ARKAL Disc Filtration for Wastewater & Industrial Applications Plastic Discs Create Superior Filtration Disc filtration is an innovative approach to solids removal from liquids. The unique structure allows for high efficient filtration, low backwash volume, reusable element. Typical applications are: Wastewater, cooling towers, mining industries, ion exchangers, food processing liquids & sea water. The Arkal discs are flat, grooved plastic rings with a hole in the center. Rings are stacked together to form a cylindrical filter element. As effluent is pressurized into the filter, it compresses the rings tightly together. The grooves in the rings criss-cross, forming a network that traps both organic and inorganic contaminants from the effluent source. Filtered liquid exits from the inside of the cylinder providing reliable operation. Disc filters come in a full range of sizes, degrees of filtration and flow capacities.

The Filtration Process The excellent filtration obtained through compressed grooved plastic discs is the outcome of a combination of surface filtration and in-depth filtration, resulting in high-precision filtration and high efficiency. The solids retained on the filter element accumulate at the intersections between the grooved faces of each pair of adjacent discs (see drawing below). The number of intersections on each groove varies between 12 and 32, depending on filtration grade. The turbulence in the varying paths and the large number of intersections create a situation in which the particles are eventually trapped, even if some of them were able to escape the first intersection. Backflushing, fully automatic models Pressure drop build up and/or time cycle initiate a pulse that is transmitted by a controller to the backflushing valve, causing backflow of filtered liquid (or inflow of clean liquid from outside source, with or without pneumatic air). The direction of backflushing is opposite to that of regular filtration flow. After a short delay, a drain valve is opened to create a high pressure differential in the backflushing direction. The withdrawal of the tightening cylinder relieves the pressure from the discs and they are loose and free to spin. Spinning is caused by the inflating sleeve which feeds the spray nozzles through which tangential jets are emitted. The jets cause the discs to spin at high speed. Backflush flow-rate is limited by the nozzle structure, resulting in low water consumption. The retained solid particles are washed outward, contaminated liquid flows out to a waste or recycling basin. At the end of the backwash cycle, the filtration element is compressed again, allowing another filtration cycle to begin. Easy Cleaning - Manual or Automatic Disc filters can easily be cleaned manually by simply removing the cover and spraying the filter element with clean water. Backflush models (semi-automatic or fully automatic) reverse the flow, forcing clean water from the inside of the disc filter element outward through the grooves, cleaning the filter completely. Extreme conditions and/or very fine filtration of effluent requires backwashing with a combination of water and pneumatic pressurized air. Definition of Water Quality Good Quality Well water - properly maintained well, no presence of iron or magnesium. Average Quality Rivers & Canals - slow flowing, good sedimentation, low biological load. Reservoirs - excellent sedimentation, cold climate. Sewage water - effective sedimentation, complete biological treatment. Bad Quality Rivers & Canals - high biological load. Reservoirs - hot climate, insufficient sedimentation. Sewage water - incomplete biological treatment. | A.R.I. | Arkal | Dorot | Bioline | Control Systems | | Home | About WWS | Using Drip Irrigation Technology | | The WWS Process | Norwood Project | Copyright © 1999 Waste Water Systems, Inc. All rights reserved.