Influence of physical-chemical characteristics of natural organic matter (NOM) on coagulation properties: An analysis of eight Norwegian water sources

Coagulation behaviour of eight natural water samples containing NOM is inve stigated to identify parameters influencing the process. A strong correlati on between colour, DOC and UV-abs. was shown, regardless of the source and fractions. Coagulation of original water samples is discussed using analyti cal parameters in raw water and various molecular weight fractions. Over 40 % of colour is given by NOM fractions with molecular weight cut-off(MWCO) < 10kD with one exception. About 1/3 of the colour is given by MWCO fraction s > 50 kD for all waters. Larger NOM molecules required less coagulants per removed colour unit compared with smaller NOM molecules. Bulk NOM paramete rs and colloidal charges were identified to be the most descriptive paramet ers of the samples and the coagulability. The possibility to predict the op timum coagulant dosage for given process conditions is illustrated. (C) 199 9 Published by Elsevier Science Ltd on behalf of the IAWQ. All rights reser ved.