Ceramic membranes are cylindrical filters used in industrial water treatment systems to cleanse contaminated water. In this setup, the ceramic membrane allows the separation of dirt and chemicals from the water in a single solution.
This article will delve into ceramic membranes, answering key questions about what they are, how they work and what they do.
How do ceramic membranes work?
Ceramic membranes work by passing a contaminated liquid through a membrane at pressure, yielding a purified liquid stream. The contaminants are too large to pass through the pores and are filtered out.
The types of contaminant treated depends on the pore size while the efficacy of the membrane depends on the surface area in the membrane. The liquid or gas is driven by a pressure gradient or an electrochemical gradient.
Ceramic membrane types
There are three types of ceramic membrane:
- Microfiltration: Blocks bacteria and suspended solids, most often for pre-treatment by reverse osmosis (RO) systems. Useful for fuel refinement, wastewater treatment and separating oil/chemical emulsions.
- Ultrafiltration: Blocks everything microfiltration blocks with the addition of viruses, requiring higher pressure (the same you get from a tap). Useful for clarification of all liquids and chemical process separation and diafiltration.
- Nanofiltration: Blocks 50-90% of monovalent ions and organic molecules and salts, making it ideal for treating hard water. Useful as a softening membrane to clarify a liquid stream with low total dissolved solids.
Ceramic membranes in water recycling
The biggest use of ceramic membranes is in water recycling, where ceramic membranes assist Membrane Bio Reactor (MBR) systems.
MBR systems treat water with a culture of microorganisms. The organic matter is eliminated by the microorganisms inside the reactor, while in the membrane, a separation between the solids (biomass) and the liquid fraction is carried out.
In addition to MBR systems, ceramic membranes are also used downstream of reverse osmosis systems. RO systems reject 99.9% of bacteria and remove salts, sugars, proteins, bacteria, ions and other particles.
The benefits of ceramic membranes
Ceramic membranes are highly effective at purifying water to a specified quality. For example, they can retain beneficial minerals and chemicals in a liquid stream while filtering out undesirables, creating a purified liquid stream.
The advantages of ceramic membranes include high efficiency, low energy consumption, chemical and thermal stability and microbiological resistance. Membranes are also regeneratable with chemicals and caustic soda.
The disadvantage of ceramic membranes is fouling. However, this disadvantage can be eliminated with a coating that is hydrophilic. Hydrophilic surfaces provide smooth flow and attract water, rejecting the deposition of molecules.
Ceramic membrane applications and uses
Ceramic membranes are found in contained systems like Membrane Bio Reactors and in separate treatments downstream of other systems.
Ceramic membranes are suitable for filtering chemicals and oils, chemical process separation, diafiltration and treating chemical emulsions. They are also used in catalyst recovery, alkaline recovery and wastewater treatment.
An example application includes separating a single gas from a gas mixture or a single chemical from a chemical/oil emulsion.
Because of their versatility and low maintenance requirements, ceramic membranes are used across various applications, including wastewater treatment, effluent treatment and in the chemical, pharmaceutical and petrochemical industries.