Lots of sludge solidifying materials are used for sludge treatment
but the role of every material is not clear. The orthogonal test is carried out to optimize materials and reveal the influences of Portland solidification materials
alkali solidification materials and clay mineral materials. Test results show that the Portland solidification material and alkali solidification material play a major role in solidified sludge. Basic materials provide early strength for solidified sludge Portland solidification material provides the latter part strength. The clay mineral materials can construct skeleton to form monolithic body.