Water treatment using MIEX®DOC/ultrafiltration process

The objective of the study was to compare the treatment efficiency obtained with the MIEX®DOC process and ultrafiltration as well as to investigate the effect of MIEX®DOC water pretreatment on the performance of ultrafiltration membranes. The influence of MIEX® resin dose and membrane cut-off on natural organic matter removal (NOM) efficiency was analyzed. Based on obtained results it might be stated that magnetic ion-exchange resin MIEX® is very effective in NOM separation from natural waters. For resin dose equal to 15 mL/L the reduction of abs 254 nm reached 90% for model solution and 80% for Odra river water. For UF membranes, their cut-off significantly influenced the NOM retention coefficient. The use of MIEX®DOC, process prior to ultrafiltration, increased permeate quality, especially for high MWCO membranes. Even very low MIEX® resin doses, significantly improved final water quality.

The organic matter removal efficiency (reduction of colour and UV254) with the use of ultrafiltration membranes of different cut-off is shown in Fig. 3. For the UF membrane of cut-off equal to 5 kDa Rcolour amounted to 79.3 and 52.5% for model solution and Odra river water respectively. With the increase of membrane cut-off, the retention of NOM decreased and for 30 kDa membrane Rcolour reached values of 35.0% for model solution and 31.3% for Odra river water. Higher values of Rcolour over Rabs 254 result from size exclusion mechanism of ultrafiltration membrane separation. NOM fractions responsible for colour intensity has generally large molecular weight, and are better retained by membrane that smaller fractions with aromatic rings in their structure (indicated by abs 254 nm).