The wastewater from a wood-processing factory is characterized by a high GOD, chlorides and nitrogen content. Various treatment processes were applied to treat this wastewater in pilot-scale units. By applying one-stage denitrification-activated sludge biological treatment it was not possible to remove nitrogen. Nitrification was inhibited by wastewater compounds. By applying a second stage of a nitrification biofilter it was possible to have a high degree of nitrification. The denitrification was complete. With biological methods the reduction of COD, and NO3--N and NH4+-N concentrations to acceptable values was not achievable. Physical-Chemical methods as H2O2/UV, electrolysis and ozonation were used as post-treatment of effluents from the biological system. Radical degradation, initiated by the powerful hydroxyl radicals which are generated from H2O2 by UV activation, is used for wastewater post-treatment. The combination of H2O2/UV was not suitable for post-treatment of this wastewater. With electrolysis, NH4+-N and COD removal can be complete. The total amount of ammonia and organic nitrogen converted to nitrate nitrogen for current density of 1.15Adm(-2) and energy consumption of 71.6 kWhm(-3) was 0.35 gdm(-3). Further biological denitrification is required for NO3--N removal to permitted values. Energy consumption for the elimination of 1kg COD was 40.4kWh and 35.8kWh for current densities of 0.7Adm(-2) and 1.15Adm(-2) respectively. The energy required to reach the Limit value of COD equal to 150 mgdm(-3) for current density of 1.15Adm(-2) was 71.6kWhm(-3). With ozonation, the COD removal can be complete. Further biological nitrification-denitrification is required to remove NH4+-N and NO3--N to permitted values. At pH 7.0, in order to reach the limit value of COD equal to 150 mgdm(-3), specific ozone dose was 6.0 g per g of COD removed and the total amount of ammonia and organic nitrogen converted to nitrate nitrogen was 0.25 gdm(-3) The total equivalent energy required is estimated to be 75.0kWhm(-3).