In water and wastewater treatment, kaolin is widely studied as an adsorbent of different components, e.g. heavy metal ions (Gupta and Bhattacharyya, 2008). Kaolin also adsorbs lipophilic extractives efficiently (Nylund et al., 2007). Furthermore, kaolin was found to enhance settling in coagulation–flocculation processes. Özacar and Sengil (2003) reported that the addition of kaolin improved the efficiency of phosphate removal and lowered the required alum dose by forming Al(OH)3-kaolinite particles, which adsorbed the phosphate while settling. The benefit of using kaolin as a coagulant aid may also be viable for waters of low turbidity (Shen, 2002).