The population growth leads to a large increase in solid waste production, notably municipal solid waste (MSW). In this context, the mechanical and biological treatment (MBT) arouses as an environmentally friendly strategy to manage MSW. In MBT plants, the organic fraction of MSW is treated, generating biogas and, as by-products, leachate and compost. The compost is mainly used as an agriculture fertilizer. However, the amount of compost produced is higher than its demand, resulting in excess and accumulation. This work deals with the valorization of compost through hydrothermal carbonization (HTC) and pyrolysis, producing respectively the catalysts HC230 and PC800, and their application in the catalytic wet peroxide oxidation (CWPO) of the leachate waters generated in the MBT plant. The catalysts were characterized by elemental analysis and ash content. The CWPO runs of the leachate waters (TOC = 27 g L-1, COD = 60 g L-1 and BOD5 = 23 g L-1) were conducted under the following operating conditions: CCatalyst = 1.8 g L-1; T = 80 ºC; CH2O2 = 85.7 g L-1 and pH from 3.0 to 7.3. At pH = 6 the HC230 achieved a COD abatement of 41 %, enhancing the BOD5/COD ratio to 0.42, shaping the leachate as suitable for further biological treatment.