TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The first reverse mixing door and the second reverse mixing door respectively comprise a first stand plate, a second stand plate, a first upper plate, a second upper plate, a first lower plate and a second lower plate. The first stand plate and the second stand plate are parallely arranged in left and right. The first upper plate and the first lower plate are parallely arranged in front and back. The first stand plate and the second stand plate are fixedly connected via the first upper plate and the first lower plate. The upper edge of the first upper plate aligns to the upper edge of the first stand plate. The lower edge of the first upper plate is higher than the first stand plate. The lower edge of the first upper plate is higher than the first stand plate. The lower edge of the first lower plate aligns with the first stand plate. The upper edge of the first lower plate is lower than the first stand plate. The first stand plate is fixedly connected with the corresponding separation wall. The second stand plate and one side wall of the reactor main body are arranged side by side. The second lower plate and the second upper plate are parallely arranged front and back. The second stand plate and one side wall of the reactor main body are fixedly connected via the second lower plate and the second upper plate. The upper edge of the second upper plate aligns with the second stand plate. The lower edge of the second upper plate is higher than the second stand plate. The lower edge of the second lower plate aligns with the second stand plate. The upper edge of the second lower plate is lower than the second stand plate. The upper edges of the first stand plate and the second stand plate align with the upper edges of the separation wall and the reactor main body. The upper edges of the first stand plate and the second stand plate are fixedly installed on the bottom plate of the reactor main body. The third reverse mixing door comprises a first connecting plate, a second connecting plate, a third stand plate, a fourth stand plate, a fifth stand plate, a third upper plate, a fourth upper plate, a third lower plate and a fourth lower plate. The third stand plate, fourth stand plate and fifth stand plate are parallely arranged between the separation wall and the side wall of the reactor main body from back to front. The third stand plate is fixedly connected with the corresponding separation wall via the first connecting plate. The fifth stand plate is fixedly connected with one side wall of the reactor main body via the second connecting plate. The third stand plate and the fourth stand plate are fixedly connected via the third upper plate and the third lower plate. The upper edge of the third upper plate aligns with the third stand plate. The lower edge of the third upper plate is higher than the third stand plate. The lower edge of the third lower plate aligns with the third stand plate. The upper edge of the third lower plate is lower than the third stand plate. The fourth upper plate and the fourth lower plate are parallely arranged in left and right. The fourth stand plate and the fifth stand plate are fixedly connected via the fourth upper plate and the fourth lower plate. The upper edge of the fourth upper plate aligns with the fourth stand plate. The lower edge of the fourth upper plate is higher than the fourth stand plate. The lower edge of the fourth lower plate aligns with the fourth stand plate. The upper edge of the fourth lower plate is lower than the fourth stand plate. The first connecting plate, upper edges of the first connecting plate, second connecting plate, third stand plate, fourth stand plate and fifth stand plate aligns with the upper edge of the separation wall and the upper edge of the reactor main body. The lower edges of the first connecting plate, second connecting plate, third stand plate, fourth stand plate and fifth stand plate are fixedly connected on the bottom plate of the reactor main body. The gas-liquid flowing device comprises a flowing device main body, a flow channel, a filter body and two water-distributing plates. The two water-distributing plates are parallely arranged in the flowing device main body up and down. The filter body is filled between the two water-distributing plates. The flow channel is fixedly installed on the lower end face of the flowing device main body and the gas-liquid flowing device is fixedly installed on the reactor main body via the flowing device main body. The filter body is made of gravel. The reactor main body top comprises a rubbery soft top and two concrete hard tops. The rubbery soft top is arranged between the two concrete hard tops. The first reaction pool and the third reaction pool are covered with a concrete hard top respectively. The rubbery soft top is covered on the second reaction pool. The upper end faces of the two separation walls are provided with a vent groove for feeding the biogas generated by the first reaction pool and the third reaction pool into the space between the second reaction pool and the rubbery soft top. The rubbery soft top is made of an ethylene propylene diene monomer. The device further comprises a cobble layer covered on the outer surface of the reactor main body. The cobble layer is a combination of stones, sand and saw dusts. The thickness of the cobble layer at the bottom of the reactor main body is 30-50 cm.