. The geometry of the gas distributor had a significant influence on the bubble behavior in the gas‐solid fluidized bed. The effects of static bed height and superficial gas velocity were also considered. Bubble diameter and bubble rise velocity increased with gas velocity. However, at low bed height, the deviation in bubble size was indistinct because at higher gas velocity the rising tendency of the bubble formed just above the gas distributor increased and the probability of bubble coalescence decreased.

Color removal from model dye effluent using PVA-GA hydrogel beads

A low cost polyvinyl alcohol-glutaraldehyde cross-linked hydrogel beads were prepared and used for color removal from model industrial effluent containing Congo Red dye, using adsorption technique. The adsorption studies were performed using batch and fixed-bed reactor. Developed adsorbent, achieved adsorption capacity as high as ~34 mg of dye per gram of bead (condition: pH 6 and 45 °C). These beads were re-used for 7 times (many more runs possible) to remove the color from model dye effluent, without much loss in removal efficiency. Batch studies revealed a multi-layer adsorption governed by Harkins Jura model. Whereas the adsorption kinetics followed fractal like pseudo second order model, controlled by intraparticle diffusion phenomena. The fixed bed studies revealed steeper break through curves during adsorption operation when high dye influent rates and low bed height were used. This behaviour by the fixed bed reactor was best explained by the Thomas mathematical model. Studies further demonstrated that an external and internal mass diffusion become no more rate limiting during these experiments.

Multicomponent column optimization of ternary adsorption based removal of phenolic compounds using modified activated carbon

The removal of phenol (P), 4-chlorophenol (CP), 4-nitrophenol (NP), catechol (C), resorcinol (R) and hydroquinone (HQ) from P-CP-NP and C-R-HQ ternary systems, via multicomponent column adsorption on modified activated carbon (MAC), was evaluated in this study to determine the characteristic parameters of the column for ternary systems. A Taguchi L9 orthogonal array matrix was applied to investigate the effect of process parameters such as flow rate (Q), bed height (Z) and column diameter (D) on the breakthrough point of the process. The BET surface area of MAC was found to be 1245 m2/g. Higher flow rate, and lower bed height and diameter resulted in faster breakthrough. Statistical analysis of the data revealed that column diameter was the most significant factor (p < 0.05) for simultaneous adsorbate removal from ternary systems. Elution of phenol, 4-chlorophenol and 4-nitrophenol or elution of catechol, resorcinol and hydroquinone from their respective ternary mixtures showed that the thermal desorption may be a better option over that of solvent desorption. MAC worked well for at least seven adsorption-desorption cycles, with the continuous decrease in adsorption efficiency after each them desorption/regeneration. Owing to its heating value, spent-MAC can be used as co-fuel in the boiler-furnace.

Hospital bed height influences biomechanics during bed egress: A comparative controlled study of patients with Parkinson disease

Although a significant proportion of patient falls occur during egress from the hospital bed, the biomechanical adaptations during egress from different bed heights are still largely unknown. The purpose of this study was to evaluate the effect of hospital bed height on natural transition during egress in patients with Parkinson disease (PD). Twelve patients with PD and fourteen healthy elderly adults (HEA) were recruited and the natural transition during egress from three different bed heights (low, medium and high) were recorded for each participant using a motion capture system and force plates. The bed egress time, joint kinematics, ground reaction force and center of mass (CoM) were compared using a two-factor repeated ANOVA to determine the effects of three bed heights and two groups. The results showed that patients with PD had a significantly increased bed egress time, decreased peak of pelvis anterior tilt, hip flexion, and anteroposterior distance between pelvis center and CoM compared to HEA. Additionally, both PD and HEA groups increased the peak of trunk, hip and knee flexions to generate forward CoM momentum and joint torque to rise from a low bed height. These findings indicated that patients with PD invoked a more conservative movement pattern than HEA during egress to improve postural stability. The low bed height increased demands of balance and postural control during egress which exacerbates the risk of falls for patients with PD.

Experimental and computational studies on gas–solid fluidization in a cylindrical column with and without internals

Gas-solid fluidization often suffers from inherent drawbacks like channeling, bubbling and slugging which affect the quality of fluidization. Efforts have been made in this present investigation to improve the quality of fluidization in gas–solid fluidized beds by conducting hydrodynamic studies in cylindrical fluidized bed column with and without internals. The effect of hydrodynamic parameters such as inlet air velocity, bed height and internal spacing on pressure drop, expansion ratio, fluctuation ratio, minimum fluidization velocity and fluidization index were studied. The pressure drop was found to increase with an increase in bed height regardless of presence or absence of internals. But in the presence of Internals (More Number of internals or less spacing) pressure drop initially decreases but beyond a certain level the resistance offered by the internals is more, and it caused a slight increase in pressure drop. The expansion ratio and fluctuation ratio reduces significantly with a decrease in the spacing of internals. The effect of the internals on quality of fluidization has been studied. By the introduction of internals, the quality of fluidization in terms of fluidization index has improved. The experimental data was used in the CFD simulations and the results obtained are in good agreement with the experimental observations. It is found from the simulation results that the bed height increased with increase in air velocity. The solids are more evenly fluidized in the presence of internals with smaller bubble size and lower bed height than the beds without internals.

Hydraulic characterisation of the backwash process in sand filters used in micro irrigation

The objective was to evaluate effects of structural design, particle size and filter media height on pressure loss and surface velocity in the expanding filter layer during the backwashing process. The hydraulic behaviour of three commercial sand filter designs were compared. Experiments were conducted in an experimental closed circuit module. The treatments were based on the evaluation of three sand particle sizes combined with three filter bed heights for each filter design. The results showed that for the evaluated sand filters, with their different drainage structures in terms of area and arrangements, had different hydraulic behaviours during the backwashing. Coarser sand particles and greater filter layer heights produced larger slopes in the surface velocity curves as a function of percentage of filter bed expansion. No difference was observed in the minimum fluidisation velocity with changing the filter media heights, but an increase in the minimum fluidisation velocity was observed with increasing sand particle size. Filter beds composed of coarse sand particles and low filter bed heights produced lower increases in the pressure loss with increasing backwash surface velocity. Determining the minimum fluidisation velocity using the graphical analysis method to determine the pressure loss across the filter bed proved to be a reliable method for evaluating the equipment used.

Enrichment effect of coal and quartz particles in gas-solid fluidized bed with applied electrical field

Electrostatic effects are commonly found in gas-solid fluidized beds. With an electrical field applied in a gas-solid fluidized bed, the charged particles there would be separated according to the opposite charge polarity. A charge-to-mass ratio test showed that quartz can easily be given a negative charge when tribo-charging with coal. A binary particle mixture was employed to explore the enrichment effect in an electrical-field fluidized bed unit. The results showed that the mass fraction of quartz in the products decrease gradually from negative plate to positive plate. The increase of fluidization time, plate voltage and gas velocity, along with low bed height, were beneficial to the improvement of the enrichment effect. The mass fraction of quartz close to the positive plate was >40%, while that of negative was around 10%. This work demonstrates the possibility of separating fine coal using a fluidized bed with applied electrical field.

Fast, low-pressure chromatographic separation of proteins using hydroxyapatite nanoparticles

Columns packed with ultrafine particles (e.g. sub-2 µm porous particles) are suitable for high-resolution, high-speed analytical separation of proteins. However, they require very expensive chromatography systems to provide the ultra-high pressure required for carrying out separations using such columns. Also, frictional heating at high pressure could result in peak broadening and on-column protein degradation. In this paper, we discuss the use of nanoparticles, packed in a box-shaped or cuboid packed-bed device having 50 mm length, 5 mm width, and 3 mm bed-height for fast, high-resolution separation of proteins at low pressure. The low bed height allows the separation to be carried out at low pressure while the cuboid device reduces dispersion effects and thereby keeps the resolution high. Two different types of hydroxyapatite nanoparticles, i.e., needle-shaped (about 20 nm × 150 nm) and spherical (<200 nm) ones, were examined. The experimental results showed that while the needle-shaped nanoparticles were suitable for the separation of small proteins such as lysozyme, the spherical nanoparticles were better suited for separation of larger proteins such as bovine serum albumin and monoclonal antibody. The separation of the two proteins could be carried out in less than 2 min at a pressure lower than 0.8 MPa, using inexpensive chromatography devices a7nd systems, and without high pressure related problems such as frictional heating and on-column protein denaturation.

고체 수송관이 있는 2 단 기포 유동층에서 붕괴 속도에 대한 하단 층 높이의 영향

고체 수송관이 있는 2 단 기포 유동층에서 붕괴 속도에 대한 하단 층 높이의 영향

Techno-economic evaluation of biomass drying in moving beds: The effect of drying kinetics on drying costs

Drying woody biomass holds the potential to improve the energy efficiency of certain processes, such as in CHP plants. Drying can also be a necessary unit process in several energy conversion processes (e.g. in biomass gasification). Belt dryers are typically used for drying when low temperature air (100–110 °C) is used. This article aims to produce new knowledge about the influence of the main design parameters on the drying costs of a low temperature belt dryer when three different materials (forest residue, bark, as well as sawdust and soot sludge mixture) are dried using it. The influence is analyzed by changing the following parameters: bed height, air temperature, air velocity and initial/final moisture contents of the material. The study aims to evaluate which of these parameters has an actual effect on drying costs. Results indicate that the lowest costs are achieved with the highest air temperature if the heat price is the same for every air temperature level. However, an optimal bed height depends on the material. Increasing the air velocity does not necessarily decrease the costs. In the sensitivity analysis, to factor in the influence of the temperature on the heat price, the price was changed for every drying air temperature (1, 5, 10 and 15 €/MWh). This analysis showed that the lowest drying costs are achieved by the lowest air temperature in all cases, thus indicating that the price of the heat has a remarkable influence on the economics of drying. Furthermore, the results support the use of low temperature heat sources in drying if they are clearly less expensive than higher temperature heat sources. However, if the prices for lower and higher air temperatures are of the same magnitude, the higher air temperatures are preferable. In general, this paper shows that it is important to pay attention to the main design parameters to optimize total drying costs. For example, if an overly low bed height is used in woodchips or bark drying, the total drying costs might be dozens of per cent higher than in the most economic case.

Investigation of Arsenic Removal from Water by Iron-Mixed Mesoporous Pellet in a Continuous Fixed-Bed Column

Natural clay combing with iron oxide and iron particle was developed to be iron-mixed mesoporous pellet that was packed in a fixed-bed column for removing arsenic from water. The performance of the column in terms of breakthrough curve analysis was investigated with the variations of influent flow rate, adsorbent bed height, initial solution pH, and initial adsorbate concentration. The results indicated that increasing in the flow rate decreased the removal capacities of the adsorbent. A relatively low bed height provided a better and beneficial performance. Higher adsorption capacity was observed with an increase of initial adsorbate concentration. At higher initial solution pH, the repulsive process occurred between adsorbate species and the surface charge of the adsorbent, resulting in a poor performance of the column. The Thomas model fitted very well to the experimental data for all cases. Estimated from the model, the highest adsorption capacity for arsenite and arsenate was found to be about 509 and 430 μg/g, respectively. The Adam-Bohart model provided only a relatively satisfactory fit to the initial part of the experimental data. From a practical view, the new developed pellet could be used as the effective and efficient adsorbent to treat elevated arsenic contaminated groundwater.

An amino-functionalized ramie stalk-based adsorbent for highly effective Cu2+ removal from water: Adsorption performance and mechanism

Abstract This study reports a potential application of a local agricultural waste, ramie stalk, as a raw material to design a highly effective adsorbent by chemical modification with tetraethylenepentamine for Cu2+ removal from water. Surface morphology and chemical structure, elements components and physicochemical properties of the adsorbent were characterized by using SEM, EDX, FTIR, Zeta potential Meter and XPS. After modification, the amine groups were successfully grafted onto the surface of ramie stalk, which have multilayered and porous structures. A batch and fixed-bed column method were used to investigate the adsorption performance and mechanism of Cu2+. The optimum pH for Cu2+ adsorption was found to be 5. In the batch adsorption experiment, the data of the kinetic experiment were better fitted by the pseudo-second-order model (R2 = 0.9917), indicating that the adsorption of Cu2+ by modified Ramie stalk was mainly controlled by chemical adsorption. The adsorption equilibrium isotherm could be better described by Langmuir model (R2 = 0.9929) which suggested a monolayer sorption and the maximum adsorption capacity was 0.587 mmol g−1. In the dynamic adsorption experiment, the operation conditions, such as flow rate, initial concentration, and bed height were evaluated. The experiments results showed that with the higher initial concentration and the lower bed height, the adsorption capacity of the adsorbent increased and the fixed-bed column displayed good capacity for treating water under dynamic condition. The coordination bonding between Cu2+ and amine groups on the modified ramie stalk is the main adsorption mechanism. The new type adsorbent exhibited good reusability for 5 cycles without deterioration in its adsorption performances. Ramie stalk could be utilized effectively as an efficient adsorbent for treatment of the copper contaminated water environment.

Effect of bed characteristics on separation behavior of coal particles in a gas-solid fluidized bed

Air dense medium fluidized bed can achieve effective separation of −50 + 6 mm coal. However, the bed characteristics significantly affect the separation behavior of coal particles. The results indicated that the bed critical expansion degree decreased with increase in static bed height, and the axial distribution coefficient of low-density particles increased from 0.798 at Hs = 60 mm to 0.950 at Hs = 180 mm with raising concentration of emulsified-phase particles, which revealed low bed height is advantageous for particles floatation, while bed density is not the main action factor in this process. As for bubble dimension calculation model, the Kato and Wen formula is favored for smaller relative error for 0.3–0.25 mm bed particles. In addition, separation was difficult when the density difference between the bed and the tracer spheres was more than 0.3 g/cm3, and the λ value was almost constant with increase in fluidization number for each sphere whose density difference was less than 0.3 g/cm3. With increasing Δρ from 0.07 g/cm3 to 0.27 g/cm3, the λ values for d = 38, 25, and 15 mm increased from 0.44, 0.69, and 1.54 to 0.64, 1.00, and 2.01, respectively.