Fig. 3 (b) shows the UV254, CODMn and DOC removal efficiencies of TiCl4 and PACl at different pH. The removal patterns of UV ,COD and DOC using TiCl and PACl at the tested range of pH were similar. For TiCl, maximum UV ,COD and DOC removal were 74.1%,51.5% and 78.4% at pH 8. Further increase of pH achieved decreased to about 33.3%,38.2% and 39.4%, respectively, at pH 11. Comparatively, TiCl was observed to have higher DOC removal than UV and COD. Fig 4 shows that the optimal coagulation pH corresponded with the condition where the zeta potential of particles was very close to zero (+0.03 mV). This implies that the charge neutralization plays an important role during coagulation process. With regard to PACl, the result in Fig.3 (b) show that the removal of UV,COD increased with the initial increase of pH and achieved the highest removal at pH 6 and subsequently decrease with further increase of pH. The optimal removal of organic matter was achieved at pH 6. This is in a good agreement with previous study [32].