Optimizing Direct Contact Membrane Distillation by RSM for Water Reclamation from Effluent of the RO Unit at Esfahan Refinery

Considering the challenges faced and emphases being put in the last two decades on the water consumption at Esfahan Oil Refining Company (EORC), substantial efforts were made on its optimization and recovery of effluent from various unit operations. The effluent re-use from the Reverse Osmosis (RO) unit, collected at the evaporating pools was considered in this research, using membrane distillation, as a modern desalination approach to recover water. In this study, RSM modelling was employed for optimization and prediction of membrane distillation operating conditions on the brackish effluent output from the RO unit at EORC. Tests were carried out on a flat module with 80cm2 effective surface area using micro porous commercial PTFE membranes based on PP. Effects of three parameters of feed temperature, and flow rate as well as permeate temperature on the permeate flux were investigated using the Design Expert software. Software modelling results indicated that feed temperature had the largest influence in increasing the permeate flux (almost twice the effect of permeate temperature and feed flow rate). The maximum optimized permeate flux in the test range investigated was 59.67 L/m2h with 0.9570 desirability at feed temperature of 70°C, permeate temperature of 15°C and feed flow rate of 2L/min. This research showed that direct contact membrane distillation (DCMD) could successfully be employed for water recovery from the RO outlet effluent at EORC. Optimization of operating condition at Esfahan climatic condition can be achieved using software modelling.