Filtration membrane comparison

What is filtration? 

Filtration is the process of passing water through a medium to remove suspended particles.

Impurities and floc are caught in the filter’s medium when the water flows through it, leaving only clean water behind.

The process of removing solids usually ends with filtration after moving through flocculation, sedimentation and coagulation.

Up to 99.5% of the suspended particles in the water, including minerals, floc and microbes, can be eliminated in the filter

Although turbidity on its own is not dangerous, murky water is challenging to disinfect for several reasons, which is why we remove it.

Microorganisms on suspended particles may be difficult to disinfect, while the particles themselves chlorophyll may chemically react, making it difficult to maintain the distribution system’s chlorine residual at a certain level.

Additionally, turbidity may result in deposits in the distribution system.

That causes bacterial growth, flavors and smells.

Sometimes influent water may be treated with polymer aids.

These substances raise the effluent water’s quality by assisting the floc to becoming trapped in the filter.

Polymers play a vital role

Polymer aids are classified into two categories.

Before flocculation, cationic polymers (DADMA) are introduced to strengthen the floc while employing comparatively large nonionic molecules right before filtration and polymers (polyacrylamides) are introduced to aid in floc removal.

In some ways, polymer aids can be problematic.

Additionally, prolonged use of polymer aids may cause the filters to clog.

As a result, polymer aids are frequently utilized, much like coagulant aids, in dire circumstances to temporarily enhance water quality.

Systems for filtration

Squeezing, putting the water through a pore-filled filter smaller than the unwanted particles.

This is the most logical method. Filtration methods include sand filters, membrane filters and disc filters.

Adsorption, frequently the most significant process of adsorption is filtration.

The collecting of gas, liquid and solid dissolved solids on another material’s surface.

Membrane separation

A membrane is either partially permeable or only partially permeable.

A physical obstruction that some molecules or ions can pass through while blocking others’ progress.

During membrane separation, a fluid component known as the membrane allows permeate (or filtrate) to pass across it, but the membrane rejects additional components and retained them in the stream of the retentate (or concentrate).

Various materials are used to make membranes, including organic and inorganic compounds like ceramics, polymers and metals.

Filters with polymeric membranes

To construct a polymeric membrane with high permeability, selectivity, mechanical strength and chemical stability, a thin polymer film is typically coated over a porous backing or support.

Polyamide, Cellulose acetate, Polysulfone, Polyether sulfone, Polyvinylidene fluoride, Polyimide, Polyetherimide, Polyethylene, and Polypropylene are the polymers most frequently utilized to make commercial membranes.

A brief overview of ceramic membrane filtration

The ceramic membranes are frequently shaped into a multi-channel, asymmetric element.

The components of these membrane modules are arranged in housings and can survive high temperatures, extreme acidity or alkalinity and high working pressures, making them appropriate for a variety of applications where polymeric and other inorganic membranes cannot be employed.

There are a variety of membrane pore sizes available to meet different filtration needs, spanning the micro, ultra and Nanofiltration ranges (from 5 mm to 1000 Daltons). * An 18-dalton molecule of water is one membrane pore size

Materials of Ceramic Membrane

The most used membrane materials are Al, Si and Zr (Zirconium) oxides or Ti.

In a few fewer instances, Stannum (Sn) or hafnium (Hf) are used as foundation elements.

In solution, the surface charges of each oxide vary.

Other membranes may include a mixture of two different oxides.

Earlier components, or their establishment by some additional substances with a low concentration.

Ceramic Membrane’s way of operation

Cross-flow filtration is the mode in which ceramic membranes are operated.

The advantage of using this option is that it keeps the rate of filtering for comparing membrane filters to direct flow filtration, standard filters.

In a continuous process known as cross-flow filtration.

The stream is parallel to the membrane filtering surface or tangential to it and produces two streams that are sent forth.

Permeate or filtrate, a small portion of the feed that separates as flowing through the membrane is a purified liquid.

Retentate or concentrate, the remainder of the feed, that contains debris that the membrane has rejected.

Ceramic membrane applications

Water filtration

1- Surface water filtration.

2- Groundwater filtration.

3- Sea water pretreatment.

4- Sewage filtration.

5- Industrial wastewater filtration.

Ceramic membranes are utilized more frequently in the water industry.

Filtering of wastewater and purification, particularly in industrial applications the membrane modules have a resistance to high humidity, pH extremes (0 to 14) and high worry, operating pressures up to 10 bar (145 psi).

This qualifies these membranes for a variety of applications, including dairy, food, beverages, pharmaceuticals and biotechnology.

In addition to metal, microelectronics, chemical and petrochemical polymers and other materials are used in finishing and power generating.

The use of inorganic membranes is prohibited. the use of a ceramic membrane fermentation broth is processed through ceramic membranes.

Successful clarification at many worldwide installations competes against different technologies like polymeric vacuum filtration, centrifugation and membranes.

There is a requirement to address various chemical process applications including recovering and reusing materials in addition to waste stream chemicals.

For this, ceramic membranes can be used.

Filtration of chemical liquids, dyes and pigments is the intended use and highly concentrated wastewater from dye production and coloring water with varying levels of detergents, polymers and organic cleaners.

Ceramic Membrane Future

conventionally designed ceramic membranes, in which Several components in housings made of stainless steel are employed people command significantly higher prices when compared to traditional membrane-based modules Polymers.

Nevertheless, cutting-edge product lines like monolithic ceramic membrane modules with a greater membrane surface per module might provide a cost reduction.

Filtration by Polymeric Membrane Filters vs. Ceramic Membrane Filters

Ceramic Membrane Filters are widely used in fewer preparatory steps and are necessary to eliminate a lot of oil, fats and grease (FOG) contents due to their strong capacity to eliminate substantial amounts of fats without having a severe impact on their performance.

Wastewater is more successfully cleaned using ceramic membrane filters at high temperatures than polymeric 75 °C membrane filters. Without the addition of emulsion-breaking agents, the Ceramic Membrane Filters can break stable fatty acid methyl ester (FAME) with surfactant emulsion.

There are more alternatives for the Ceramic Membrane Filters.

Filters using polymeric membranes that measure their burst pressure has fewer bars than seven.

When chemicals are not adequate or a membrane needs to be sterilized in addition to being cleaned, steam (CIP) is utilized with ceramic membrane filters but cannot be used with polymeric membrane filters.

In a last-ditch effort to regenerate the ceramic membrane, it would be heated to 400 degrees in an environment of air to entirely burn off the accumulated organic pollutants.

Ceramic has a highly porous and hydrophilic surface.

Membranes enable high-filtration operation fluxes.

The membrane is used to ensure a certain plant capacity.

The surface area will be less than that of polymer membranes.

Using ceramic membranes has the added benefit of a high degree of mechanical stability

CAPEX and OPEX

Ceramic membrane filters are roughly five times more expensive than polymeric membrane filters in terms of CAPEX, but they also have operational lives that are more than five times longer.

By switching to ceramic membrane filters, operational and maintenance expenses can be cut by up to 50%.

Ceramic membrane disadvantages

1- The expensive cost of ceramic membranes is its principal drawback.

2- High weight which requires special care while installation.

3-The brittleness of ceramic membranes is regarded as a disadvantage; Different thermal expansion of the membrane material and the housing require special sealing techniques.

4- Direct treatment of surface water with ceramic membranes without the usage of flocculants showed the influence of steric and charge mechanisms on the removal of particles in the size range of viruses.

Size exclusion was found to be a major, but not the only, mechanism which influences the efficiency of phage removal by filtration with ceramic membranes.

Conclusion

1-Ceramic membranes are used in all applications of water and Wastewater filtering and seawater desalination.

2-Ceramic membranes are considered resistant to mechanical, Chemical and thermal stress.

3- Ceramic membranes are more efficient in operation because it has More options to backwash.

4- Ceramic membranes are used mainly for industrial applications.

5- The use of ceramic membranes in drinking water supplies is limited due to the relatively high investment costs however the high capital cost is generally compensated for by a long service life.

6-We can begin to use Ceramic membranes on small scales for Wastewater applications.

References

[1] lenntech.com, Rishi Sondhi, Ramesh Bhave, and Gary Jung, ‘Applications and benefits of ceramic membranes’, Membrane Technology November 2003

[2] siemens.com, Panglisch, S. Advances in Ceramic Membrane Filtration. Proc. Of AWWA Membrane Technology The conference, Memphis, TN (03/17/2009).

[3] http://water.me.vccs.edu

[4] http://www.tzw.de/

[5] http://www.aiche.org/cep/

[6] usbr.gov/research/AWT/ Katie Benko, Bureau of Reclamation  Jörg Drewes, Colorado School of Mines

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