Sedimentation: after the addition of coagulant and the mixture reaction, colloid impurities in water coagulate into larger alum grains, which are further removed from the sedimentation tank.

• （二）沉淀：原水加混凝剂后，经过混合反应，水中胶体杂质凝聚成较大的矾花颗粒，进一步在沉淀池中去除。