P. tsukubaensis is a yeast-like microorganism that synthesized the biosurfactant mannosylerythritol lipids-B (MEL-B). Production cost can be one of the drawbacks of biosurfactants production. Therefore the development of efficient and cost effective purification strategies and the use of by-products in the culture medium could serve as important strategies to reduce overall process cost. The aim of this work was to evaluate the production of MEL using cassava wastewater, a hydrophilic medium composed of a low-cost substrate which is a by-product of cassava processing, followed by foam fractionation and ultra filtration of MEL. Cassava wastewater proved to be a feasible culture medium for P. tsukubaensis and MELB production as the yield (1.26 g L-1) was similar to that reported by others using water-soluble carbon sources (up to 2 g L-1). Interestingly ultrafiltration with 100 kDa MWCO membranes (using 20 mL centrifugal devices) led to the purification of MEL-B in one step since approximate to 80% of MEL was recovered, while more than 95% of proteins were found in the permeate. The scale up of the ultrafiltration (up to 500 mL) using a cross flow filtration unit led to very similar results. Overall the ultrafiltration led to a threefold increase in MEL purity in terms of protein (at both scales). The chemical characterization by NMR confirmed the production of MEL-B homologue and also the production of a second stereoisomer approximate to 9%, while the CG-MS and MALDI-TOFMS analysis confirmed the main fatty acids within the structure of MEL-B (C8:0 and 12:0 and C8:0 and C14:1). Therefore, the process developed here was found to be a good alternative to the conventional production of MEL which uses synthetic culture medium, solvent extraction (ethyl acetate) and column chromatography (silica) for its purification. (C) 2017 Elsevier B.V. All rights reserved.