Removal of dissolved organic matter from algae-polluted surface water by coagulation

Dissolved organic matter (DOM) is ubiquitous in the algae-polluted surface water and it possesses a potential threat to drinking water safety. It is important to investigate the removal efficiency of DOM by coagulation. Polyaluminum chloride a widely used coagulant is applied in the treatment of DOM derived from Minzhu Lake in Chongqing of China. Based on the analysis of dissolved organic carbon, UV254, specific ultraviolet absorbance, and fluorescence excitation-emission matrix spectroscopy, the results indicate that the small proportion of DOM, such as aromatic-like organic substances, is removed with algae and other colloid particles via coagulation, but most of DOM, such as he tryptophan-like and fulvic-like organic substances, is remained in the treated water. Co-flocculation, bridging, adsorption, and entrapment would be the main removal mechanisms of DOM. DOM removal will be slightly improved through optimizing pH of surface water and using a composite coagulant.