Building construction wastewater treatment device

A rectangular box body of the building construction wastewater treatment device comprises a deposition box, a main box and a scum box, the main box comprises an upper cavity, a middle cavity and a lower cavity, and an up-down dredging mechanism is used for dredging sewage from the upper cavity to the middle cavity and dredging the sewage from the middle cavity to the lower cavity; the back side of the middle cavity is sleeved with a skimmer, the skimmer comprises an upper floating body, the upper floating body comprises a top panel and a plurality of parallel U-shaped pipes, a transverse side hole is formed in the side face of each U-shaped pipe, a transverse receiving groove is formed in the outer end of the upper floating body, the lower portion of the receiving groove is communicated with a scum box through a spring pipe, and a transverse side floating rod is installed at the inner end of the upper floating body; a sedimentation mechanism is arranged below the front side of the middle cavity and is communi