Device for discharging toxic gas after sludge treatment

The utility model belongs to the technical field of sewage treatment equipment, and particularly relates to a device for discharging toxic gas after sludge treatment, which comprises a gas inlet box and a filter box, the filter box is mounted on the gas inlet box, and a first annular plate, a second annular plate and a third annular plate are sequentially mounted at the bottom in the filter box from inside to outside. The radiuses of the first annular plate, the second annular plate and the third annular plate are sequentially increased, the first annular plate, the second annular plate and the third annular plate are coaxially distributed, a center groove, a first annular groove, a second annular groove and a third annular groove are sequentially formed by the first annular plate, the second annular plate and the bottom in the box body from inside to outside, and a filter screen is arranged at the bottom of the third annular groove. According to the waste gas purification device disclosed by the utility mode