FIELD: wastewater treatment plants.
SUBSTANCE: invention relates to a filter medium, to a method for its manufacture, and to the use of a filter media according to the present invention. Filter material comprises at least one layer of textile nonwoven material (layer 1) and at least one additional layer of textile nonwoven material (layer 2), which is applied to at least one side of layer 1. Layers are preferably layers of a spun-bonded nonwoven fabric containing synthetic polymeric fibres. Layers have a mass per unit area from 50 to 500 g/m2, preferably from 80 to 300 g/m2. Fibres of layer 1 have a diameter in the range of 0.7 to ≤6 dtex, preferably from 1 to ≤4 dtex. Layer 1 was preferably densified by calendering to an air permeability of 500-2000 l/m2⋅s. Fibres of layer 2 have a diameter in the range of 3.0 to ≤ 15 dtex, preferably 4 to ≤12. Air permeability of layer 2 is preferably at least 10% higher than the air permeability of layer 1. Layer 2 has a fibre diameter gradient that decreases in the direction of layer 1. Layers are joined to each other by mechanical piercing and the diameter of the holes formed on the outer side of layer 1 which faces away from layer 2, is reduced by the action of the heated surface, preferably a calender, by at least 50%, preferably at least 80%.
EFFECT: technical result is higher efficiency.
21 cl, 2 dwg
