Experimental Determination of Pressure Loss Through Porous Membranes

Air with carbon dioxide is bubbled through Photobioreactors (PBRs) to add carbon dioxide to the reactor medium, remove oxygen, and mix the medium. Most PBR systems use various types of spargers/diffusers that consist of straight or curved tubes with perforation in them to inject air into the PBR reactor volume. A possible novel approach to introducing air into the PBR reactor volume is to use a plenum under the PBR reactor volume in conjunction with a porous membrane that separates the air in the plenum from the liquid medium in the reactor volume. The resistance offered by the porous membrane and the liquid in the reactor volume to air flow needs to be established so that power requirements to provide the desired air flow through the PBR can be determined. Four types of porous membranes were tested: 1)Sintered High Density Polyethylene HDPE 1.59 mm thick with 15–45 μm pore size, 2) Sintered HDPE 0.79 mm thick with 20μm pore size, 3) Genpore black plastic sheet with 45 μm pore size, and 4) Porex 7896 HDPE with pore size of 35 μm). Specimens were tested in a 76.2 mm inside diameter reactor with a depth of 304.8mm and a 76.2 mm plenum depth. Water was used as the reactor medium and the depth was varied between 0 and 228.6 mm. Results showed that the Porex 7896 membrane had little resistance to air flow when the water depth was 0.0mm (1–22 Pa), 1–200 Pa for the Genpore plastic sheet, 1200–1400Pa for the Porex with 20μm pores, and 1100–2500 Pa for the Porex with the 15–45 μm pore sizes for superficial air velocities between 0.00345 m/s to 0.0242 m/s. Water depth was then increased to 228.6 mm in 25.4 mm increments and tested with the same air flow rates. The addition of water significantly increased the resistance to air flow for all membranes (highest being 4200 Pa). Least square correlations for the membranes using water depth and superficial air velocity indicate that resistance to air flow of the membranes was linear with superficial velocity but parabolic with water depth.

Download Full-text

Operation of a Porous Membrane Photobioreactor

Volume 1: Biofuels, Hydrogen, Syngas, and Alternate Fuels; CHP and Hybrid Power and Energy Systems; Concentrating Solar Power; Energy Storage; Environmental, Economic, and Policy Considerations of Advanced Energy Systems; Geothermal, Ocean, and Emerging Energy Technologies; Photovoltaics; Posters; Solar Chemistry; Sustainable Building Energy Systems; Sustainable Infrastructure and Transportation; Thermodynamic Analysis of Energy Systems; Wind Energy Systems and Technologies ◽

10.1115/es2016-59625 ◽

2016 ◽

Author(s):

Gary A. Anderson ◽

Sarmila Katuwal ◽

Anil Kommareddy ◽

Stephen Gent

Keyword(s):

Carbon Dioxide ◽

Flow Pattern ◽

Growth Medium ◽

Light Guide ◽

Porous Membrane ◽

Lag Phase ◽

Growth Media ◽

Wall Area ◽

Reactor Volume ◽

Light Guides

A unique photobioreactor (PBR) constructed with acrylic sheet was used to grow S. Leopoliensis in 3.36 litters of Scully’s growth media. The PBR width was 51mm with a 273mm length and a growth media depth of 271mm. One of the PBR unique features was that it used a plenum and a porous membrane to inject air enriched with carbon dioxide into the growth medium. The HDPE (high-density polyethylene sintered beads) porous membrane served as the barrier between the reactor volume and the mixing plenum of the PBR. The air bubbled up through the porous membrane into the reactor volume with the growth medium mixing the contents of the reactor volume and transfer oxygen and carbon dioxide between the growth media and the bubbles. The second unique feature of the PBR is that it incorporated light guides in the design. The light guides were acrylic rods 9.5mm in diameter and a length projecting into the reactor volume of 38.1mm. The guides did not touch the opposite PBR wall. The light guides were abraded with sand paper on the outer to enhance light transfer from the guide to the growth medium. There were eight rows of light guides on each of the two PBR walls that were 273mm in length. Each row consisted of eight light guides space 34.1mm apart and 17.1mm from the side (short) walls of the PBR. Light was provided by two LED panels with 384 LED lights on each panel. The light from the panels had a wavelength of 650nm. The Light guides protruded through the PBR wall and light from the LED panels entered the light guide ends or transferred through the wall directly into the PBR reactor volume. The light guide ends occupied approximately 16% of the PBR wall area lit by the LED panels. The PBR produced 7.1g per litter of algal biomass in a 14 day growth cycle which encompassed a 3 day lag phase. The light guides disrupted the bubble flow pattern not allowing an obvious riser and/or downcomer to develop in the reactor volume. The disrupted flow pattern enhanced mixing and gas transfer. The enhanced mixing rotated the algal cells from more to less areas of the reactor volume more often aiding photosynthesis in a manner similar to flashing lights.

Download Full-text

Application of the ceramic membrane with hydrophobic skin layer to separation of activated sludge

Water Science & Technology ◽

10.2166/wst.1997.0306 ◽

1997 ◽

Vol 35 (8) ◽

pp. 137-144 ◽

Cited By ~ 1

Author(s):

Tsuyoshi Nomura ◽

Takao Fujii ◽

Motoyuki Suzuki

Keyword(s):

Activated Sludge ◽

Pore Size ◽

Ceramic Membrane ◽

Membrane Separation ◽

Porous Ceramic ◽

Porous Membrane ◽

Skin Layer ◽

Gas Permeation ◽

Wide Range ◽

Cake Layer

Porous membrane of poly(tetrafluoroethylene) (PTFE) was formed on the surface of porous ceramic tubes by means of heat treatment of the PTFE particles deposit layer prepared by filtering PTFE microparticles emulsified in aqueous phase. By means of inert gas permeation, pore size was determined and compared with scanning electron micrograph observation. Also rejection measurement of aqueous dextran solutions of wide range of molecular weights showed consistent results regarding the pore size. Since the membrane prepared by this method is stable and has unique features derived from PTFE, it is expected that the membrane has interesting applications in the field of water treatment. Membrane separation of activated sludge by this composite membrane and original ceramics membrane showed that the PTFE membrane gives better detachability of the cake layer formed on the membrane. This might be due to the hydrophobic nature of the PTFE skin layer.

Download Full-text

Effect of moisture condensation on vapour transmission through porous membranes

Journal of Industrial Textiles ◽

10.1177/15280837211014239 ◽

2021 ◽

pp. 152808372110142

Author(s):

Ariana Khakpour ◽

Michael Gibbons ◽

Sanjeev Chandra

Keyword(s):

Water Vapour ◽

Moisture Diffusion ◽

Porous Membrane ◽

Water Evaporation ◽

Porous Membranes ◽

Water Vapour Concentration ◽

Vapour Concentration ◽

Vapour Diffusion ◽

Pore Blockage ◽

The Impact

Porous membranes find natural application in various fields and industries. Water condensation on membranes can block pores, reduce vapour transmissibility, and diminish the porous membranes' performance. This research investigates the rate of water vapour transmission through microporous nylon and nanofibrous Gore-Tex membranes. Testing consisted of placing the membrane at the intersection of two chambers with varied initial humidity conditions. One compartment is initially set to a high ([Formula: see text]water vapour concentration and the other low ([Formula: see text], with changes in humidity recorded as a function of time. The impact of pore blockage was explored by pre-wetting the membranes with water or interposing glycerine onto the membrane pores before testing. Pore blockage was measured using image analysis for the nylon membrane. The mass flow rate of water vapour ( ṁv) diffusing through a porous membrane is proportional to both its area (A) and the difference in vapour concentration across its two faces ([Formula: see text], such that [Formula: see text] where K is defined as the moisture diffusion coefficient. Correlations are presented for the variation of K as a function of [Formula: see text]. Liquid contamination on the porous membrane has been shown to reduce the moisture diffusion rate through the membrane due to pore blockage and the subsequent reduced open area available for vapour diffusion. Water evaporation from the membrane's surface was observed to add to the mass of vapour diffusing through the membrane. A model was developed to predict the effect of membrane wetting on vapour diffusion and showed good agreement with experimental data.

Download Full-text

A novel approach to estimation of E. coli promoter gene sequences: Combining feature selection and least square support vector machine (FS_LSSVM)

Applied Mathematics and Computation ◽

10.1016/j.amc.2007.02.033 ◽

2007 ◽

Vol 190 (2) ◽

pp. 1574-1582 ◽

Cited By ~ 15

Author(s):

Kemal Polat ◽

Salih Güneş

Keyword(s):

Support Vector Machine ◽

Feature Selection ◽

Least Square ◽

Support Vector ◽

Gene Sequences ◽

E Coli ◽

Novel Approach ◽

Promoter Gene ◽

Coli Promoter

Download Full-text

Colorless and Transparent Polyimide Microporous Film with Excellent Physicochemical Property

Polymers ◽

10.3390/polym13081298 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1298

Author(s):

Jong Won Kim ◽

Seon Ju Lee ◽

Moon Young Choi ◽

Jin-Hae Chang

Keyword(s):

Pore Size ◽

Porous Membrane ◽

Amic Acid ◽

Water Soluble ◽

Poly Vinyl Alcohol ◽

Thermal Stabilities ◽

Blend Films ◽

Hydrogen Bonding Interactions ◽

Heat Treated ◽

Microporous Film

4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA) as a dianhydride and bis(3-aminophenyl) sulfone (APS) and bis(3-amino-4-hydroxyphenyl) sulfone (APS-OH) as diamines were used to synthesize two types of poly(amic acid) (PAA). Varying amounts (0–5.0 wt%) of water-soluble poly(vinyl alcohol) (PVA) were mixed with PAA, and the resulting blend was heat-treated at different stages to obtain the colorless and transparent polyimide (CPI) blend films. The synthesized blended film completely removed water-soluble PVA in water. The possibility as a porous membrane according to the pore size varied according to the amount of PVA was investigated. The dispersibility and compatibility of CPI containing APS-OH monomer were higher than those of the APS monomer. This could be attributed to the hydrogen-bonding interactions between the CPI main chains and PVA. Scanning electron microscopy was conducted to characterize the material. The results revealed that the pore size of the CPI blend film increased as the PVA concentration increased. It was confirmed that uniform pores of μm-size were observed in CPI. The thermal stabilities, morphologies, optical properties, and solubilities of two CPIs obtained using APS and APS-OH monomers were investigated and their properties were compared with each other.

Download Full-text

A novel approach to alginate aerogels: carbon dioxide induced gelation

RSC Advances ◽

10.1039/c4ra14653k ◽

2015 ◽

Vol 5 (11) ◽

pp. 7812-7818 ◽

Cited By ~ 54

Author(s):

P. Gurikov ◽

S. P. Raman ◽

D. Weinrich ◽

M. Fricke ◽

I. Smirnova

Keyword(s):

Carbon Dioxide ◽

Supercritical Drying ◽

Novel Approach

A novel process, carbon dioxide induced gelation, opens new pathways towards hydrogels and can be coupled with supercritical drying to produce aerogels.

Download Full-text

Adaptive Bacteria Colony Picking in Unstructured Environments Using Intensity Histogram and Unascertained LS-SVM Classifier

The Scientific World JOURNAL ◽

10.1155/2014/928395 ◽

2014 ◽

Vol 2014 ◽

pp. 1-10

Author(s):

Kun Zhang ◽

Minrui Fei ◽

Xin Li ◽

Huiyu Zhou

Keyword(s):

Support Vector Machine ◽

Mean Shift ◽

Least Square ◽

Support Vector ◽

Svm Classifier ◽

Least Square Estimation ◽

Unstructured Environments ◽

Novel Approach ◽

Traditional Approaches ◽

Improved Support Vector Machine

Features analysis is an important task which can significantly affect the performance of automatic bacteria colony picking. Unstructured environments also affect the automatic colony screening. This paper presents a novel approach for adaptive colony segmentation in unstructured environments by treating the detected peaks of intensity histograms as a morphological feature of images. In order to avoid disturbing peaks, an entropy based mean shift filter is introduced to smooth images as a preprocessing step. The relevance and importance of these features can be determined in an improved support vector machine classifier using unascertained least square estimation. Experimental results show that the proposed unascertained least square support vector machine (ULSSVM) has better recognition accuracy than the other state-of-the-art techniques, and its training process takes less time than most of the traditional approaches presented in this paper.

Download Full-text

The pathway toward pollution mitigation in EU28 region: does bioenergy growth make a difference?

Management of Environmental Quality An International Journal ◽

10.1108/meq-08-2020-0177 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Mohd Alsaleh ◽

A.S. Abdul-Rahim

Keyword(s):

Carbon Dioxide ◽

Carbon Dioxide Emissions ◽

Fossil Fuel ◽

Panel Data Analysis ◽

Random Effect ◽

Trade Openness ◽

The Body ◽

Least Square ◽

Content Type ◽

Improved Model

PurposeThis research explores the effect of bioenergy use on carbon dioxide releases in 28 European Union (EU-28) affiliated members starting from 1990 to 2018.Design/methodology/approachApplying panels' fixed effect (FE) estimator and random effect (RE) estimator, the regressed findings are highly validated as they were robust by panel least square dummy variable corrected (LSDVC) and pooled ordinary least square (Pooled OLS) estimators.FindingsThe findings claimed that carbon dioxide releases decrease with an incline in bioenergy use and trade openness. On the other hand, fossil-fuel and economic growth indicators mounting carbon dioxide releases. The result implies that carbon dioxide releases in EU-28 region members can be mitigated significantly by mounting the quantity bioenergy use in generation channel. This will mostly participate in combating environmental pollution.Practical implicationsThe study suggests for EU28 region members to enhance the portion of bioenergy in their fuel access to decrease emitted carbon dioxide. Governors in EU28 members should mainly encourage bioenergy expansion to raise its security and availability. The politicians of the EU28 members must assert on efficacy and productivity of bioenergy production to achieve energy accessibility and decrease dependency on conventional energy.Originality/valueThis research applies the recently improved model, the panel data analysis approach, which considered for the first-class impacts of estimators on the dependent variable and deals with the several problems of the common Pooled OLS estimator's manner and performance. Finally, this research contributes to the previous studies on ecological sustainability by examining the presence correlation among carbon dioxide emissions, bioenergy sustainability, trade openness, fossil fuel and gross domestic product in the EU28 region. Hence, it proves our research novelty, originality and contribution to the body of knowledge.

Download Full-text