May 2020

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 D isposable 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, Focus on: Water & Waste Management Energy, the Environment & Water May 2020 www.pwemag.co.uk Plant & Works Engineering | 29 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. Is this the end of single use filters?