Water shortage has become a global issue and not only a problem relevant to and zones. In the past decade desalination of sea and brackish water has been found to be a technically and economically acceptable solution for water shortage. More recently, desalination of wastewater effluents has also begun to be considered for sustainable water reclamation and reuse. Performance of membrane desalination processes, such as reverse osmosis (RO), is restricted by different fouling and clogging constraints, including inorganic scaling as well as organic fouling and biofouling. Utilization of effluents for desalination introduced to the membrane systems new feed water characteristics with reduced salinity but higher concentration of dissolved organic matter and predominant inorganic ions that are less common in sea water. Phosphate scaling is found to be a main obstacle for effluents desalination, mainly due to the lack of appropriate antiscalants to cope with its precipitation, especially at high recovery rates. This work was aimed to study the chemical coagulation of phosphate from wastewater effluents as a pretreatment for RO desalination. Based on preliminary jar test experiments, sodium aluminate (SAL) at concentrations of 20-30 mg/L, was found as an efficient coagulant for phosphate and turbidity reduction. SAL coagulation was tested either as simultaneous phosphate removal during membrane bioreactor (MBR) treatment or as post-removal of phosphate from secondary effluents from activated sludge process, followed by microfiltration. Both alternative treatments resulted in almost complete phosphate removal (>= 99%). Batch desalination of both kinds of pretreated effluents showed also that calcium carbonate was a second scaling agent upon phosphate removal. The simultaneous MBR-coagulation, which in addition to complete phosphate removal displayed a significant reduction of alkalinity (75%), produced higher quality effluents and reduced the effect of calcium carbonate scaling, as compared to the post-coagulation of secondary effluents. Furthermore, the simultaneous MBR-coagulation process showed no detrimental effects on the MBR membrane performance or on the biological activity and avoided the need of an additional sedimentation or filtration step prior to RO. In conclusion, the MBR-chemical coagulation process seems to be a technically feasible pretreatment of domestic effluents for further desalination.