The use of physical/chemical processes and the application of contact-assisted activated sludge process have been investigated. These tests were carried out in a 310-m(3)/d plant. The analysis of plant performance was based on the quality of treated water produced and the cost of the plant relative to each configuration. The results show that a two stage dissolved air flotation units combined with contact-assisted activated sludge process would enable the plant to meet the discharge standards proposed by the Kuwait Environmental Protection Authority. Fat/oil/grease is reduced by about 84 %; suspended solids are reduced by about 72% across the 1st stage DAF. The contact-assisted activated sludge reduces the final effluent COD to less than 250 mg/L. Finally, substantial amounts of total suspended solids are removed during the 2nd stage DAF process. The global cost analysis for a well-designed and properly operated contact-assisted activated sludge process is presented in this paper.