Rotorflush Filters - The Front-line in the Battle Against Microplastics

The Front-line in the Battle Against Microplastics in water are the places where we screen and filter the water we use.  This means where we take water from the natural environment and, equally important, where we return water to the natural environment.

Microplastics are pervasive, everywhere, and found in almost all environments and the life they support. Even us.

What are Microplastics….

The common definition of Microplastics is that microplastics are tiny plastic particles that measure between five millimetres in size and 5 microns in size. Plastic pieces below 5 microns in size are classified as nano-plastics, but they are a whole other story for another article.

…and where do they come from?

Plastic particles within this size range are either made that size - for example the microbeads in washing powders and cosmetics, or plastic pellets used in manufacturing - or they are the result of the breakdown or deterioration of larger plastic items. The latter being by far the largest contributor to global microplastics.

And they are everywhere - how come?

Plastics manufacturing technology geared up in the late 1940's - global plastics production in 1950 was 2 million tons. Demand was there (and still is) for lightweight, strong, inert and corrosion resistant, flexible and versatile, inexpensive manufacturing materials.

There is now an extensive range of plastics, and global production is now pushing 300 million tons annually.

Add ‘disposable’ to plastic's enviable attributes, and it is easy to see how light, long-lasting durable bits of plastic can now be found anywhere on the planet.  As plastics accumulate, they can degrade in soil and concentrate in the food chain; the health and safety risks are at best uncertain.

Water is a very efficient medium for spreading microplastics; it is also one of the least tricky media from which to remove them.

Filtration Technology

Filtration technology has evolved - and continues to evolve - significantly since the beginning of the plastic era. Cynics might suggest that this is merely a corollary of our species' lack of concern for our environment. Nonetheless, there are many ways and means of removing particulate from water. Microplastics are endemic to our water courses and seas - whatever tech we have, we cannot feasibly clean up whole oceans. 

We can however remove plastic pollution from water we take from water sources, and ensure that water returned to the natural environment is plastic free.  The water that we use can be screened and filtered to remove microplastics for recycling or environmentally sound disposal.

A word about filtration. It can be costly and time-consuming particularly when using fine aperture mesh to screen out tiny pieces of plastic from large volumes of water. Screens can block, flow can be interrupted. Time and Money.

Frontline

Initial filtration by self-cleaning intake screens sited directly in a closed water source - a lagoon or tank or sump to collect the screened out plastic - is a good first step. This is the front line of microplastics filtration, the heavy lifting, getting the bulk of the larger pieces out before the finer filtration required to remove the tiniest particulate.

Filtering out microplastics from water is a staged process, remove the big bits, work down to removing the smallest bits. It makes sense to capture as much of the larger particulate as possible with an open system. Removing the smallest plastics requires closed systems and pipework, often under pressure.

Pre-Filtration

Pre-filtration of secondary and tertiary filter systems is crucial. Reducing the amount of larger microplastic entering closed filtration systems the better, as this prolongs the life of filter media and reduces the probability of clogging and blocking pipework and equipment. 

Those pesky small bits…

Removing the smallest microplastics requires a degree of filtration that borders on the microscopic. 5 microns means five thousandths of a millimetre.  Tiny. 

There are several methods for filtering out particulate this small, and this is an area of research continually developing new tech and methods. Currently, the most common methods of fine microplastic removal are:

• Ultrafiltration
• Activated Carbon Filters
• Reverse Osmosis

All of which require at least one stage of pre-filtration, often a combination of filters diminishing in aperture to get down to below 1 micron.

Ultrafiltration

Ultrafiltration (UF) typically needs pre-filtration to remove larger particles that can clog or damage the UF membrane. Without pre-filtration, suspended solids can form a layer on the membrane, which reduces water flow, increases pressure drop, and shortens the membrane's lifespan. Pre-filters, such as fine screen filters and sediment filters, protect the UF membrane and help maintain system efficiency. 

Pre-filtration is crucial for ultrafiltration: 

• Protects the membrane: UF membranes have very small pores (around 0.01 to 0.1 microns) designed to block bacteria, viruses, and colloids, but they are not meant to handle large debris. Large, hard particles can physically damage the delicate UF membrane fibres. Pre-filters act as a protective barrier against this type of physical damage. 
• Maintains efficiency: By removing a majority of suspended solids, pre-filters allow the UF system to run longer between cleaning cycles, maintaining a more consistent and higher flow rate. 

Activated Carbon Filters

Activated carbon filters need pre-filtration to protect them from dust and larger particles that can clog the porous carbon surface, reduce flow, and shorten the filter's lifespan

Pre-filters are a standard and highly recommended component in both air and water filtration systems using activated carbon. Pre-filtration:

• Protects the carbon: Activated carbon has a very porous surface structure. Pre-filters trap larger particles like organic material, lint, sand, etc., preventing them from getting lodged in the carbon's pores.
• Maintains flow: Clogged carbon filters restrict the flow of water, which reduces efficiency and may be a significant cost in maintenance and downtime.
• Extends filter life: By removing particulate matter, pre-filters prolong the life of the carbon filter, reducing the frequency and cost of replacement. 

Reverse Osmosis

Reverse Osmosis (RO) systems absolutely require pre-filtration. The fragile semi-permeable RO membrane is expensive and can be easily damaged or clogged by larger particles and chemicals present in the source water. A multi-stage pre-filtration process, which typically includes a screen filter, sediment and carbon filters, protects the membrane and ensures the entire system operates efficiently. 

Pre-filtration is critical for an RO system to protect against damage, increase the life of the RO membrane and ensure efficiency of operation.

Find out more about Rotorflush self-cleaning suction intake filtration products. 

Call us now on 01297 560 229  or Email sales@rotorflush.com and a member of our expert, friendly team will call you back and find the filterpump to suit your needs.

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