Clean water is a scarce resource, and ceramic membranes are vital in solving this massive global problem. With ceramic membranes, multiple objects such as suspended solids, oil droplets, oil emulsions, particles, and bacteria can be removed from liquids. Likewise, ceramic membranes can purify and clean fluids at different levels depending on the specific filtration requirements, making membranes extremely relevant for numerous tasks in various industries.
In water filtration, we operate within different filtration ranges, which are denoted microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO), where the latter is the finest.
Microfiltration (MF) and ultrafiltration (UF), also known as low-pressure membrane filtration, are processes in which contaminated waste streams pass through a semi-permeable membrane that removes suspended solids, including colloids and viruses, which are larger than the membrane's pore size to produce a purified liquid.
The particles' size retained by the membrane is defined by the membrane's pore size (0.1 microns to 0.01 microns for ultrafiltration and larger than 0.1 microns for microfiltration).
Nanofiltration involves the partial separation of salts and is thereby closely linked to reverse osmosis. It is the membranes' pore size that determines within what filtration range a membrane filters. Still, the membranes within nanofiltration and reverse osmosis are sensitive. Therefore, it is often recommended to have a microfiltration or ultrafiltration process before nanofiltration or reverse osmosis in order to handle the separation of larger objects first. This can both protect the pump as well as ensure longer operating time and improved OPEX.
See the below video to get an understanding of what a ceramic membrane is, how it works, and the massive difference between the different filtration ranges.
The Filtration Process
To filter industrial liquids, feedwater, which is the liquid to be filtered, enters the ceramic membranes. A feed-pump triggers the filtration process by generating a pressure, which will make the feedwater move through the membranes. The permeate will start to move through the membrane structure as filtered liquid. Firstly, the permeate will move through the silicon carbide membrane layer. Read more about what the membrane layer does here. Secondly, the permeate will move through the membrane substrate structure, which is easier as this layer is made of larger silicon carbide grains than the membrane coating layer. Read more about how a ceramic membrane is made here to understand a membrane’s structure. The permeate will end up in a permeate tank, where it is ready for further usage.
Meanwhile, the concentrate, which is concentrated feedwater, is sent to subsequent processing. As this is concentrated feedwater, it is much dirtier than the actual feedwater. Both the permeate and the concentrate are now ready for further processing, reuse, or recycling. The permeate can be reused as it is filtered, while the concentrate can be reused as it may contain essential unexploited resources, which can show to be valuable assets within other production processes.
A water filtration system can thereby be considered a tightly coupled system, where all parts play a significant role in water filtration. It is the feed-pump that initiates the filtration, but the filtration occurs within the ceramic membranes.
Liquid Filtration Is the Lever to a Sustainable Future
With liquid filtration, you can optimize your operation by utilizing all your resources to the fullest as you can separate permeate from concentrate. This can both lead to cost savings and process optimizations within other production areas. But more significantly, liquid filtration is the lever to a sustainable future with cleaner water, meaning that you can turn your operation into something which directly makes a sustainable impact and supports a green transition for an improved tomorrow.
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