Vibration signals at the early stage of fouling in reverse osmosis system

For the first time, the approach to detect early fouling in reverse osmosis (RO) system by vibration sensor is introduced. The vibration sensor attached to the high-pressure pump collects the vibration data of the RO system, which are affected by foulants accumulated on the membrane surface. Labscale fouling tests were carried out using humic acid in two different approaches: the constant-control test and the variation test, where the former is to maintain the constant test conditions and the latter is to intentionally change some test conditions during the fouling test. The vibration sensor collected three-axis vibration data 8,192 data points per second and the size of the data file is about one gigabyte per hour. The raw data files were trimmed to smaller-sized files (six vibration data-sets per one fouling test) using R version 3.5.1 for the fouling analysis. The vibration data analyses for both the constant-control and variation tests revealed that some of six vibration data-sets could be used to figure out the early fouling even in the test condition in variation, where the early fouling is defined as the period when the average of the vibration data drops by over some percentage compared to that in no-fouling period.