Synthetic wastewater containing 0-10% salt (NaCl) was treated in a rotating biodisc unit operating in continuous mode. Salt tolerant, Halobacter halobium-supplemented activated sludge culture was used ill order to alleviate salt inactivation effects. Effects of important process variables suck as inclusion of Halobacter, A/Q ratio, COD lending rate, and salt concentration on the COD removal rate and efficiency, were investigated. The system performance improved with increasing A/Q ratio; however, it decreased with increasing COD lending rate and salt content. The liquid phase Ic as aerated in order to keep suspended cells active at feed COD concentrations of 5,000 mg l(-1). A mathematical model was developed to describe the system behavior Model parameters were determined by using the experimental data. Salt inhibition was Sound to be significant for salt contents larger then 3% NaCl.