Fouling Resistant RO Membranes in Municipal Water Reuse Applications

In several regions on earth, water reuse is becoming increasingly important due to the scarcity of fresh water. Reasons for water shortage can be related either to natural environment and hanging climate or to the general increase on water demand in certain regions. Especially urbanization and rapid population growth combined with industrialization and increased living standards can create a large imbalance between water supply and demand. Dow Water & Separation Technologies is focused on facing the challenge by offering a variety of solutions for state-of-the-art water treatment. Reverse Osmosis (RO) membrane technology has been touted as suitable, cost-effective technology to achieve the very high quality requirements of the reused water.Although membrane technologies have been used for several years in water reuse (WRU) activities, there are still opportunities for improved performance. The essential problem that has to be solved is the membrane's tendency towards fouling. Fouling prevention or minimization leads to savings in operational costs due lower required operating feed pressure and lower cleaning frequency of the membrane system. In the long run, this will lead to longer membrane life time, thus lowering the costs of membrane replacements. In recent years various technologies have been proposed to tackle the fouling issue. Among these, upgraded pretreatment, novel membrane chemistry and new RO design concepts are some of the most interesting ones.This paper presents an approach, based on new RO membrane chemistry, resulting in higher resistance against fouling when compared to conventional membranes. Dow Water & Separation Technologies has recently developed a new membrane, BW30XFR, which offers the benefits of the conventional FILMTECTM membranes (robust membrane with a long life span, highest pH range for cleaning etc.) with the additional benefit of having improved resistance against common fouling types. Laboratory tests have indicated better resistance against common fouling sources such as biological fouling, oil and surfactant fouling and particulate fouling. In real world situations fouling is often a combination of all types of fouling and a measure of fouling in multiple streams is needed to evaluate membrane fouling. This can be best achieved by conducting pilot trials with natural feed waters.In this paper we show results of three field trials. The first trial shows the improved membrane performance compared to Dow's BW30 membrane, the second trial shows stable operation at waste water feed, with a high fouling potential and the last trial compares the new BW30XFR membrane to three equivalent membranes from competitors', showing the clear benefit of the BW30XFR membrane when exposed to waste water.