A modeling and simulation study along with economic analysis was carried out for arsenic separation by a membrane-integrated hybrid treatment system that consisted of an oxidation unit integrated with a cross flow nanofiltration membrane module. About 96-98% arsenic removal efficiency was achieved in the membrane module after pre-oxidation. When pH was increased from 3 to 10, arsenic rejections reached as high as 98.5%. The dynamic mathematical model developed for the system used Extended Nernst-Plank equation as the basis for the nanofiltration model. A linearized approach in modeling was adopted that reduced the computation time significantly. Model predictions were found to corroborate very well with the experimental findings as indicated in the small relative errors of the order of only 0.003 and Willmott d-index of 0.993 reflecting very good model performance. Thus the developed model is expected to be very useful in scale-up, design and optimization of the membrane-integrated hybrid treatment system for removal of arsenic from contaminated groundwater.