Characterizing DOM and removal by enhanced coagulation: A survey with typical Chinese source waters

Abstract

The properties of dissolved organic matter (DOM) present in 29 source waters and their treatability by enhanced coagulation were investigated. DOM from these waters was investigated based on chemical (hydrophobicity/hydrophilicity) and physical (molecular weight profiles) characteristics in relation to geographical locations of source waters and seasonal variation. Relationships between DOM chemical and physical characteristics, and treatability by coagulants, for DOM removal from drinking water sources, were investigated. Four coagulants, FeCl3, Alum, PACl and HPAC were used in this study. Waters of east China were generally of low DOM content, low SUVA, low percentage content of hydrophobic and high molecular weight DOM resulting in overall low DOM removability, even by enhanced coagulation. Waters of the Songhua River system were found to have relatively higher levels of DOC, hydrophobic, higher molecular weight organics than other river systems. Clear relationships were found between the relative abundances of hydrophobic DOM and higher MW DOM with its removability by coagulation. Percentages of hydrophobic and higher MW organic fractions were found to be better indicators for DOM removability than SUVA value. A general composition map of DOM based on chemical and physical characteristics developed as selection criteria for the four coagulants is proposed.