Pilot-scale Upflow Pelletizer for THM Precursor and Turbidity Removal from Raw Water for Water Supply Production

Abstract

In order to reduce trihalomethane (THM) formation in drinking water treatment, the presence of THM precursors in raw water must be minimized. This pilot-scale study was carried out using raw water from Pra-Pa canal to assess the effectiveness of upflow pelletization process in THM precursors removal. The experiments were conducted with different dosages of coagulant (Polyaluminium chloride) and coagulant aid (nonionic polymer). Process effectiveness was
evaluated in terms of effluent turbidity, THM precursors removal and characteristics of pellet formation. Two parameters were used as indicators for THM precursors: total organic carbon (TOC) and ultraviolet absorbance at 260 nm (UV260). From this research, PACl and nonionic polymer dosages of 5 and 0.2
mg/L, respectively were suggested to be used in the system operation since removal efficiencies up to 48.6% for TOC, 78.9% for UV260 and 98.0 % for turbidity could be achieved. The diameter and settling velocity of pellets formed in this study were 0.19-0.33 mm and 19.66-53.96 m/h, respectively.