Mechanical filtration is the most common method for wastewater treatment. Based on the different filter media, mechanical filtration equipment is divided into two categories: granular media filtration and fiber filtration. Granular media filtration mainly uses granular filter media such as sand and gravel as the filter medium. Filtration is achieved through the adsorption of granular filter media and the retention of suspended solids in the water by the pores between sand particles. Its advantages are easy backwashing, but its disadvantages include slow filtration speed (generally not exceeding 7 m/h), low dirt-holding capacity (its core filter layer is only the surface of the filter layer), and low filtration accuracy (only 20-40 μm), making it unsuitable for rapid filtration of wastewater with high turbidity.
The high-efficiency asymmetric fiber filter system uses asymmetric fiber bundle material as filter media. The filter media is asymmetric fiber, with an added core on the basis of fiber bundle filter media, which combines the advantages of fiber filter media and granular filter media. Due to the special structure of the filter media, the porosity of the filter bed quickly forms a gradient density with larger porosity at the top and smaller porosity at the bottom, making the filter fast, with a large interception capacity, and easy backwashing. Through special design, the processes of chemical addition, mixing, flocculation, and filtration are carried out in one reactor, enabling the equipment to effectively remove suspended organic matter in aquaculture water and reduce COD, ammonia nitrogen, nitrite, etc., and is particularly suitable for filtering solid suspended matter in circulating water of temporary holding ponds.