In this thesis, five kinds of sludge collected from different sources were conditioned chemically by dosing polyaluminium chloride (PAC), polymeric ferric sulfate (PFS), chitosan (CTS) and rectorite. The optimal dosages of those materials were obtained based on the measurement of specific resistance to filtration (SRF). A composite coagulant was developed and its optimal ratio of components was also determined. The effects of the bound water and Zeta potential(ZP) of sludge on SRF were discussed and the rel...