Is this the end of single use filters?

Published:  28 May, 2020

For years disposable cartridge filters have formed a key part of the water filtration market. Globally the consumable filtration market accounts for $1.6 Billion per year. PWE reports.

Disposable cartridge and bag filters are a simple and typically lightweight filter element, manufactured from a variety of materials and can cater to a wide range of filtration requirements. These consumable filters are placed inside a pressure vessel housing and the water flows through the filter material. Solid particles suspended in the water are trapped on the filter and will build up over time. The Differential Pressure (DP) across the filter will increase over time and once it reaches a maximum value the disposable filter will need to be replaced. Consumable filters generally work best in situations where there is not much solid material in the water as otherwise, they would block very quickly and need regular replacement.

Replacement will mean stopping the water flow, opening the filter vessel housing removing the blocked cartridge or bag and replacing with new. Once the vessel is bolted shut the water flow can be resumed and the old filter is thrown away. Once used these single use filters are thrown away and because they are classified as a waste they typically end up in landfill.

As the cost of disposal increases along with increased concern over single use plastics, what was once viewed as an essential part of the filtration market is now being questioned.

In the first instance we are not talking about needing to invent anything new here as the technologies are already available. Self-cleaning filter systems have been around for decades. The principle of a self-cleaning filter is that unlike the disposable filter when the filter element is blocked there is a system that removes the solid particles from the filter element and returns it to a clean condition. Once the self-cleaning process is complete the filter can then carry on filtering the water until it needs its next cleaning cycle.

The question must be asked, if the technology is available then why are disposable filters still used? The answer is broadly speaking broken into 3 parts.

1. Capital costs – a throw away item is likely to be cheaper in the short term

2. Good for small systems

3. An accepted technology for a given filtration degree

As we are talking about a consumable item the purchase cost may be lower but you will need to consider the total cost of ownership and factor in labour cost for changes, production downtime and waste disposal costs.

The long-standing Achilles heel of the self-cleaning filter has been its relative capital cost and complexity when compared to equivalent sized consumable filter system. It was this market challenge that the research and development team at water filtration specialist Amiad tackled. The company embraced users perceived problems and sought to develop a self-cleaning filter, which could compete at the same price point as the equivalent consumable filter system.

In 2016 the company launched the Sigma series filter and then followed this up in 2018 with the award winning Mini-Sigma filter. The Sigma is a series of automatic self-cleaning filters which are lightweight and constructed from a durable, corrosion resistant polymeric housing. Being compact and modular the system can be used in various installation configurations. The new range also includes the Sigma Pro automatic polymeric multi-screen filters, offering a large screen area whilst maintaining a small footprint, and the ADI-P electronic controller, which can be linked to a mobile app for advanced monitoring capabilities and control functionality.

By lowering the capex cost the argument has now been turned in favour of the automatic self-cleaning filter. With the purchase price no-longer ‘too high’ to consider as a viable alternative to the single use filter, users will undeniably see a return on their investment through reduced downtime and increase in productivity.

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Single use vs self-cleaning filter

A steel mill in Yorkshire, UK had an existing bag filter housing installed on one of their critical water supply lines. The filter bags had to be changed every 12 hours, resulting in high operational costs and a significant time impact for the site personnel.

The mill was looking for a solution that would reduce their operational costs, remove the need for site engineers to change the filter bags each shift, and improve their water quality to the spray nozzles.

A series of water samples were analysed for TSS, oils and Particle Size Distribution (PSD). These results were reviewed by Amiad Water Systems to understand which particles were causing the mill issues. Following this analysis it was recommended that the mill utilise a high solid handling filter with a 200micron wedge-wire screen [the automatic ABF 3000 brush cleaning filter].

Following the filter’s installation, the bag filter housing downstream was able to go one week between bag changes instead of only 12 hours.

After 9 months operation the steel mill then decided to upgrade their entire mill water feed system and installed a higher grade filter, again with a 200 micron screen. This filter now treats all incoming water supply to the mill and is capable of filtering up to 650 m3/hr. Water quality to the whole steel mill has been greatly improved.

It is clear that both consumers and companies are becoming more alert to the problems caused by single use plastics and throw away items and the long term effect these have on our planet. However, we all live in a reality where the ‘cost’ argument is still right at the top of the agenda. Therefore the single use filter market will continue to have its place as the solutions it can bring are heavily embedded and it will take time for the conventional approaches to adapt.

And yet, improvements in technology, which embrace a more sustainable approach should be favoured. Changes are starting to emerge with improved alternatives being developed which are disrupting the status quo and offering cost effective alternatives; and when considering the ‘cost’ we need to remember the hidden costs like the disposal and the fact that each of those single use filters are going to remain in our landfills beyond our great grandchildren’s lifetimes.

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