Neutralization and sedimentation tank is equipped with a decanter, its structure is to be a rubber ring below the fixed a hose, the other end of the hose is connected to the lower part of the pool sewage outlet pipe. Its working principle is the rubber ring floating on the water surface, with the water surface up and down. As the mud and water separation always starts from the water surface, the water surface as long as there is clear liquid formation, clear liquid will flow out of the pool through the hose, so the drainage and mud and water separation is synchronized, do not have to wait for the mud and water are completely separated and then discharged, drainage, saving operating time. However, the operation should pay attention to the mixing of coagulation, to carry the decanter out of the water to prevent the mud into the hose.