Fouling is the major obstacle in membrane processes applied in water and wastewater treatment. To improve the efficiency, a sustainable membrane cleaning procedure is required as well as the determination of fouling reducing operating conditions. Those depend on many parameters such as membrane surface properties, module design and the characteristics of the water to be treated and reliable analytical methods are essential. This study deals with the removal of foulants from polyethersulfone hollow fibres integrated in drinking and wastewater treatment. Membrane samples were taken from pilot-scale plants and cleaned in bench-scale tests using water, NaOH, H2SO4, NaOCl and H2O2. LC-OCD was used successfully to compare the chemical cleaning solutions, regarding their potential to wash off major foulants. The second aspect of this study is fouling prevention by means of membrane modification. Two modification methods, O-2-Plasma and Corona Treatment, were selected for long-term fouling trials in pilot scale under real operating conditions. After about one month of stable operation, membrane samples were taken and also cleaned with the chemical solutions mentioned above. The results of these experiments show that LC-OCD is not only suitable for describing a cleaning solution's efficiency but also for analysis of the adsorption affinity for foulants of unmodified and modified membranes.