Sludge dehydrator

The invention discloses a sludge dehydrator. A filter piece device comprises a plurality of filter piece shafts; the filter piece device is arranged as two layers; a sludge channel is formed between the two layers; mounting heights of filter pieces are gradually increased in a direction from the inlet to the outlet of a dehydration tank; the filter piece shafts close to the inlet are positioned below the inlet; a plurality of filter pieces are fixedly connected with each filter piece shaft; the filter pieces on each filter piece shaft are repeatedly arranged; filter pieces of two adjacent filter piece shafts are arranged in a staggered manner; a filter piece body comprises an inner column part and an outer conical part of which the thickness is smaller than that of the outer column part; two bosses are formed relative to the conical part, of the column part, that is, a boss I and a boss II with a lug respectively. By setting mounting positions of the filter piece shafts, gaps through which dehydrated water pa