A nanofiltration (NF) pilot plant was used to recover a contaminated single phase detergent from a cleaning in place system in a yoghurt industrial plant. The main objective of the work was to study the robustness of the NF membrane in real industrial conditions and the efficiency of the permeate as a cleaner. The KOCH MPS-34 membrane (Koch Membrane Systems, USA) was considered. The main operating parameters were previously optimized. Some parameters were selected according to membrane manufacturer's recommendations. After 1800 h of continuous operation, the permeate flux remained constant at around 45 L h(-1) M(-2). The membrane did not require any chemical cleaning. To study the cleaning ability of the permeate, an ultra high temperature (UHT) pilot plant sterilizer was fouled by different foods and then it was cleaned with the NF permeate. The cleanliness of the UHT equipment was checked by means of bioluminescence and cell count methods. The NF permeate was also used to clean an industrial yoghurt filling machine. Very good cleaning efficiency was observed both at pilot plant and industrial scale. (C) 2009 Published by Elsevier Ltd.