Seasonal influences of surface water on fouling potential in UF

The link between seasonal changes in the quality of surface waters and the operation of a membrane plant (especially ultrafiltration) regularly causes problems in practice. With a new analysis technique, this research relates the pollution potential of surface water to specific water quality parameters. This is done by determining the change in water quality of three surface waters in different seasons, including the associated pollution potential for ultrafiltration membranes.

Use of ultrafiltration for various purposes

Ultrafiltration (UF) has been in use at PWN for a long time as the final pre-treatment step prior to reverse osmosis (RO). In 2021, Dunea aims to launch a pilot project for producing drinking water from surface water using UF-RO. Robust operations are extremely important in applications such as these. It is known that the quality of surface water varies from season to season and this is reflected at PWN in a seasonal approach to the operation of the ultrafiltration unit. By analysing the fouling potential from different surface waters for the ultrafiltration membranes and comparing them, existing knowledge based on the experience of process technologists and operators can be supplemented with insights based on measured water quality. Ultimately, this knowledge results in practical tools for more stable operations. It is expected that ultrafiltration will play an increasingly prominent role in various processes, such as drinking water production, industrial processes and eliminating particular matter from water prior to deep infiltration.

Systematic analyses and tests for knowledge development

Mapping out the water quality of three surface water bodies at set intervals establishes a picture of the natural variations in these bodies. The selection criteria for the analysis parameters are:

  1. the presumption that these parameters provide relevant information about the fouling potential for ultrafiltration membranes;
  2. most of the parameters are not included in the standard water quality analyses made by the water companies.

The systematic mapping of out these ‘exotic’ water quality parameters over time, in combination with standard water quality analyses made by water companies, will generate a unique dataset with complementary data. With the Flow-Field-Fractionation analysis method it is possible to analyse the particle size distribution on a sub-micrometer scale. Since the typical pore size of ultrafiltration membranes is in this range, these small particles may be relevant for membrane clogging. When these water quality data are linked to observations of the fouling mechanism in a KWR test array, detailed knowledge can be acquired about the underlying mechanisms of ultrafiltration fouling.

Impression of the KWR test array with an ultrafiltration membrane unit (white pressure tube in the centre of the picture)

Sharing insights

The knowledge acquired from this project will be described in a peer-reviewed publication so that it will be widely accessible. In this way, the foundations will be laid for implementation and industrial parties that use ultrafiltration can also be approached for additional research. On the basis of the publication, a report will also be made available to drinking water technologists and source hydrologists at the Dutch drinking water companies. It will include a Dutch executive summary, the publication itself and all the detailed analysis data.