The Defender® rotary screens are designed to remove solids transported by the water which must be treated so it can be avoided the obstruction and mechanical problems in the aftercoming equipment. These devices are self-cleaning, automatic propelled and they filter the wastewater through a filtration drum made of a grid or perforated mesh with different apertures of 3.0 to 0.15 mm depending on the type and amount of solids. Their installation in wastewater treatment plants of settlements can allow the replacement of primary sedimentation tanks, ensuring the elimination of coarse sands and up to 30% of the fats. The offered equipment is easy to operate due to the fact that the treatment stream enters through a flange located on the outside of the drum and is distributed evenly by an overflow over the drum filter. The solids are retained on the surface of the drum as it rotates and the inflow water passing the drum in both upper and bottom sides performs as cleaning function. When passing through the external scraper, the solids are separated from the net and fall off by gravity. The Defender rotary screens are divided into several models depending on the diameter of the filter drum and the flow rate:
