NOVELTY - Microaeration biofilter comprises first filter (20) and second filter (21), sewage inlet pipe (1), filtration chamber (18) installed inside the first filter, and parallel bamboo tubes (11) vertically arranged in the filtration chamber. Biochemical bed (10) which can be moved out and in is arranged in the second filter. Massive filter material is put in the biochemical bed. The second filter below the biochemical bed is provided with aerator (9). The second filter above the biochemical bed is provided with drain pipe (6). Fluid guiding cavity (5) is installed in the second filter.    USE - Microaeration biofilter for treating organic wastewater.    ADVANTAGE - Time of biochemical reaction is shortened, device investment is decreased and operation technique is simplified.    DETAILED DESCRIPTION - Microaeration biofilter comprises first filter (20) and second filter (21), sewage inlet pipe (1) arranged on the first filter, filtration chamber (18) installed inside the first filter, and parallel bamboo tubes (11) vertically arranged in the filtration chamber. Bottom end of each bamboo tube is communicated with lower part of the first filter, and top end of each bamboo tube is communicated with overflow chute (3) located on the first filter. Biochemical bed (10) which can be moved out and in is arranged in the second filter. Massive filter material is put in the biochemical bed. The second filter below the biochemical bed is provided with aerator (9). The second filter above the biochemical bed is provided with drain pipe (6). Fluid guiding cavity (5) used for guiding the sewage into the bottom of the biochemical bed is installed in the second filter. The fluid guiding cavity is communicated with overflow chute. The massive filtration material comprises moso bamboo with the weight less than 1, wood, shell, kieselguhr, active carbon and/or plastic ball.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of microaeration biofilter.    Sewage inlet pipe (1)    Overflow chute (3)    Fluid guiding cavity (5)    Drain pipe (6)    Aerator (9)    Biochemical bed (10)    Bamboo tubes (11)    Filtration chamber (18)    First filter (20)    Second filter (21)