An effluent containing diclofenac sodium is treated using a combination of two processes. The first one is the nanofiltration which allows a concentration of the diclofenac molecule, and the second one is an enzymatic biological degradation through an immobilization of laccase on a carbon felt. Optimized parameters have been determined through the treatment of wastes issued from an Algerian pharmaceutical industrial company. The optimal performance of the nanofiltration, using the NF270 membrane, is obtained with a trans-membranous pressure of 3 bars, a pH equal to 7 and a filtration time of 75 min. A diclofenac concentration of about 3 mg/ml is obtained, and the optimal degradation of diclofenac sodium (95%) occurs at a pH equal to 6, while the laccase concentration is 1 mg/ml in a complete reaction time of 7 h. It is noticed that the yield to the enzymatic degradation of the diclofenac sodium by the laccase is increased by the nanofiltration pretreatment.