Based on quantitative and qualitative characteristics of reject waters (RWC) generated during dewatering of digested sewage sludge on centrifuges in conventional WWTP and municipal landfill leachate (LL), the pilot constructed wetlands for treatment of both types wastewater were designed and built. In the paper the conception, design and assumed treatment efficiencies of the pilot plants are presented. The water balance of the pilot treatment wetlands is presented and potential implications of water losses through evapotranspiration in case of treating wastewater with high concentrations of pollutants are discussed. Preliminary treatment results, obtained during the start-up period, showed good treatment effectiveness of BOD (74% for RWC and 84.5% for LL), while the effectiveness of ammonia nitrogen removal was below 20% for LL and from 48 to 59% for RWC.