Abstract
Today around 160 small and medium-sized waterworks in Norway are using membranes for treatment of raw water with high content of natural organic material (NOM). Most of the membrane-based waterworks use nanofiltration (NF) as treatment process. The first NF facilities were commissioned late 1980s, and it is anticipated that significant experience and knowledge on operation of membrane facilities exists. A survey has been conducted with the objective of mapping the status regarding design and operation of membrane facilities. The key findings from 18 plants answering the survey demonstrate that membranes provide efficient NOM removal, and that most plants operate with few reported challenges. However, some facilities suffer from performance decline due to fouling. Nevertheless, given optimal process design and operation, the use of membranes is considered well suited for treatment of coloured surface water for drinking water production.