TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Components: In the vertical soft-membrane anaerobic fermentation device, the four-item separator comprises a central column for supporting the four-item separator, a reaction area, a gas collecting area, a settlement area, a water outlet area, and a residue discharging area around the central column; the reaction area, settlement area, water outlet area, and residue discharging area are located under the liquid level; the reaction area is located at the most bottom of the four-item separator; the residue discharging area and water outlet area are located on the settlement area and distributed from the outside to inside; the gas collecting area is arranged on the liquid level; a gas collecting hole is opened at the upper end of the central column; the gas collecting holes are elongated and around the upper end of the central column; the gas collecting holes have the same form and size and can be distributed symmetrically; the central column is located under the gas collecting holes and set with an air leading-out pipe, a water leading-out pipe, and a residue leading-out pipe extended from the anaerobic fermentation reactor; the upper side of the central column on the reaction area is connected with an air stopping plate; the air stopping plate is fixed by an angle steel frame; the air stopping plate is an inverted conical structure with an opening; a guiding plate is installed on the air stopping plate around the central column; the space of a three-dimensional structure of the guiding plate is the settlement area; a space is kept between the guiding plate and air stopping plate to take as the inlet of the settlement area; the central column is further connected with a reflection hammer for reflowing the sludge; the reflection hammer is located under the air stopping plate and has the space with the air stopping plate; the reflection hammer is the conical structure; a residue discharging groove and a water outlet groove are arranged on the top of the guiding plate from the outside to inside; a water channel is installed between the residue discharging groove and water outlet groove; the area inside the residue discharging groove is the residue discharging area, while the area inside the water outlet groove is the water outlet area; the bottom of the water outlet groove is connected with the central column by a water outlet pipe; and the bottom of the residue discharging groove is connected with the central column by two residue discharging pipes. The central column comprises two sealed upper and lower pipes connected by a flange; where the upper and lower pipes are separate pipes; the upper pipe comprises an air outlet section and a water outlet section from the top to bottom; the bottom of the air outlet section is led out from the air leading-out pipe, while the bottom of the water outlet section is led out from the water leading-out pipe; the lower pipe is the residue discharging section; a sludge discharging section is arranged at the bottom of the lower pipe; a sludge discharging hopper is further arranged at the bottom of the sludge discharging section; the bottom of the residue discharging section is led out from the residue leading-out pipe, while the bottom of the sludge discharging hopper is led out from the sludge leading-out pipe; a triangular overflow wall is arranged in the water outlet area; the triangular overflow wall is located on the top of the outer wall of the water outlet groove; and the inner wall of the sludge discharging groove is higher than the water outlet level. The multi-point self-rotating water distributor comprises a water inlet pipe, two water distribution pipes, and a water distribution cover; where a nozzle is opened on the water distribution pipe; the water inlet pipe is fixed and connected through with the central column; the water distribution cover is rotationally sleeved outside the central column; an eccentric annular water distribution area is formed between the water distribution cover and central column; two water distribution pipes are arranged at both sides of the water distribution cover symmetrically and connected through with the water distribution cover; the two water distribution pipes and water distribution cover are formed into a rotary body; a spraying hole is opened at one side of the two water distribution pipes along the vertical section of the water distribution pipe; the spraying holes on the left and right water distribution pipes are opposite to each other; the spraying hole on any water distribution pipe is enlarged from the rotating centre to the outside; the space between adjacent two holes is shrunk; and the tail end of the water distribution pipe is bent downwardly and can be hooked but not blocked. The biogas stirring unit comprises a biogas stirring pipe inside the anaerobic fermentation reactor, a gas purifying unit, a gas storing unit, a pressure increasing unit, and a self-control system outside the anaerobic fermentation reactor; where the input end of the gas purifying unit is connected with the gas collecting area of the anaerobic fermentation tank, while the output end is connected with the gas storing unit, pressure increasing unit and biogas stirring pipe; and the self-control system is connected with the pressure increasing unit and biogas stirring pipe.