scholarly journals Fouling Mitigation in Tubular Membranes by 3D-printed Twisted Tape Turbulence Promoters

2019 ◽  
Author(s):  
Matthias Wessling
Keyword(s):  
Energy Consumption ◽  
Membrane Filtration ◽  
Specific Energy Consumption ◽  
Twisted Tape ◽  
Static Mixer ◽  
Permeate Flux ◽  
Severe Problem ◽  
Static Mixers ◽  
3D Printed ◽  
Tubular Membranes

Despite intensive research, fouling remains a severe problem in membrane filtration. It is often controlled by applying turbulent flow which requires a higher energy consumption. So-called turbulence promoters or static mixers can be inserted into the flow channel of tubular membranes. They deflect the fluid, induce vortices, enhance particle back-transport and increase the shear rate at the membrane surface, thus mitigating fouling. However, little is known how the geometry of such turbulence promotors affects the reduction of fouling. We investigate how different 3D-printed mixer geometries affect fouling and improve the flux during filtration with humic acid. Most mixer geometries used in the present study are based on a twisted tape; a Kenics static mixer is investigated as well. Static mixers with changing diameter prove to be less effective than twisted tape mixers with constant diameter which lead to an increase in permeate flux of around 130%. The highest flux improvement of 140% can be reached by applying a Kenics mixer. Regardless of their geometry, all investigated static mixer cause higher permeate fluxes at same specific energy consumption. Again, the Kenics mixer proves to be the most efficient static mixer. The presented mixer geometries can be fabricated with undercut injection molding techniques and represent a simple and viable option to make tubular membrane based filtration processes more efficient.

scholarly journals Testing of 3D Printed Turbulence Promoters for Membrane Filtration

2020 ◽  
Vol 64 (3) ◽  
pp. 371-376
Author(s):  
Igor Gáspár ◽  
Réka Neczpál
Keyword(s):  
Pressure Drop ◽  
3D Printing ◽  
Membrane Filtration ◽  
Permeate Flux ◽  
Water Emulsion ◽  
Static Mixers ◽  
Oil In Water ◽  
Negative Effect ◽  
3D Printed ◽  
Oil In Water Emulsion

Membrane filtration process can be intensified by using static mixers inside tubular membranes. Most of commercial static mixers are optimized for mixing fluids, not for membrane filtration. We have developed new turbulence promoter geometries designed for intensification of permeate flux and retention without significant pressure drop along the membrane. In previous experiments, we used metallic turbulence promoters, but in this work, FDM 3D printing technology was used to create these improved geometries, which are new in membrane filtration and they have the same geometry as existing metallic versions. New 3D printed objects were tested with filtration of stable oil-in-water emulsion. Our experiments proved that 3D printed static mixers might be as effective as metallic versions. The effect on initial flux and retention of oil was very similar. Pressure drop along membrane was slightly higher (but significantly lower from pressure drop along the membrane resulted by commercial static mixers, designed only for mixing fluids). Higher pressure drop may be the result of rougher surface due the layer-technology of 3D printing. This negative effect can be reduced by using a smaller nozzle (which will produce smaller layers) or smoothing the surface. PLA is material easier for printing, but from these two materials, PETG is a better choice due its higher operating temperature and better water-resist properties too.

scholarly journals Data-driven Modelling of Microfiltration Process with Embedded Static Mixer for Steepwater from Corn Starch Industry

2017 ◽  
Author(s):  
Laslo Šereš ◽  
Ljubica Dokić ◽  
Bojana Ikonić ◽  
Dragana Šoronja-Simović ◽  
Miljana Djordjević ◽  
...  
Keyword(s):  
Corn Starch ◽  
Desirability Function ◽  
Specific Energy Consumption ◽  
Cross Flow ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Static Mixer ◽  
Permeate Flux ◽  
Experimental Conditions ◽  
Starch Industry

Cross-flow microfiltration using ceramic tubular membrane was applied for treatment of steepwater from corn starch industry. Experiments are conducted according to the faced centered central composite design at three different transmembrane pressures (1, 2 and 3 bar) and cross-flow velocities (100, 150 and 200 L/h) with and without the usage of Kenics static mixer. For examination of the influence of the selected operating conditions at which usage of the static mixer is justified, a response surface methodology and desirability function approach were used. Obtained results showed improvement in the average permeate flux by using Kenics static mixer for 211 % to 269 % depending on experimental conditions when compared to the system without the static mixer. As a result of optimization, the best results considering flux improvement as well as reduction of specific energy consumption were obtained at low transmembrane pressure and lower feed cross-flow rates.

Comparison of ceramic capillary membrane and ceramic tubular membrane with inserted static mixer

2011 ◽  
Vol 65 (5) ◽  
Author(s):  
Igor Gaspar ◽  
Andras Koris ◽  
Zsolt Bertalan ◽  
Gyula Vatai
Keyword(s):  
Specific Energy Consumption ◽  
Cross Flow ◽  
Ceramic Membranes ◽  
High Price ◽  
Transmembrane Pressure ◽  
Permeate Flux ◽  
Water Emulsion ◽  
Oil In Water ◽  
Capillary Membranes ◽  
Tubular Membranes

AbstractOily wastewaters are produced in large amounts in many fields of food, mechanical, and other types of industry. In order to protect the environment, wastewaters must not be discharged directly into sewers. First, they must be cleaned at least down to 50 mg L−1 of oil content (according to Hungarian standard). In previous research, the authors found that oil-in-water emulsions can be separated with filtration using ceramic ultrafiltration tubular membranes. The relatively high price of ceramic membranes can be compensated by the fact that this separation process can be significantly intensified by static mixers inside the tubular membranes. New generations of ceramic membranes are the ceramic capillary membranes. These two different types of membranes and their effects on permeate flux, oil retention and specific energy consumption were compared in this work. The results, obtained with a stable oil-in-water emulsion as feed, showed that the use of novel ceramic capillary membranes at optimal operating cross-flow rate and transmembrane pressure is reasonable. The results have also shown the advantage of static mixing in the lumen side of the membrane tube providing a wider range of satisfactory separation level and increased permeate flux.

scholarly journals Short and Spaced Twisted Tapes to Mitigate Fouling in Tubular Membranes

2019 ◽  
Author(s):  
Matthias Wessling
Keyword(s):  
Shear Rate ◽  
Pressure Drop ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Full Length ◽  
Twisted Tape ◽  
Static Mixers ◽  
Fouling Mitigation ◽  
Twisted Tapes ◽  
3D Printed

Static mixers are an efficient means to mitigate membrane fouling as they deflect the fluid, thus increasing the shear rate at the membrane surface and enhancing back-transport of rejected matter. However, inserting static mixers in the flow channel of a membrane imposes an additional pressure drop. To decrease this detrimental effect of static mixers, we shorten twisted tape mixers and investigate how this shortening translates into a reduction of fouling mitigation. We follow two approaches known from heat transfer enhancement: i) shorten the total length of the twisted tape and ii) use regularly spaced short twisted tape elements which are kept at their position by smooth rods placed in between the twisted elements. Computational fluid dynamics (CFD) is applied to analyze the flow pattern, the shear rate at the membrane and the resulting pressure drop. The results allow for the selection of modified twisted tape mixers with lower pressure loss, but sufficient flow properties for fouling mitigation. The most promising mixer designs were selected according to the CFD study, 3D-printed, and their fouling mitigation effect experimentally investigated using silica suspensions. Additionally, the effect of foulant concentration in this system is analyzed. For low silica concentrations (0.03 g/L) the short and spaced twisted tapes mitigate fouling as efficiently as the full-length twisted tape. At high silica concentrations and fluxes, the full-length mixer mitigates fouling more strongly than the short and spaced twisted tapes. However, the modified twisted tapes prove to be more energy-efficient up to a certain fouling exposure.

Stable operation of MBR under high permeate flux

2012 ◽  
Vol 7 (4) ◽  
Author(s):  
H. Y. Liu ◽  
B. Freeman ◽  
S. Sunano ◽  
N. Munehiro ◽  
C. Bartels ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Specific Energy ◽  
Municipal Wastewater ◽  
Critical Role ◽  
Specific Energy Consumption ◽  
Pilot Scale ◽  
Stable Operation ◽  
Municipal Wastewater Treatment ◽  
Permeate Flux ◽  
Operating Condition

Permeate flux plays a critical role on the stable operation of membrane bioreactor (MBR) system for municipal wastewater treatment. The current commercially available submerged MBR systems, Zenon, Kobota, and Huber, etc. maintained their permeate fluxes at about 20–30 LMH to minimize the fouling potential of the membranes. A pilot scale MBR plant using HYDRASub®/Sterapore SADF® PVDF membrane module was stably operated at flux as high as 35 LMH for about 1 year by optimizing the operating condition of MBR system. The applied high permeate flux also resulted in low specific energy consumption per unit product water. This paper introduced the performance of membrane operated at high flux and discussed the factors affecting the stable operation of MBR. By applying the operating condition to an actual MBR plant, the specific energy consumption could reach a very low level, about 0.46 kWh/m3.

Determination of grinding parameters of fenugreek seed

1970 ◽  
Vol 26 (1) ◽  
pp. 16 ◽  
Author(s):  
S Balasubramanian ◽  
Rajkumar Rajkumar ◽  
K K Singh
Keyword(s):  
Particle Size ◽  
Energy Consumption ◽  
Moisture Content ◽  
Specific Energy ◽  
Feed Rate ◽  
Average Particle Size ◽  
Specific Energy Consumption ◽  
Average Particle ◽  
Fenugreek Seeds ◽  
Fenugreek Seed

Experiment to identify ambient grinding conditions and energy consumed was conducted for fenugreek. Fenugreek seeds at three moisture content (5.1%, 11.5% and 17.3%, d.b.) were ground using a micro pulverizer hammer mill with different grinding screen openings (0.5, 1.0 and 1.5 mm) and feed rate (8, 16 and 24 kg h-1) at 3000 rpm. Physical properties of fenugreek seeds were also determined. Specific energy consumptions were found to decrease from 204.67 to 23.09 kJ kg-1 for increasing levels of feed rate and grinder screen openings. On the other hand specific energy consumption increased with increasing moisture content. The highest specific energy consumption was recorded for 17.3% moisture content and 8 kg h-1 feed rate with 0.5 mm screen opening. Average particle size decreased from 1.06 to 0.39 mm with increase of moisture content and grinder screen opening. It has been observed that the average particle size was minimum at 0.5 mm screen opening and 8 kg h-1 feed rate at lower moisture content. Bond’s work index and Kick’s constant were found to increase from 8.97 to 950.92 kWh kg-1 and 0.932 to 78.851 kWh kg-1 with the increase of moisture content, feed rate and grinder screen opening, respectively. Size reduction ratio and grinding effectiveness of fenugreek seed were found to decrease from 4.11 to 1.61 and 0.0118 to 0.0018 with the increase of moisture content, feed rate and grinder screen opening, respectively. The loose and compact bulk densities varied from 219.2 to 719.4 kg m-3 and 137.3 to 736.2 kg m-3, respectively.  

Sign in / Sign up

Export Citation Format

Share Document