In the existing process of sewage treatment plant,the grit chamber has the problem of difficult removal of fine inorganic sand particles.Chemical flocculation was used to remove fine sand.The treat-ment effects of inorganic flocculant,synthetic organic polymer flocculant and natural organic polymer floc-culant on simulated wastewater with low and high sand content and raw water of sewage treatment plant were introduced.The result showed that the use of chitosan(CTS)as a single flocculant had a better re-moval effect on the sand content of the supernatant of each wastewater and the suspended solids with a particle size greater than 50 μm.The sand content of the supernatant of simulated wastewater with low and high sand content decreased from 130 mg/L to 31.8 mg/L and 240 mg/L to 31.3 mg/L,respectively,and the removal rate reached 75.5%and 86.9%,respectively.