Background & Aims of the Study: Recently membranes have been widely used in Mena region especially Iran, due to purify the brackish water and solved the water scarcity. Qom province is located in desert like area of Iran and faced to water shortage. The aim of this study is evaluation of the best method of membrane process in the ground water wells of Qom province, Iran, in 2016. Materials and Methods: This descriptive cross sectional survey carried out at the central laboratory of water and Wastewater Company of Qom. The experimental tests were done in order to evaluate the treatment process of 12 physical-chemical water parameters such as: salinity, pH, TDS, EC, TH and Mg, Ca, SO 4 , Na, K, Cl and temperature, which performed by NF.RO Hybrid NF/RO desalination membranes installed on water desalination plant with pretreatment devices. All laboratory tested carried out undertaken of standard method of water and waste water 2012 with P value <0.05 .Then, the result of experimental tests weighted and ranked by AHP method and expert choice software11. Results: The evaluation of experimental tests showed the brackish water purified by NF membrane in ranges of 21.5%-95.5%, RO membrane 43%-97.2% and Hybrid NF/RO 63.95%-98.4%. Afterward the analyses of membrane performance carried out by weighting and scoring with AHP method and expert choice .The outcomes of the AHP revealed that Hybrid process obtained the best preference of membrane desalination by weight 0.449 .Then, RO by weight of 0.308, got second turn and NF, by weight of 0.243, followed by RO. It is considerable that the quality of brackish ground water treatment by Hybrid process has the highest function as the highest weight.
Conclusion:The experimental tests were done by performed housing desalination plant with three membranes NF, RO, Hybrid NF/RO. The results showed the Hybrid membrane has the highest function as treatment and removal of 12 water parameters. Also, the result of hierarchy process with an expert choice and AHP method confirmed the best desalination process belongs to Hybrid membrane.