Biofouling of membranes

In order to produce safe and healthy water, membrane fi ltration is more often applied in water treatment. Biofouling is the accumulation and growth of micro organisms on the membrane surface. Biofouling leads to an increase in the required feed pressure. Nanofi ltration and reverse osmosis applied in surface water and wastewater treatment result in severe membrane fouling when no pretreatment is installed. One of the fouling mechanisms is biofouling. This may result in a reduced production capacity and/or a frequent membrane cleaning. In all cases the consequence is an increase in costs per amount of produced or treated water.

Biofouling control At present two strategies are used in order to control biofouling in practice.
One is to extend the pretreatment so that nutrients and micro organisms are removed before the membrane fi ltration installation. In this way biofouling may be signifi cantly reduced. However, investment costs are considerable. A cheaper way is cleaning the membranes more often, leading to an increased use of chemicals. This latter approach is not without risks because cleaning is not always successful and biofouling may evolve rather quickly after cleaning.
In addition, the dosage of biocides or disinfectants may be considered. As the first approach is seen in drinking water treatment the second is preferred in process water production. Research approach

The challenge of the research within Wetsus is to develop membrane systems that are less susceptible to biofouling. This may lead to the development of chemical biofouling inhibitors, adapted operational conditions or new membrane module designs. Know-how areas that are used in the research program are, microbiology, molecular biology, surface chemistry and membrane and process technology.