Selection of anionic exchange resins for removal of natural organic matter (NOM) fractions.

Early elimination of natural organic matter (NOM) by ion exchange (IEX) in water treatment is expected to improve subsequent water treatment processes and the final drinking water quality. Nine anionic exchange resins were investigated to remove NOM and specific NOM fractions determined by liquid chromatography in combination with organic carbon detection (LC-OCD) and fluorescence excitation-emission matrices (EEM). Breakthrough of NOM was predicted by model calculations using Freundlich isotherms and IEX rate experiments. The time to breakthrough varied from 4 to 38 days. Removal of specific NOM fractions proved to vary considerably for the different types of IEX resins, ranging from 1% to almost 60%. The removal of NOM fractions, specifically humic substances, increased with an increase in water content of the investigated IEX resins and with a decrease in resin size. The best-performing IEX resins consisted of the smallest resins and/or those with the highest water content. The worst-performing IEX resins reflected the highest exchanging capacities and the lowest water contents.

The membrane fouling simulator: a suitable tool for prediction and characterisation of membrane fouling.

A new tool--the Membrane Fouling Simulator (MFS)--is developed to measure membrane fouling (pressure drop increase) in a small and simple system, representative for spiral wound membranes applied in water treatment. With the MFS, fouling development can be monitored systematically by (i) pressure drop, (ii) in situ and non-destructive (visual) observations using the sight glass and (iii) analysis of coupons sampled from the membrane sheet in the MFS. A comparison study of the MFS with spiral wound membrane elements (test rigs and a full scale installation) showed the same fouling. The MFS provided reproducible data. The small size and low water and chemical use of the MFS facilitate to perform systematic parallel studies. With the MFS, fouling of membranes applied in water treatment can be characterised.