This study investigates the simultaneous treatment of different real produced water streams using forward
osmosis-membrane distillation (FO-MD) hybrid system. The water–oil separator outlet (WO) was used simul-
taneously as FO draw solution (DS) and MD feed solution (FS). The FO process generated stable average fluxes of
13.6 L/m2/h and 15.8 L/m2/h with desalter effluent (DE) and wash water (WW) as FO feed streams, while MD
produced 13.2 L/m2/h and 11 L/m2/h, respectively. Monovalent ions induced internal concentration polariza-
tion and CaSiO3 colloidal scaling on the support layer reduced the FO flux. Further FO flux reduction was caused
by CaSO4 and NaCl crystals on the active layer. Moreover, CaSO4 created partial pore covering while oil and
grease depicted pore clogging of the MD membrane, which decreased the MD flux. Volatile fatty acids and
organic nano pollutants reached MD permeate and FO FS. Humic acid scaling was fully recovered by ethyl-
enediaminetetraacetic acid by masking calcium ions and reducing the pH. No membrane wetting was observed in
the system. No bacteria were found in real streams as analyzed with Epifluorescence microscopy, eliminating the
potential of microbial fouling. The hybrid system showed > 93 % removal of oil, inorganics and organics, making
the permeate quality excellent for re-injection or industrial reuse. The FS streams were concentrated by 77–84 %
resulting in smaller disposal volumes. No utilization of chemicals and water makes this hybrid concept practical
and sustainable. The findings of this study can serve as design criteria for future onsite pilot plant applications
