NOM increase in drinking water reservoirs - relevance for drinking water production

Abstract

In the last 10–15 years in some German drinking water reservoirs an increase in the NOM (natural organic matter) content has occurred. The impact of such a change on the drinking water quality was almost unknown. A research project was carried out at several drinking water reservoirs and water works concerning the change in the NOM quality and the nutrient situation. The results indicate that the NOM increase in the reservoir is predominately caused by an increasing input of high and intermediate molecular weight humic substances from the catchment area into the reservoir. The fractions of the polysaccharides and the high molecular weight humic substances are significantly reduced in the treatment process. In contrast, the elimination rate for the substances with an intermediate and low molecular weight was low. Due to the low elimination rate particularly of the intermediate humic fraction, the NOM content of the treated water increased with the change in the raw water. Furthermore, the BDOC of the treated water increased with the NOM content. For the AOC of the treated water no relationship was found with the NOM content. However, the change of this parameter was affected by the snowmelt and the circulation in the reservoir.

The impact of natural organic matter seasonal variations in drinking water quality

“…Therefore, the changes in NOM composition and concentration over time should be properly controlled by water treatment operators. Also, some authors [8][9][10][11] referred recently an increase of NOM concentration in natural waters on the last decade, as a result of the global warning, intense rain events, and declining acid deposition and rising temperatures.…”

Prediction of DOM removal of low specific UV absorbance surface waters using HPSEC combined with peak fitting

“…Peak 3 may comprise fulvic acids, conjugated unsaturated acids, or keto-acids (Allpike et al, 2005). Peak 4 can be ascribed to building blocks of humic substances (Korth et al, 2004). The low molecular weight fractions (Peaks 5 and 6) are thought to be particularly important in drinking water treatment as these are poorly removed by conventional (coagulation/flocculationsedimentation-filtration) processes and are considered to be bio-available.…”

Assessing Natural Organic Matter Treatability Using High Performance Size Exclusion Chromatography

“…Six peaks were identified in the raw water NOM profile and the MW of the resolved peaks were calculated to be 50 000 Da (Peak 1), 1900 Da (Peak 2), 1200 Da (Peak 3), 800 Da (Peak 4), 500 Da (Peak 5), and 300 Da (Peak 6). These can be associated with the chemical groups of organometallic colloids and biological residues (Peak 1), high molecular weight humic substances (Peak 2), low molecular weight humics (Peaks 3 and 4), building blocks (Peak 5), and low molecular weight acids and nitrogen containing aromatics (Peak 6) (4,21). Figure 2c highlights the region between 100-2000 Da after the successive application of alum.…”