Method for distinguishing between abiotic organic and biological fouling of reverse osmosis elements used to treat wastewater

Fouling is one of the issues that is hindering the long-term performance of reverse osmosis systems. The aim of this study is to selectively quantify the extracellular polymeric substances (EPS) from the organic substances present in samples of autopsied elements. Samples were collected from elements used to treat wastewater, operated under two different fouling scenarios. In the first, fouling was mainly organic while in the second, biofouling was promoted by dosing nutrients. The overall percentage of carbohydrates and proteins as organic foulants was quantified. In the first test, the percentage of the foulant consisting of EPS was only 19–34% vs. approximately 100% in the biofouling scenario. At the same time, the increase in the feed-concentrate pressure for the elements after the first test was only 50%, but more than 500% after the second test. This confirms that quantifying the EPS percentage on the foulant can be useful for determining the extent of biofouling versus abiotic organic fouling.