Study On The Comprehensive Fractional Characteristics Of DOM In Luan River And Its Removal By Coagulation

Dissolved organic matter (DOM), the potential carrier of micro-pollutant and primary precursors of disinfection by-products, may also become micro-pollutant itself. Therefore, it is important to characterize the DOM for minimizing it in drinking water.The DOM from Luan river, a typical source water in north of China, was fractionated and characterized by resin adsorption (RA) and ultrafiltration (UF) techniques.The chemical fractions distribution of the DOM is that the hydrophobic acids (HoA) and the hydrophilic matter (HiM) is richer than others across all the sampling seasons. The physical (size)distribution of the DOM is that the fractions with molecular weight below1kDa and of which the range between 3kDa and 10kDa are dominated fractions during most of the sampling period. Al₂(SO₄)₃, FeCl₃, PAC produced by plant was choosed as coagulant to research the DOM removal mechanism by coagulation process. The results showed that HoA and the molecular weight between 3kDa and 10kDa fractions are easy to be removed. Contrarily, the DOM of which the molecular weight between 10kDa and 30kDa has a lower removal efficiency. It could be concluded that the chemical property of DOM is more important than physical property in coagulation. Especialy, we found that the molecular weight of most HoA is above 10kDa when each component of DOM was fractionated by UF. Organics with molecular weight below 1kDa are mostly HiM, and then HoA and WHoA. This makes it possible that part of organics below 1kDa are removed by coagulation in specific conditions. Moreover, HoA can be divided into two parts according to its molecular weight and removal efficiency, of which one part molecular weight between 3kDa and 10kDa could be easily removed and the other between 10kDa and 30kDa is contrary. It indicates that there are some other factors possibly interfering the coagulation of DOM.