TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preferred Method: In biologically filtering fiber bundle, the filtering material component mainly comprises a fiber bundle filter core, an upper filtering plate, a lower filtering plate, an upper connecting piece and a lower connecting piece; the upper end of fiber bundle filter core is connected with the upper filtering plate via the upper connecting piece, the lower end of fiber bundle filter core is connected with the lower filtering plate via the lower connecting piece, the upper and lower connecting pieces are inflexible cables, metal rings, or flexible cable, rubber strips and springs. The method for biologically filtering fiber bundle is biologic filtering of aeration, there is an aeration device arranged below the filtering material component, the aerobic microbial films are cultured and grown on the surfaces of fiber filaments, the air or the oxygen are charged into the filtering layers by the aeration device when filtering, the water flows through the filtering layers loaded with the microbial films, so as to perform an oxidative degradation to the organic matter in water, and to filter and remove a part of suspensions in water. The method for biologically filtering fiber bundle is anaerobic biological filtering, the anaerobic microbial films are cultured and grown on the surfaces of fiber filaments, the water flows through the filtering layers loaded with the microbial films, so as to degrade the organic matter in water into the organic matters with relative small molecular weight such as methanol, and to filter and remove a part of suspensions in water. The method for biologically filtering fiber bundle is denitrifying biological filtering, the denitrifying microbial films are cultured and grown on the surfaces of fiber filaments, the water flows through the filtering layers loaded with the microbial films, so as to reduce the nitro nitrogen in water to nitrogen gas, and to filter and remove the suspension in water. According to the water flowing direction in the filtering layer when filtering, there are a downwards flowing mode (namely the water flows through the filtering layer from top to bottom), an upwards flowing mode (namely the water flows through the filtering layer from bottom to top), and a lateral flowing mode (namely the water flows through the filtering layer laterally). When the filtering layer is washed, the washing air flows through the filtering layer from bottom to top, the washing water uses the washing water downwards flowing evacuation washing mode, or the washing water downwards flowing charge washing mode, or the washing water downwards flowing and upwards flowing alternative washing mode. The filtering layers are compressed or not when filtering. Preferred Device: In the device, the device for biologically filtering fiber bundle is fiber bundle aeration biological filtering device, comprising a pressure-type fiber bundle aeration biological filter and a gravity-type fiber bundle aeration biological filter, where the device mainly comprises a shell, a filtering material component, a water distribution device, a water collecting device, a washing gas distribution device, a filtering water inlet pipe or channel, a filtering water outlet pipe or channel, a washing gas inlet pipe, and a downwards flowing washing water discharge pipe or channel; the filtering material component is mounted in the shell, the washing gas distribution device is arranged below the filtering material component, the water distribution device is arranged above or below the filtering material component, the water collecting device is arranged below or above the filtering material component, the filtering water inlet pipe or channel is connected with the upper part or lower part of shell, the filtering water outlet pipe or channel is connected with the upper part or lower part of shell, the washing gas inlet pipe is connected with the washing gas distribution device, the downwards flowing washing water discharge pipe or channel is connected with the lower part of shell. The device for biologically filtering fiber bundle is fiber bundle anaerobic biological filtering device, comprising a pressure-type fiber bundle anaerobic biological filter and a gravity-type fiber bundle anaerobic biological filter, where the device mainly comprises a shell, a filtering material component, a water distribution device, a water collecting device, a washing gas distribution device, a filtering water inlet pipe or channel, a filtering water outlet pipe or channel, a washing gas inlet pipe, and a downwards flowing washing water discharge pipe or channel; the filtering material component is mounted in the shell, the washing gas distribution device is arranged below the filtering material component, the water distribution device is arranged above or below the filtering material component, the water collecting device is arranged below or above the filtering material component, the filtering water inlet pipe or channel is connected with the upper part or lower part of shell, the filtering water outlet pipe or channel is connected with the upper part or lower part of shell, the washing gas inlet pipe is connected with the washing gas distribution device, the downwards flowing washing water discharge pipe or channel is connected with the lower part of shell. The device for biologically filtering fiber bundle is fiber bundle denitrifying biological filtering device, comprising a pressure-type fiber bundle denitrifying biological filter and a gravity-type fiber bundle denitrifying biological filter, where the device mainly comprises a shell, a filtering material component, a water distribution device, a water collecting device, a washing gas distribution device, a filtering water inlet pipe or channel, a filtering water outlet pipe or channel, a washing gas inlet pipe, and a downwards flowing washing water discharge pipe or channel; the filtering material component is mounted in the shell, the washing gas distribution device is arranged below the filtering material component, the water distribution device is arranged above or below the filtering material component, the water collecting device is arranged below or above the filtering material component, the filtering water inlet pipe or channel is connected with the upper part or lower part of shell, the filtering water outlet pipe or channel is connected with the upper part or lower part of shell, the washing gas inlet pipe is connected with the washing gas distribution device, the downwards flowing washing water discharge pipe or channel is connected with the lower part of shell. The filtering material component mainly comprises a fiber bundle filter core, an upper filtering plate, a lower filtering plate, an upper connecting piece and a lower connecting piece; the upper end of fiber bundle filter core is connected with the upper filtering plate via the upper connecting piece, the lower end of fiber bundle filter core is connected with the lower filtering plate via the lower connecting piece, the upper and lower connecting pieces are inflexible cables, metal rings, or flexible cable, rubber strips and springs. It comprises pressure-type and gravity-type fiber bundle aeration biological filtering device, fiber bundle anaerobic biological filtering device, fiber bundle denitrifying biological filtering device, where in the fiber bundle biological filtering device, the positions of the upper and lower filtering plates are stationary when filtering and washing, the density of filtering layer composed of fiber bundle filter core is invariable; or the positions of the upper and lower filtering plates are stationary when filtering and washing, the density of filtering layer compressed by filtering water stream when filtering is increased, the density of filtering layer released by washing water stream is reduced; or the upper and lower filtering plates are pushed by hydraulic force or mechanical force to compress the filtering layers when filtering, while the upper and lower filtering plates are pushed by hydraulic force or mechanical force to release the filtering layers when washing. It comprises pressure-type and gravity-type fiber bundle aeration biological filtering device, fiber bundle anaerobic biological filtering device, fiber bundle denitrifying biological filtering device, where according to the water flowing direction in the filtering layer when filtering, there are a downwards flowing mode (namely the water flows through the filtering layer from top to bottom), an upwards flowing mode (namely the water flows through the filtering layer from bottom to top), and a lateral flowing mode (namely the water flows through the filtering layer laterally). It comprises pressure-type and gravity-type fiber bundle aeration biological filtering device, fiber bundle anaerobic biological filtering device, fiber bundle denitrifying biological filtering device, where when the filtering layer is washed, the washing air flows through the filtering layer from bottom to top, the washing water uses the washing water downwards flowing evacuation washing mode, or the washing water downwards flowing charge washing mode, or the washing water downwards flowing and upwards flowing alternative washing mode. The fiber filaments for preparing the fiber bundle filter core can select the materials with rough surface which are in favor of the formation of microbial films, also can select the material with selectivity to the microbes which are easy to form the microbial films with specific function, such as polypropylene fiber, polyester fiber, polyamide fiber, polyvinyl alcohol fiber, functional fiber, functional fiber after surface treatment, and so on.