Water and Effluent Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/816363
20 WET NEWS MAY 2017 Can fine process water filtration meet growing demand to keep systems solids free? Unclogging the sandstorm impact INSIGHT Filtration & screening F or heavy industry across the Middle East the economic impact of the clouds of sand that sweep across the region is considerable. With sandstorms becoming more and more unseasonal and ferocious, the expectations being placed on process water filtration manufacturers to keep systems free of solids is becoming ever more demanding. As reported by the World Metrology Organisation*, the Middle East has seen a significant increase in the frequency and intensity of sand and dust storms in the past 15 years. It claims that the main source of sand and dust storms originates from Iraq where the flow of rivers has decreased because of a race in dam construction in upstream countries. This has led to the disappearance of marshes and drying up of lakes both in Iraq and Iran, and the sediments le‚ behind creating the dust and sand. A sandstorm consists of a massive amount of particulate in the air and has a significant effect on a person's health. When breathed in it can cause serous respiratory problems. Industry operating in these conditions suffer a not too dissimilar issue. Cooling systems used by a manufacturing process of any type use air and water to transfer generated heat. Air borne contaminants get drawn into the cooling system which effectively block up its 'arteries' resulting in, at the very least, inefficiencies in operation; or, at worst, complete failure of processes. Anomolies Andy Evans from process water filtration engineer Amiad Water Systems UK, says: "Contamination by smaller particulate and fine dust has seen a comprehensive review of filtration technology techniques for industries operating across the Middle East. "The problem has been that finer filtration brings with it a limited open surface area available on the filter media on which to retain solids. It is this "open area", ie holes or porosity, within the filter media that determine the dirt holding capacity and the frequency of cleaning required." The table (see Fig 1) demonstrates the effect of finer filtration on the open surface area of a typical filter screen and shows the impact on dirt holding capability. There are a few anomalies in the values as these will vary from manufacture to manufacturer and wire diameters change but this is a general guide. "To accommodate the problem, we have developed • Fig 1 Filtration degree Filtration open area Weave wire 500 micron 40% 130 micron 32% 50 micron 30% 25 micron 19% 10 micron 6%