Removal of pesticides and other micropollutants with cellulose-acetate, polyamide and ultra-low pressure reverse osmosis membranes

In 1995 several membrane manufacturers started to sell ultra low-pressure reverse osmosis membranes. The specifications of these membranes indicated that they have rejections for dissolved salts comparable to “conventional” composite (polyamide) membranes, while the required feed pressure to realize a specific production capacity is 30–40% less. This article describes the results of a preliminary study on the performance of these new membranes. The results showed that the rejections and productivity as specified by the manufacturers could be reproduced. Also the results of the spiking experiments with organic micropollutants showed that the ultra low pressure membranes have excellent properties to remove these compounds from water. NV PWN Water Supply Company of North Holland selected these membranes for their new water treatment plant Heemskerk when previously it was determined that cellulose acetate membranes were not suitable for the removal of organic micropollutants.